/*
 * Copyright (C) 2009      Citrix Ltd.
 * Author Vincent Hanquez <vincent.hanquez@eu.citrix.com>
 * Author Stefano Stabellini <stefano.stabellini@eu.citrix.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; version 2.1 only. with the special
 * exception on linking described in file LICENSE.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 */

#ifndef LIBXL_INTERNAL_H
#define LIBXL_INTERNAL_H

#include "libxl_osdeps.h" /* must come before any other headers */

#include "xentoolcore_internal.h"

#include "libxl_sr_stream_format.h"

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <pthread.h>
#include <signal.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>

#include <sys/mman.h>
#include <poll.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/file.h>
#include <sys/ioctl.h>

#include <xenevtchn.h>
#include <xenstore.h>
#define XC_WANT_COMPAT_MAP_FOREIGN_API
#include <xenctrl.h>
#include <xenguest.h>
#include <xenhypfs.h>
#include <xenctrl_dom.h>

#include <xen-tools/libs.h>

#include "xentoollog.h"

#include <xen/io/xenbus.h>

#ifdef LIBXL_H
# error libxl.h should be included via libxl_internal.h, not separately
#endif
#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
# define LIBXL_EXTERNAL_CALLERS_ONLY \
    __attribute__((warning("may not be called from within libxl")))
#endif

#include "libxl.h"
#include "_paths.h"
#include "_libxl_save_msgs_callout.h"

#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)
#define _hidden __attribute__((visibility("hidden")))
#define _protected __attribute__((visibility("protected")))
#else
#define _hidden
#define _protected
#endif

#include "flexarray.h"
#include "libxl_utils.h"

#include "libxl_json.h"

#include "_libxl_types_internal.h"
#include "_libxl_types_internal_json.h"

#define LIBXL_INIT_TIMEOUT 10
#define LIBXL_DESTROY_TIMEOUT 10
#define LIBXL_HOTPLUG_TIMEOUT 40
/* QEMU may be slow to load and start due to a bug in Linux where the I/O
 * subsystem sometime produce high latency under load. */
#define LIBXL_DEVICE_MODEL_START_TIMEOUT 60
#define LIBXL_DEVICE_MODEL_SAVE_FILE XEN_LIB_DIR "/qemu-save" /* .$domid */
#define LIBXL_DEVICE_MODEL_RESTORE_FILE XEN_LIB_DIR "/qemu-resume" /* .$domid */
#define LIBXL_QMP_CMD_TIMEOUT 10
#define LIBXL_STUBDOM_START_TIMEOUT 30
#define LIBXL_QEMU_BODGE_TIMEOUT 2
#define LIBXL_XENCONSOLE_LIMIT 1048576
#define LIBXL_XENCONSOLE_PROTOCOL "vt100"
#define LIBXL_MAXMEM_CONSTANT 1024
#define LIBXL_PV_EXTRA_MEMORY 1024
#define LIBXL_HVM_EXTRA_MEMORY 2048
#define LIBXL_MIN_DOM0_MEM (128*1024)
#define LIBXL_INVALID_GFN (~(uint64_t)0)
#define LIBXL_VGA_HOLE_SIZE 0x20
/* use 0 as the domid of the toolstack domain for now */
#define LIBXL_TOOLSTACK_DOMID 0
#define QEMU_SIGNATURE "DeviceModelRecord0002"
#define STUBDOM_CONSOLE_LOGGING 0
#define STUBDOM_CONSOLE_SAVE 1
#define STUBDOM_CONSOLE_RESTORE 2
#define STUBDOM_CONSOLE_SERIAL 3
#define STUBDOM_SPECIAL_CONSOLES 3
#define LIBXL_LINUX_STUBDOM_MEM 128
#define TAP_DEVICE_SUFFIX "-emu"
#define DOMID_XS_PATH "domid"
#define PVSHIM_BASENAME "xen-shim"
#define PVSHIM_CMDLINE "pv-shim console=xen,pv"

/* Size macros. */
#define __AC(X,Y)   (X##Y)
#define _AC(X,Y)    __AC(X,Y)
#define MB(_mb)     (_AC(_mb, ULL) << 20)
#define GB(_gb)     (_AC(_gb, ULL) << 30)

#define DIV_ROUNDUP(n, d) (((n) + (d) - 1) / (d))

#define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
#define MASK_INSR(v, m) (((v) * ((m) & -(m))) & (m))

#define LIBXL__LOGGING_ENABLED

#ifdef LIBXL__LOGGING_ENABLED
#define LIBXL__LOG(ctx, loglevel, _f, _a...)   libxl__log(ctx, loglevel, -1, __FILE__, __LINE__, __func__, INVALID_DOMID, _f, ##_a)
#define LIBXL__LOG_ERRNO(ctx, loglevel, _f, _a...)   libxl__log(ctx, loglevel, errno, __FILE__, __LINE__, __func__, INVALID_DOMID, _f, ##_a)
#define LIBXL__LOG_ERRNOVAL(ctx, loglevel, errnoval, _f, _a...)   libxl__log(ctx, loglevel, errnoval, __FILE__, __LINE__, __func__, INVALID_DOMID, _f, ##_a)

/* Same log functions as above, but with _d being a domain id. */
#define LIBXL__LOGD(ctx, loglevel, _d, _f, _a...)   libxl__log(ctx, loglevel, -1, __FILE__, __LINE__, __func__, _d, _f, ##_a)
#define LIBXL__LOGD_ERRNO(ctx, loglevel, _d, _f, _a...)   libxl__log(ctx, loglevel, errno, __FILE__, __LINE__, __func__, _d, _f, ##_a)
#define LIBXL__LOGD_ERRNOVAL(ctx, loglevel, errnoval, _d, _f, _a...)   libxl__log(ctx, loglevel, errnoval, __FILE__, __LINE__, __func__, _d, _f, ##_a)
#else
#define LIBXL__LOG(ctx, loglevel, _f, _a...)
#define LIBXL__LOG_ERRNO(ctx, loglevel, _f, _a...)
#define LIBXL__LOG_ERRNOVAL(ctx, loglevel, errnoval, _f, _a...)

#define LIBXLD__LOG(ctx, loglevel, _d, _f, _a...)
#define LIBXLD__LOG_ERRNO(ctx, loglevel, _d, _f, _a...)
#define LIBXLD__LOG_ERRNOVAL(ctx, loglevel, errnoval, _d, _f, _a...)
#endif
  /* all of these macros preserve errno (saving and restoring) */

/* 
 * A macro to help retain the first failure in "do as much as you can"
 * situations.  Note the hard-coded use of the variable name `rc`.
 */
#define ACCUMULATE_RC(rc_acc) ((rc_acc) = (rc_acc) ?: rc)

/* Convert pfn to physical address space. */
#define pfn_to_paddr(x) ((uint64_t)(x) << XC_PAGE_SHIFT)

/* logging */
_hidden void libxl__logv(libxl_ctx *ctx, xentoollog_level msglevel, int errnoval,
             const char *file /* may be 0 */, int line /* ignored if !file */,
             const char *func /* may be 0 */,
             uint32_t domid /* may be INVALID_DOMID */,
             const char *fmt, va_list al)
     __attribute__((format(printf,8,0)));

_hidden void libxl__log(libxl_ctx *ctx, xentoollog_level msglevel, int errnoval,
            const char *file /* may be 0 */, int line /* ignored if !file */,
            const char *func /* may be 0 */,
            uint32_t domid /* may be INVALID_DOMID */,
            const char *fmt, ...)
     __attribute__((format(printf,8,9)));

     /* these functions preserve errno (saving and restoring) */

typedef struct libxl__gc libxl__gc;
typedef struct libxl__egc libxl__egc;
typedef struct libxl__ao libxl__ao;
typedef struct libxl__aop_occurred libxl__aop_occurred;
typedef struct libxl__osevent_hook_nexus libxl__osevent_hook_nexus;
typedef struct libxl__osevent_hook_nexi libxl__osevent_hook_nexi;
typedef struct libxl__device_type libxl__device_type;
typedef struct libxl__json_object libxl__json_object;
typedef struct libxl__carefd libxl__carefd;
typedef struct libxl__ev_slowlock libxl__ev_slowlock;
typedef struct libxl__dm_resume_state libxl__dm_resume_state;
typedef struct libxl__ao_device libxl__ao_device;
typedef struct libxl__multidev libxl__multidev;
typedef struct libxl__ev_immediate libxl__ev_immediate;

typedef struct libxl__domain_create_state libxl__domain_create_state;
typedef void libxl__domain_create_cb(struct libxl__egc *egc,
                                     libxl__domain_create_state *dcs,
                                     int rc, uint32_t domid);

typedef struct libxl__colo_device_nic libxl__colo_device_nic;
typedef struct libxl__colo_qdisk libxl__colo_qdisk;
typedef struct libxl__colo_proxy_state libxl__colo_proxy_state;
typedef struct libxl__colo_save_state libxl__colo_save_state;
typedef struct libxl__colo_restore_state libxl__colo_restore_state;

_hidden void libxl__alloc_failed(libxl_ctx *, const char *func,
                         size_t nmemb, size_t size) __attribute__((noreturn));
  /* func, size and nmemb are used only in the log message.
   * You may pass size==0 if size and nmemb are not meaningful
   * and should not be printed. */

typedef struct libxl__ev_fd libxl__ev_fd;
typedef void libxl__ev_fd_callback(libxl__egc *egc, libxl__ev_fd *ev,
                                   int fd, short events, short revents);
  /* Note that revents may contain POLLERR or POLLHUP regardless of
   * events; otherwise revents contains only bits in events.  Contrary
   * to the documentation for poll(2), POLLERR and POLLHUP can occur
   * even if only POLLIN was set in events.  (POLLNVAL is a fatal
   * error and will cause libxl event machinery to fail an assertion.)
   *
   * It is not permitted to listen for the same or overlapping events
   * on the same fd using multiple different libxl__ev_fd's.
   *
   * Note that (depending on the underlying event loop implementation)
   * it is possible that a the fd callback system is `level triggered'
   * or `event triggered'.  That is, the callback may be called only
   * once for each transition from not ready to ready.  So the
   * callback must generally contain a loop which exhausts the fd,
   * rather than relying on being called again if the fd is still
   * ready.
   *
   * (Spurious wakeups, and spurious bits set in revents, are
   * suppressed by the libxl event core.)
   */
struct libxl__ev_fd {
    /* caller should include this in their own struct */
    /* read-only for caller, who may read only when registered: */
    int fd;
    short events;
    libxl__ev_fd_callback *func;
    /* remainder is private for libxl__ev_fd... */
    LIBXL_LIST_ENTRY(libxl__ev_fd) entry;
    libxl__osevent_hook_nexus *nexus;
};


typedef struct libxl__ao_abortable libxl__ao_abortable;
typedef void libxl__ao_abortable_callback(libxl__egc *egc,
                  libxl__ao_abortable *ao_abortable, int rc /* ABORTED */);

struct libxl__ao_abortable {
    /* caller must fill this in and it must remain valid */
    libxl__ao *ao;
    libxl__ao_abortable_callback *callback;
    /* remainder is private for abort machinery */
    bool registered;
    LIBXL_LIST_ENTRY(libxl__ao_abortable) entry;
    /*
     * For nested aos:
     *  Semantically, abort affects the whole tree of aos,
     *    not just the parent.
     *  libxl__ao_abortable.ao refers to the child, so
     *    that the child callback sees the right ao.  (After all,
     *    it was code dealing with the child that set .ao.)
     *  But, the abortable is recorded on the "abortables" list
     *    for the ultimate root ao, so that every possible child
     *    abort occurs as a result of the abort of the parent.
     *  We set ao->aborting only in the root.
     */
};

_hidden int libxl__ao_abortable_register(libxl__ao_abortable*);
_hidden void libxl__ao_abortable_deregister(libxl__ao_abortable*);

static inline void libxl__ao_abortable_init
  (libxl__ao_abortable *c) { c->registered = 0; }
static inline bool libxl__ao_abortable_isregistered
  (const libxl__ao_abortable *c) { return c->registered; }

int libxl__ao_aborting(libxl__ao *ao); /* -> 0 or ERROR_ABORTED */


typedef struct libxl__ev_time libxl__ev_time;
typedef void libxl__ev_time_callback(libxl__egc *egc, libxl__ev_time *ev,
                                     const struct timeval *requested_abs,
                                     int rc); /* TIMEDOUT or ABORTED */
struct libxl__ev_time {
    /* caller should include this in their own struct */
    /* read-only for caller, who may read only when registered: */
    libxl__ev_time_callback *func;
    /* remainder is private for libxl__ev_time... */
    int infinite; /* not registered in list or with app if infinite */
    LIBXL_TAILQ_ENTRY(libxl__ev_time) entry;
    struct timeval abs;
    libxl__osevent_hook_nexus *nexus;
    libxl__ao_abortable abrt;
};

typedef struct libxl__ev_xswatch libxl__ev_xswatch;
typedef void libxl__ev_xswatch_callback(libxl__egc *egc, libxl__ev_xswatch*,
                            const char *watch_path, const char *event_path);
struct libxl__ev_xswatch {
    /* caller should include this in their own struct */
    /* read-only for caller, who may read only when registered: */
    char *path;
    libxl__ev_xswatch_callback *callback;
    /* remainder is private for libxl__ev_xswatch... */
    int slotnum; /* registered iff slotnum >= 0 */
    uint32_t counterval;
};

typedef struct libxl__ev_evtchn libxl__ev_evtchn;
typedef void libxl__ev_evtchn_callback(libxl__egc *egc, libxl__ev_evtchn*);
struct libxl__ev_evtchn {
    /* caller must fill these in, and they must all remain valid */
    libxl__ev_evtchn_callback *callback;
    int port;
    /* remainder is private for libxl__ev_evtchn_... */
    bool waiting;
    LIBXL_LIST_ENTRY(libxl__ev_evtchn) entry;
};

/*
 * An entry in the watch_slots table is either:
 *  1. an entry in the free list, ie NULL or pointer to next free list entry
 *  2. an pointer to a libxl__ev_xswatch
 *
 * But we don't want to use unions or type-punning because the
 * compiler might "prove" that our code is wrong and misoptimise it.
 *
 * The rules say that all struct pointers have identical
 * representation and alignment requirements (C99+TC1+TC2 6.2.5p26) so
 * what we do is simply declare our array as containing only the free
 * list pointers, and explicitly convert from and to our actual
 * xswatch pointers when we store and retrieve them.
 */
typedef struct libxl__ev_watch_slot {
    LIBXL_SLIST_ENTRY(struct libxl__ev_watch_slot) empty;
} libxl__ev_watch_slot;

_hidden libxl__ev_xswatch *libxl__watch_slot_contents(libxl__gc *gc,
                                                      int slotnum);


typedef struct libxl__ev_child libxl__ev_child;
typedef void libxl__ev_child_callback(libxl__egc *egc, libxl__ev_child*,
                                      pid_t pid, int status);
struct libxl__ev_child {
    /* caller should include this in their own struct */
    /* read-only for caller: */
    pid_t pid; /* -1 means unused ("unregistered", ie Idle) */
    libxl__ev_child_callback *callback;
    /* remainder is private for libxl__ev_... */
    LIBXL_LIST_ENTRY(struct libxl__ev_child) entry;
};

/* libxl__ev_immediate
 *
 * Allow to call a non-reentrant callback.
 *
 * `callback' will be called immediately as a new event.
 */
struct libxl__ev_immediate {
    /* filled by user */
    void (*callback)(libxl__egc *, libxl__ev_immediate *);
    /* private to libxl__ev_immediate */
    LIBXL_STAILQ_ENTRY(libxl__ev_immediate) entry;
};
void libxl__ev_immediate_register(libxl__egc *, libxl__ev_immediate *);

/*
 * Lock for device hotplug, qmp_lock.
 *
 * libxl__ev_slowlock implement a lock that is outside of CTX_LOCK in the
 * lock hierarchy. It can be used when one want to make QMP calls to QEMU,
 * which may take a significant amount time.
 * It is to be acquired by an ao event callback.
 *
 * If libxl__ev_devlock is needed, it should be acquired while every
 * libxl__ev_qmp are Idle for the current domain.
 *
 * It is to be acquired when adding/removing devices or making changes
 * to them when this is a slow operation and json_lock isn't appropriate.
 *
 * Possible states of libxl__ev_slowlock:
 *   Undefined
 *    Might contain anything.
 *  Idle
 *    Struct contents are defined enough to pass to any
 *    libxl__ev_slowlock_* function.
 *    The struct does not contain references to any allocated private
 *    resources so can be thrown away.
 *  Active
 *    Waiting to get a lock.
 *    Needs to wait until the callback is called.
 *  LockAcquired
 *    libxl__ev_slowlock_unlock will need to be called to release the lock
 *    and the resources of libxl__ev_slowlock.
 *
 *  libxl__ev_*lock_init: Undefined/Idle -> Idle
 *  libxl__ev_slowlock_lock: Idle -> Active
 *    May call callback synchronously.
 *  libxl__ev_slowlock_unlock: LockAcquired/Idle -> Idle
 *  libxl__ev_slowlock_dispose: Idle/Active/LockAcquired -> Idle
 *    The callback will not be called anymore.
 *  callback:     When called: Active -> LockAcquired (on error: Idle)
 *    The callback is only called once.
 */
struct libxl__ev_slowlock {
    /* filled by user */
    libxl__ao *ao;
    libxl_domid domid;
    void (*callback)(libxl__egc *, libxl__ev_slowlock *, int rc);
    /* private to libxl__ev_slowlock* */
    libxl__ev_child child;
    const char *userdata_userid;
    char *path; /* path of the lock file itself */
    int fd;
    bool held;
};
_hidden void libxl__ev_devlock_init(libxl__ev_slowlock *);
_hidden void libxl__ev_qmplock_init(libxl__ev_slowlock *);
_hidden void libxl__ev_slowlock_lock(libxl__egc *, libxl__ev_slowlock *);
_hidden void libxl__ev_slowlock_unlock(libxl__gc *, libxl__ev_slowlock *);
_hidden void libxl__ev_slowlock_dispose(libxl__gc *, libxl__ev_slowlock *);

/*
 * QMP asynchronous calls
 *
 * This facility allows a command to be sent to QEMU, and the response
 * to be handed to a callback function.
 *
 * Commands can be submited one after an other with the same
 * connection (e.g. the result from the "add-fd" command need to be
 * use in a follow-up command before disconnecting from QMP). A
 * libxl__ev_qmp can be reused when the callback is been called in
 * order to use the same connection.
 *
 * Only one connection at a time can be made to one QEMU, so avoid
 * keeping a libxl__ev_qmp Connected for to long and call
 * libxl__ev_qmp_dispose as soon as it is not needed anymore.
 *
 * Possible states of a libxl__ev_qmp:
 *  Undefined
 *    Might contain anything.
 *  Idle
 *    Struct contents are defined enough to pass to any
 *    libxl__ev_qmp_* function.
 *    The struct does not contain references to any allocated private
 *    resources so can be thrown away.
 *  Active
 *    Currently waiting for the callback to be called.
 *    _dispose must be called to reclaim resources.
 *  Connected
 *    Struct contain allocated ressources.
 *    Calling _send() with this same ev will use the same QMP connection.
 *    _dispose() must be called to reclaim resources.
 *
 * libxl__ev_qmp_init: Undefined/Idle -> Idle
 *
 * libxl__ev_qmp_send: Idle/Connected -> Active (on error: Idle)
 *    Sends a command to QEMU.
 *    callback will be called when a response is received or when an
 *    error as occured.
 *    callback isn't called synchronously.
 *
 * libxl__ev_qmp_dispose: Connected/Active/Idle -> Idle
 *
 * callback: When called: Active -> Connected (on error: Idle/Connected)
 *    When called, ev is Connected and can be reused or disposed of.
 *    On error, the callback is called with response == NULL and the
 *    error code in rc. The new state of ev depending on the value of rc:
 *    - rc == ERROR_QMP_*: This is an error associated with the cmd to
 *      run, ev is Connected.
 *    - otherwise: An other error happend, ev is now Idle.
 *    The callback is only called once.
 */
typedef struct libxl__ev_qmp libxl__ev_qmp;
typedef void libxl__ev_qmp_callback(libxl__egc *egc, libxl__ev_qmp *ev,
                                    const libxl__json_object *response,
                                    int rc);

_hidden void libxl__ev_qmp_init(libxl__ev_qmp *ev);
_hidden int libxl__ev_qmp_send(libxl__egc *egc, libxl__ev_qmp *ev,
                               const char *cmd, libxl__json_object *args);
_hidden void libxl__ev_qmp_dispose(libxl__gc *gc, libxl__ev_qmp *ev);

typedef enum {
    /* initial state */
    qmp_state_disconnected = 1,
    /* waiting for lock */
    qmp_state_waiting_lock,
    /* connected to QMP socket, waiting for greeting message */
    qmp_state_connecting,
    /* qmp_capabilities command sent, waiting for reply */
    qmp_state_capability_negotiation,
    /* sending user's cmd and waiting for reply */
    qmp_state_waiting_reply,
    /* ready to send commands */
    qmp_state_connected,
} libxl__qmp_state;

struct libxl__ev_qmp {
    /* caller should include this in their own struct */
    /* caller must fill these in, and they must all remain valid */
    libxl__ao *ao;
    libxl_domid domid;
    libxl__ev_qmp_callback *callback;
    int payload_fd; /* set to send a fd with the command, -1 otherwise */

    /* read-only when Connected
     * and not to be accessed by the caller otherwise */
    struct {
        int major;
        int minor;
        int micro;
    } qemu_version;

    /*
     * remaining fields are private to libxl_ev_qmp_*
     */

    libxl__carefd *cfd;
    libxl__ev_fd efd;
    libxl__qmp_state state;
    libxl__ev_slowlock lock;
    libxl__ev_immediate ei;
    int rc;
    int id;
    int next_id;        /* next id to use */
    /* receive buffer */
    char *rx_buf;
    size_t rx_buf_size; /* current allocated size */
    size_t rx_buf_used; /* actual data in the buffer */
    /* sending buffer */
    char *tx_buf;
    size_t tx_buf_len;  /* tx_buf size */
    size_t tx_buf_off;  /* already sent */
    /* The message to send when ready */
    char *msg;
    int msg_id;
};

/* QMP parameters helpers */

_hidden void libxl__qmp_param_add_string(libxl__gc *gc,
                                         libxl__json_object **param,
                                         const char *name, const char *s);
_hidden void libxl__qmp_param_add_bool(libxl__gc *gc,
                                       libxl__json_object **param,
                                       const char *name, bool b);
_hidden void libxl__qmp_param_add_integer(libxl__gc *gc,
                                          libxl__json_object **param,
                                          const char *name, const int i);
#define QMP_PARAMETERS_SPRINTF(args, name, format, ...) \
    libxl__qmp_param_add_string(gc, args, name, \
                                GCSPRINTF(format, __VA_ARGS__))


/*
 * evgen structures, which are the state we use for generating
 * events for the caller.
 *
 * In general in each case there's an internal and an external
 * version of the _evdisable_FOO function; the internal one is
 * used during cleanup.
 */
struct libxl__evgen_domain_death {
    uint32_t domid;
    unsigned shutdown_reported:1, death_reported:1;
    LIBXL_TAILQ_ENTRY(libxl_evgen_domain_death) entry;
        /* on list .death_reported ? CTX->death_list : CTX->death_reported */
    libxl_ev_user user;
};
_hidden void
libxl__evdisable_domain_death(libxl__gc*, libxl_evgen_domain_death*);

struct libxl__evgen_disk_eject {
    libxl__ev_xswatch watch;
    uint32_t domid;
    LIBXL_LIST_ENTRY(libxl_evgen_disk_eject) entry;
    libxl_ev_user user;
    char *vdev, *be_ptr_path;
};
_hidden void
libxl__evdisable_disk_eject(libxl__gc*, libxl_evgen_disk_eject*);

typedef struct libxl__poller libxl__poller;
struct libxl__poller {
    /*
     * These are used to allow other threads to wake up a thread which
     * may be stuck in poll, because whatever it was waiting for
     * hadn't happened yet.  Threads which generate events will write
     * a byte to each pipe.  A thread which is waiting will empty its
     * own pipe, and put its poller on the pollers_event list, before
     * releasing the ctx lock and going into poll; when it comes out
     * of poll it will take the poller off the pollers_event list.
     *
     * A thread which is waiting for completion of a synchronous ao
     * will allocate a poller and record it in the ao, so that other
     * threads can wake it up.
     *
     * When a thread is done with a poller it should put it onto
     * pollers_idle, where it can be reused later.
     *
     * The "poller_app" is never idle, but is sometimes on
     * pollers_event.
     */
    LIBXL_LIST_ENTRY(libxl__poller) entry;

    struct pollfd *fd_polls;
    int fd_polls_allocd;

    int fd_rindices_allocd;
    int (*fd_rindices)[3]; /* see libxl_event.c:beforepoll_internal */

    int wakeup_pipe[2]; /* 0 means no fd allocated */
    bool pipe_nonempty;

    /*
     * We also use the poller to record whether any fds have been
     * deregistered since we entered poll.  Each poller which is not
     * idle is on the list pollers_active.  fds_deregistered is
     * cleared by beforepoll, and tested by afterpoll.  Whenever an fd
     * event is deregistered, we set the fds_deregistered of all non-idle
     * pollers.  So afterpoll can tell whether any POLLNVAL is
     * plausibly due to an fd being closed and reopened.
     *
     * Additionally, we record whether any fd or time event sources
     * have been registered.  This is necessary because sometimes we
     * need to wake up the only libxl thread stuck in
     * eventloop_iteration so that it will pick up new fds or earlier
     * timeouts.  osevents_added is cleared by beforepoll, and set by
     * fd or timeout event registration.  When we are about to leave
     * libxl (strictly, when we are about to give up an egc), we check
     * whether there are any pollers.  If there are, then at least one
     * of them must have osevents_added clear.  If not, we wake up the
     * first one on the list.  Any entry on pollers_active constitutes
     * a promise to also make this check, so the baton will never be
     * dropped.
     */
    LIBXL_LIST_ENTRY(libxl__poller) active_entry;
    bool fds_deregistered;
    bool osevents_added;
};

struct libxl__gc {
    /* mini-GC */
    int alloc_maxsize; /* -1 means this is the dummy non-gc gc */
    void **alloc_ptrs;
    libxl_ctx *owner;
};

struct libxl__ctx {
    xentoollog_logger *lg;
    xc_interface *xch;
    struct xs_handle *xsh;
    libxl__gc nogc_gc;

    const libxl_event_hooks *event_hooks;
    void *event_hooks_user;

    pthread_mutex_t lock; /* protects data structures hanging off the ctx */
      /* Always use libxl__ctx_lock and _unlock (or the convenience
       * macors CTX_LOCK and CTX_UNLOCK) to manipulate this.
       *
       * You may acquire this mutex recursively if it is convenient to
       * do so.  You may not acquire this lock at the same time as any
       * other lock.  If you need to call application code outside
       * libxl (ie, a callback) with this lock held then it is
       * necessaray to impose restrictions on the caller to maintain a
       * proper lock hierarchy, and these restrictions must then be
       * documented in the libxl public interface.
       */

    LIBXL_TAILQ_HEAD(libxl__event_list, libxl_event) occurred;

    int osevent_in_hook;
    const libxl_osevent_hooks *osevent_hooks;
    void *osevent_user;
      /* See the comment for OSEVENT_HOOK_INTERN in libxl_event.c
       * for restrictions on the use of the osevent fields. */

    libxl__poller *poller_app; /* libxl_osevent_beforepoll and _afterpoll */
    LIBXL_LIST_HEAD(, libxl__poller) pollers_event, pollers_idle;
    LIBXL_LIST_HEAD(, libxl__poller) pollers_active;

    LIBXL_SLIST_HEAD(libxl__osevent_hook_nexi, libxl__osevent_hook_nexus)
        hook_fd_nexi_idle, hook_timeout_nexi_idle;
    LIBXL_LIST_HEAD(, libxl__ev_fd) efds;
    LIBXL_TAILQ_HEAD(, libxl__ev_time) etimes;

    libxl__ev_watch_slot *watch_slots;
    int watch_nslots, nwatches;
    LIBXL_SLIST_HEAD(, libxl__ev_watch_slot) watch_freeslots;
    uint32_t watch_counter; /* helps disambiguate slot reuse */
    libxl__ev_fd watch_efd;

    xenevtchn_handle *xce; /* waiting must be done only with libxl__ev_evtchn* */
    LIBXL_LIST_HEAD(, libxl__ev_evtchn) evtchns_waiting;
    libxl__ev_fd evtchn_efd;

    LIBXL_LIST_HEAD(, libxl__ao) aos_inprogress;

    LIBXL_TAILQ_HEAD(libxl__evgen_domain_death_list, libxl_evgen_domain_death)
        death_list /* sorted by domid */,
        death_reported;
    libxl__ev_xswatch death_watch;

    LIBXL_LIST_HEAD(, libxl_evgen_disk_eject) disk_eject_evgens;

    const libxl_childproc_hooks *childproc_hooks;
    void *childproc_user;
    int sigchld_selfpipe[2]; /* [0]==-1 means handler not installed */
    libxl__ev_fd sigchld_selfpipe_efd;
    LIBXL_LIST_HEAD(, libxl__ev_child) children;
    bool sigchld_user_registered;
    LIBXL_LIST_ENTRY(libxl_ctx) sigchld_users_entry;

    libxl_version_info version_info;

    bool libxl_domain_need_memory_0x041200_called,
         libxl_domain_need_memory_called;
};

/*
 * libxl__device is a transparent structure that doesn't contain private fields
 * or external memory references, and as such can be copied by assignment.
 */
typedef struct {
    uint32_t backend_devid;
    uint32_t backend_domid;
    uint32_t devid;
    uint32_t domid;
    libxl__device_kind backend_kind;
    libxl__device_kind kind;
} libxl__device;

/* Used to know if backend of given device is QEMU */
#define QEMU_BACKEND(dev) (\
    (dev)->backend_kind == LIBXL__DEVICE_KIND_QDISK || \
    (dev)->backend_kind == LIBXL__DEVICE_KIND_VFB || \
    (dev)->backend_kind == LIBXL__DEVICE_KIND_QUSB || \
    (dev)->backend_kind == LIBXL__DEVICE_KIND_9PFS || \
    (dev)->backend_kind == LIBXL__DEVICE_KIND_VKBD)

#define XC_PCI_BDF             "0x%x, 0x%x, 0x%x, 0x%x"
#define PCI_DEVFN(slot, func)   ((((slot) & 0x1f) << 3) | ((func) & 0x07))
#define PCI_SLOT(devfn)         (((devfn) >> 3) & 0x1f)
#define PCI_FUNC(devfn)         ((devfn) & 0x07)
#define AUTO_PHP_SLOT          0x100

#define PROC_PCI_NUM_RESOURCES 7
#define PCI_BAR_IO             0x01

#define PRINTF_ATTRIBUTE(x, y) __attribute__((format(printf, x, y)))

struct libxl__egc {
    /* For event-generating functions only.
     * The egc and its gc may be accessed only on the creating thread. */
    struct libxl__gc gc;
    struct libxl__event_list occurred_for_callback;
    LIBXL_TAILQ_HEAD(, libxl__ao) aos_for_callback;
    LIBXL_TAILQ_HEAD(, libxl__aop_occurred) aops_for_callback;
    LIBXL_STAILQ_HEAD(, libxl__ev_immediate) ev_immediates;
};

struct libxl__aop_occurred {
    /*
     * An aop belongs to, and may be accessed only on, the thread
     * which created it.  It normally lives in that thread's egc.
     *
     * While an aop exists, it corresponds to one refcount in
     * ao->progress_reports_outstanding, preventing ao destruction.
     */
    LIBXL_TAILQ_ENTRY(libxl__aop_occurred) entry;
    libxl__ao *ao;
    libxl_event *ev;
    const libxl_asyncprogress_how *how;
};

#define LIBXL__AO_MAGIC              0xA0FACE00ul
#define LIBXL__AO_MAGIC_DESTROYED    0xA0DEAD00ul

struct libxl__ao {
    /*
     * An ao and its gc may be accessed only with the ctx lock held.
     *
     * Special exception: If an ao has been added to
     * egc->aos_for_callback, the thread owning the egc may remove the
     * ao from that list and make the callback without holding the
     * lock.
     *
     * Corresponding restriction: An ao may be added only to one
     * egc->aos_for_callback, once; rc and how must already have been
     * set and may not be subsequently modified.  (This restriction is
     * easily and obviously met since the ao is queued for callback
     * only in libxl__ao_complete.)
     */
    uint32_t magic;
    unsigned constructing:1, in_initiator:1, complete:1, notified:1,
        aborting:1;
    int manip_refcnt;
    libxl__ao *nested_root;
    int nested_progeny;
    int progress_reports_outstanding;
    int rc;
    LIBXL_LIST_HEAD(, libxl__ao_abortable) abortables;
    LIBXL_LIST_ENTRY(libxl__ao) inprogress_entry;
    libxl__gc gc;
    libxl_asyncop_how how;
    libxl__poller *poller;
    uint32_t domid;
    LIBXL_TAILQ_ENTRY(libxl__ao) entry_for_callback;
    int outstanding_killed_child;
};

#define LIBXL_INIT_GC(gc,ctx) do{               \
        (gc).alloc_maxsize = 0;                 \
        (gc).alloc_ptrs = 0;                    \
        (gc).owner = (ctx);                     \
    } while(0)
    /* NB, also, a gc struct ctx->nogc_gc is initialised in libxl_ctx_alloc */

static inline libxl_ctx *libxl__gc_owner(libxl__gc *gc)
{
    return gc->owner;
}

static inline int libxl__gc_is_real(const libxl__gc *gc)
{
    return gc->alloc_maxsize >= 0;
}

/*
 * Memory allocation tracking/helpers
 *
 * See comment "libxl memory management" in libxl.h for a description
 * of the framework which these calls belong to.
 *
 * These functions deal with memory allocations of type (a) and (d) in
 * that description.
 *
 * All pointers returned by these functions are registered for garbage
 * collection on exit from the outermost libxl callframe.
 *
 * However, where the argument is stated to be "gc_opt", &ctx->nogc_gc
 * may be passed instead, in which case no garbage collection will
 * occur; the pointer must later be freed with free().  (Passing NULL
 * for gc_opt is not permitted.)  This is for memory allocations of
 * types (b) and (c).  The convenience macro NOGC should be used where
 * possible.
 *
 * NOGC (and ctx->nogc_gc) may ONLY be used with functions which
 * explicitly declare that it's OK.  Use with nonconsenting functions
 * may result in leaks of those functions' internal allocations on the
 * psuedo-gc.
 */
/* register ptr in gc for free on exit from outermost libxl callframe. */

#define NN(...) __attribute__((nonnull(__VA_ARGS__)))
#define NN1 __attribute__((nonnull(1)))
 /* It used to be legal to pass NULL for gc_opt.  Get the compiler to
  * warn about this if any slip through. */

_hidden void libxl__ptr_add(libxl__gc *gc_opt, void *ptr /* may be NULL */) NN1;
/* if this is the outermost libxl callframe then free all pointers in @gc */
_hidden void libxl__free_all(libxl__gc *gc);
/* allocate @size bytes. (a gc'd malloc(3)) */
_hidden void *libxl__malloc(libxl__gc *gc_opt, size_t size) NN1;
/* allocate and zero @size. (similar to a gc'd malloc(3)+memzero()) */
_hidden void *libxl__zalloc(libxl__gc *gc_opt, size_t size) NN1;
/* allocate and zero memory for an array of @nmemb members of @size each.
 * (similar to a gc'd calloc(3)). */
_hidden void *libxl__calloc(libxl__gc *gc_opt, size_t nmemb, size_t size) NN1;
/* change the size of the memory block pointed to by @ptr to @new_size bytes.
 * unlike other allocation functions here any additional space between the
 * oldsize and @new_size is not initialised (similar to a gc'd realloc(3)).
 * if @ptr is non-NULL and @gc_opt is not nogc_gc then @ptr must have been
 * registered with @gc_opt previously. */
_hidden void *libxl__realloc(libxl__gc *gc_opt, void *ptr, size_t new_size) NN1;
/* print @fmt into an allocated string large enoughto contain the result.
 * (similar to gc'd asprintf(3)). */
_hidden char *libxl__sprintf(libxl__gc *gc_opt, const char *fmt, ...) PRINTF_ATTRIBUTE(2, 3) NN1;
_hidden char *libxl__vsprintf(libxl__gc *gc, const char *format, va_list ap) PRINTF_ATTRIBUTE(2, 0);
/* duplicate the string @c (similar to a gc'd strdup(3)). */
_hidden char *libxl__strdup(libxl__gc *gc_opt,
                            const char *c /* may be NULL */) NN1;
/* duplicate at most @n bytes of string @c (similar to a gc'd strndup(3)). */
_hidden char *libxl__strndup(libxl__gc *gc_opt,
                             const char *c /* may be NULL */,
                             size_t n) NN1;
/* strip the last path component from @s and return as a newly allocated
 * string. (similar to a gc'd dirname(3)). */
_hidden char *libxl__dirname(libxl__gc *gc_opt, const char *s) NN1;

/* Make a pipe and set both ends nonblocking.  On error, nothing
 * is left open and both fds[]==-1, and a message is logged.
 * Useful for self-pipes. */
_hidden int libxl__pipe_nonblock(libxl_ctx *ctx, int fds[2]);
/* Closes the pipe fd(s).  Either or both of fds[] may be -1 meaning
 * `not open'.  Ignores any errors.  Sets fds[] to -1. */
_hidden void libxl__pipe_close(int fds[2]);

/* Change the flags for the file description associated with fd to
 *    (flags & mask) | val.
 * If r_oldflags != NULL then sets *r_oldflags to the original set of
 * flags.
 */
_hidden int libxl__fd_flags_modify_save(libxl__gc *gc, int fd,
                                        int mask, int val, int *r_oldflags);
/* Restores the flags for the file description associated with fd to
 * to the previous value (returned by libxl__fd_flags_modify_save)
 */
_hidden int libxl__fd_flags_restore(libxl__gc *gc, int fd, int old_flags);

/* Each of these logs errors and returns a libxl error code.
 * They do not mind if path is already removed.
 * For _file, path must not be a directory; for _directory it must be. */
_hidden int libxl__remove_file(libxl__gc *gc, const char *path);
_hidden int libxl__remove_directory(libxl__gc *gc, const char *path);
_hidden int libxl__remove_file_or_directory(libxl__gc *gc, const char *path);


_hidden char **libxl__xs_kvs_of_flexarray(libxl__gc *gc, flexarray_t *array);

/* treats kvs as pairs of keys and values and writes each to dir. */
_hidden int libxl__xs_writev(libxl__gc *gc, xs_transaction_t t,
                             const char *dir, char **kvs);
/* as writev but also sets the permissions on each path */
_hidden int libxl__xs_writev_perms(libxl__gc *gc, xs_transaction_t t,
                                   const char *dir, char *kvs[],
                                   struct xs_permissions *perms,
                                   unsigned int num_perms);
/* _atonce creates a transaction and writes all keys at once */
_hidden int libxl__xs_writev_atonce(libxl__gc *gc,
                             const char *dir, char **kvs);
   /* Each fn returns 0 on success.
    * On error: returns -1, sets errno (no logging) */

_hidden char *libxl__xs_get_dompath(libxl__gc *gc, uint32_t domid);
   /* On error: logs, returns NULL, sets errno. */

_hidden char *libxl__xs_read(libxl__gc *gc, xs_transaction_t t,
                             const char *path);
_hidden char **libxl__xs_directory(libxl__gc *gc, xs_transaction_t t,
                                   const char *path, unsigned int *nb);
   /* On error: returns NULL, sets errno (no logging) */
_hidden char *libxl__xs_libxl_path(libxl__gc *gc, uint32_t domid);

_hidden int libxl__backendpath_parse_domid(libxl__gc *gc, const char *be_path,
                                           libxl_domid *domid_out);

/*----- "checked" xenstore access functions -----*/
/* Each of these functions will check that it succeeded; if it
 * fails it logs and returns ERROR_FAIL.
 */

int libxl__xs_vprintf(libxl__gc *gc, xs_transaction_t t,
                      const char *path, const char *fmt, va_list ap) PRINTF_ATTRIBUTE(4, 0);
int libxl__xs_printf(libxl__gc *gc, xs_transaction_t t,
                     const char *path, const char *fmt, ...) PRINTF_ATTRIBUTE(4, 5);

/* On success, path will exist and will have an empty value */
int libxl__xs_mknod(libxl__gc *gc, xs_transaction_t t,
                    const char *path, struct xs_permissions *perms,
                    unsigned int num_perms);

/* On success, *result_out came from the gc.
 * On error, *result_out is undefined.
 * ENOENT is regarded as error.
 */
int libxl__xs_read_mandatory(libxl__gc *gc, xs_transaction_t t,
                             const char *path, const char **result_out);

/* On success, *result_out came from the gc.
 * On error, *result_out is undefined.
 * ENOENT counts as success but sets *result_out=0
 */
int libxl__xs_read_checked(libxl__gc *gc, xs_transaction_t t,
                           const char *path, const char **result_out);

/* Does not include a trailing null.
 * May usefully be combined with GCSPRINTF if the format string
 * behaviour of libxl__xs_printf is desirable. */
int libxl__xs_write_checked(libxl__gc *gc, xs_transaction_t t,
                            const char *path, const char *string);

/* ENOENT is not an error (even if the parent directories don't exist) */
int libxl__xs_rm_checked(libxl__gc *gc, xs_transaction_t t, const char *path);

/* Transaction functions, best used together.
 * The caller should initialise *t to 0 (XBT_NULL) before calling start.
 * Each function leaves *t!=0 iff the transaction needs cleaning up.
 *
 * libxl__xs_transaction_commit returns:
 *   <0  failure - a libxl error code
 *   +1  commit conflict; transaction has been destroyed and caller
 *        must go round again (call _start again and retry)
 *    0  committed successfully
 *
 * The intended usage pattern looks like this:
 *    int some_function()
 *    {
 *        int rc;
 *        xs_transaction_t t = 0;
 *        // other initialisations
 *
 *        // do whatever you need to do before the xenstore stuff
 *        // errors?  set rc and goto out.
 *
 *        for (;;) {
 *            rc = libxl__xs_transaction_start(gc, &t);
 *            if (rc) goto out;
 *
 *            // do your work here, including all xenstore reads and writes
 *            // libxl__xs_*_checked are useful; pass them t.
 *            // errors?  set rc and goto out.
 *
 *            rc = libxl__xs_transaction_commit(gc, &t);
 *            if (!rc) break;
 *            if (rc<0) goto out;
 *        }
 *
 *        // now the xenstore transaction succeeded
 *        // do whatever else you need to do
 *        // errors?  set rc and goto out.
 *
 *        return something;
 *
 *     out:
 *        // other cleanups
 *        libxl__xs_transaction_abort(gc, &t);
 *        // other cleanups
 *        return rc;
 *    }
 *
 * Formally the states of *t are:
 *
 *  name     value of *t  description
 *   Idle         0         no transaction exists
 *   Ready        non-0     ready for work, nothing done yet
 *   Busy         non-0     writes have been made but we are not finished
 *   Uncommitted  non-0     writes have been made and should be committed
 *
 * libxl__xs_transaction_start:  Idle -> Ready (on error: Idle)
 *
 * The transaction goes from Ready to Busy, and from Busy to
 * Uncommitted, by the use of xenstore read and write operations
 * (libxl__xs_..., xs_...) made by libxl__xs_transaction's caller.
 *
 * libxl__xs_transaction_commit:  Ready/Uncommitted -> Idle
 *     on success (returns 0): xenstore has been updated
 *     on error (<0) or conflict (+1): updates discarded
 *
 * libxl__xs_transaction_abort:  Any -> Idle  (any updates discarded)
 */
int libxl__xs_transaction_start(libxl__gc *gc, xs_transaction_t *t);
int libxl__xs_transaction_commit(libxl__gc *gc, xs_transaction_t *t);
void libxl__xs_transaction_abort(libxl__gc *gc, xs_transaction_t *t);



/*
 * This is a recursive delete, from top to bottom. What this function does
 * is remove empty folders that contained the deleted entry.
 *
 * It mimics xenstore-rm -t behaviour.
 */
_hidden int libxl__xs_path_cleanup(libxl__gc *gc, xs_transaction_t t,
                                   const char *user_path);

/*
 * Event generation functions provided by the libxl event core to the
 * rest of libxl.  Implemented in terms of _beforepoll/_afterpoll
 * and/or the fd registration machinery, as provided by the
 * application.
 *
 * Semantics are similar to those of the fd and timeout registration
 * functions provided to libxl_osevent_register_hooks.
 *
 * Non-0 returns from libxl__ev_{modify,deregister} have already been
 * logged by the core and should be returned unmodified to libxl's
 * caller; NB that they may be valid libxl error codes but they may
 * also be positive numbers supplied by the caller.
 *
 * In each case, there is a libxl__ev_FOO structure which can be in
 * one of three states:
 *
 *   Undefined   - Might contain anything.  All-bits-zero is
 *                 an undefined state.
 *
 *   Idle        - Struct contents are defined enough to pass to any
 *                 libxl__ev_FOO function but not registered and
 *                 callback will not be called.  The struct does not
 *                 contain references to any allocated resources so
 *                 can be thrown away.
 *
 *   Active      - Request for events has been registered and events
 *                 may be generated.  _deregister must be called to
 *                 reclaim resources.
 *
 * These functions are provided for each kind of event KIND:
 *
 *   int libxl__ev_KIND_register(libxl__gc *gc, libxl__ev_KIND *GEN,
 *                              libxl__ev_KIND_callback *FUNC,
 *                              DETAILS);
 *      On entry *GEN must be in state Undefined or Idle.
 *      Returns a libxl error code; on error return *GEN is Idle.
 *      On successful return *GEN is Active and FUNC wil be
 *      called by the event machinery in future.  FUNC will
 *      not be called from within the call to _register.
 *      FUNC will be called with the context locked (with CTX_LOCK).
 *
 *  void libxl__ev_KIND_deregister(libxl__gc *gc, libxl__ev_KIND *GEN_upd);
 *      On entry *GEN must be in state Active or Idle.
 *      On return it is Idle.  (Idempotent.)
 *
 *  void libxl__ev_KIND_init(libxl__ev_KIND *GEN);
 *      Provided for initialising an Undefined KIND.
 *      On entry *GEN must be in state Idle or Undefined.
 *      On return it is Idle.  (Idempotent.)
 *
 *  int libxl__ev_KIND_isregistered(const libxl__ev_KIND *GEN);
 *      On entry *GEN must be Idle or Active.
 *      Returns nonzero if it is Active, zero otherwise.
 *      Cannot fail.
 *
 *  int libxl__ev_KIND_modify(libxl__gc*, libxl__ev_KIND *GEN,
 *                            DETAILS);
 *      Only provided for some kinds of generator.
 *      On entry *GEN must be Active and on return, whether successful
 *      or not, it will be Active.
 *      Returns a libxl error code; on error the modification
 *      is not effective.
 *
 * All of these functions are fully threadsafe and may be called by
 * general code in libxl even from within event callback FUNCs.
 * The ctx will be locked on entry to each FUNC and FUNC should not
 * unlock it.
 *
 * Callers of libxl__ev_KIND_register must ensure that the
 * registration is undone, with _deregister, in libxl_ctx_free.
 * This means that normally each kind of libxl__evgen (ie each
 * application-requested event source) needs to be on a list so that
 * it can be automatically deregistered as promised in libxl_event.h.
 */


_hidden int libxl__ev_fd_register(libxl__gc*, libxl__ev_fd *ev_out,
                                  libxl__ev_fd_callback*,
                                  int fd, short events /* as for poll(2) */);
_hidden int libxl__ev_fd_modify(libxl__gc*, libxl__ev_fd *ev,
                                short events);
_hidden void libxl__ev_fd_deregister(libxl__gc*, libxl__ev_fd *ev);
static inline void libxl__ev_fd_init(libxl__ev_fd *efd)
                    { efd->fd = -1; }
static inline int libxl__ev_fd_isregistered(const libxl__ev_fd *efd)
                    { return efd->fd >= 0; }

_hidden int libxl__ev_time_register_rel(libxl__ao*, libxl__ev_time *ev_out,
                                        libxl__ev_time_callback*,
                                        int milliseconds /* as for poll(2) */);
_hidden int libxl__ev_time_register_abs(libxl__ao*, libxl__ev_time *ev_out,
                                        libxl__ev_time_callback*,
                                        struct timeval);
_hidden int libxl__ev_time_modify_rel(libxl__gc*, libxl__ev_time *ev,
                                      int milliseconds /* as for poll(2) */);
_hidden int libxl__ev_time_modify_abs(libxl__gc*, libxl__ev_time *ev,
                                      struct timeval);
_hidden void libxl__ev_time_deregister(libxl__gc*, libxl__ev_time *ev);
static inline void libxl__ev_time_init(libxl__ev_time *ev)
                { ev->func = 0; libxl__ao_abortable_init(&ev->abrt); }
static inline int libxl__ev_time_isregistered(const libxl__ev_time *ev)
                { return !!ev->func; }


_hidden int libxl__ev_xswatch_register(libxl__gc*, libxl__ev_xswatch *xsw_out,
                                       libxl__ev_xswatch_callback*,
                                       const char *path /* copied */);
_hidden void libxl__ev_xswatch_deregister(libxl__gc *gc, libxl__ev_xswatch*);

static inline void libxl__ev_xswatch_init(libxl__ev_xswatch *xswatch_out)
                { xswatch_out->slotnum = -1; }
static inline int libxl__ev_xswatch_isregistered(const libxl__ev_xswatch *xw)
                { return xw->slotnum >= 0; }


/*
 * The evtchn facility is one-shot per call to libxl__ev_evtchn_wait.
 * You should:
 *   Use libxl__ctx_evtchn_init to make sure CTX->xce is valid;
 *   Call some suitable xc bind function on (or to obtain) the port;
 *   Then call libxl__ev_evtchn_wait.
 *
 * When the event is signaled then the callback will be made, once.
 * Then you must call libxl__ev_evtchn_wait again, if desired.
 *
 * You must NOT call xenevtchn_unmask.  wait will do that for you.
 *
 * Calling libxl__ev_evtchn_cancel will arrange for libxl to disregard
 * future occurrences of event.  Both libxl__ev_evtchn_wait and
 * libxl__ev_evtchn_cancel are idempotent.
 *
 * (Note of course that an event channel becomes signaled when it is
 * first bound, so you will get one call to libxl__ev_evtchn_wait
 * "right away"; unless you have won a very fast race, the condition
 * you were waiting for won't exist yet so when you check for it
 * you'll find you need to call wait again.)
 *
 * You must not wait on the same port twice at once (that is, with
 * two separate libxl__ev_evtchn's).
 */
_hidden int libxl__ev_evtchn_wait(libxl__gc*, libxl__ev_evtchn *evev);
_hidden void libxl__ev_evtchn_cancel(libxl__gc *gc, libxl__ev_evtchn *evev);

static inline void libxl__ev_evtchn_init(libxl__ev_evtchn *evev)
                { evev->waiting = 0; }
static inline bool libxl__ev_evtchn_iswaiting(const libxl__ev_evtchn *evev)
                { return evev->waiting; }

_hidden int libxl__ctx_evtchn_init(libxl__gc *gc); /* for libxl_ctx_alloc */

/*
 * For making subprocesses.  This is the only permitted mechanism for
 * code in libxl to do so.
 *
 * In the parent, returns the pid, filling in childw_out.
 * In the child, returns 0.
 * If it fails, returns a libxl error (all of which are -ve).
 *
 * The child should go on to exec (or exit) soon.  The child may not
 * make any further calls to libxl infrastructure, except for memory
 * allocation and logging.  If the child needs to use xenstore it
 * must open its own xs handle and use it directly, rather than via
 * the libxl event machinery.
 *
 * The parent may signal the child but it must not reap it.  That will
 * be done by the event machinery.
 *
 * The child death event will generate exactly one event callback; until
 * then the childw is Active and may not be reused.
 *
 * libxl__ev_child_kill_deregister: Active -> Idle
 *   This will transfer ownership of the child process death event from
 *   `ch' to `ao', thus deregister the callback.
 *   The `ao' completion will wait until the child have been reaped by the
 *   event machinery.
 */
_hidden pid_t libxl__ev_child_fork(libxl__gc *gc, libxl__ev_child *childw_out,
                                 libxl__ev_child_callback *death);
static inline void libxl__ev_child_init(libxl__ev_child *childw_out)
                { childw_out->pid = -1; }
static inline int libxl__ev_child_inuse(const libxl__ev_child *childw_out)
                { return childw_out->pid >= 0; }
_hidden void libxl__ev_child_kill_deregister(libxl__ao *ao,
                                             libxl__ev_child *ch,
                                             int sig);

/* Useable (only) in the child to once more make the ctx useable for
 * xenstore operations.  logs failure in the form "what: <error
 * message>". */
_hidden int libxl__ev_child_xenstore_reopen(libxl__gc *gc, const char *what);


/*
 * Other event-handling support provided by the libxl event core to
 * the rest of libxl.
 */

_hidden void libxl__event_occurred(libxl__egc*, libxl_event *event);
  /* Arranges to notify the application that the event has occurred.
   * event should be suitable for passing to libxl_event_free. */

_hidden libxl_event *libxl__event_new(libxl__egc*, libxl_event_type,
                                      uint32_t domid,
                                      libxl_ev_user for_user);
  /* Convenience function.
   * Allocates a new libxl_event, fills in domid and type.
   * Cannot fail. */

#define NEW_EVENT(egc, type, domid, user)                        \
    libxl__event_new((egc), LIBXL_EVENT_TYPE_##type, (domid), (user))
    /* Convenience macro. */

/*
 * In general, call this via the macro LIBXL__EVENT_DISASTER.
 *
 * Event-generating functions, or ao machinery, may call this if they
 * might have wanted to generate an event (either an internal one ie a
 * libxl__ev_FOO_callback or an application event), but are prevented
 * from doing so due to eg lack of memory.
 *
 * NB that this function may return and the caller isn't supposed to
 * then crash, although it may fail (and henceforth leave things in a
 * state where many or all calls fail).
 */
_hidden void libxl__event_disaster(libxl__gc*, const char *msg, int errnoval,
                                   libxl_event_type type /* may be 0 */,
                                   const char *file, int line,
                                   const char *func);
#define LIBXL__EVENT_DISASTER(gc, msg, errnoval, type) \
    libxl__event_disaster(gc, msg, errnoval, type, __FILE__,__LINE__,__func__)


/* Fills in, or disposes of, the resources held by, a poller whose
 * space the caller has allocated.  ctx must be locked. */
_hidden int libxl__poller_init(libxl__gc *gc, libxl__poller *p);
_hidden void libxl__poller_dispose(libxl__poller *p);

/* Obtain a fresh poller from malloc or the idle list, and put it
 * away again afterwards.  _get can fail, returning NULL.
 * ctx must be locked. */
_hidden libxl__poller *libxl__poller_get(libxl__gc *gc);
_hidden void libxl__poller_put(libxl_ctx*, libxl__poller *p /* may be NULL */);

/* Notifies whoever is polling using p that they should wake up.
 * ctx must be locked. */
_hidden void libxl__poller_wakeup(libxl__gc *egc, libxl__poller *p);

/* Internal to fork and child reaping machinery */
extern const libxl_childproc_hooks libxl__childproc_default_hooks;
int libxl__sigchld_needed(libxl__gc*); /* non-reentrant idempotent, logs errs */
void libxl__sigchld_notneeded(libxl__gc*); /* non-reentrant idempotent */
void libxl__sigchld_check_stale_handler(void);
int libxl__self_pipe_wakeup(int fd); /* returns 0 or -1 setting errno */
int libxl__self_pipe_eatall(int fd); /* returns 0 or -1 setting errno */


_hidden int libxl__atfork_init(libxl_ctx *ctx);


/* File references */
typedef struct {
    /*
     * Path is always set if the file reference is valid. However if
     * mapped is true then the actual file may already be unlinked.
     */
    const char * path;
    int mapped;
    void * data;
    size_t size;
} libxl__file_reference;
_hidden int libxl__file_reference_map(libxl__file_reference *f);
_hidden int libxl__file_reference_unmap(libxl__file_reference *f);

/* from xl_dom */
_hidden libxl_domain_type libxl__domain_type(libxl__gc *gc, uint32_t domid);
_hidden int libxl__domain_cpupool(libxl__gc *gc, uint32_t domid);
_hidden libxl_scheduler libxl__domain_scheduler(libxl__gc *gc, uint32_t domid);
_hidden int libxl__sched_set_params(libxl__gc *gc, uint32_t domid,
                                    libxl_domain_sched_params *scparams);
_hidden int libxl__grant_vga_iomem_permission(libxl__gc *gc, const uint32_t domid,
                                              libxl_domain_config *const d_config);

typedef struct {
    uint32_t store_port;
    uint32_t store_domid;
    unsigned long store_mfn;

    uint32_t console_port;
    uint32_t console_domid;
    unsigned long console_mfn;
    char *console_tty;

    char *saved_state;
    int dm_monitor_fd;

    libxl__file_reference pv_kernel;
    libxl__file_reference pv_ramdisk;
    const char *shim_path;
    const char *shim_cmdline;
    const char *pv_cmdline;

    /* 
     * dm_runas: If set, pass qemu the `-runas` parameter with this
     *  string as an argument
     * dm_kill_uid: If set, the devicemodel should be killed by
     *  destroying all processes with this uid.
     */
    char *dm_runas, *dm_kill_uid;

    xen_vmemrange_t *vmemranges;
    uint32_t num_vmemranges;

    xen_pfn_t vuart_gfn;
    evtchn_port_t vuart_port;

    /* ARM only to deal with broken firmware */
    uint32_t clock_frequency;

    /* Whether this domain is being migrated/restored, or booting fresh.  Only
     * applicable to the primary domain, not support domains (e.g. stub QEMU). */
    bool restore;
} libxl__domain_build_state;

_hidden void libxl__domain_build_state_init(libxl__domain_build_state *s);
_hidden void libxl__domain_build_state_dispose(libxl__domain_build_state *s);

_hidden int libxl__build_pre(libxl__gc *gc, uint32_t domid,
              libxl_domain_config * const d_config,
              libxl__domain_build_state *state);
_hidden int libxl__build_post(libxl__gc *gc, uint32_t domid,
               libxl_domain_build_info *info, libxl__domain_build_state *state,
               char **vms_ents, char **local_ents);

_hidden int libxl__build_pv(libxl__gc *gc, uint32_t domid,
             libxl_domain_config *const d_config, libxl__domain_build_state *state);
_hidden int libxl__build_hvm(libxl__gc *gc, uint32_t domid,
              libxl_domain_config *d_config,
              libxl__domain_build_state *state);

_hidden int libxl__qemu_traditional_cmd(libxl__gc *gc, uint32_t domid,
                                        const char *cmd);
_hidden int libxl__domain_rename(libxl__gc *gc, uint32_t domid,
                                 const char *old_name, const char *new_name,
                                 xs_transaction_t trans);

/* Deprecated, use libxl__dm_resume instead. */
_hidden int libxl__domain_resume_device_model_deprecated(libxl__gc *gc, uint32_t domid);

_hidden const char *libxl__userdata_path(libxl__gc *gc, uint32_t domid,
                                         const char *userdata_userid,
                                         const char *wh);
_hidden void libxl__userdata_destroyall(libxl__gc *gc, uint32_t domid);
/* Caller must hold userdata store lock before calling
 * libxl__userdata_{retrieve,store}
 * See libxl__{un,}lock_domain_userdata.
 */
_hidden int libxl__userdata_retrieve(libxl__gc *gc, uint32_t domid,
                                     const char *userdata_userid,
                                     uint8_t **data_r, int *datalen_r);
_hidden int libxl__userdata_store(libxl__gc *gc, uint32_t domid,
                                  const char *userdata_userid,
                                  const uint8_t *data, int datalen);

/* Deprecated, use libxl__domain_resume instead */
_hidden int libxl__domain_resume_deprecated(libxl__gc *gc, uint32_t domid,
                                            int suspend_cancel);
/* Deprecated, use libxl__domain_unpause instead */
_hidden int libxl__domain_unpause_deprecated(libxl__gc *,
                                             libxl_domid domid);

/* Call libxl__dm_resume_init() and fill the first few fields,
 * then call one of libxl__domain_resume / libxl__domain_unpause
 * or directly libxl__dm_resume if only the device model needs to be
 * "resumed". */
struct libxl__dm_resume_state {
    /* caller must fill these in, and they must all remain valid */
    libxl__ao *ao;
    libxl_domid domid;
    void (*callback)(libxl__egc *, libxl__dm_resume_state *, int rc);

    /* private to libxl__domain_resume and libxl__domain_unpause */
    void (*dm_resumed_callback)(libxl__egc *,
                                libxl__dm_resume_state *, int rc);
    /* private to libxl__domain_resume */
    bool suspend_cancel;

    /* private to libxl__dm_resume */
    libxl__ev_qmp qmp;
    libxl__ev_time time;
    libxl__ev_xswatch watch;
};
_hidden void libxl__dm_resume(libxl__egc *egc,
                              libxl__dm_resume_state *dmrs);
_hidden void libxl__domain_resume(libxl__egc *egc,
                                  libxl__dm_resume_state *dmrs,
                                  bool suspend_cancel);
_hidden void libxl__domain_unpause(libxl__egc *,
                                   libxl__dm_resume_state *dmrs);

/* returns 0 or 1, or a libxl error code */
_hidden int libxl__domain_pvcontrol_available(libxl__gc *gc, uint32_t domid);

_hidden const char *libxl__domain_pvcontrol_xspath(libxl__gc*, uint32_t domid);
_hidden char * libxl__domain_pvcontrol_read(libxl__gc *gc,
                                            xs_transaction_t t, uint32_t domid);

/* from xl_device */
_hidden char *libxl__device_disk_string_of_backend(libxl_disk_backend backend);
_hidden char *libxl__device_disk_string_of_format(libxl_disk_format format);
_hidden const char *libxl__qemu_disk_format_string(libxl_disk_format format);
_hidden int libxl__device_disk_set_backend(libxl__gc*, libxl_device_disk*);

_hidden int libxl__device_physdisk_major_minor(const char *physpath, int *major, int *minor);
_hidden int libxl__device_disk_dev_number(const char *virtpath,
                                          int *pdisk, int *ppartition);
_hidden char *libxl__devid_to_vdev(libxl__gc *gc, int devid);

_hidden int libxl__device_console_add(libxl__gc *gc, uint32_t domid,
                                      libxl__device_console *console,
                                      libxl__domain_build_state *state,
                                      libxl__device *device);
_hidden int libxl__device_vuart_add(libxl__gc *gc, uint32_t domid,
                                    libxl__device_console *console,
                                    libxl__domain_build_state *state);

/* Returns 1 if device exists, 0 if not, ERROR_* (<0) on error. */
_hidden int libxl__device_exists(libxl__gc *gc, xs_transaction_t t,
                                 libxl__device *device);
_hidden int libxl__device_generic_add(libxl__gc *gc, xs_transaction_t t,
        libxl__device *device, char **bents, char **fents, char **ro_fents);
_hidden char *libxl__domain_device_frontend_path(libxl__gc *gc, uint32_t domid, uint32_t devid,
                                                 libxl__device_kind device_kind);
_hidden char *libxl__device_backend_path(libxl__gc *gc, libxl__device *device);
_hidden char *libxl__domain_device_backend_path(libxl__gc *gc, uint32_t backend_domid,
                                                uint32_t domid, uint32_t devid,
                                                libxl__device_kind device_kind);
_hidden char *libxl__device_libxl_path(libxl__gc *gc, libxl__device *device);
_hidden char *libxl__domain_device_libxl_path(libxl__gc *gc, uint32_t domid, uint32_t devid,
                                              libxl__device_kind device_kind);
_hidden int libxl__parse_backend_path(libxl__gc *gc, const char *path,
                                      libxl__device *dev);
_hidden int libxl__console_tty_path(libxl__gc *gc, uint32_t domid, int cons_num,
                                    libxl_console_type type, char **tty_path);
_hidden int libxl__device_destroy(libxl__gc *gc, libxl__device *dev);
_hidden int libxl__wait_for_backend(libxl__gc *gc, const char *be_path,
                                    const char *state);
_hidden int libxl__nic_type(libxl__gc *gc, libxl__device *dev,
                            libxl_nic_type *nictype);
_hidden int libxl__init_console_from_channel(libxl__gc *gc,
                                             libxl__device_console *console,
                                             int dev_num,
                                             libxl_device_channel *channel);
_hidden int libxl__device_nextid(libxl__gc *gc, uint32_t domid,
                                 libxl__device_kind device);
_hidden int libxl__resolve_domid(libxl__gc *gc, const char *name,
                                 uint32_t *domid);

/*
 * For each aggregate type which can be used as an input we provide:
 *
 * int libxl__<type>_setdefault(gc, <type> *p):
 *
 *     Idempotently sets any members of "p" which is currently set to
 *     a special value indicating that the defaults should be used
 *     (per libxl_<type>_init) to a specific value.
 *
 *     All libxl API functions are expected to have arranged for this
 *     to be called before using any values within these structures.
 */
_hidden int libxl__domain_config_setdefault(libxl__gc *gc,
                                            libxl_domain_config *d_config,
                                            uint32_t domid /* logging only */);
_hidden int libxl__domain_create_info_setdefault(libxl__gc *gc,
                                        libxl_domain_create_info *c_info,
                                        const libxl_physinfo *info);
_hidden int libxl__domain_build_info_setdefault(libxl__gc *gc,
                                        libxl_domain_build_info *b_info);
_hidden void libxl__rdm_setdefault(libxl__gc *gc,
                                   libxl_domain_build_info *b_info);

_hidden int libxl__domain_need_memory_calculate(libxl__gc *gc,
                                      libxl_domain_build_info *b_info,
                                      uint64_t *need_memkb);

_hidden const char *libxl__device_nic_devname(libxl__gc *gc,
                                              uint32_t domid,
                                              uint32_t devid,
                                              libxl_nic_type type);

_hidden int libxl__get_domid(libxl__gc *gc, uint32_t *domid);

/*----- xswait: wait for a xenstore node to be suitable -----*/

typedef struct libxl__xswait_state libxl__xswait_state;

/*
 * rc describes the circumstances of this callback:
 *
 * rc==0
 *
 *     The xenstore path (may have) changed.  It has been read for
 *     you.  The result is in data (allocated from the ao gc).
 *     data may be NULL, which means that the xenstore read gave
 *     ENOENT.
 *
 *     If you are satisfied, you MUST call libxl__xswait_stop.
 *     Otherwise, xswait will continue waiting and watching and
 *     will call you back later.
 *
 * rc==ERROR_TIMEDOUT, rc==ERROR_ABORTED
 *
 *     The specified timeout was reached.
 *     This has NOT been logged (except to the debug log).
 *     xswait will not continue (but calling libxl__xswait_stop is OK).
 *
 * rc!=0, !=ERROR_TIMEDOUT, !=ERROR_ABORTED
 *
 *     Some other error occurred.
 *     This HAS been logged.
 *     xswait will not continue (but calling libxl__xswait_stop is OK).
 *
 * xswait.path may start with with '@', in which case no read is done
 * and the callback will always get data==0.
 */
typedef void libxl__xswait_callback(libxl__egc *egc,
      libxl__xswait_state *xswa, int rc, const char *data);

struct libxl__xswait_state {
    /* caller must fill these in, and they must all remain valid */
    libxl__ao *ao;
    const char *what; /* for error msgs: noun phrase, what we're waiting for */
    const char *path;
    int timeout_ms; /* as for poll(2) */
    libxl__xswait_callback *callback;
    /* remaining fields are private to xswait */
    libxl__ev_time time_ev;
    libxl__ev_xswatch watch_ev;
};

void libxl__xswait_init(libxl__xswait_state*);
void libxl__xswait_stop(libxl__gc*, libxl__xswait_state*); /*idempotent*/
bool libxl__xswait_inuse(const libxl__xswait_state *ss);

int libxl__xswait_start(libxl__gc*, libxl__xswait_state*);

/*
 * libxl__ev_devstate - waits a given time for a device to
 * reach a given state.  Follows the libxl_ev_* conventions.
 * Will generate only one event, and after that is automatically
 * cancelled.
 */
typedef struct libxl__ev_devstate libxl__ev_devstate;
typedef void libxl__ev_devstate_callback(libxl__egc *egc, libxl__ev_devstate*,
                                         int rc);
  /* rc will be 0, ERROR_TIMEDOUT, ERROR_ABORTED, ERROR_INVAL
   * (meaning path was removed), or ERROR_FAIL if other stuff went
   * wrong (in which latter case, logged) */

struct libxl__ev_devstate {
    /* read-only for caller, who may read only when waiting: */
    int wanted;
    libxl__ev_devstate_callback *callback;
    /* as for the remainder, read-only public parts may also be
     * read by the caller (notably, watch.path), but only when waiting: */
    libxl__xswait_state w;
};

static inline void libxl__ev_devstate_init(libxl__ev_devstate *ds)
{
    libxl__xswait_init(&ds->w);
}

static inline void libxl__ev_devstate_cancel(libxl__gc *gc,
                                             libxl__ev_devstate *ds)
{
    libxl__xswait_stop(gc,&ds->w);
}

_hidden int libxl__ev_devstate_wait(libxl__ao *ao, libxl__ev_devstate *ds,
                                    libxl__ev_devstate_callback cb,
                                    const char *state_path,
                                    int state, int milliseconds);

/*
 * libxl__ev_domaindeathcheck_register - arranges to call back (once)
 * if the domain is destroyed.  If the domain dies, we log a message
 * of the form "<what>: <explanation of the situation, including the domid>".
 */

typedef struct libxl__domaindeathcheck libxl__domaindeathcheck;
typedef void libxl___domaindeathcheck_callback(libxl__egc *egc,
        libxl__domaindeathcheck*,
        int rc /* DESTROYED or ABORTED */);

struct libxl__domaindeathcheck {
    /* must be filled in by caller, and remain valid: */
    const char *what;
    uint32_t domid;
    libxl___domaindeathcheck_callback *callback;
    /* private */
    libxl__ao_abortable abrt;
    libxl__ev_xswatch watch;
};

_hidden int libxl__domaindeathcheck_start(libxl__ao *ao,
                                          libxl__domaindeathcheck *dc);

void libxl__domaindeathcheck_init(libxl__domaindeathcheck *dc);
void libxl__domaindeathcheck_stop(libxl__gc *gc, libxl__domaindeathcheck *dc);


/*
 * libxl__try_phy_backend - Check if there's support for the passed
 * type of file using the PHY backend
 * st_mode: mode_t of the file, as returned by stat function
 *
 * Returns 1 on success, and 0 if not suitable for phy backend.
 */
_hidden int libxl__try_phy_backend(mode_t st_mode);


_hidden char *libxl__devid_to_localdev(libxl__gc *gc, int devid);

_hidden int libxl__pci_numdevs(libxl__gc *gc);
_hidden int libxl__pci_topology_init(libxl__gc *gc,
                                     physdev_pci_device_t *devs,
                                     int num_devs);

/* from libxl_pci */

_hidden void libxl__device_pci_add(libxl__egc *egc, uint32_t domid,
                                   libxl_device_pci *pcidev, bool starting,
                                   libxl__ao_device *aodev);
_hidden void libxl__device_pci_destroy_all(libxl__egc *egc, uint32_t domid,
                                           libxl__multidev *);
_hidden int libxl__device_pci_setdefault(libxl__gc *gc, uint32_t domid,
                                         libxl_device_pci *pci, bool hotplug);
_hidden bool libxl__is_igd_vga_passthru(libxl__gc *gc,
                                        const libxl_domain_config *d_config);

/* from libxl_dtdev */

_hidden int libxl__device_dt_add(libxl__gc *gc, uint32_t domid,
                                 const libxl_device_dtdev *dtdev);

/*
 *----- spawn -----
 *
 * Higher-level double-fork and separate detach eg as for device models
 *
 * Each libxl__spawn_state is in one of these states
 *    Undefined, Idle, Attached, Detaching
 */

typedef struct libxl__obsolete_spawn_starting libxl__spawn_starting;
/* this type is never defined, so no objects of this type exist
 * fixme-ao  This should go away completely.  */

typedef struct libxl__spawn_state libxl__spawn_state;

/* Clears out a spawn state; idempotent. */
_hidden void libxl__spawn_init(libxl__spawn_state*);

/*
 * libxl__spawn_spawn - Create a new process which will become daemonic
 * Forks twice, to allow the child to detach entirely from the parent.
 *
 * We call the two generated processes the "middle child" (result of
 * the first fork) and the "inner child" (result of the second fork
 * which takes place in the middle child).
 *
 * The inner child must soon exit or exec.  It must also soon exit or
 * notify the parent of its successful startup by writing to the
 * xenstore path xspath OR via other means that the parent will have
 * to set up.
 *
 * The user (in the parent) will be called back (confirm_cb) every
 * time that xenstore path is modified.
 *
 * In both children, the ctx is not fully usable: gc and logging
 * operations are OK, but operations on Xen and xenstore are not.
 * (The restrictions are the same as those which apply to children
 * made with libxl__ev_child_fork.)
 *
 * midproc_cb will be called in the middle child, with the pid of the
 * inner child; this could for example record the pid.  midproc_cb
 * should be fast, and should return.  It will be called (reentrantly)
 * within libxl__spawn_init.
 *
 * failure_cb will be called in the parent on failure of the
 * intermediate or final child; an error message will have been
 * logged.
 *
 * confirm_cb, failure_cb and detached_cb will not be called
 * reentrantly from within libxl__spawn_spawn.
 *
 * what: string describing the spawned process, used for logging
 *
 * Logs errors.  A copy of "what" is taken.
 * Return values:
 *  < 0   error, *spawn is now Idle and need not be detached
 *   +1   caller is the parent, *spawn is Attached and must be detached
 *    0   caller is now the inner child, should probably call libxl__exec
 *
 * The spawn state must be Undefined or Idle on entry.
 */
_hidden int libxl__spawn_spawn(libxl__egc *egc, libxl__spawn_state *spawn);

/*
 * libxl__spawn_request_detach - Detaches the daemonic child.
 *
 * Works by killing the intermediate process from spawn_spawn.
 * After this function returns, failures of either child are no
 * longer reported via failure_cb.
 *
 * This is not synchronous: there will be a further callback when
 * the detach is complete.
 *
 * If called before the inner child has been created, this may prevent
 * it from running at all.  Thus this should be called only when the
 * inner child has notified that it is ready.  Normally it will be
 * called from within confirm_cb.
 *
 * Logs errors.
 *
 * The spawn state must be Attached entry and will be Detaching
 * on return.
 */
_hidden void libxl__spawn_initiate_detach(libxl__gc *gc, libxl__spawn_state*);

/*
 * libxl__spawn_initiate_failure - Propagate failure from the caller to the
 * callee.
 *
 * Works by killing the intermediate process from spawn_spawn.
 * After this function returns, a failure will be reported.
 *
 * This is not synchronous: there will be a further callback when
 * the detach is complete.
 *
 * Caller must have logged a failure reason.
 *
 * The spawn state must be Attached on entry and will remain Attached. It
 * is possible for a spawn to fail for multiple reasons, for example
 * call(s) to libxl__spawn_initiate_failure and also for some other reason.
 * In that case the first rc value from any source will take precedence.
 */
_hidden void libxl__spawn_initiate_failure(libxl__egc *egc,
                                           libxl__spawn_state *ss, int rc);

/*
 * If successful, this should return 0.
 *
 * Otherwise it should return a signal number, which will be
 * sent to the inner child; the overall spawn will then fail.
 */
typedef int /* signal number */
libxl__spawn_midproc_cb(libxl__gc*, libxl__spawn_state*, pid_t inner);

/*
 * Called if the spawn failed.  The reason will have been logged.
 * The spawn state will be Idle on entry to the callback (and
 * it may be reused immediately if desired).
 */
typedef void libxl__spawn_failure_cb(libxl__egc*, libxl__spawn_state*,
                                     int rc);

/*
 * Called when the xspath watch triggers.  xspath will have been read
 * and the result placed in xsdata; if that failed because the key
 * didn't exist, xspath==0.  (If it failed for some other reason,
 * the spawn machinery calls failure_cb instead.)
 *
 * If the child has indicated its successful startup, or a failure
 * has occurred, this should call libxl__spawn_detach.
 *
 * If the child is still starting up, should simply return, doing
 * nothing.
 *
 * The spawn state will be Active on entry to the callback; there
 * are no restrictions on the state on return; it may even have
 * been detached and reused.
 */
typedef void libxl__spawn_confirm_cb(libxl__egc*, libxl__spawn_state*,
                                     const char *xsdata);

/*
 * Called when the detach (requested by libxl__spawn_initiate_detach) has
 * completed.  On entry to the callback the spawn state is Idle.
 */
typedef void libxl__spawn_detached_cb(libxl__egc*, libxl__spawn_state*);

struct libxl__spawn_state {
    /* must be filled in by user and remain valid */
    libxl__ao *ao;
    const char *what;
    const char *xspath;
    const char *pidpath; /* only used by libxl__spawn_midproc_record_pid */
    int timeout_ms; /* -1 means forever */
    libxl__spawn_midproc_cb *midproc_cb;
    libxl__spawn_failure_cb *failure_cb;
    libxl__spawn_confirm_cb *confirm_cb;
    libxl__spawn_detached_cb *detached_cb;

    /* remaining fields are private to libxl_spawn_... */
    int detaching; /* we are in Detaching */
    int rc; /* might be non-0 whenever we are not Idle */
    libxl__ev_child mid; /* always in use whenever we are not Idle */
    libxl__xswait_state xswait;
};

static inline int libxl__spawn_inuse(const libxl__spawn_state *ss)
    { return libxl__ev_child_inuse(&ss->mid); }

/*
 * libxl_spawner_record_pid - Record given pid in xenstore
 *
 * This function can be passed directly as an intermediate_hook to
 * libxl__spawn_spawn.  On failure, returns the value SIGTERM.
 */
_hidden int libxl__spawn_record_pid(libxl__gc*, libxl__spawn_state*,
                                    pid_t innerchild);

/*
 * libxl__xenstore_child_wait_deprecated - Wait for daemonic child IPC
 *
 * This is a NOT function for waiting for ordinary child processes.
 * If you want to run (fork/exec/wait) subprocesses from libxl:
 *  - Make your libxl entrypoint use the ao machinery
 *  - Use libxl__ev_child_fork, and use the callback programming style
 *
 * This function is intended for interprocess communication with a
 * service process.  If the service process does not respond quickly,
 * the whole caller may be blocked.  Therefore this function is
 * deprecated.  This function is currently used only by
 * libxl__wait_for_device_model_deprecated.
 *
 * gc: allocation pool
 * domid: guest to work with
 * timeout: how many seconds to wait for the state to appear
 * what: string describing the spawned process
 * path: path to the state file in xenstore
 * state: expected string to wait for in path (optional)
 * spawning: malloc'd pointer to libxl__spawn_starting (optional)
 * check_callback: (optional)
 * check_callback_userdata: data to pass to the callback function
 *
 * Returns 0 on success, and < 0 on error.
 *
 * This function waits the given timeout for the given path to appear
 * in xenstore, and optionally for state in path.
 * If path appears and state matches, check_callback is called.
 * If check_callback returns > 0, waiting for path or state continues.
 * Otherwise libxl__xenstore_child_wait_deprecated returns.
 */
_hidden int libxl__xenstore_child_wait_deprecated(libxl__gc *gc,
                                 uint32_t domid,
                                 uint32_t timeout, char *what,
                                 char *path, char *state,
                                 libxl__spawn_starting *spawning,
                                 int (*check_callback)(libxl__gc *gc,
                                                       uint32_t domid,
                                                       const char *state,
                                                       void *userdata),
                                 void *check_callback_userdata);


 /* low-level stuff, for synchronous subprocesses etc. */

/*
 * env should be passed using the following format,
 *
 * env[0]: name of env variable
 * env[1]: value of env variable
 * env[n]: ...
 *
 * So it efectively becomes something like:
 * export env[n]=env[n+1]
 * (where n%2 = 0)
 *
 * The last entry of the array always has to be NULL.
 *
 * stdinfd, stdoutfd, stderrfd will be dup2'd onto the corresponding
 * fd in the child, if they are not -1.  The original copy of the
 * descriptor will be closed in the child (unless it's 0, 1 or 2
 * ie the source descriptor is itself stdin, stdout or stderr).
 *
 * Logs errors, never returns.
 */
_hidden  void libxl__exec(libxl__gc *gc, int stdinfd, int stdoutfd,
                          int stderrfd, const char *arg0, char *const args[],
                          char *const env[]) __attribute__((noreturn));

/* from xl_create */

 /* on entry, libxl_domid_valid_guest(domid) must be false;
  * on exit (even error exit), domid may be valid and refer to a domain */
_hidden int libxl__domain_make(libxl__gc *gc,
                               libxl_domain_config *d_config,
                               libxl__domain_build_state *state,
                               uint32_t *domid, bool soft_reset);

_hidden int libxl__domain_build(libxl__gc *gc,
                                libxl_domain_config *d_config,
                                uint32_t domid,
                                libxl__domain_build_state *state);

/* for device model creation */
_hidden const char *libxl__domain_device_model(libxl__gc *gc,
                                        const libxl_domain_build_info *info);
_hidden int libxl__need_xenpv_qemu(libxl__gc *gc,
                                   libxl_domain_config *d_config);
_hidden bool libxl__query_qemu_backend(libxl__gc *gc,
                                       uint32_t domid,
                                       uint32_t backend_id,
                                       const char *type,
                                       bool def);
_hidden int libxl__dm_active(libxl__gc *gc, uint32_t domid);
_hidden int libxl__dm_check_start(libxl__gc *gc,
                                  libxl_domain_config *d_config,
                                  uint32_t domid);

/*
 * This function will fix reserved device memory conflict
 * according to user's configuration.
 */
_hidden int libxl__domain_device_construct_rdm(libxl__gc *gc,
                                   libxl_domain_config *d_config,
                                   uint64_t rdm_mem_guard,
                                   struct xc_dom_image *dom);

/*
 * This function will cause the whole libxl process to hang
 * if the device model does not respond.  It is deprecated.
 *
 * Instead of calling this function:
 *  - Make your libxl entrypoint use the ao machinery
 *  - Use libxl__ev_xswatch_register, and use the callback programming
 *    style
 */
_hidden int libxl__wait_for_device_model_deprecated(libxl__gc *gc,
                                uint32_t domid, char *state,
                                libxl__spawn_starting *spawning
                                                    /* NULL allowed */,
                                int (*check_callback)(libxl__gc *gc,
                                                      uint32_t domid,
                                                      const char *state,
                                                      void *userdata),
                                void *check_callback_userdata);

_hidden const libxl_vnc_info *libxl__dm_vnc(const libxl_domain_config *g_cfg);

_hidden char *libxl__abs_path(libxl__gc *gc, const char *s, const char *path);

#define LIBXL__LOG_DEBUG   XTL_DEBUG
#define LIBXL__LOG_VERBOSE XTL_VERBOSE
#define LIBXL__LOG_INFO    XTL_INFO
#define LIBXL__LOG_WARNING XTL_WARN
#define LIBXL__LOG_ERROR   XTL_ERROR

_hidden char *libxl__domid_to_name(libxl__gc *gc, uint32_t domid);
_hidden char *libxl__cpupoolid_to_name(libxl__gc *gc, uint32_t poolid);

_hidden int libxl__enum_from_string(const libxl_enum_string_table *t,
                                    const char *s, int *e) NN(2);

_hidden yajl_gen_status libxl__yajl_gen_asciiz(yajl_gen hand, const char *str);

_hidden yajl_gen_status libxl__string_gen_json(yajl_gen hand, const char *p);

typedef yajl_gen_status (*libxl__gen_json_callback)(yajl_gen hand, void *);
_hidden char *libxl__object_to_json(libxl_ctx *ctx, const char *type,
                                    libxl__gen_json_callback gen, void *p);

_hidden void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool retore,
                                 libxl_domain_build_info *info);

/* Calls poll() again - useful to check whether a signaled condition
 * is still true.  Cannot fail.  Returns currently-true revents. */
_hidden short libxl__fd_poll_recheck(libxl__egc *egc, int fd, short events);

_hidden char *libxl__uuid2string(libxl__gc *gc, const libxl_uuid uuid);

struct libxl__xen_console_reader {
    char *buffer;
    unsigned int size;
    unsigned int count;
    unsigned int clear;
    unsigned int incremental;
    unsigned int index;
};

/* parse the string @s as a sequence of 6 colon separated bytes in to @mac */
_hidden int libxl__parse_mac(const char *s, libxl_mac mac);
/* compare mac address @a and @b. 0 if the same, -ve if a<b and +ve if a>b */
_hidden int libxl__compare_macs(libxl_mac *a, libxl_mac *b);
/* return true if mac address is all zero (the default value) */
_hidden int libxl__mac_is_default(libxl_mac *mac);
/* init a recursive mutex */
_hidden int libxl__init_recursive_mutex(libxl_ctx *ctx, pthread_mutex_t *lock);

_hidden int libxl__gettimeofday(libxl__gc *gc, struct timeval *now_r);

#define STRINGIFY(x) #x
#define TOSTRING(x) STRINGIFY(x)

/* from libxl_qmp */
typedef struct libxl__qmp_handler libxl__qmp_handler;

/* Initialise and connect to the QMP socket.
 *   Return an handler or NULL if there is an error
 */
_hidden libxl__qmp_handler *libxl__qmp_initialize(libxl__gc *gc,
                                                  uint32_t domid);
/* Resume QEMU. */
_hidden int libxl__qmp_resume(libxl__gc *gc, int domid);
/* Load current QEMU state from file. */
_hidden int libxl__qmp_restore(libxl__gc *gc, int domid, const char *filename);
/* Start NBD server */
_hidden int libxl__qmp_nbd_server_start(libxl__gc *gc, int domid,
                                        const char *host, const char *port);
/* Add a disk to NBD server */
_hidden int libxl__qmp_nbd_server_add(libxl__gc *gc, int domid,
                                      const char *disk);
/* Start replication */
_hidden int libxl__qmp_start_replication(libxl__gc *gc, int domid,
                                         bool primary);
/* Get replication error that occurs when the vm is running */
_hidden int libxl__qmp_query_xen_replication_status(libxl__gc *gc, int domid);
/* Do checkpoint */
_hidden int libxl__qmp_colo_do_checkpoint(libxl__gc *gc, int domid);
/* Stop replication */
_hidden int libxl__qmp_stop_replication(libxl__gc *gc, int domid,
                                        bool primary);
/* Stop NBD server */
_hidden int libxl__qmp_nbd_server_stop(libxl__gc *gc, int domid);
/* Add or remove a child to/from quorum */
_hidden int libxl__qmp_x_blockdev_change(libxl__gc *gc, int domid,
                                         const char *parant,
                                         const char *child, const char *node);
/* run a hmp command in qmp mode */
_hidden int libxl__qmp_hmp(libxl__gc *gc, int domid, const char *command_line,
                           char **out);
/* close and free the QMP handler */
_hidden void libxl__qmp_close(libxl__qmp_handler *qmp);
/* remove the socket file, if the file has already been removed,
 * nothing happen */
_hidden void libxl__qmp_cleanup(libxl__gc *gc, uint32_t domid);

/* `data' should contain a byte to send.
 * When dealing with a non-blocking fd, it returns
 *   ERROR_NOT_READY on EWOULDBLOCK
 * logs on other failures. */
int libxl__sendmsg_fds(libxl__gc *gc, int carrier,
                       const char data,
                       int nfds, const int fds[], const char *what);

/* Insists on receiving exactly nfds and datalen.  On failure, logs
 * and leaves *fds untouched. */
int libxl__recvmsg_fds(libxl__gc *gc, int carrier,
                       void *databuf, size_t datalen,
                       int nfds, int fds[], const char *what);

/* from libxl_json */
#include <yajl/yajl_gen.h>

_hidden yajl_gen_status libxl__yajl_gen_asciiz(yajl_gen hand, const char *str);
_hidden yajl_gen_status libxl__yajl_gen_enum(yajl_gen hand, const char *str);

typedef enum {
    JSON_NULL    = (1 << 0),
    JSON_BOOL    = (1 << 1),
    JSON_INTEGER = (1 << 2),
    JSON_DOUBLE  = (1 << 3),
    /* number is store in string, it's too big to be a long long or a double */
    JSON_NUMBER  = (1 << 4),
    JSON_STRING  = (1 << 5),
    JSON_MAP     = (1 << 6),
    JSON_ARRAY   = (1 << 7),
    JSON_ANY     = 255 /* this is a mask of all values above, adjust as needed */
} libxl__json_node_type;

struct libxl__json_object {
    libxl__json_node_type type;
    union {
        bool b;
        long long i;
        double d;
        char *string;
        /* List of libxl__json_object */
        flexarray_t *array;
        /* List of libxl__json_map_node */
        flexarray_t *map;
    } u;
    struct libxl__json_object *parent;
};

typedef int (*libxl__json_parse_callback)(libxl__gc *gc,
                                          libxl__json_object *o,
                                          void *p);
_hidden int libxl__object_from_json(libxl_ctx *ctx, const char *type,
                                    libxl__json_parse_callback parse,
                                    void *p,
                                    const char *s);

typedef struct {
    char *map_key;
    libxl__json_object *obj;
} libxl__json_map_node;

static inline bool libxl__json_object_is_null(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_NULL;
}
static inline bool libxl__json_object_is_bool(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_BOOL;
}
static inline bool libxl__json_object_is_string(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_STRING;
}
static inline bool libxl__json_object_is_integer(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_INTEGER;
}
static inline bool libxl__json_object_is_double(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_DOUBLE;
}
static inline bool libxl__json_object_is_number(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_NUMBER;
}
static inline bool libxl__json_object_is_map(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_MAP;
}
static inline bool libxl__json_object_is_array(const libxl__json_object *o)
{
    return o != NULL && o->type == JSON_ARRAY;
}

/*
 * `o` may be NULL for all libxl__json_object_get_* functions.
 */

static inline bool libxl__json_object_get_bool(const libxl__json_object *o)
{
    if (libxl__json_object_is_bool(o))
        return o->u.b;
    else
        return false;
}
static inline
const char *libxl__json_object_get_string(const libxl__json_object *o)
{
    if (libxl__json_object_is_string(o))
        return o->u.string;
    else
        return NULL;
}
static inline
const char *libxl__json_object_get_number(const libxl__json_object *o)
{
    if (libxl__json_object_is_number(o))
        return o->u.string;
    else
        return NULL;
}
static inline
flexarray_t *libxl__json_object_get_map(const libxl__json_object *o)
{
    if (libxl__json_object_is_map(o))
        return o->u.map;
    else
        return NULL;
}
static inline
flexarray_t *libxl__json_object_get_array(const libxl__json_object *o)
{
    if (libxl__json_object_is_array(o))
        return o->u.array;
    else
        return NULL;
}
static inline long long libxl__json_object_get_integer(const libxl__json_object *o)
{
    if (libxl__json_object_is_integer(o))
        return o->u.i;
    else
        return -1;
}

/*
 * `o` may be NULL for the following libxl__json_*_get functions.
 */

_hidden libxl__json_object *libxl__json_array_get(const libxl__json_object *o,
                                                  int i);
_hidden
libxl__json_map_node *libxl__json_map_node_get(const libxl__json_object *o,
                                               int i);
_hidden const libxl__json_object *libxl__json_map_get(const char *key,
                                          const libxl__json_object *o,
                                          libxl__json_node_type expected_type);

/*
 * NOGC can be used with those json_object functions, but the
 * libxl__json_object* will need to be freed with libxl__json_object_free.
 */
_hidden libxl__json_object *libxl__json_object_alloc(libxl__gc *gc_opt,
                                                     libxl__json_node_type type);
_hidden yajl_status libxl__json_object_to_yajl_gen(libxl__gc *gc_opt,
                                                   yajl_gen hand,
                                                   const libxl__json_object *param);
_hidden void libxl__json_object_free(libxl__gc *gc_opt,
                                     libxl__json_object *obj);

_hidden libxl__json_object *libxl__json_parse(libxl__gc *gc_opt, const char *s);

/* `args` may be NULL */
_hidden char *libxl__json_object_to_json(libxl__gc *gc,
                                         const libxl__json_object *args);
/* Always return a valid string, but invalid json on error. */
#define JSON(o) \
    (libxl__json_object_to_json(gc, (o)) ? : "<invalid-json-object>")

  /* Based on /local/domain/$domid/dm-version xenstore key
   * default is qemu xen traditional */
_hidden int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
  /* Return the system-wide default device model */
_hidden libxl_device_model_version libxl__default_device_model(libxl__gc *gc);

static inline
bool libxl__stubdomain_is_linux_running(libxl__gc *gc, uint32_t domid)
{
    /* same logic as in libxl__stubdomain_is_linux */
    return libxl__device_model_version_running(gc, domid)
        == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
}

static inline
bool libxl__stubdomain_is_linux(libxl_domain_build_info *b_info)
{
    /* right now qemu-tranditional implies MiniOS stubdomain and qemu-xen
     * implies Linux stubdomain */
    return libxl_defbool_val(b_info->device_model_stubdomain) &&
        b_info->device_model_version == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
}

#define DEVICE_MODEL_XS_PATH(gc, dm_domid, domid, fmt, _a...)              \
    libxl__sprintf(gc, "/local/domain/%u/device-model/%u" fmt, dm_domid,   \
                   domid, ##_a)

/*
 * Calling context and GC for event-generating functions:
 *
 * These are for use by parts of libxl which directly or indirectly
 * call libxl__event_occurred.  These contain a gc but also a list of
 * deferred events.
 *
 * You should never need to initialise an egc unless you are part of
 * the event machinery itself.  Otherwise you will always be given an
 * egc if you need one.  Even functions which generate specific kinds
 * of events don't need to - rather, they will be passed an egc into
 * their own callback function and should just use the one they're
 * given.
 *
 * Functions using LIBXL_INIT_EGC may *not* generally be called from
 * within libxl, because libxl__egc_cleanup may call back into the
 * application.  This should be enforced by declaring all such
 * functions in libxl.h or libxl_event.h with
 * LIBXL_EXTERNAL_CALLERS_ONLY.  You should in any case not find it
 * necessary to call egc-creators from within libxl.
 *
 * The callbacks must all take place with the ctx unlocked because
 * the application is entitled to reenter libxl from them.  This
 * would be bad not because the lock is not recursive (it is) but
 * because the application might make blocking libxl calls which
 * would hold the lock unreasonably long.
 *
 * For the same reason libxl__egc_cleanup (or EGC_FREE) must be called
 * with the ctx *unlocked*.  So the right pattern has the EGC_...
 * macro calls on the outside of the CTX_... ones.
 */

/* useful for all functions which take an egc: */

#define EGC_GC                                  \
    libxl__gc *const gc __attribute__((unused)) = &egc->gc

/* egc initialisation and destruction: */

#define LIBXL_INIT_EGC(egc,ctx) do{                     \
        LIBXL_INIT_GC((egc).gc,ctx);                    \
        LIBXL_TAILQ_INIT(&(egc).occurred_for_callback); \
        LIBXL_TAILQ_INIT(&(egc).aos_for_callback);      \
        LIBXL_TAILQ_INIT(&(egc).aops_for_callback);     \
        LIBXL_STAILQ_INIT(&(egc).ev_immediates);        \
    } while(0)

_hidden void libxl__egc_ao_cleanup_1_baton(libxl__gc *gc);
  /* Passes the baton for added osevents.  See comment for
   * osevents_added in struct libxl__poller. */
_hidden void libxl__egc_cleanup_2_ul_cb_gc(libxl__egc *egc);
  /* Frees memory allocated within this egc's gc, and and report all
   * occurred events via callback, if applicable.  May reenter the
   * application; see restrictions above.  The ctx must be UNLOCKED. */

/* convenience macros: */

#define EGC_INIT(ctx)                       \
    libxl__egc egc[1]; LIBXL_INIT_EGC(egc[0],ctx);      \
    EGC_GC

#define CTX_UNLOCK_EGC_FREE  do{                        \
        libxl__egc_ao_cleanup_1_baton(&egc->gc);        \
        CTX_UNLOCK;                                     \
        libxl__egc_cleanup_2_ul_cb_gc(egc);             \
    }while(0)


/*
 * Machinery for asynchronous operations ("ao")
 *
 * All "slow" functions (see below for the exact definition) need to
 * use the asynchronous operation ("ao") machinery.  The function
 * should take a parameter const libxl_asyncop_how *ao_how and must
 * start with a call to AO_CREATE or equivalent.  These functions MAY
 * NOT be called from inside libxl (regardless of what is passed for
 * ao_how), because they can cause reentrancy hazards due to
 * callbacks.
 *
 * For the same reason functions taking an ao_how may make themselves
 * an egc with EGC_INIT (and they will generally want to, to be able
 * to immediately complete an ao during its setup).
 *
 *
 * "Slow" functions includes any that might block on a guest or an
 * external script.  More broadly, it includes any operations which
 * are sufficiently slow that an application might reasonably want to
 * initiate them, and then carry on doing something else, while the
 * operation completes.  That is, a "fast" function must be fast
 * enough that we do not mind blocking all other management operations
 * on the same host while it completes.
 *
 * There are certain primitive functions which make a libxl operation
 * necessarily "slow" for API reasons.  These are:
 *  - awaiting xenstore watches (although read-modify-write xenstore
 *    transactions are OK for fast functions)
 *  - spawning subprocesses
 *  - anything with a timeout
 *
 *
 * Lifecycle of an ao:
 *
 * - Created by libxl__ao_create (or the AO_CREATE convenience macro).
 *
 * - After creation, can be used by code which implements
 *   the operation as follows:
 *      - the ao's gc, for allocating memory for the lifetime
 *        of the operation (possibly with the help of the AO_GC
 *        macro to introduce the gc into scope)
 *      - the ao itself may be passed about to sub-functions
 *        so that they can stash it away etc.
 *      - in particular, the ao pointer must be stashed in some
 *        per-operation structure which is also passed as a user
 *        pointer to the internal event generation request routines
 *        libxl__evgen_FOO, so that at some point a CALLBACK will be
 *        made when the operation is complete.
 *      - if the operation provides progress reports, the aop_how(s)
 *        must be copied into the per-operation structure using
 *        libxl__ao_progress_gethow.
 *
 * - If the initiation is unsuccessful, the initiating function must
 *   call libxl__ao_create_fail before unlocking and returning whatever
 *   error code is appropriate (AO_CREATE_FAIL macro).
 *
 * If initiation is successful:
 *
 * - The initiating function must run libxl__ao_inprogress right
 *   before unlocking and returning, and return whatever it returns.
 *   This is best achieved with the AO_INPROGRESS macro.
 *
 * - If the operation supports progress reports, it may generate
 *   suitable events with NEW_EVENT and report them with
 *   libxl__ao_progress_report (with the ctx locked).
 *
 * - Eventually, some callback function, whose callback has been
 *   requested directly or indirectly, should call libxl__ao_complete
 *   (with the ctx locked, as it will generally already be in any
 *   event callback function).  This must happen exactly once for each
 *   ao, as the last that happens with that ao.
 *
 * - However, it is permissible for the initiating function to call
 *   libxl__ao_inprogress and/or libxl__ao_complete (directly or
 *   indirectly), before it uses AO_INPROGRESS to return.  (The ao
 *   infrastructure will arrange to defer destruction of the ao, etc.,
 *   until the proper time.)  An initiating function should do this
 *   if it takes a codepath which completes synchronously.
 *
 * - Conversely it is forbidden to call libxl__ao_complete in the
 *   initiating function _after_ AO_INPROGRESS, because
 *   libxl__ao_complete requires the ctx to be locked.
 *
 * - Note that during callback functions, two gcs are available:
 *    - The one in egc, whose lifetime is only this callback
 *    - The one in ao, whose lifetime is the asynchronous operation
 *   Usually a callback function should use CONTAINER_OF to obtain its
 *   own state structure, containing a pointer to the ao.  It should
 *   then obtain the ao and use the ao's gc; this is most easily done
 *   using the convenience macro STATE_AO_GC.
 */

#define AO_CREATE(ctx, domid, ao_how)                           \
    libxl__ctx_lock(ctx);                                       \
    libxl__ao *ao = libxl__ao_create(ctx, domid, ao_how,        \
                               __FILE__, __LINE__, __func__);   \
    if (!ao) { libxl__ctx_unlock(ctx); return ERROR_NOMEM; }    \
    libxl__egc egc[1]; LIBXL_INIT_EGC(egc[0],ctx);              \
    AO_GC;

#define AO_INPROGRESS ({                                        \
        libxl_ctx *ao__ctx = libxl__gc_owner(&ao->gc);          \
        /* __ao_inprogress will do egc..1_baton if needed */	\
        CTX_UNLOCK;                                             \
        libxl__egc_cleanup_2_ul_cb_gc(egc);                     \
        CTX_LOCK;                                               \
        int ao__rc = libxl__ao_inprogress(ao,                   \
                               __FILE__, __LINE__, __func__);   \
        libxl__ctx_unlock(ao__ctx); /* gc is now invalid */     \
        (ao__rc);                                               \
   })

#define AO_CREATE_FAIL(rc) ({                                   \
        libxl_ctx *ao__ctx = libxl__gc_owner(&ao->gc);          \
        assert(rc);                                             \
        libxl__ao_create_fail(ao);                              \
        libxl__egc_ao_cleanup_1_baton(&egc->gc);                \
        libxl__ctx_unlock(ao__ctx); /* gc is now invalid */     \
        libxl__egc_cleanup_2_ul_cb_gc(egc);                     \
        (rc);                                                   \
    })


/*
 * Given, in scope,
 *   libxl__ao *ao;
 * produces, in scope,
 *   libxl__gc *gc;
 */
#define AO_GC                                   \
    libxl__gc *const gc __attribute__((unused)) = &ao->gc

/*
 * void STATE_AO_GC(libxl__ao *ao_spec);
 * // Produces, in scope:
 *   libxl__ao *ao;  // set from ao_spec
 *   libxl__gc *gc;
 */
#define STATE_AO_GC(op_ao)                      \
    libxl__ao *const ao = (op_ao);              \
    libxl__gc *const gc __attribute__((unused)) = libxl__ao_inprogress_gc(ao)


/* All of these MUST be called with the ctx locked.
 * libxl__ao_inprogress MUST be called with the ctx locked exactly once. */
_hidden libxl__ao *libxl__ao_create(libxl_ctx*, uint32_t domid,
                                    const libxl_asyncop_how*,
       const char *file, int line, const char *func);
_hidden int libxl__ao_inprogress(libxl__ao *ao,
       const char *file, int line, const char *func); /* temporarily unlocks */
_hidden void libxl__ao_create_fail(libxl__ao *ao);
_hidden void libxl__ao_complete(libxl__egc *egc, libxl__ao *ao, int rc);
_hidden libxl__gc *libxl__ao_inprogress_gc(libxl__ao *ao);

/* Can be called at any time.  Use is essential for any aop user. */
_hidden void libxl__ao_progress_gethow(libxl_asyncprogress_how *in_state,
                                       const libxl_asyncprogress_how *from_app);

/* Must be called with the ctx locked.  Will fill in ev->for_user,
 * so caller need not do that. */
_hidden void libxl__ao_progress_report(libxl__egc *egc, libxl__ao *ao,
   const libxl_asyncprogress_how *how, libxl_event *ev /* consumed */);

/* For use by ao machinery ONLY */
_hidden void libxl__ao__destroy(libxl_ctx*, libxl__ao *ao);
_hidden void libxl__ao_complete_check_progress_reports(libxl__egc*, libxl__ao*);


/*
 * Short-lived sub-ao, aka "nested ao".
 *
 * Some asynchronous operations are very long-running.  Generally,
 * since an ao has a gc, any allocations made in that ao will live
 * until the ao is completed.  When this is not desirable, these
 * functions may be used to manage a "sub-ao".
 *
 * The returned sub-ao is suitable for passing to gc-related functions
 * and macros such as libxl__ao_inprogress_gc, AO_GC, and STATE_AO_GC.
 *
 * It MUST NOT be used with AO_INPROGRESS, AO_CREATE_FAIL,
 * libxl__ao_complete, libxl__ao_progress_report, and so on.
 *
 * The caller must ensure that all of the sub-ao's are freed before
 * the parent is.  Multiple levels of nesting are OK (although
 * hopefully they won't be necessary).
 */

_hidden libxl__ao *libxl__nested_ao_create(libxl__ao *parent); /* cannot fail */
_hidden void libxl__nested_ao_free(libxl__ao *child);


/*
 * File descriptors and CLOEXEC
 */

/*
 * For libxl functions which create file descriptors, at least one
 * of the following must be true:
 *  (a) libxl does not care if copies of this open-file are inherited
 *      by random children and might remain open indefinitely
 *  (b) libxl must take extra care for the fd (the actual descriptor,
 *      not the open-file) as below.  We call this a "carefd".
 *
 * The rules for opening a carefd are:
 *  (i)   Before bringing any carefds into existence,
 *        libxl code must call libxl__carefd_begin.
 *  (ii)  Then for each carefd brought into existence,
 *        libxl code must call libxl__carefd_record
 *        and remember the libxl__carefd_record*.
 *  (iii) Then it must call libxl__carefd_unlock.
 *  (iv)  When in a child process the fd is to be passed across
 *        exec by libxl, the libxl code must unset FD_CLOEXEC
 *        on the fd eg by using libxl_fd_set_cloexec.
 *  (v)   Later, when the fd is to be closed in the same process,
 *        libxl code must not call close.  Instead, it must call
 *        libxl__carefd_close.
 * Steps (ii) and (iii) can be combined by calling the convenience
 * function libxl__carefd_opened.
 */
/* libxl__carefd_begin and _unlock (or _opened) must be called always
 * in pairs.  They may be called with the CTX lock held.  In between
 * _begin and _unlock, the following are prohibited:
 *   - anything which might block
 *   - any callbacks to the application
 *   - nested calls to libxl__carefd_begin
 *   - fork (libxl__fork)
 * In general nothing should be done before _unlock that could be done
 * afterwards.
 */

_hidden void libxl__carefd_begin(void);
_hidden void libxl__carefd_unlock(void);

/* fd may be -1, in which case this returns a dummy libxl__fd_record
 * on which it _carefd_close is a no-op.  Cannot fail. */
_hidden libxl__carefd *libxl__carefd_record(libxl_ctx *ctx, int fd);

/* Combines _record and _unlock in a single call.  If fd==-1,
 * still does the unlock, but returns 0. */
_hidden libxl__carefd *libxl__carefd_opened(libxl_ctx *ctx, int fd);

/* Works just like close(2).  You may pass NULL, in which case it's
 * a successful no-op. */
_hidden int libxl__carefd_close(libxl__carefd*);

/* You may pass NULL in which case the answer is -1. */
_hidden int libxl__carefd_fd(const libxl__carefd*);

/* common paths */
_hidden const char *libxl__private_bindir_path(void);
_hidden const char *libxl__xenfirmwaredir_path(void);
_hidden const char *libxl__xen_config_dir_path(void);
_hidden const char *libxl__xen_script_dir_path(void);
_hidden const char *libxl__lock_dir_path(void);
_hidden const char *libxl__run_dir_path(void);
_hidden const char *libxl__seabios_path(void);
_hidden const char *libxl__ovmf_path(void);
_hidden const char *libxl__ipxe_path(void);

/*----- subprocess execution with timeout -----*/

typedef struct libxl__async_exec_state libxl__async_exec_state;

typedef void libxl__async_exec_callback(libxl__egc *egc,
                        libxl__async_exec_state *aes, int rc, int status);
/*
 * Meaning of status and rc:
 *  rc==0, status==0    all went well
 *  rc==0, status!=0    everything OK except child exited nonzero (logged)
 *  rc!=0               something else went wrong (status is real
 *                       exit status; maybe reflecting SIGKILL, and
 *                       therefore not very interesting, if aes code
 *                       killed the child).  Logged unless ABORTED.
 */

struct libxl__async_exec_state {
    /* caller must fill these in */
    libxl__ao *ao;
    const char *what; /* for error msgs, what we're executing */
    int timeout_ms;
    libxl__async_exec_callback *callback;
    /* caller must fill in; as for libxl__exec */
    int stdfds[3];
    char **args; /* execution arguments */
    char **env; /* execution environment */

    /* private */
    libxl__ev_time time;
    libxl__ev_child child;
    int rc;
};

void libxl__async_exec_init(libxl__async_exec_state *aes);
int libxl__async_exec_start(libxl__async_exec_state *aes);
bool libxl__async_exec_inuse(const libxl__async_exec_state *aes);

_hidden void libxl__kill(libxl__gc *gc, pid_t pid, int sig, const char *what);
/* kill SIGHUP a pid stored in xenstore */
_hidden int libxl__kill_xs_path(libxl__gc *gc, const char *xs_path_pid,
                                const char *what);

/*----- device addition/removal -----*/

typedef void libxl__device_callback(libxl__egc*, libxl__ao_device*);

/* This functions sets the necessary libxl__ao_device struct values to use
 * safely inside functions. It marks the operation as "active"
 * since we need to be sure that all device status structs are set
 * to active before start queueing events, or we might call
 * ao_complete before all devices had finished
 *
 * libxl__initiate_device_{remove/addition} should not be called without
 * calling libxl__prepare_ao_device first, since it initializes the private
 * fields of the struct libxl__ao_device to what this functions expect.
 *
 * Once _prepare has been called on a libxl__ao_device, it is safe to just
 * discard this struct, there's no need to call any destroy function.
 * _prepare can also be called multiple times with the same libxl__ao_device.
 *
 * But if any of the fields `backend_ds', `timeout', `xswait', `qmp' is
 * used by a caller of _prepare, the caller will have to arrange to clean
 * or dispose of them.
 */
_hidden void libxl__prepare_ao_device(libxl__ao *ao, libxl__ao_device *aodev);

/* generic callback for devices that only need to set ao_complete */
_hidden void device_addrm_aocomplete(libxl__egc *egc, libxl__ao_device *aodev);

struct libxl__ao_device {
    /* filled in by user */
    libxl__ao *ao;
    libxl__device_action action;
    libxl__device *dev;
    int force;
    libxl__device_callback *callback;
    /* return value, zeroed by user on entry, is valid on callback */
    int rc;
    /* private for multidev */
    int active;
    libxl__multidev *multidev; /* reference to the containing multidev */
    /* private for add/remove implementation */
    libxl__ev_devstate backend_ds;
    /* Bodge for Qemu devices */
    libxl__ev_time timeout;
    /* xenstore watch for backend path of driver domains */
    libxl__xswait_state xswait;
    int num_exec;
    /* for calling hotplug scripts */
    libxl__async_exec_state aes;
    /* If we need to update JSON config */
    bool update_json;
    /* for asynchronous execution of synchronous-only syscalls etc. */
    libxl__ev_child child;
    libxl__ev_qmp qmp;
    /* 'device_config' can be used to to pass to callbacks a pointer of one
     * of the type 'libxl_device_$type' corresponding to the device been
     * hotplug. 'device_type' should have the corresponding
     * 'libxl__$type_devtype'. */
    void *device_config;
    const libxl__device_type *device_type;
};

/*
 * Multiple devices "multidev" handling.
 *
 * Firstly, you should
 *    libxl__multidev_begin
 *    multidev->callback = ...
 * Then zero or more times
 *    libxl__multidev_prepare
 *    libxl__initiate_device_{remove/addition}
 *       (or some other thing which will eventually call
 *        aodev->callback or libxl__multidev_one_callback)
 * Finally, once
 *    libxl__multidev_prepared
 * which will result (perhaps reentrantly) in one call to
 * multidev->callback().
 */

/* Starts preparing to add/remove a bunch of devices. */
_hidden void libxl__multidev_begin(libxl__ao *ao, libxl__multidev*);

/* Prepares to add/remove one of many devices.
 * Calls libxl__prepare_ao_device on libxl__ao_device argument provided and
 * also sets the aodev->callback (to libxl__multidev_one_callback)
 * The user should not mess with aodev->callback.
 */
_hidden void libxl__multidev_prepare_with_aodev(libxl__multidev*,
                                                libxl__ao_device*);

/* A wrapper function around libxl__multidev_prepare_with_aodev.
 * Allocates a libxl__ao_device and prepares it for addition/removal.
 * Returns the newly allocated libxl__ao_dev.
 */
_hidden libxl__ao_device *libxl__multidev_prepare(libxl__multidev*);

/* Indicates to multidev that this one device has been processed.
 * Normally the multidev user does not need to touch this function, as
 * multidev_prepare will name it in aodev->callback.  However, if you
 * want to do something more complicated you can set aodev->callback
 * yourself to something else, so long as you eventually call
 * libxl__multidev_one_callback.
 */
_hidden void libxl__multidev_one_callback(libxl__egc *egc,
                                          libxl__ao_device *aodev);

/* Notifies the multidev machinery that we have now finished preparing
 * and initiating devices.  multidev->callback may then be called as
 * soon as there are no prepared but not completed operations
 * outstanding, perhaps reentrantly.  If rc!=0 (error should have been
 * logged) multidev->callback will get a non-zero rc.
 * callback may be set by the user at any point before prepared. */
_hidden void libxl__multidev_prepared(libxl__egc*, libxl__multidev*, int rc);

typedef void libxl__devices_callback(libxl__egc*, libxl__multidev*, int rc);
struct libxl__multidev {
    /* set by user: */
    libxl__devices_callback *callback;
    /* for private use by libxl__...ao_devices... machinery: */
    libxl__ao *ao;
    libxl__ao_device **array;
    int used, allocd;
    libxl__ao_device *preparation;
};

/*
 * Algorithm for handling device removal (including domain
 * destruction).  This is somewhat subtle because we may already have
 * killed the domain and caused the death of qemu.
 *
 * In current versions of qemu there is no mechanism for ensuring that
 * the resources used by its devices (both emulated and any PV devices
 * provided by qemu) are freed (eg, fds closed) before it shuts down,
 * and no confirmation from a terminating qemu back to the toolstack.
 *
 * This will need to be fixed in future Xen versions. In the meantime
 * (Xen 4.2) we implement a bodge.
 *
 *      WE WANT TO UNPLUG         WE WANT TO SHUT DOWN OR DESTROY
 *                    |                           |
 *                    |             LIBXL SENDS SIGHUP TO QEMU
 *                    |      .....................|........................
 *                    |      : XEN 4.3+ PLANNED   |                       :
 *                    |      :      QEMU TEARS DOWN ALL DEVICES           :
 *                    |      :      FREES RESOURCES (closing fds)         :
 *                    |      :      SETS PV BACKENDS TO STATE 5,          :
 *                    |      :       waits for PV frontends to shut down  :
 *                    |      :       SETS PV BACKENDS TO STATE 6          :
 *                    |      :                    |                       :
 *                    |      :      QEMU NOTIFIES TOOLSTACK (via          :
 *                    |      :       xenstore) that it is exiting         :
 *                    |      :      QEMU EXITS (parent may be init)       :
 *                    |      :                    |                       :
 *                    |      :        TOOLSTACK WAITS FOR QEMU            :
 *                    |      :        notices qemu has finished           :
 *                    |      :....................|.......................:
 *                    |      .--------------------'
 *                    V      V
 *                  for each device
 *                 we want to unplug/remove
 *       ..................|...........................................
 *       :                 V                       XEN 4.2 RACY BODGE :
 *       :      device is provided by    qemu                         :
 *       :            |            `-----------.                      :
 *       :   something|                        V                      :
 *       :    else, eg|             domain (that is domain for which  :
 *       :     blkback|              this PV device is the backend,   :
 *       :            |              which might be the stub dm)      :
 *       :            |                is still alive?                :
 *       :            |                  |        |                   :
 *       :            |                  |alive   |dead               :
 *       :            |<-----------------'        |                   :
 *       :            |    hopefully qemu is      |                   :
 *       :            |       still running       |                   :
 *       :............|.................          |                   :
 *             ,----->|                :     we may be racing         :
 *             |    backend state?     :      with qemu's death       :
 *             ^      |         |      :          |                   :
 *     xenstore|      |other    |6     :      WAIT 2.0s               :
 *     conflict|      |         |      :       TIMEOUT                :
 *             |   WRITE B.E.   |      :          |                   :
 *             |    STATE:=5    |      :     hopefully qemu has       :
 *             `---'  |         |      :      gone by now and         :
 *                    |ok       |      :      freed its resources     :
 *                    |         |      :          |                   :
 *              WAIT FOR        |      :     SET B.E.                 :
 *              STATE==6        |      :      STATE:=6                :
 *              /     |         |      :..........|...................:
 *      timeout/    ok|         |                 |
 *            /       |         |                 |
 *           |    RUN HOTPLUG <-'<----------------'
 *           |      SCRIPT
 *           |        |
 *           `---> NUKE
 *                  BACKEND
 *                    |
 *                   DONE.
 */

/*
 * As of Xen 4.5 we maintain various information, including hotplug
 * device information, in JSON files, so that we can use this JSON
 * file as a template to reconstruct domain configuration.
 *
 * In essense there are now two views of device state, one is the
 * primary config (xenstore or QEMU), the other is JSON file.
 *
 * Here we maintain one invariant: every device in the primary config
 * must have an entry in JSON file.
 *
 * All device hotplug routines should comply to following pattern:
 *   lock json config (json_lock)
 *       read json config
 *       update in-memory json config with new entry, replacing
 *          any stale entry
 *       for loop -- xs transaction
 *           open xs transaction
 *           check device existence, bail if it exists
 *           write in-memory json config to disk
 *           commit xs transaction
 *       end for loop
 *   unlock json config
 *
 * Or in case QEMU is the primary config, this pattern can be use:
 *   qmp_lock (libxl__ev_devlock_init)
 *      lock json config (json_lock)
 *          read json config
 *          update in-memory json config with new entry, replacing
 *             any stale entry
 *      unlock json config
 *      apply new config to primary config
 *      lock json config (json_lock)
 *          read json config
 *          update in-memory json config with new entry, replacing
 *             any stale entry
 *          write in-memory json config to disk
 *      unlock json config
 *   unlock qmp_lock
 *   (CTX_LOCK can be acquired and released several time while holding the
 *    qmp_lock)
 *
 * Device removal routines are not touched.
 *
 * Here is the proof that we always maintain that invariant and we
 * don't leak files during interaction of hotplug thread and other
 * threads / processes.
 *
 * # Safe against parallel add
 *
 * When another thread / process tries to add same device, it's
 * blocked by json_lock. The loser of two threads will bail at
 * existence check, so that we don't overwrite anything.
 *
 * # Safe against domain destruction
 *
 * If the thread / process trying to destroy domain loses the race, it's
 * blocked by json_lock. If the hotplug thread is loser, it bails at
 * acquiring lock because lock acquisition function checks existence of
 * the domain.
 *
 * # Safe against parallel removal
 *
 * When another thread / process tries to remove a device, it's _NOT_
 * blocked by json_lock, but xenstore transaction can help maintain
 * invariant. The removal threads either a) sees that device in
 * xenstore, b) doesn't see that device in xenstore.
 *
 * In a), it sees that device in xenstore. At that point hotplug is
 * already finished (both JSON and xenstore changes committed). So that
 * device can be safely removed. JSON entry is left untouched and
 * becomes stale, but this is a valid state -- next time when a
 * device with same identifier gets added, the stale entry gets
 * overwritten.
 *
 * In b), it doesn't see that device in xenstore, but it will commence
 * anyway. Eventually a forcibly removal is initiated, which will forcely
 * remove xenstore entry.
 *
 * If hotplug threads creates xenstore entry (therefore JSON entry as
 * well) before force removal, that xenstore entry is removed. We're
 * left with JSON stale entry but not xenstore entry, which is a valid
 * state.
 *
 * If hotplug thread has not created xenstore entry when the removal
 * is committed, we're obviously safe. Hotplug thread will add in
 * xenstore entry afterwards. We have both JSON and xenstore entry,
 * it's a valid state.
 */

/* Waits for the passed device to reach state XenbusStateInitWait.
 * This is not really useful by itself, but is important when executing
 * hotplug scripts, since we need to be sure the device is in the correct
 * state before executing them.
 *
 * Once finished, aodev->callback will be executed.
 */
_hidden void libxl__wait_device_connection(libxl__egc*,
                                           libxl__ao_device *aodev);

/* Arranges that dev will be removed to the guest, and the
 * hotplug scripts will be executed (if necessary). When
 * this is done (or an error happens), the callback in
 * aodev->callback will be called.
 *
 * The libxl__ao_device passed to this function should be
 * prepared using libxl__prepare_ao_device prior to calling
 * this function.
 *
 * Once finished, aodev->callback will be executed.
 */
_hidden void libxl__initiate_device_generic_remove(libxl__egc *egc,
                                                   libxl__ao_device *aodev);

_hidden void libxl__initiate_device_usbctrl_remove(libxl__egc *egc,
                                                   libxl__ao_device *aodev);

/*
 * libxl__get_hotplug_script_info returns the args and env that should
 * be passed to the hotplug script for the requested device.
 *
 * Since a device might not need to execute any hotplug script, this function
 * can return the following values:
 * < 0: Error
 * 0: No need to execute hotplug script
 * 1: Execute hotplug script
 *
 * The last parameter, "num_exec" refeers to the number of times hotplug
 * scripts have been called for this device.
 *
 * The main body of libxl will, for each device, keep calling
 * libxl__get_hotplug_script_info, with incrementing values of
 * num_exec, and executing the resulting script accordingly,
 * until libxl__get_hotplug_script_info returns<=0.
 */
_hidden int libxl__get_hotplug_script_info(libxl__gc *gc, libxl__device *dev,
                                           char ***args, char ***env,
                                           libxl__device_action action,
                                           int num_exec);

/*----- local disk attach: attach a disk locally to run the bootloader -----*/

typedef struct libxl__disk_local_state libxl__disk_local_state;
typedef void libxl__disk_local_state_callback(libxl__egc*,
                                              libxl__disk_local_state*,
                                              int rc);

/* A libxl__disk_local_state may be in the following states:
 * Undefined, Idle, Attaching, Attached, Detaching.
 */
struct libxl__disk_local_state {
    /* filled by the user */
    libxl__ao *ao;
    const libxl_device_disk *in_disk;
    libxl_device_disk disk;
    const char *blkdev_start;
    libxl__disk_local_state_callback *callback;
    /* filled by libxl__device_disk_local_initiate_attach */
    char *diskpath;
    /* private for implementation of local detach */
    libxl__ao_device aodev;
    int rc;
};

/*
 * Prepares a dls for use.
 * State Undefined -> Idle
 */
static inline void libxl__device_disk_local_init(libxl__disk_local_state *dls)
{
    dls->rc = 0;
}

/*
 * See if we can find a way to access a disk locally
 */
_hidden char * libxl__device_disk_find_local_path(libxl__gc *gc,
                                                  libxl_domid guest_domid,
                                                  const libxl_device_disk *disk,
                                                  bool qdisk_direct);


/* Make a disk available in this (the control) domain. Always calls
 * dls->callback when finished.
 * State Idle -> Attaching
 *
 * The state of dls on entry to the callback depends on the value
 * of rc passed to the callback:
 *     rc == 0: Attached if rc == 0
 *     rc != 0: Idle
 */
_hidden void libxl__device_disk_local_initiate_attach(libxl__egc *egc,
                                                libxl__disk_local_state *dls);

/* Disconnects a disk device form the control domain. If the passed
 * dls is not attached (or has already been detached),
 * libxl__device_disk_local_initiate_detach will just call the callback
 * directly.
 * State Idle/Attached -> Detaching
 *
 * The state of dls on entry to the callback is Idle.
 */
_hidden void libxl__device_disk_local_initiate_detach(libxl__egc *egc,
                                                libxl__disk_local_state *dls);

/*----- datacopier: copies data from one fd to another -----*/

typedef struct libxl__datacopier_state libxl__datacopier_state;
typedef struct libxl__datacopier_buf libxl__datacopier_buf;

/* onwrite==1 means problem happened when writing
 *     rc==FAIL    errnoval >0    we had a write error, logged
 * onwrite==0 means problem happened when reading
 *     rc==0       errnoval==0    we got eof and all data was written
 *     rc==FAIL    errnoval >0    we had a read error, logged
 * onwrite==-1 means some other internal problem
 *     rc==FAIL    errnoval==EIO  some other internal failure, logged
 *     rc==ABORTED errnoval==0    abort requested, not logged
 * If we get POLLHUP, we call callback_pollhup with
 *     rc==FAIL    errnoval==-1   POLLHUP signalled
 * or if callback_pollhup==0 this is treated as eof (if POLLIN|POLLHUP
 * on the reading fd) or an internal failure (otherwise), as above.
 * In all cases copier is killed before calling this callback */
typedef void libxl__datacopier_callback(libxl__egc *egc,
     libxl__datacopier_state *dc, int rc, int onwrite, int errnoval);

struct libxl__datacopier_buf {
    /* private to datacopier */
    LIBXL_TAILQ_ENTRY(libxl__datacopier_buf) entry;
    int used;
    char buf[1000];
};

struct libxl__datacopier_state {
    /* caller must fill these in, and they must all remain valid */
    libxl__ao *ao;
    int readfd, writefd;
    ssize_t maxsz;
    ssize_t bytes_to_read; /* set to -1 to read until EOF */
    const char *copywhat, *readwhat, *writewhat; /* for error msgs */
    FILE *log; /* gets a copy of everything */
    libxl__datacopier_callback *callback;
    libxl__datacopier_callback *callback_pollhup;
    void *readbuf; /* Set this to read data into it without writing to an
                      fd. The buffer should be at least as large as the
                      bytes_to_read parameter, which should not be -1. */
    /* remaining fields are private to datacopier */
    libxl__ao_abortable abrt;
    libxl__ev_fd toread, towrite;
    ssize_t used;
    LIBXL_TAILQ_HEAD(libxl__datacopier_bufs, libxl__datacopier_buf) bufs;
};

_hidden void libxl__datacopier_init(libxl__datacopier_state *dc);
_hidden void libxl__datacopier_kill(libxl__datacopier_state *dc);
_hidden int libxl__datacopier_start(libxl__datacopier_state *dc);

/* Inserts literal data into the output stream.  The data is copied.
 * May safely be used only immediately after libxl__datacopier_start
 * (before the ctx is unlocked).  But may be called multiple times.
 * NB exceeding maxsz will fail an assertion! */
_hidden void libxl__datacopier_prefixdata(libxl__egc*, libxl__datacopier_state*,
                                          const void *data, size_t len);

/*----- Save/restore helper (used by creation and suspend) -----*/

typedef struct libxl__srm_save_callbacks {
    libxl__srm_save_autogen_callbacks a;
} libxl__srm_save_callbacks;

typedef struct libxl__srm_restore_callbacks {
    libxl__srm_restore_autogen_callbacks a;
} libxl__srm_restore_callbacks;

/* a pointer to this struct is also passed as "user" to the
 * save callout helper callback functions */
typedef struct libxl__save_helper_state {
    /* public, caller of run_helper initialises */
    libxl__ao *ao;
    uint32_t domid;
    union {
        libxl__srm_save_callbacks save;
        libxl__srm_restore_callbacks restore;
    } callbacks;
    int (*recv_callback)(const unsigned char *msg, uint32_t len, void *user);
    void (*completion_callback)(libxl__egc *egc, void *caller_state,
                                int rc, int retval, int errnoval);
    void *caller_state;
    int need_results; /* set to 0 or 1 by caller of run_helper;
                       * if set to 1 then the ultimate caller's
                       * results function must set it to 0 */
    /* private */
    int rc;
    int completed; /* retval/errnoval valid iff completed */
    int retval, errnoval; /* from xc_domain_save / xc_domain_restore */
    libxl__ao_abortable abrt;
    libxl__carefd *pipes[2]; /* 0 = helper's stdin, 1 = helper's stdout */
    libxl__ev_fd readable;
    libxl__ev_child child;
    const char *stdin_what, *stdout_what;

    libxl__egc *egc; /* valid only for duration of each event callback;
                      * is here in this struct for the benefit of the
                      * marshalling and xc callback functions */
} libxl__save_helper_state;

/*----- checkpoint device related state structure -----*/
/*
 * The abstract checkpoint device layer exposes a common
 * set of API to [external] libxl for manipulating devices attached to
 * a guest protected by Remus/COLO. The device layer also exposes a set of
 * [internal] interfaces that every device type must implement.
 *
 * The following API are exposed to libxl:
 *
 * One-time configuration operations:
 *  +libxl__checkpoint_devices_setup
 *    > Enable output buffering for NICs, setup disk replication, etc.
 *  +libxl__checkpoint_devices_teardown
 *    > Disable output buffering and disk replication; teardown any
 *       associated external setups like qdiscs for NICs.
 *
 * Operations executed every checkpoint (in order of invocation):
 *  +libxl__checkpoint_devices_postsuspend
 *  +libxl__checkpoint_devices_preresume
 *  +libxl__checkpoint_devices_commit
 *
 * Each device type needs to implement the interfaces specified in
 * the libxl__checkpoint_device_instance_ops if it wishes to support Remus/COLO.
 *
 * The high-level control flow through the checkpoint device layer is shown
 * below:
 *
 * xl remus
 *  |->  libxl_domain_remus_start
 *    |-> libxl__checkpoint_devices_setup
 *      |-> Per-checkpoint libxl__checkpoint_devices_[postsuspend,preresume,commit]
 *        ...
 *        |-> On backup failure, network error or other internal errors:
 *            libxl__checkpoint_devices_teardown
 */

typedef struct libxl__checkpoint_device libxl__checkpoint_device;
typedef struct libxl__checkpoint_devices_state libxl__checkpoint_devices_state;
typedef struct libxl__checkpoint_device_instance_ops libxl__checkpoint_device_instance_ops;

/*
 * Interfaces to be implemented by every device subkind that wishes to
 * support Remus/COLO. Functions must be implemented unless otherwise
 * stated. Many of these functions are asynchronous. They call
 * dev->aodev.callback when done.  The actual implementations may be
 * synchronous and call dev->aodev.callback directly (as the last
 * thing they do).
 */
struct libxl__checkpoint_device_instance_ops {
    /* the device kind this ops belongs to... */
    libxl__device_kind kind;

    /*
     * Checkpoint operations. May be NULL, meaning the op is not
     * implemented and the caller should treat them as a no-op (and do
     * nothing when checkpointing).
     * Asynchronous.
     */

    void (*postsuspend)(libxl__egc *egc, libxl__checkpoint_device *dev);
    void (*preresume)(libxl__egc *egc, libxl__checkpoint_device *dev);
    void (*commit)(libxl__egc *egc, libxl__checkpoint_device *dev);

    /*
     * setup() and teardown() are refer to the actual checkpoint device.
     * Asynchronous.
     * teardown is called even if setup fails.
     */
    /*
     * setup() should first determines whether the subkind matches the specific
     * device. If matched, the device will then be managed with this set of
     * subkind operations.
     * Yields 0 if the device successfully set up.
     * CHECKPOINT_DEVOPS_DOES_NOT_MATCH if the ops does not match the device.
     * any other rc indicates failure.
     */
    void (*setup)(libxl__egc *egc, libxl__checkpoint_device *dev);
    void (*teardown)(libxl__egc *egc, libxl__checkpoint_device *dev);
};

int init_subkind_nic(libxl__checkpoint_devices_state *cds);
void cleanup_subkind_nic(libxl__checkpoint_devices_state *cds);
int init_subkind_drbd_disk(libxl__checkpoint_devices_state *cds);
void cleanup_subkind_drbd_disk(libxl__checkpoint_devices_state *cds);

typedef void libxl__checkpoint_callback(libxl__egc *,
                                        libxl__checkpoint_devices_state *,
                                        int rc);

/*
 * State associated with a checkpoint invocation, including parameters
 * passed to the checkpoint abstract device layer by the remus
 * save/restore machinery.
 */
struct libxl__checkpoint_devices_state {
    /*-- must be set by caller of libxl__checkpoint_device_(setup|teardown) --*/

    libxl__ao *ao;
    uint32_t domid;
    libxl__checkpoint_callback *callback;
    void *concrete_data;
    int device_kind_flags;
    /* The ops must be pointer array, and the last ops must be NULL. */
    const libxl__checkpoint_device_instance_ops **ops;

    /*----- private for abstract layer only -----*/

    int num_devices;
    /*
     * this array is allocated before setup the checkpoint devices by the
     * checkpoint abstract layer.
     * devs may be NULL, means there's no checkpoint devices that has been
     * set up.
     * the size of this array is 'num_devices', which is the total number
     * of libxl nic devices and disk devices(num_nics + num_disks).
     */
    libxl__checkpoint_device **devs;

    libxl_device_nic *nics;
    int num_nics;
    libxl_device_disk *disks;
    int num_disks;

    libxl__multidev multidev;
};

/*
 * Information about a single device being handled by remus.
 * Allocated by the checkpoint abstract layer.
 */
struct libxl__checkpoint_device {
    /*----- shared between abstract and concrete layers -----*/
    /*
     * if this is true, that means the subkind ops match the device
     */
    bool matched;

    /*----- set by checkpoint device abstruct layer -----*/
    /* libxl__device_* which this checkpoint device related to */
    const void *backend_dev;
    libxl__device_kind kind;
    libxl__checkpoint_devices_state *cds;
    libxl__ao_device aodev;

    /*----- private for abstract layer only -----*/

    /*
     * Control and state variables for the asynchronous callback
     * based loops which iterate over device subkinds, and over
     * individual devices.
     */
    int ops_index;
    const libxl__checkpoint_device_instance_ops *ops;

    /*----- private for concrete (device-specific) layer -----*/

    /* concrete device's private data */
    void *concrete_data;
};

/* the following 5 APIs are async ops, call cds->callback when done */
_hidden void libxl__checkpoint_devices_setup(libxl__egc *egc,
                                        libxl__checkpoint_devices_state *cds);
_hidden void libxl__checkpoint_devices_teardown(libxl__egc *egc,
                                        libxl__checkpoint_devices_state *cds);
_hidden void libxl__checkpoint_devices_postsuspend(libxl__egc *egc,
                                        libxl__checkpoint_devices_state *cds);
_hidden void libxl__checkpoint_devices_preresume(libxl__egc *egc,
                                        libxl__checkpoint_devices_state *cds);
_hidden void libxl__checkpoint_devices_commit(libxl__egc *egc,
                                        libxl__checkpoint_devices_state *cds);

/*----- Remus related state structure -----*/
typedef struct libxl__remus_state libxl__remus_state;
struct libxl__remus_state {
    /* private */
    libxl__ev_time checkpoint_timeout; /* used for Remus checkpoint */
    int interval; /* checkpoint interval */

    /*----- private for concrete (device-specific) layer only -----*/
    /* private for nic device subkind ops */
    char *netbufscript;
    struct nl_sock *nlsock;
    struct nl_cache *qdisc_cache;

    /* private for drbd disk subkind ops */
    char *drbd_probe_script;
};
_hidden int libxl__netbuffer_enabled(libxl__gc *gc);

/*----- Legacy conversion helper -----*/
typedef struct libxl__conversion_helper_state libxl__conversion_helper_state;

struct libxl__conversion_helper_state {
    /* Public - Must be filled by caller unless noted. */
    libxl__ao *ao;
    int legacy_fd;             /* fd to read the legacy stream from. */
    bool hvm;                  /* pv or hvm domain? */
    libxl__carefd *v2_carefd;  /* Filled by successful call to
                                * libxl__convert_legacy_stream().  Caller
                                * assumes ownership of the fd. */
    void (*completion_callback)(
        libxl__egc *egc, libxl__conversion_helper_state *chs, int rc);
    /* private */
    int rc;
    libxl__ao_abortable abrt;
    libxl__ev_child child;
};

_hidden void libxl__conversion_helper_init
                    (libxl__conversion_helper_state *chs);
_hidden int libxl__convert_legacy_stream(libxl__egc *egc,
                    libxl__conversion_helper_state *chs);
_hidden void libxl__conversion_helper_abort(libxl__egc *egc,
                    libxl__conversion_helper_state *chs, int rc);
static inline bool libxl__conversion_helper_inuse
                    (const libxl__conversion_helper_state *chs)
{ return libxl__ev_child_inuse(&chs->child); }

/* State for reading a libxl migration v2 stream */
typedef struct libxl__stream_read_state libxl__stream_read_state;

typedef struct libxl__sr_record_buf {
    /* private to stream read helper */
    LIBXL_STAILQ_ENTRY(struct libxl__sr_record_buf) entry;
    libxl__sr_rec_hdr hdr;
    void *body; /* iff hdr.length != 0 */
} libxl__sr_record_buf;

struct libxl__stream_read_state {
    /* filled by the user */
    libxl__ao *ao;
    libxl__domain_create_state *dcs;
    int fd;
    bool legacy;
    bool back_channel;
    void (*completion_callback)(libxl__egc *egc,
                                libxl__stream_read_state *srs,
                                int rc);
    void (*checkpoint_callback)(libxl__egc *egc,
                                libxl__stream_read_state *srs,
                                int rc);
    /* Private */
    int rc;
    bool running;
    bool in_checkpoint;
    bool sync_teardown; /* Only used to coordinate shutdown on error path. */
    bool in_checkpoint_state;
    libxl__save_helper_state shs;
    libxl__conversion_helper_state chs;

    /* Main stream-reading data. */
    libxl__datacopier_state dc; /* Only used when reading a record */
    libxl__sr_hdr hdr;
    LIBXL_STAILQ_HEAD(, libxl__sr_record_buf) record_queue; /* NOGC */
    enum {
        SRS_PHASE_NORMAL,
        SRS_PHASE_BUFFERING,
        SRS_PHASE_UNBUFFERING,
    } phase;
    bool recursion_guard;

    /* Only used while actively reading a record from the stream. */
    libxl__sr_record_buf *incoming_record; /* NOGC */

    /* Both only used when processing an EMULATOR record. */
    libxl__datacopier_state emu_dc;
    libxl__carefd *emu_carefd;
};

_hidden void libxl__stream_read_init(libxl__stream_read_state *stream);
_hidden void libxl__stream_read_start(libxl__egc *egc,
                                      libxl__stream_read_state *stream);
_hidden void libxl__stream_read_start_checkpoint(libxl__egc *egc,
                                                 libxl__stream_read_state *stream);
_hidden void libxl__stream_read_checkpoint_state(libxl__egc *egc,
                                                 libxl__stream_read_state *stream);
_hidden void libxl__stream_read_abort(libxl__egc *egc,
                                      libxl__stream_read_state *stream, int rc);
static inline bool
libxl__stream_read_inuse(const libxl__stream_read_state *stream)
{
    return stream->running;
}

#include "libxl_colo.h"

/*----- Domain suspend (save) state structure -----*/
/*
 * "suspend" refers to quiescing the VM, so pausing qemu, making a
 * remote_shutdown(SHUTDOWN_suspend) hypercall etc.
 *
 * "save" refers to the actions involved in actually shuffling the
 * state of the VM, so xc_domain_save() etc.
 */

typedef struct libxl__domain_suspend_state libxl__domain_suspend_state;
typedef struct libxl__domain_save_state libxl__domain_save_state;

typedef void libxl__domain_save_cb(libxl__egc*,
                                   libxl__domain_save_state*, int rc);
typedef void libxl__save_device_model_cb(libxl__egc*,
                                         libxl__domain_save_state*, int rc);

/* State for writing a libxl migration v2 stream */
typedef struct libxl__stream_write_state libxl__stream_write_state;
typedef void (*sws_record_done_cb)(libxl__egc *egc,
                                   libxl__stream_write_state *sws);
struct libxl__stream_write_state {
    /* filled by the user */
    libxl__ao *ao;
    libxl__domain_save_state *dss;
    int fd;
    bool back_channel;
    void (*completion_callback)(libxl__egc *egc,
                                libxl__stream_write_state *sws,
                                int rc);
    void (*checkpoint_callback)(libxl__egc *egc,
                                libxl__stream_write_state *sws,
                                int rc);
    /* Private */
    int rc;
    bool running;
    bool in_checkpoint;
    bool sync_teardown;  /* Only used to coordinate shutdown on error path. */
    bool in_checkpoint_state;
    libxl__save_helper_state shs;

    /* Main stream-writing data. */
    libxl__datacopier_state dc;
    sws_record_done_cb record_done_callback;

    /* Cache device model version. */
    libxl_device_model_version device_model_version;

    /* Only used when constructing EMULATOR records. */
    libxl__datacopier_state emu_dc;
    libxl__carefd *emu_carefd;
    libxl__sr_rec_hdr emu_rec_hdr;
    libxl__sr_emulator_hdr emu_sub_hdr;
    void *emu_body;
};

_hidden void libxl__stream_write_init(libxl__stream_write_state *stream);
_hidden void libxl__stream_write_start(libxl__egc *egc,
                                       libxl__stream_write_state *stream);
_hidden void
libxl__stream_write_start_checkpoint(libxl__egc *egc,
                                     libxl__stream_write_state *stream);
_hidden void
libxl__stream_write_checkpoint_state(libxl__egc *egc,
                                     libxl__stream_write_state *stream,
                                     libxl_sr_checkpoint_state *srcs);
_hidden void libxl__stream_write_abort(libxl__egc *egc,
                                       libxl__stream_write_state *stream,
                                       int rc);
static inline bool
libxl__stream_write_inuse(const libxl__stream_write_state *stream)
{
    return stream->running;
}

typedef struct libxl__logdirty_switch {
    /* Set by caller of libxl__domain_common_switch_qemu_logdirty */
    libxl__ao *ao;
    void (*callback)(libxl__egc *egc, struct libxl__logdirty_switch *lds,
                     int rc);

    const char *cmd;
    const char *cmd_path;
    const char *ret_path;
    libxl__ev_xswatch watch;
    libxl__ev_time timeout;
    libxl__ev_qmp qmp;
} libxl__logdirty_switch;

_hidden void libxl__logdirty_init(libxl__logdirty_switch *lds);

struct libxl__domain_suspend_state {
    /* set by caller of libxl__domain_suspend_init */
    libxl__ao *ao;
    uint32_t domid;
    bool live;

    /* private */
    libxl_domain_type type;

    libxl__ev_evtchn guest_evtchn;
    int guest_evtchn_lockfd;
    int guest_responded;

    libxl__xswait_state pvcontrol;
    libxl__ev_xswatch guest_watch;
    libxl__ev_time guest_timeout;
    libxl__ev_qmp qmp;

    const char *dm_savefile;
    void (*callback_device_model_done)(libxl__egc*,
                              struct libxl__domain_suspend_state*, int rc);
    void (*callback_common_done)(libxl__egc*,
                                 struct libxl__domain_suspend_state*, int ok);
};
int libxl__domain_suspend_init(libxl__egc *egc,
                               libxl__domain_suspend_state *dsps,
                               libxl_domain_type type);

/* calls dsps->callback_device_model_done when done
 * may synchronously calls this callback */
_hidden void libxl__qmp_suspend_save(libxl__egc *egc,
                                     libxl__domain_suspend_state *dsps);

struct libxl__domain_save_state {
    /* set by caller of libxl__domain_save */
    libxl__ao *ao;
    libxl__domain_save_cb *callback;

    uint32_t domid;
    int fd;
    int fdfl; /* original flags on fd */
    int recv_fd;
    libxl_domain_type type;
    int live;
    int debug;
    int checkpointed_stream;
    const libxl_domain_remus_info *remus;
    /* private */
    int rc;
    int xcflags;
    libxl__domain_suspend_state dsps;
    union {
        /* for Remus */
        libxl__remus_state rs;
        /* for COLO */
        libxl__colo_save_state css;
    };
    libxl__checkpoint_devices_state cds;
    libxl__stream_write_state sws;
    libxl__logdirty_switch logdirty;
};


/*----- openpty -----*/

/*
 * opens count (>0) ptys like count calls to openpty, and then
 * calls back.  On entry, all op[].master and op[].slave must be
 * 0.  On callback, either rc==0 and master and slave are non-0,
 * or rc is a libxl error and they are both 0.  If libxl__openpty
 * returns non-0 no callback will happen and everything is left
 * cleaned up.
 */

typedef struct libxl__openpty_state libxl__openpty_state;
typedef struct libxl__openpty_result libxl__openpty_result;
typedef void libxl__openpty_callback(libxl__egc *egc, libxl__openpty_state *op);

struct libxl__openpty_state {
    /* caller must fill these in, and they must all remain valid */
    libxl__ao *ao;
    libxl__openpty_callback *callback;
    int count;
    libxl__openpty_result *results; /* actual size is count, out parameter */
    /* public, result, caller may only read in callback */
    int rc;
    /* private for implementation */
    libxl__ev_child child;
};

struct libxl__openpty_result {
    libxl__carefd *master, *slave;
};

int libxl__openptys(libxl__openpty_state *op,
                    struct termios *termp,
                    struct winsize *winp);


/*----- bootloader -----*/

typedef struct libxl__bootloader_state libxl__bootloader_state;
typedef void libxl__run_bootloader_callback(libxl__egc*,
                                libxl__bootloader_state*, int rc);
typedef void libxl__bootloader_console_callback(libxl__egc*,
                                libxl__bootloader_state*);

struct libxl__bootloader_state {
    /* caller must fill these in, and they must all remain valid */
    libxl__ao *ao;
    libxl__run_bootloader_callback *callback;
    libxl__bootloader_console_callback *console_available;
    const libxl_domain_build_info *info;
    libxl_device_disk *disk;
    /* Should be zeroed by caller on entry.  Will be filled in by
     * bootloader machinery; represents the local attachment of the
     * disk for the benefit of the bootloader.  Must be detached by
     * the caller using libxl__device_disk_local_initiate_detach.
     * (This is safe to do after ->callback() has happened since
     * the domain's kernel and initramfs will have been copied
     * out of the guest's disk into a temporary directory, mapped
     * as file references, and deleted. */
    libxl__disk_local_state dls;
    uint32_t domid;
    /* outputs:
     *  - caller must initialise kernel and ramdisk to point to file
     *    references, these will be updated and mapped;
     *  - caller must initialise cmdline to NULL, it will be updated with a
     *    string allocated from the gc;
     */
    libxl__file_reference *kernel, *ramdisk;
    const char *cmdline;
    /* private to libxl__run_bootloader */
    char *outputpath, *outputdir, *logfile;
    libxl__openpty_state openpty;
    libxl__openpty_result ptys[2];  /* [0] is for bootloader */
    libxl__ev_child child;
    libxl__domaindeathcheck deathcheck;
    int nargs, argsspace;
    const char **args;
    libxl__datacopier_state keystrokes, display;
    int rc, got_pollhup;
};

_hidden void libxl__bootloader_init(libxl__bootloader_state *bl);

/* Will definitely call st->callback, perhaps reentrantly.
 * If callback is passed rc==0, will have updated st->info appropriately */
_hidden void libxl__bootloader_run(libxl__egc*, libxl__bootloader_state *st);

/*----- Generic Device Handling -----*/
#define LIBXL_DEFINE_DEVICE_ADD(type)                                   \
    int libxl_device_##type##_add(libxl_ctx *ctx,                       \
        uint32_t domid, libxl_device_##type *type,                      \
        const libxl_asyncop_how *ao_how)                                \
    {                                                                   \
        AO_CREATE(ctx, domid, ao_how);                                  \
        libxl__ao_device *aodev;                                        \
                                                                        \
        GCNEW(aodev);                                                   \
        libxl__prepare_ao_device(ao, aodev);                            \
        aodev->action = LIBXL__DEVICE_ACTION_ADD;                       \
        aodev->callback = device_addrm_aocomplete;                      \
        aodev->update_json = true;                                      \
        libxl__device_##type##_add(egc, domid, type, aodev);            \
                                                                        \
        return AO_INPROGRESS;                                           \
    }

#define LIBXL_DEFINE_DEVICES_ADD(type)                                  \
    void libxl__add_##type##s(libxl__egc *egc, libxl__ao *ao, uint32_t domid, \
                              libxl_domain_config *d_config,            \
                              libxl__multidev *multidev)                \
    {                                                                   \
        AO_GC;                                                          \
        int i;                                                          \
        for (i = 0; i < d_config->num_##type##s; i++) {                 \
            libxl__ao_device *aodev = libxl__multidev_prepare(multidev);  \
            libxl__device_##type##_add(egc, domid, &d_config->type##s[i], \
                                       aodev);                          \
        }                                                               \
    }

#define LIBXL_DEFINE_DEVICE_REMOVE_EXT(type, remtype, removedestroy, f) \
    int libxl_device_##type##_##removedestroy(libxl_ctx *ctx,           \
        uint32_t domid, libxl_device_##type *type,                      \
        const libxl_asyncop_how *ao_how)                                \
    {                                                                   \
        AO_CREATE(ctx, domid, ao_how);                                  \
        libxl__device *device;                                          \
        libxl__ao_device *aodev;                                        \
        int rc;                                                         \
                                                                        \
        GCNEW(device);                                                  \
        rc = libxl__device_from_##type(gc, domid, type, device);        \
        if (rc != 0) goto out;                                          \
                                                                        \
        GCNEW(aodev);                                                   \
        libxl__prepare_ao_device(ao, aodev);                            \
        aodev->action = LIBXL__DEVICE_ACTION_REMOVE;                    \
        aodev->dev = device;                                            \
        aodev->callback = device_addrm_aocomplete;                      \
        aodev->force = f;                                               \
        libxl__initiate_device_##remtype##_remove(egc, aodev);          \
                                                                        \
    out:                                                                \
        if (rc) return AO_CREATE_FAIL(rc);                              \
        return AO_INPROGRESS;                                           \
    }

#define LIBXL_DEFINE_UPDATE_DEVID(name)                                 \
    int libxl__device_##name##_update_devid(libxl__gc *gc,              \
                                            uint32_t domid,             \
                                            libxl_device_##name *type)  \
    {                                                                   \
        if (type->devid == -1)                                          \
            type->devid = libxl__device_nextid(gc, domid,               \
                          libxl__##name##_devtype.type);                \
        if (type->devid < 0)                                            \
            return ERROR_FAIL;                                          \
        return 0;                                                       \
    }

#define LIBXL_DEFINE_DEVICE_FROM_TYPE(name)                             \
    int libxl__device_from_##name(libxl__gc *gc, uint32_t domid,        \
                                  libxl_device_##name *type,            \
                                  libxl__device *device)                \
    {                                                                   \
        device->backend_devid   = type->devid;                          \
        device->backend_domid   = type->backend_domid;                  \
        device->backend_kind    = libxl__##name##_devtype.type;         \
        device->devid           = type->devid;                          \
        device->domid           = domid;                                \
        device->kind            = libxl__##name##_devtype.type;         \
                                                                        \
        return 0;                                                       \
    }

#define LIBXL_DEFINE_DEVID_TO_DEVICE(name)                              \
    int libxl_devid_to_device_##name(libxl_ctx *ctx, uint32_t domid,    \
                                     int devid,                         \
                                     libxl_device_##name *type)         \
    {                                                                   \
        GC_INIT(ctx);                                                   \
                                                                        \
        char *device_path;                                              \
        const char *tmp;                                                \
        int rc;                                                         \
                                                                        \
        libxl_device_##name##_init(type);                               \
                                                                        \
        device_path = GCSPRINTF("%s/device/%s/%d",                      \
                                libxl__xs_libxl_path(gc, domid),        \
                                libxl__device_kind_to_string(           \
                                libxl__##name##_devtype.type),          \
                                devid);                                 \
                                                                        \
        if (libxl__xs_read_mandatory(gc, XBT_NULL, device_path, &tmp)) {\
            rc = ERROR_NOTFOUND; goto out;                              \
        }                                                               \
                                                                        \
        if (libxl__##name##_devtype.from_xenstore) {                    \
            rc = libxl__##name##_devtype.from_xenstore(gc, device_path, \
                                                       devid, type);    \
            if (rc) goto out;                                           \
        }                                                               \
                                                                        \
        rc = 0;                                                         \
                                                                        \
    out:                                                                \
                                                                        \
        GC_FREE;                                                        \
        return rc;                                                      \
    }


#define LIBXL_DEFINE_DEVICE_REMOVE(type)                                \
    LIBXL_DEFINE_DEVICE_REMOVE_EXT(type, generic, remove, 0)            \
    LIBXL_DEFINE_DEVICE_REMOVE_EXT(type, generic, destroy, 1)

#define LIBXL_DEFINE_DEVICE_REMOVE_CUSTOM(type)                         \
    LIBXL_DEFINE_DEVICE_REMOVE_EXT(type, type, remove, 0)               \
    LIBXL_DEFINE_DEVICE_REMOVE_EXT(type, type, destroy, 1)

#define LIBXL_DEFINE_DEVICE_LIST(type)                                  \
    libxl_device_##type *libxl_device_##type##_list(libxl_ctx *ctx,     \
                                                    uint32_t domid,     \
                                                    int *num)           \
    {                                                                   \
        libxl_device_##type *r;                                         \
        GC_INIT(ctx);                                                   \
        r = libxl__device_list(gc, &libxl__##type##_devtype,            \
                               domid, num);                             \
        GC_FREE;                                                        \
        return r;                                                       \
    }                                                                   \
                                                                        \
    void libxl_device_##type##_list_free(libxl_device_##type *list,     \
                                         int num)                       \
    {                                                                   \
        libxl__device_list_free(&libxl__##type##_devtype, list, num);   \
    }

typedef void (*device_add_fn_t)(libxl__egc *, libxl__ao *, uint32_t,
                                libxl_domain_config *, libxl__multidev *);
typedef int (*device_set_default_fn_t)(libxl__gc *, uint32_t, void *, bool);
typedef int (*device_to_device_fn_t)(libxl__gc *, uint32_t, void *,
                                     libxl__device *);
typedef void (*device_init_fn_t)(void *);
typedef void (*device_copy_fn_t)(libxl_ctx *, void *dst, const void *src);
typedef void (*device_dispose_fn_t)(void *);
typedef int (*device_compare_fn_t)(const void *, const void *);
typedef void (*device_merge_fn_t)(libxl_ctx *, void *, void *);
typedef int (*device_dm_needed_fn_t)(void *, unsigned);
typedef void (*device_update_config_fn_t)(libxl__gc *, void *, void *);
typedef int (*device_update_devid_fn_t)(libxl__gc *, uint32_t, void *);
typedef int (*device_get_num_fn_t)(libxl__gc *, const char *, unsigned int *);
typedef int (*device_from_xenstore_fn_t)(libxl__gc *, const char *,
                                         libxl_devid, void *);
typedef int (*device_set_xenstore_config_fn_t)(libxl__gc *, uint32_t, void *,
                                               flexarray_t *, flexarray_t *,
                                               flexarray_t *);

struct libxl__device_type {
    libxl__device_kind type;
    int skip_attach;   /* Skip entry in domcreate_attach_devices() if 1 */
    int ptr_offset;    /* Offset of device array ptr in libxl_domain_config */
    int num_offset;    /* Offset of # of devices in libxl_domain_config */
    int dev_elem_size; /* Size of one device element in array */
    device_add_fn_t                 add;
    device_set_default_fn_t         set_default;
    device_to_device_fn_t           to_device;
    device_init_fn_t                init;
    device_copy_fn_t                copy;
    device_dispose_fn_t             dispose;
    device_compare_fn_t             compare;
    device_merge_fn_t               merge;
    device_dm_needed_fn_t           dm_needed;
    device_update_config_fn_t       update_config;
    device_update_devid_fn_t        update_devid;
    device_get_num_fn_t             get_num;
    device_from_xenstore_fn_t       from_xenstore;
    device_set_xenstore_config_fn_t set_xenstore_config;
};

#define DEFINE_DEVICE_TYPE_STRUCT_X(name, sname, kind, ...)                    \
    const libxl__device_type libxl__ ## name ## _devtype = {                   \
        .type          = LIBXL__DEVICE_KIND_ ## kind,                       \
        .ptr_offset    = offsetof(libxl_domain_config, name ## s),             \
        .num_offset    = offsetof(libxl_domain_config, num_ ## name ## s),     \
        .dev_elem_size = sizeof(libxl_device_ ## sname),                       \
        .add           = libxl__add_ ## name ## s,                             \
        .set_default   = (device_set_default_fn_t)                             \
                         libxl__device_ ## sname ## _setdefault,               \
        .to_device     = (device_to_device_fn_t)libxl__device_from_ ## name,   \
        .init          = (device_init_fn_t)libxl_device_ ## sname ## _init,    \
        .copy          = (device_copy_fn_t)libxl_device_ ## sname ## _copy,    \
        .dispose       = (device_dispose_fn_t)                                 \
                         libxl_device_ ## sname ## _dispose,                   \
        .compare       = (device_compare_fn_t)                                 \
                         libxl_device_ ## sname ## _compare,                   \
        .update_devid  = (device_update_devid_fn_t)                            \
                         libxl__device_ ## sname ## _update_devid,             \
        __VA_ARGS__                                                            \
    }

#define DEFINE_DEVICE_TYPE_STRUCT(name, kind, ...)                             \
    DEFINE_DEVICE_TYPE_STRUCT_X(name, name, kind, __VA_ARGS__)

static inline void **libxl__device_type_get_ptr(
    const libxl__device_type *dt, const libxl_domain_config *d_config)
{
    return (void **)((void *)d_config + dt->ptr_offset);
}

static inline void *libxl__device_type_get_elem(
    const libxl__device_type *dt, const libxl_domain_config *d_config,
    int e)
{
    return *libxl__device_type_get_ptr(dt, d_config) + dt->dev_elem_size * e;
}

static inline int *libxl__device_type_get_num(
    const libxl__device_type *dt, const libxl_domain_config *d_config)
{
    return (int *)((void *)d_config + dt->num_offset);
}

extern const libxl__device_type libxl__vfb_devtype;
extern const libxl__device_type libxl__vkb_devtype;
extern const libxl__device_type libxl__disk_devtype;
extern const libxl__device_type libxl__nic_devtype;
extern const libxl__device_type libxl__vtpm_devtype;
extern const libxl__device_type libxl__usbctrl_devtype;
extern const libxl__device_type libxl__usbdev_devtype;
extern const libxl__device_type libxl__pcidev_devtype;
extern const libxl__device_type libxl__vdispl_devtype;
extern const libxl__device_type libxl__p9_devtype;
extern const libxl__device_type libxl__pvcallsif_devtype;
extern const libxl__device_type libxl__vsnd_devtype;

extern const libxl__device_type *device_type_tbl[];

/*----- Domain destruction -----*/

/* Domain destruction has been split into two functions:
 *
 * libxl__domain_destroy is the main destroy function, which detects
 * stubdoms and calls libxl__destroy_domid on the domain and its
 * stubdom if present, creating a different libxl__destroy_domid_state
 * for each one of them.
 *
 * libxl__destroy_domid actually destroys the domain, but it
 * doesn't check for stubdomains, since that would involve
 * recursion, which we want to avoid.
 */

typedef struct libxl__domain_destroy_state libxl__domain_destroy_state;
typedef struct libxl__destroy_domid_state libxl__destroy_domid_state;
typedef struct libxl__destroy_devicemodel_state libxl__destroy_devicemodel_state;
typedef struct libxl__devices_remove_state libxl__devices_remove_state;

typedef void libxl__domain_destroy_cb(libxl__egc *egc,
                                      libxl__domain_destroy_state *dds,
                                      int rc);

typedef void libxl__domid_destroy_cb(libxl__egc *egc,
                                     libxl__destroy_domid_state *dis,
                                     int rc);

typedef void libxl__devicemodel_destroy_cb(libxl__egc *egc,
                                     libxl__destroy_devicemodel_state *ddms,
                                     int rc);

typedef void libxl__devices_remove_callback(libxl__egc *egc,
                                            libxl__devices_remove_state *drs,
                                            int rc);

struct libxl__devices_remove_state {
    /* filled in by user */
    libxl__ao *ao;
    uint32_t domid;
    libxl__devices_remove_callback *callback;
    int force; /* libxl_device_TYPE_destroy rather than _remove */
    /* private */
    libxl__multidev multidev;
    int num_devices;
};

struct libxl__destroy_devicemodel_state {
    /* filled in by user */
    libxl__ao *ao;
    uint32_t domid;
    libxl__devicemodel_destroy_cb *callback; /* May be called re-entrantly */
    /* private to implementation */
    libxl__ev_child destroyer;
    int rc; /* Accumulated return value for the destroy operation */
};

struct libxl__destroy_domid_state {
    /* filled in by user */
    libxl__ao *ao;
    uint32_t domid;
    libxl__domid_destroy_cb *callback;
    /* private to implementation */
    libxl__devices_remove_state drs;
    libxl__destroy_devicemodel_state ddms;
    libxl__ev_child destroyer;
    bool soft_reset;
    libxl__multidev multidev;
};

struct libxl__domain_destroy_state {
    /* filled by the user */
    libxl__ao *ao;
    uint32_t domid;
    libxl__domain_destroy_cb *callback;
    /* Private */
    int rc;
    uint32_t stubdomid;
    libxl__destroy_domid_state stubdom;
    int stubdom_finished;
    libxl__destroy_domid_state domain;
    int domain_finished;
    bool soft_reset;
};

/*
 * Entry point for domain destruction
 * This function checks for stubdom presence and then calls
 * libxl__destroy_domid on the passed domain and its stubdom if found.
 */
_hidden void libxl__domain_destroy(libxl__egc *egc,
                                   libxl__domain_destroy_state *dds);

/* Used to destroy a domain with the passed id (it doesn't check for stubs) */
_hidden void libxl__destroy_domid(libxl__egc *egc,
                                  libxl__destroy_domid_state *dis);

/* Used to detroy the device model */
_hidden void libxl__destroy_device_model(libxl__egc *egc,
                                         libxl__destroy_devicemodel_state *ddms);

/* Entry point for devices destruction */
_hidden void libxl__devices_destroy(libxl__egc *egc,
                                    libxl__devices_remove_state *drs);

/* Helper function to add a bunch of disks. This should be used when
 * the caller is inside an async op. "multidev" will NOT be prepared by
 * this function, so the caller must make sure to call
 * libxl__multidev_begin before calling this function.
 *
 * The "callback" will be called for each device, and the user is responsible
 * for calling libxl__ao_device_check_last on the callback.
 */
_hidden void libxl__add_disks(libxl__egc *egc, libxl__ao *ao, uint32_t domid,
                              libxl_domain_config *d_config,
                              libxl__multidev *multidev);

_hidden void libxl__add_nics(libxl__egc *egc, libxl__ao *ao, uint32_t domid,
                             libxl_domain_config *d_config,
                             libxl__multidev *multidev);

/*----- device model creation -----*/

/* First layer; wraps libxl__spawn_spawn. */

typedef struct libxl__dm_spawn_state libxl__dm_spawn_state;

typedef void libxl__dm_spawn_cb(libxl__egc *egc, libxl__dm_spawn_state*,
                                int rc /* if !0, error was logged */);

/* Call dmss_init and dmss_dispose to initialise and dispose of
 * libxl__dm_spawn_state */
struct libxl__dm_spawn_state {
    /* mixed - spawn.ao must be initialised by user; rest is private: */
    libxl__spawn_state spawn;
    libxl__ev_qmp qmp;
    libxl__ev_time timeout;
    libxl__dm_resume_state dmrs;
    /* filled in by user, must remain valid: */
    uint32_t guest_domid; /* domain being served */
    libxl_domain_config *guest_config;
    libxl__domain_build_state *build_state; /* relates to guest_domid */
    libxl__dm_spawn_cb *callback;
};

_hidden void libxl__spawn_local_dm(libxl__egc *egc, libxl__dm_spawn_state*);

/*
 * Called after forking but before executing the local devicemodel.
 */
_hidden int libxl__local_dm_preexec_restrict(libxl__gc *gc);

/* Stubdom device models. */

typedef struct {
    /* Mixed - user must fill in public parts EXCEPT callback,
     * which may be undefined on entry.  (See above for details) */
    libxl__dm_spawn_state dm; /* the stub domain device model */
    /* filled in by user, must remain valid: */
    libxl__dm_spawn_cb *callback; /* called as callback(,&sdss->dm,) */
    /* private to libxl__spawn_stub_dm: */
    libxl_domain_config dm_config;
    libxl__domain_build_state dm_state;
    libxl__dm_spawn_state pvqemu;
    libxl__destroy_domid_state dis;
    libxl__multidev multidev;
    libxl__xswait_state xswait;
    libxl__spawn_state qmp_proxy_spawn;
} libxl__stub_dm_spawn_state;

_hidden void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state*);

_hidden char *libxl__stub_dm_name(libxl__gc *gc, const char * guest_name);

/* Qdisk backend launch helpers */

_hidden void libxl__spawn_qdisk_backend(libxl__egc *egc,
                                        libxl__dm_spawn_state *dmss);
_hidden int libxl__destroy_qdisk_backend(libxl__gc *gc, uint32_t domid);

/*----- Domain creation -----*/


struct libxl__domain_create_state {
    /* filled in by user */
    libxl__ao *ao;
    libxl_domain_config *guest_config;
    libxl_domain_config guest_config_saved; /* vanilla config */
    int restore_fd, libxc_fd;
    int restore_fdfl; /* original flags of restore_fd */
    int send_back_fd;
    libxl_domain_restore_params restore_params;
    uint32_t domid;
    bool soft_reset;
    libxl__domain_create_cb *callback;
    libxl_asyncprogress_how aop_console_how;
    /* private to domain_create */
    int guest_domid;
    int device_type_idx;
    const char *colo_proxy_script;
    libxl__domain_build_state build_state;
    libxl__colo_restore_state crs;
    libxl__checkpoint_devices_state cds;
    libxl__bootloader_state bl;
    libxl__stub_dm_spawn_state sdss;
        /* If we're not doing stubdom, we use only sdss.dm,
         * for the non-stubdom device model. */
    libxl__stream_read_state srs;
    /* necessary if the domain creation failed and we have to destroy it */
    libxl__domain_destroy_state dds;
    libxl__multidev multidev;
    libxl__xswait_state console_xswait;
};

_hidden int libxl__device_nic_set_devids(libxl__gc *gc,
                                         libxl_domain_config *d_config,
                                         uint32_t domid);

/*----- Domain suspend (save) functions -----*/

/* calls dss->callback when done */
_hidden void libxl__domain_save(libxl__egc *egc,
                                libxl__domain_save_state *dss);


/* calls libxl__xc_domain_suspend_done when done */
_hidden void libxl__xc_domain_save(libxl__egc *egc,
                                   libxl__domain_save_state *dss,
                                   libxl__save_helper_state *shs);
/* If rc==0 then retval is the return value from xc_domain_save
 * and errnoval is the errno value it provided.
 * If rc!=0, retval and errnoval are undefined. */
_hidden void libxl__xc_domain_save_done(libxl__egc*, void *dss_void,
                                        int rc, int retval, int errnoval);

/* Used by asynchronous callbacks: ie ones which xc regards as
 * returning a value, but which we want to handle asynchronously.
 * Such functions' actual callback function return void in libxl
 * When they are ready to indicate completion, they call this. */
void libxl__xc_domain_saverestore_async_callback_done(libxl__egc *egc,
                           libxl__save_helper_state *shs, int return_value);


_hidden void libxl__domain_suspend_common_switch_qemu_logdirty
                               (uint32_t domid, unsigned int enable, void *data);
_hidden void libxl__domain_common_switch_qemu_logdirty(libxl__egc *egc,
                                               int domid, unsigned enable,
                                               libxl__logdirty_switch *lds);
_hidden int libxl__save_emulator_xenstore_data(libxl__domain_save_state *dss,
                                               char **buf, uint32_t *len);
_hidden int libxl__restore_emulator_xenstore_data
    (libxl__domain_create_state *dcs, const char *ptr, uint32_t size);


/* calls libxl__xc_domain_restore_done when done */
_hidden void libxl__xc_domain_restore(libxl__egc *egc,
                                      libxl__domain_create_state *dcs,
                                      libxl__save_helper_state *shs);
/* If rc==0 then retval is the return value from xc_domain_save
 * and errnoval is the errno value it provided.
 * If rc!=0, retval and errnoval are undefined. */
_hidden void libxl__xc_domain_restore_done(libxl__egc *egc, void *dcs_void,
                                           int rc, int retval, int errnoval);

_hidden void libxl__save_helper_init(libxl__save_helper_state *shs);
_hidden void libxl__save_helper_abort(libxl__egc *egc,
                                      libxl__save_helper_state *shs);

static inline bool libxl__save_helper_inuse(const libxl__save_helper_state *shs)
{
    return libxl__ev_child_inuse(&shs->child);
}

/* Each time the dm needs to be saved, we must call suspend and then save
 * calls dsps->callback_device_model_done when done */
_hidden void libxl__domain_suspend_device_model(libxl__egc *egc,
                                           libxl__domain_suspend_state *dsps);

_hidden const char *libxl__device_model_savefile(libxl__gc *gc, uint32_t domid);

/* calls dsps->callback_common_done when done */
_hidden void libxl__domain_suspend(libxl__egc *egc,
                                   libxl__domain_suspend_state *dsps);
/* used by libxc to suspend the guest during migration */
_hidden void libxl__domain_suspend_callback(void *data);

/* Remus setup and teardown */
_hidden void libxl__remus_setup(libxl__egc *egc,
                                libxl__remus_state *rs);
_hidden void libxl__remus_teardown(libxl__egc *egc,
                                   libxl__remus_state *rs,
                                   int rc);
_hidden void libxl__remus_restore_setup(libxl__egc *egc,
                                        libxl__domain_create_state *dcs);

_hidden char *libxl__domid_history_path(libxl__gc *gc,
                                        const char *suffix);

/*
 * Convenience macros.
 */

#define FILLZERO LIBXL_FILLZERO


/*
 * All of these assume (or define)
 *    libxl__gc *gc;
 * as a local variable.
 */

#define GC_INIT(ctx)  libxl__gc gc[1]; LIBXL_INIT_GC(gc[0],ctx)
#define GC_FREE       libxl__free_all(gc)
#define CTX           libxl__gc_owner(gc)
#define NOGC          (&CTX->nogc_gc) /* pass only to consenting functions */

/* Allocation macros all of which use the gc. */

#define ARRAY_SIZE_OK(ptr, nmemb) ((nmemb) < INT_MAX / (sizeof(*(ptr)) * 2))

/*
 * Expression statement  <type> *GCNEW(<type> *var);
 * Uses                  libxl__gc *gc;
 *
 * Allocates a new object of type <type> from the gc and zeroes it
 * with memset.  Sets var to point to the new object or zero (setting
 * errno).  Returns the new value of var.
 */
#define GCNEW(var)                                      \
    (((var) = libxl__zalloc((gc),sizeof(*(var)))))

/*
 * Expression statement  <type> *GCNEW_ARRAY(<type> *var, ssize_t nmemb);
 * Uses                  libxl__gc *gc;
 *
 * Like GCNEW but allocates an array of nmemb elements, as if from
 * calloc.  Does check for integer overflow due to large nmemb.  If
 * nmemb is 0 may succeed by returning 0.
 */
#define GCNEW_ARRAY(var, nmemb)                                 \
    ((var) = libxl__calloc((gc), (nmemb), sizeof(*(var))))

/*
 * Expression statement  <type> *GCREALLOC_ARRAY(<type> *var, size_t nmemb);
 * Uses                  libxl__gc *gc;
 *
 * Reallocates the array var to be of size nmemb elements.  Updates
 * var and returns the new value of var.  Does check for integer
 * overflow due to large nmemb.
 *
 * Do not pass nmemb==0.  old may be 0 on entry.
 */
#define GCREALLOC_ARRAY(var, nmemb)                                     \
    (assert(nmemb > 0),                                                 \
     assert(ARRAY_SIZE_OK((var), (nmemb))),                             \
     (var) = libxl__realloc((gc), (var), (nmemb)*sizeof(*(var))))


/*
 * Expression            char *GCSPRINTF(const char *fmt, ...);
 * Uses                  libxl__gc *gc;
 *
 * Trivial convenience wrapper for libxl__sprintf.
 */
#define GCSPRINTF(fmt, ...) (libxl__sprintf((gc), (fmt), __VA_ARGS__))


/*
 * Expression statements
 *    void LOG(<xtl_level_suffix>, const char *fmt, ...);
 *    void LOGE(<xtl_level_suffix>, const char *fmt, ...);
 *    void LOGEV(<xtl_level_suffix>, int errnoval, const char *fmt, ...);
 *
 *    void LOGD(<xtl_level_suffix>, uint32_t domid, const char *fmt, ...);
 *    void LOGED(<xtl_level_suffix>, uint32_t domid, const char *fmt, ...);
 *    void LOGEVD(<xtl_level_suffix>, int errnoval, uint32_t domid, const char *fmt, ...);
 * Use
 *    libxl__gc *gc;
 *
 * Trivial convenience wrappers for LIBXL__LOG, LIBXL__LOG_ERRNO,
 * LIBXL__LOG_ERRNOVAL, LIBXL__LOGD, LIBXL__LOGD_ERRNO and
 * LIBXL__LOGD_ERRNOVAL respectively (and thus for libxl__log).
 *
 * XTL_<xtl_level_suffix> should exist and be an xentoollog.h log level
 * So <xtl_level_suffix> should be one of
 *   DEBUG VERBOSE DETAIL PROGRESS INFO NOTICE WARN ERROR ERROR CRITICAL
 * Of these, most of libxl uses
 *   DEBUG INFO WARN ERROR
 *
 * The LOG*D family will preprend the log message with a string formatted
 * as follows: 'Domain %PRIu32:'. This should help better automatic sorting
 * of log messages per domain.
 */
#define LOG(l,f, ...)     LIBXL__LOG(CTX,XTL_##l,(f),##__VA_ARGS__)
#define LOGE(l,f, ...)    LIBXL__LOG_ERRNO(CTX,XTL_##l,(f),##__VA_ARGS__)
#define LOGEV(l,e,f, ...) LIBXL__LOG_ERRNOVAL(CTX,XTL_##l,(e),(f),##__VA_ARGS__)

#define LOGD(l,d,f, ...)     LIBXL__LOGD(CTX,XTL_##l,(d),(f),##__VA_ARGS__)
#define LOGED(l,d,f, ...)    LIBXL__LOGD_ERRNO(CTX,XTL_##l,(d),(f),##__VA_ARGS__)
#define LOGEVD(l,e,d,f, ...) LIBXL__LOGD_ERRNOVAL(CTX,XTL_##l,(e),(d),(f),##__VA_ARGS__)


/* Locking functions.  See comment for "lock" member of libxl__ctx. */

static inline void libxl__ctx_lock(libxl_ctx *ctx) {
    int r = pthread_mutex_lock(&ctx->lock);
    assert(!r);
}

static inline void libxl__ctx_unlock(libxl_ctx *ctx) {
    int r = pthread_mutex_unlock(&ctx->lock);
    assert(!r);
}

#define CTX_LOCK (libxl__ctx_lock(CTX))
#define CTX_UNLOCK (libxl__ctx_unlock(CTX))

/*
 * Automatic NUMA placement
 *
 * These functions and data structures deal with the initial placement of a
 * domain onto the host NUMA nodes.
 *
 * The key concept here is the one of "NUMA placement candidate", which is
 * basically a set of nodes whose characteristics have been successfully
 * checked against some specific requirements. More precisely, a candidate
 * is the nodemap associated with one of the possible subset of the host
 * NUMA nodes providing a certain amount of free memory, or a given number
 * of cpus, or even both (depending in what the caller wants). For
 * convenience of use, some of this information are stored within the
 * candidate itself, instead of always being dynamically computed. A single
 * node can be valid placement candidate, as well as it is possible for a
 * candidate to contain all the nodes of the host. The fewer nodes there
 * are in a candidate, the better performance a domain placed onto it
 * should get (at least from a NUMA point of view). For instance, looking
 * for a numa candidates with 2GB of free memory means we want the subsets
 * of the host NUMA nodes with, cumulatively, at least 2GB of free memory.
 * This condition can be satisfied by just one particular node, or it may
 * require more nodes, depending on the characteristics of the host, on how
 * many domains have been created already, on how big they are, etc.
 *
 * The intended usage is as follows:
 *  1. first of all, call libxl__get_numa_candidates(), and specify the
 *     proper constraints to it (e.g., the amount of memory a domain need
 *     as the minimum amount of free memory for the candidates). If a
 *     candidate comparison function is provided, the candidate with fewer
 *     nodes that is found to be best according to what such fucntion says
 *     is returned. If no comparison function is passed, the very first
 *     candidate is.
 *  2. The chosen candidate's nodemap should be utilized for computing the
 *     actual affinity of the domain which, given the current NUMA support
 *     in the hypervisor, is what determines the placement of the domain's
 *     vcpus and memory.
 */

typedef struct {
    int nr_cpus, nr_nodes;
    int nr_vcpus;
    uint64_t free_memkb;
    libxl_bitmap nodemap;
} libxl__numa_candidate;

/* Signature for the comparison function between two candidates */
typedef int (*libxl__numa_candidate_cmpf)(const libxl__numa_candidate *c1,
                                          const libxl__numa_candidate *c2);

/*
 * This looks for the best NUMA placement candidate satisfying some
 * specific conditions. If min_nodes and/or max_nodes are not 0, their
 * value is used to determine the minimum and maximum number of nodes the
 * candidate can have. If they are 0, it means the candidate can contain
 * from 1 node (min_nodes=0) to the total number of nodes of the host
 * (max_ndoes=0). If min_free_memkb and/or min_cpus are not 0, the caller
 * only wants candidates with at least the amount of free memory and the
 * number of cpus they specify, respectively. If they are 0, the
 * candidates' free memory and/or number of cpus won't be checked at all.
 *
 * Candidates are compared among each others by calling numa_cmpf(), which
 * is where the heuristics for determining which candidate is the best
 * one is actually implemented. The only bit of it that is hardcoded in
 * this function is the fact that candidates with fewer nodes are always
 * preferrable.
 *
 * If at least one suitable candidate is found, it is returned in cndt_out,
 * cndt_found is set to one, and the function returns successfully. On the
 * other hand, if not even one single candidate can be found, the function
 * still returns successfully but cndt_found will be zero.
 *
 * Finally, suitable_cpumap is useful for telling that only the cpus in that
 * mask should be considered when generating placement candidates (for
 * example because of cpupools).
 *
 * It is up to the function to properly allocate cndt_out (by calling
 * libxl__numa_candidate_alloc()), while it is the caller that should init
 * (libxl__numa_candidate_init()) and free (libxl__numa_candidate_dispose())
 * it.
 */
_hidden int libxl__get_numa_candidate(libxl__gc *gc,
                                      uint64_t min_free_memkb, int min_cpus,
                                      int min_nodes, int max_nodes,
                                      const libxl_bitmap *suitable_cpumap,
                                      libxl__numa_candidate_cmpf numa_cmpf,
                                      libxl__numa_candidate *cndt_out,
                                      int *cndt_found);

/* Initialization, allocation and deallocation for placement candidates */
static inline void libxl__numa_candidate_init(libxl__numa_candidate *cndt)
{
    cndt->free_memkb = 0;
    cndt->nr_cpus = cndt->nr_nodes = cndt->nr_vcpus = 0;
    libxl_bitmap_init(&cndt->nodemap);
}

static inline int libxl__numa_candidate_alloc(libxl__gc *gc,
                                              libxl__numa_candidate *cndt)
{
    return libxl_node_bitmap_alloc(CTX, &cndt->nodemap, 0);
}
static inline void libxl__numa_candidate_dispose(libxl__numa_candidate *cndt)
{
    libxl_bitmap_dispose(&cndt->nodemap);
}

/* Retrieve (in nodemap) the node map associated to placement candidate cndt */
static inline
void libxl__numa_candidate_get_nodemap(libxl__gc *gc,
                                       const libxl__numa_candidate *cndt,
                                       libxl_bitmap *nodemap)
{
    libxl_bitmap_copy(CTX, nodemap, &cndt->nodemap);
}
/* Set the node map of placement candidate cndt to match nodemap */
static inline
void libxl__numa_candidate_put_nodemap(libxl__gc *gc,
                                       libxl__numa_candidate *cndt,
                                       const libxl_bitmap *nodemap)
{
    libxl_bitmap_copy(CTX, &cndt->nodemap, nodemap);
}

/* Check if vNUMA config is valid. Returns 0 if valid,
 * ERROR_VNUMA_CONFIG_INVALID otherwise.
 */
int libxl__vnuma_config_check(libxl__gc *gc,
                              const libxl_domain_build_info *b_info,
                              const libxl__domain_build_state *state);
int libxl__vnuma_build_vmemrange_pv_generic(libxl__gc *gc,
                                            uint32_t domid,
                                            libxl_domain_build_info *b_info,
                                            libxl__domain_build_state *state);
int libxl__vnuma_build_vmemrange_pv(libxl__gc *gc,
                                    uint32_t domid,
                                    libxl_domain_build_info *b_info,
                                    libxl__domain_build_state *state);
int libxl__vnuma_build_vmemrange_hvm(libxl__gc *gc,
                                     uint32_t domid,
                                     libxl_domain_build_info *b_info,
                                     libxl__domain_build_state *state,
                                     struct xc_dom_image *dom);
bool libxl__vnuma_configured(const libxl_domain_build_info *b_info);

_hidden int libxl__ms_vm_genid_set(libxl__gc *gc, uint32_t domid,
                                   const libxl_ms_vm_genid *id);


/* Som handy macros for defbool type. */
#define LIBXL__DEFBOOL_DEFAULT     (0)
#define LIBXL__DEFBOOL_FALSE       (-1)
#define LIBXL__DEFBOOL_TRUE        (1)
#define LIBXL__DEFBOOL_STR_DEFAULT "<default>"
#define LIBXL__DEFBOOL_STR_FALSE   "False"
#define LIBXL__DEFBOOL_STR_TRUE    "True"
static inline int libxl__defbool_is_default(libxl_defbool *db)
{
    return !db->val;
}

/*
 * Inserts "elm_new" into the sorted list "head".
 *
 * "elm_search" must be a loop search variable of the same type as
 * "elm_new".  "new_after_search_p" must be an expression which is
 * true iff the element "elm_new" sorts after the element
 * "elm_search".
 *
 * "search_body" can be empty, or some declaration(s) and statement(s)
 * needed for "new_after_search_p".
 */
#define LIBXL_TAILQ_INSERT_SORTED(head, entry, elm_new, elm_search,     \
                                  search_body, new_after_search_p)      \
    do {                                                                \
        for ((elm_search) = LIBXL_TAILQ_FIRST((head));                  \
             (elm_search);                                              \
             (elm_search) = LIBXL_TAILQ_NEXT((elm_search), entry)) {    \
            search_body;                                                \
            if (!(new_after_search_p))                                  \
                break;                                                  \
        }                                                               \
        /* now elm_search is either the element before which we want    \
         * to place elm_new, or NULL meaning we want to put elm_new at  \
         * the end */                                                   \
        if ((elm_search))                                               \
            LIBXL_TAILQ_INSERT_BEFORE((elm_search), (elm_new), entry);  \
        else                                                            \
            LIBXL_TAILQ_INSERT_TAIL((head), (elm_new), entry);          \
    } while(0)


/*
 * int CTYPE(ISFOO, char c);
 * int CTYPE(toupper, char c);
 * int CTYPE(tolower, char c);
 *
 * This is necessary because passing a simple char to a ctype.h
 * is forbidden.  ctype.h macros take ints derived from _unsigned_ chars.
 *
 * If you have a char which might be EOF then you should already have
 * it in an int representing an unsigned char, and you can use the
 * <ctype.h> macros directly.  This generally happens only with values
 * from fgetc et al.
 *
 * For any value known to be a character (eg, anything that came from
 * a char[]), use CTYPE.
 */
#define CTYPE(isfoo,c) (isfoo((unsigned char)(c)))

int libxl__defbool_parse_json(libxl__gc *gc, const libxl__json_object *o,
                              libxl_defbool *p);
int libxl__bool_parse_json(libxl__gc *gc, const libxl__json_object *o,
                           bool *p);
int libxl__mac_parse_json(libxl__gc *gc, const libxl__json_object *o,
                          libxl_mac *p);
int libxl__bitmap_parse_json(libxl__gc *gc, const libxl__json_object *o,
                             libxl_bitmap *p);
int libxl__uuid_parse_json(libxl__gc *gc, const libxl__json_object *o,
                           libxl_uuid *p);
int libxl__cpuid_policy_list_parse_json(libxl__gc *gc,
                                        const libxl__json_object *o,
                                        libxl_cpuid_policy_list *p);
int libxl__string_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
                                  libxl_string_list *p);
int libxl__key_value_list_parse_json(libxl__gc *gc,
                                     const libxl__json_object *o,
                                     libxl_key_value_list *p);
int libxl__hwcap_parse_json(libxl__gc *gc, const libxl__json_object *o,
                            libxl_hwcap *p);
int libxl__ms_vm_genid_parse_json(libxl__gc *gc, const libxl__json_object *o,
                                  libxl_ms_vm_genid *p);
int libxl__int_parse_json(libxl__gc *gc, const libxl__json_object *o,
                          void *p);
int libxl__uint8_parse_json(libxl__gc *gc, const libxl__json_object *o,
                            void *p);
int libxl__uint16_parse_json(libxl__gc *gc, const libxl__json_object *o,
                             void *p);
int libxl__uint32_parse_json(libxl__gc *gc, const libxl__json_object *o,
                             void *p);
int libxl__uint64_parse_json(libxl__gc *gc, const libxl__json_object *o,
                             void *p);
int libxl__string_parse_json(libxl__gc *gc, const libxl__json_object *o,
                             char **p);

int libxl__random_bytes(libxl__gc *gc, uint8_t *buf, size_t len);

#include "_libxl_types_private.h"
#include "_libxl_types_internal_private.h"

/* This always return false, there's no "default value" for hw cap */
static inline int libxl__hwcap_is_default(libxl_hwcap *hwcap)
{
    return 0;
}

static inline int libxl__string_list_is_empty(libxl_string_list *psl)
{
    return !libxl_string_list_length(psl);
}

static inline int libxl__key_value_list_is_empty(libxl_key_value_list *pkvl)
{
    return !libxl_key_value_list_length(pkvl);
}

int libxl__cpuid_policy_is_empty(libxl_cpuid_policy_list *pl);

/* Portability note: a proper flock(2) implementation is required */
typedef struct {
    libxl__carefd *carefd;
    char *path; /* path of the lock file itself */
} libxl__flock;
/* The CTX_LOCK must be held around uses of this lock */

libxl__flock *libxl__lock_file(libxl__gc *gc, const char *filename);
void libxl__unlock_file(libxl__flock *lock);

libxl__flock *libxl__lock_domain_userdata(libxl__gc *gc, uint32_t domid);
libxl__flock *libxl__lock_domid_history(libxl__gc *gc);

/*
 * Retrieve / store domain configuration from / to libxl private
 * data store. The registry entry in libxl private data store
 * is "libxl-json".
 * Caller must hold user data lock.
 *
 * Other names used for this lock throughout the libxl code are json_lock,
 * libxl__domain_userdata_lock, "libxl-json", data store lock.
 *
 * See the comment for libxl__ao_device, and "Algorithm for handling device
 * removal", for information about using the libxl-json lock / json_lock.
 */
int libxl__get_domain_configuration(libxl__gc *gc, uint32_t domid,
                                    libxl_domain_config *d_config);
int libxl__set_domain_configuration(libxl__gc *gc, uint32_t domid,
                                    libxl_domain_config *d_config);

/* ------ Things related to updating domain configurations ----- */
void libxl__update_domain_configuration(libxl__gc *gc,
                                        libxl_domain_config *dst,
                                        const libxl_domain_config *src);

/* Target memory in xenstore is different from what user has
 * asked for. The difference is video_memkb + (possible) fudge.
 * See libxl_set_memory_target.
 */
static inline
uint64_t libxl__get_targetmem_fudge(libxl__gc *gc,
                                    const libxl_domain_build_info *info)
{
    int64_t mem_target_fudge = (info->type == LIBXL_DOMAIN_TYPE_HVM &&
                                info->max_memkb > info->target_memkb)
                                ? LIBXL_MAXMEM_CONSTANT : 0;

    return info->video_memkb + mem_target_fudge;
}

int libxl__get_memory_target(libxl__gc *gc, uint32_t domid,
                             uint64_t *out_target_memkb,
                             uint64_t *out_max_memkb);
void libxl__xcinfo2xlinfo(libxl_ctx *ctx,
                          const xc_domaininfo_t *xcinfo,
                          libxl_dominfo *xlinfo);

/* Macros used to compare device identifier. Returns true if the two
 * devices have same identifier. */
#define COMPARE_DEVID(a, b) ((a)->devid == (b)->devid)
#define COMPARE_DISK(a, b) (!strcmp((a)->vdev, (b)->vdev))
#define COMPARE_PCI(a, b) ((a)->func == (b)->func &&    \
                           (a)->bus == (b)->bus &&      \
                           (a)->dev == (b)->dev)
#define COMPARE_USB(a, b) ((a)->ctrl == (b)->ctrl && \
                           (a)->port == (b)->port)
#define COMPARE_USBCTRL(a, b) ((a)->devid == (b)->devid)

/* This function copies X bytes from source to destination bitmap,
 * where X is the smaller of the two sizes.
 *
 * If destination's size is larger than source, the extra bytes are
 * untouched.
 *
 * XXX This is introduced to fix a regression for 4.5. It shall
 * be revisited in 4.6 time frame.
 */
void libxl__bitmap_copy_best_effort(libxl__gc *gc, libxl_bitmap *dptr,
                                    const libxl_bitmap *sptr);

int libxl__count_physical_sockets(libxl__gc *gc, int *sockets);

_hidden int libxl__read_sysfs_file_contents(libxl__gc *gc,
                                            const char *filename,
                                            void **data_r,
                                            int *datalen_r);

#define LIBXL_QEMU_USER_PREFIX "xen-qemuuser"
#define LIBXL_QEMU_USER_SHARED LIBXL_QEMU_USER_PREFIX"-shared"
#define LIBXL_QEMU_USER_RANGE_BASE LIBXL_QEMU_USER_PREFIX"-range-base"
#define LIBXL_QEMU_USER_REAPER LIBXL_QEMU_USER_PREFIX"-reaper"

static inline bool libxl__acpi_defbool_val(const libxl_domain_build_info *b_info)
{
    return libxl_defbool_val(b_info->acpi) &&
           libxl_defbool_val(b_info->u.hvm.acpi);
}

/*
 * Add a device in libxl_domain_config structure
 *
 * If there is already a device with the same identifier in d_config,
 * that entry is updated.
 *
 * parameters:
 *  d_config: pointer to template domain config
 *  dt:       type of `dev'
 *  dev:      the device that is to be added / removed / updated
 *            (a copy of `dev' will be made)
 */
void device_add_domain_config(libxl__gc *gc, libxl_domain_config *d_config,
                              const libxl__device_type *dt,
                              const void *dev);

void libxl__device_add_async(libxl__egc *egc, uint32_t domid,
                             const libxl__device_type *dt, void *type,
                             libxl__ao_device *aodev);
int libxl__device_add(libxl__gc *gc, uint32_t domid,
                      const libxl__device_type *dt, void *type);

/* Caller is responsible for freeing the memory by calling
 * libxl__device_list_free
 */
void* libxl__device_list(libxl__gc *gc, const libxl__device_type *dt,
                         uint32_t domid, int *num);
void libxl__device_list_free(const libxl__device_type *dt,
                             void *list, int num);

static inline bool libxl__timer_mode_is_default(libxl_timer_mode *tm)
{
    return *tm == LIBXL_TIMER_MODE_DEFAULT;
}

static inline bool libxl__string_is_default(char **s)
{
    return *s == NULL;
}

_hidden int libxl__prepare_sockaddr_un(libxl__gc *gc, struct sockaddr_un *un,
                                       const char *path, const char *what);
static inline const char *libxl__qemu_qmp_path(libxl__gc *gc, int domid)
{
    return GCSPRINTF("%s/qmp-libxl-%d", libxl__run_dir_path(), domid);
}

/* Send control commands over xenstore and wait for an Ack. */
_hidden int libxl__domain_pvcontrol(libxl__egc *egc,
                                    libxl__xswait_state *pvcontrol,
                                    domid_t domid, const char *cmd);

/*
 * Maximum number of seconds after desctruction then a domid remains
 * 'recent'. Recent domids are not allowed to be re-used. This can be
 * overidden, for debugging purposes, by the environment variable of the
 * same name.
 */
#define LIBXL_DOMID_REUSE_TIMEOUT 60

/* Check whether a domid is recent */
int libxl__is_domid_recent(libxl__gc *gc, uint32_t domid, bool *recent);

#endif

/*
 * Local variables:
 * mode: C
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 */
