/*
 * Copyright (c) 2007-2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
#include <stdarg.h>
#include <string.h>
#include <mach-o/loader.h>
#include <mach-o/nlist.h>
#include <mach-o/reloc.h>
#if KERNEL
    #include <kern/kalloc.h>
    #include <libkern/libkern.h>
    #include <mach/vm_param.h>
    #include <vm/vm_kern.h>
#else
    #include <stdio.h>
    #include <stdlib.h>
    #include <mach/mach_init.h>
    #include <mach-o/swap.h>
#endif

#define DEBUG_ASSERT_COMPONENT_NAME_STRING "kxld"
#include <AssertMacros.h>

#include "kxld_util.h"

#if !KERNEL
static void unswap_macho_32(u_char *file, enum NXByteOrder host_order, 
    enum NXByteOrder target_order);
static void unswap_macho_64(u_char *file, enum NXByteOrder host_order, 
    enum NXByteOrder target_order);
#endif /* !KERNEL */

#if DEBUG
static unsigned long num_allocations = 0;
static unsigned long num_frees = 0;
static unsigned long bytes_allocated = 0;
static unsigned long bytes_freed = 0;
#endif

static KXLDLoggingCallback s_logging_callback = NULL;
static char s_callback_name[64] = "internal";
static void *s_callback_data = NULL;

#if !KERNEL
static boolean_t s_cross_link_enabled  = FALSE;
static kxld_size_t s_cross_link_page_size = PAGE_SIZE;
#endif


/*******************************************************************************
*******************************************************************************/
void 
kxld_set_logging_callback(KXLDLoggingCallback logging_callback)
{
    s_logging_callback = logging_callback;
}

/*******************************************************************************
*******************************************************************************/
void 
kxld_set_logging_callback_data(const char *name, void *user_data)
{
    if (name) {
        (void)strlcpy(s_callback_name, name, sizeof(s_callback_name));
        /* disallow format strings in the kxld logging callback name */
        for (size_t i = 0; i < sizeof(s_callback_name); i++) {
            if (s_callback_name[i] == '%') {
                s_callback_name[i] = '.';
            }
        }
    } else {
        (void)strlcpy(s_callback_name, "internal", sizeof(s_callback_name));
    }

    s_callback_data = user_data;
}

/*******************************************************************************
*******************************************************************************/
void 
kxld_log(KXLDLogSubsystem subsystem, KXLDLogLevel level, 
    const char *in_format, ...)
{
    char stack_buffer[256];
    char *alloc_buffer = NULL;
    char *format = stack_buffer;
    u_int length = 0;
    va_list ap;

    if (s_logging_callback) {

        length = snprintf(stack_buffer, sizeof(stack_buffer), "kxld[%s]: %s",
                          s_callback_name, in_format);

        if (length >= sizeof(stack_buffer)) {
            length += 1;
            alloc_buffer = kxld_alloc(length);
            if (!alloc_buffer) return;

            snprintf(alloc_buffer, length, "kxld[%s]: %s",
                     s_callback_name, in_format);
            format = alloc_buffer;
        }

        va_start(ap, in_format);
        s_logging_callback(subsystem, level, format, ap, s_callback_data);
        va_end(ap);

        if (alloc_buffer) {
            kxld_free(alloc_buffer, length);
        }
    }
}

/* We'll use kalloc for any page-based allocations under this threshold, and
 * kmem_alloc otherwise.
 */
#define KALLOC_MAX 16 * 1024

/*******************************************************************************
*******************************************************************************/
void * 
kxld_alloc(size_t size)
{
    void * ptr = NULL;
    
#if KERNEL
    ptr = kalloc(size);
#else
    ptr = malloc(size);
#endif

#if DEBUG
    if (ptr) {
        ++num_allocations;
        bytes_allocated += size;
    }
#endif

    return ptr;
}

/*******************************************************************************
*******************************************************************************/
void *
kxld_page_alloc_untracked(size_t size)
{
    void * ptr = NULL;
#if KERNEL
    kern_return_t rval = 0;
    vm_offset_t addr = 0;
#endif /* KERNEL */

    size = round_page(size);

#if KERNEL
    if (size < KALLOC_MAX) {
        ptr = kalloc(size);
    } else {
        rval = kmem_alloc(kernel_map, &addr, size, VM_KERN_MEMORY_OSKEXT);
        if (!rval) ptr = (void *) addr;
    }
#else /* !KERNEL */
    ptr = malloc(size);
#endif /* KERNEL */

    return ptr;
}

/*******************************************************************************
*******************************************************************************/
void *
kxld_page_alloc(size_t size)
{
    void * ptr = NULL;

    ptr = kxld_page_alloc_untracked(size);
#if DEBUG
    if (ptr) {
        ++num_allocations;
        bytes_allocated += round_page(size);
    }
#endif /* DEBUG */

    return ptr;
}

/*******************************************************************************
*******************************************************************************/
void *
kxld_alloc_pageable(size_t size)
{
    size = round_page(size);

#if KERNEL
    kern_return_t rval = 0;
    vm_offset_t ptr = 0;

    rval = kmem_alloc_pageable(kernel_map, &ptr, size, VM_KERN_MEMORY_OSKEXT);
    if (rval) ptr = 0;

    return (void *) ptr;
#else
    return kxld_page_alloc_untracked(size);
#endif
}

/*******************************************************************************
*******************************************************************************/
void
kxld_free(void *ptr, size_t size __unused)
{
#if DEBUG
    ++num_frees;
    bytes_freed += size;
#endif

#if KERNEL
    kfree(ptr, size);
#else
    free(ptr);
#endif
}

/*******************************************************************************
*******************************************************************************/
void
kxld_page_free_untracked(void *ptr, size_t size __unused)
{
#if KERNEL
    size = round_page(size);

    if (size < KALLOC_MAX) {
        kfree(ptr, size);
    } else {
        kmem_free(kernel_map, (vm_offset_t) ptr, size);
    }
#else /* !KERNEL */
    free(ptr);
#endif /* KERNEL */
}
    

/*******************************************************************************
*******************************************************************************/
void
kxld_page_free(void *ptr, size_t size)
{
#if DEBUG
    ++num_frees;
    bytes_freed += round_page(size);
#endif /* DEBUG */
    kxld_page_free_untracked(ptr, size);
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
validate_and_swap_macho_32(u_char *file, u_long size
#if !KERNEL
    , enum NXByteOrder host_order
#endif /* !KERNEL */
    )
{
    kern_return_t rval = KERN_FAILURE;
    struct mach_header *mach_hdr = (struct mach_header *) ((void *) file);
    struct load_command *load_hdr = NULL;
    struct segment_command *seg_hdr = NULL;
    struct section *sects = NULL;
    struct relocation_info *relocs = NULL;
    struct symtab_command *symtab_hdr = NULL;
    struct nlist *symtab = NULL;
    u_long offset = 0;
    u_int cmd = 0;
    u_int cmdsize = 0;
    u_int i = 0; 
    u_int j = 0; 
#if !KERNEL
    boolean_t swap = FALSE;
#endif /* !KERNEL */

    check(file);
    check(size);

    /* Verify that the file is big enough for the mach header */
    require_action(size >= sizeof(*mach_hdr), finish, 
        rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));
    offset = sizeof(*mach_hdr);

#if !KERNEL
    /* Swap the mach header if necessary */
    if (mach_hdr->magic == MH_CIGAM) {
        swap = TRUE;
        (void) swap_mach_header(mach_hdr, host_order);
    }
#endif /* !KERNEL */

    /* Validate the mach_header's magic number */
    require_action(mach_hdr->magic == MH_MAGIC, finish,
        rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
            "Invalid magic number: 0x%x.", mach_hdr->magic));

   /* If in the running kernel, and asked to validate the kernel
    * (which is the only file of type MH_EXECUTE we should ever see),
    * then just assume it's ok or we wouldn't be running to begin with.
    */
#if KERNEL
    if (mach_hdr->filetype == MH_EXECUTE) {
        rval = KERN_SUCCESS;
        goto finish;
    }
#endif /* KERNEL */

    /* Validate and potentially swap the load commands */
    for(i = 0; i < mach_hdr->ncmds; ++i, offset += cmdsize) {

        /* Get the load command and size */
        load_hdr = (struct load_command *) ((void *) (file + offset));
        cmd = load_hdr->cmd;
        cmdsize = load_hdr->cmdsize;

#if !KERNEL
        if (swap) {
            cmd = OSSwapInt32(load_hdr->cmd);
            cmdsize = OSSwapInt32(load_hdr->cmdsize);
        }
#endif /* !KERNEL */

        /* Verify that the file is big enough to contain the load command */        
        require_action(size >= offset + cmdsize, finish,
            rval=KERN_FAILURE;
            kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

        switch(cmd) {
        case LC_SEGMENT:
            /* Get and swap the segment header */
            seg_hdr = (struct segment_command *) load_hdr;
#if !KERNEL
            if (swap) swap_segment_command(seg_hdr, host_order);
#endif /* !KERNEL */

            /* Get and swap the section headers */
            sects = (struct section *) &seg_hdr[1];
#if !KERNEL
            if (swap) swap_section(sects, seg_hdr->nsects, host_order);
#endif /* !KERNEL */

            /* Ignore segments with no vm size */
            if (!seg_hdr->vmsize) continue;

            /* Verify that the file is big enough for the segment data. */
            require_action(size >= seg_hdr->fileoff + seg_hdr->filesize, finish,
                rval=KERN_FAILURE;
                kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

            for (j = 0; j < seg_hdr->nsects; ++j) {

                /* Verify that, if the section is not to be zero filled on
                 * demand, that file is big enough for the section's data.
                 */
                require_action((sects[j].flags & S_ZEROFILL) ||
                    (size >= sects[j].offset + sects[j].size), finish,
                    rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

                /* Verify that the file is big enough for the section's
                 * relocation entries.
                 */
                require_action(size >= 
                    sects[j].reloff + sects[j].nreloc * sizeof(*relocs), finish,
                    rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

                /* Swap the relocation entries */
                relocs = (struct relocation_info *) ((void *) (file + sects[j].reloff));
#if !KERNEL
                if (swap) {
                    swap_relocation_info(relocs, sects[j].nreloc, 
                        host_order);
                }
#endif /* !KERNEL */
            }

            break;
        case LC_SYMTAB:
            /* Get and swap the symtab header */
            symtab_hdr = (struct symtab_command *) load_hdr;
#if !KERNEL
            if (swap) swap_symtab_command(symtab_hdr, host_order);
#endif /* !KERNEL */

            /* Verify that the file is big enough for the symbol table */
            require_action(size >= 
                symtab_hdr->symoff + symtab_hdr->nsyms * sizeof(*symtab), finish,
                rval=KERN_FAILURE;
                kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

            /* Verify that the file is big enough for the string table */
            require_action(size >= symtab_hdr->stroff + symtab_hdr->strsize, finish,
                rval=KERN_FAILURE;
                kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

#if !KERNEL
            /* Swap the symbol table entries */
            symtab = (struct nlist *) ((void *) (file + symtab_hdr->symoff));
            if (swap) swap_nlist(symtab, symtab_hdr->nsyms, host_order);
#endif /* !KERNEL */

            break;
        default:
#if !KERNEL
            /* Swap the load command */
            if (swap) swap_load_command(load_hdr, host_order);
#endif /* !KERNEL */
            break;
        }
    }

    rval = KERN_SUCCESS;

finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
validate_and_swap_macho_64(u_char *file, u_long size
#if !KERNEL
    , enum NXByteOrder host_order
#endif /* !KERNEL */
    )
{
    kern_return_t rval = KERN_FAILURE;
    struct mach_header_64 *mach_hdr = (struct mach_header_64 *) ((void *) file);
    struct load_command *load_hdr = NULL;
    struct segment_command_64 *seg_hdr = NULL;
    struct section_64 *sects = NULL;
    struct relocation_info *relocs = NULL;
    struct symtab_command *symtab_hdr = NULL;
    struct nlist_64 *symtab = NULL;
    u_long offset = 0;
    u_int cmd = 0;
    u_int cmdsize = 0;
    u_int i = 0; 
    u_int j = 0; 
#if !KERNEL
    boolean_t swap = FALSE;
#endif /* !KERNEL */

    check(file);
    check(size);

    /* Verify that the file is big enough for the mach header */
    require_action(size >= sizeof(*mach_hdr), finish, 
        rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));
    offset = sizeof(*mach_hdr);

#if !KERNEL
    /* Swap the mach header if necessary */
    if (mach_hdr->magic == MH_CIGAM_64) {
        swap = TRUE;
        (void) swap_mach_header_64(mach_hdr, host_order);
    }
#endif /* !KERNEL */

    /* Validate the mach_header's magic number */
    require_action(mach_hdr->magic == MH_MAGIC_64, finish,
        rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
            "Invalid magic number: 0x%x.", mach_hdr->magic));

   /* If in the running kernel, and asked to validate the kernel
    * (which is the only file of type MH_EXECUTE we should ever see),
    * then just assume it's ok or we wouldn't be running to begin with.
    */
#if KERNEL
    if (mach_hdr->filetype == MH_EXECUTE) {
        rval = KERN_SUCCESS;
        goto finish;
    }
#endif /* KERNEL */

    /* Validate and potentially swap the load commands */
    for(i = 0; i < mach_hdr->ncmds; ++i, offset += cmdsize) {
        /* Get the load command and size */
        load_hdr = (struct load_command *) ((void *) (file + offset));
        cmd = load_hdr->cmd;
        cmdsize = load_hdr->cmdsize;

#if !KERNEL
        if (swap) {
            cmd = OSSwapInt32(load_hdr->cmd);
            cmdsize = OSSwapInt32(load_hdr->cmdsize);
        }
#endif /* !KERNEL */

        /* Verify that the file is big enough to contain the load command */        
        require_action(size >= offset + cmdsize, finish,
            rval=KERN_FAILURE;
            kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));
        switch(cmd) {
        case LC_SEGMENT_64:
            /* Get and swap the segment header */
            seg_hdr = (struct segment_command_64 *) ((void *) load_hdr);
#if !KERNEL
            if (swap) swap_segment_command_64(seg_hdr, host_order);
#endif /* !KERNEL */

            /* Get and swap the section headers */
            sects = (struct section_64 *) &seg_hdr[1];
#if !KERNEL
            if (swap) swap_section_64(sects, seg_hdr->nsects, host_order);
#endif /* !KERNEL */

            /* If the segment has no vm footprint, skip it */
            if (!seg_hdr->vmsize) continue;

            /* Verify that the file is big enough for the segment data. */
            require_action(size >= seg_hdr->fileoff + seg_hdr->filesize, finish, 
                rval=KERN_FAILURE;
                kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

            for (j = 0; j < seg_hdr->nsects; ++j) {

                /* Verify that, if the section is not to be zero filled on
                 * demand, that file is big enough for the section's data.
                 */
                require_action((sects[j].flags & S_ZEROFILL) ||
                    (size >= sects[j].offset + sects[j].size), finish,
                    rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

                /* Verify that the file is big enough for the section's
                 * relocation entries.
                 */
                require_action(size >= 
                    sects[j].reloff + sects[j].nreloc * sizeof(*relocs), finish,
                    rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

                /* Swap the relocation entries */
                relocs = (struct relocation_info *) ((void *) (file + sects[j].reloff));
#if !KERNEL
                if (swap) {
                    swap_relocation_info(relocs, sects[j].nreloc, 
                        host_order);
                }
#endif /* !KERNEL */
            }

            break;
        case LC_SYMTAB:
            /* Get and swap the symtab header */
            symtab_hdr = (struct symtab_command *) load_hdr;
#if !KERNEL
            if (swap) swap_symtab_command(symtab_hdr, host_order);
#endif /* !KERNEL */

            /* Verify that the file is big enough for the symbol table */
            require_action(size >= 
                symtab_hdr->symoff + symtab_hdr->nsyms * sizeof(*symtab), finish, 
                rval=KERN_FAILURE;
                kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

            /* Verify that the file is big enough for the string table */
            require_action(size >= symtab_hdr->stroff + symtab_hdr->strsize, finish,
                rval=KERN_FAILURE;
                kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

#if !KERNEL
            /* Swap the symbol table entries */
            symtab = (struct nlist_64 *) ((void *) (file + symtab_hdr->symoff));
            if (swap) swap_nlist_64(symtab, symtab_hdr->nsyms, host_order);
#endif /* !KERNEL */

            break;
        default:
#if !KERNEL
            /* Swap the load command */
            if (swap) swap_load_command(load_hdr, host_order);
#endif /* !KERNEL */
            break;
        }
    }

    rval = KERN_SUCCESS;

finish:
    return rval;
}

#if !KERNEL
/*******************************************************************************
*******************************************************************************/
void unswap_macho(u_char *file, enum NXByteOrder host_order, 
    enum NXByteOrder target_order)
{
    struct mach_header *hdr = (struct mach_header *) ((void *) file);

    if (!hdr) return;

    if (hdr->magic == MH_MAGIC) {
        unswap_macho_32(file, host_order, target_order);
    } else if (hdr->magic == MH_MAGIC_64) {
        unswap_macho_64(file, host_order, target_order);
    }
}

/*******************************************************************************
*******************************************************************************/
static void
unswap_macho_32(u_char *file, enum NXByteOrder host_order, 
    enum NXByteOrder target_order)
{
    struct mach_header *mach_hdr = (struct mach_header *) ((void *) file);
    struct load_command *load_hdr = NULL;
    struct segment_command *seg_hdr = NULL;
    struct section *sects = NULL;
    struct symtab_command *symtab_hdr = NULL;
    struct nlist *symtab = NULL;
    u_long offset = 0;
    u_int cmd = 0;
    u_int size = 0;
    u_int i = 0; 

    check(file);

    if (target_order == host_order) return;

    offset = sizeof(*mach_hdr);
    for(i = 0; i < mach_hdr->ncmds; ++i, offset += size) {
        load_hdr = (struct load_command *) ((void *) (file + offset));
        cmd = load_hdr->cmd;
        size = load_hdr->cmdsize;

        switch(cmd) {
        case LC_SEGMENT:
            seg_hdr = (struct segment_command *) load_hdr;
            sects = (struct section *) &seg_hdr[1];

            /* We don't need to unswap relocations because this function is
             * called when linking is completed (so there are no relocations).
             */

            swap_section(sects, seg_hdr->nsects, target_order);
            swap_segment_command(seg_hdr, target_order);
            break;
        case LC_SYMTAB:
            symtab_hdr = (struct symtab_command *) load_hdr;
            symtab = (struct nlist*) ((void *) (file + symtab_hdr->symoff));

            swap_nlist(symtab, symtab_hdr->nsyms, target_order);
            swap_symtab_command(symtab_hdr, target_order);
            
            break;
        default:
            swap_load_command(load_hdr, target_order);
            break;
        }
    }

    (void) swap_mach_header(mach_hdr, target_order);
}

/*******************************************************************************
*******************************************************************************/
static void
unswap_macho_64(u_char *file, enum NXByteOrder host_order, 
    enum NXByteOrder target_order)
{
    struct mach_header_64 *mach_hdr = (struct mach_header_64 *) ((void *) file);
    struct load_command *load_hdr = NULL;
    struct segment_command_64 *seg_hdr = NULL;
    struct section_64 *sects = NULL;
    struct symtab_command *symtab_hdr = NULL;
    struct nlist_64 *symtab = NULL;
    u_long offset = 0;
    u_int cmd = 0;
    u_int size = 0;
    u_int i = 0; 

    check(file);

    if (target_order == host_order) return;

    offset = sizeof(*mach_hdr);
    for(i = 0; i < mach_hdr->ncmds; ++i, offset += size) {
        load_hdr = (struct load_command *) ((void *) (file + offset));
        cmd = load_hdr->cmd;
        size = load_hdr->cmdsize;

        switch(cmd) {
        case LC_SEGMENT_64:
            seg_hdr = (struct segment_command_64 *) ((void *) load_hdr);
            sects = (struct section_64 *) &seg_hdr[1];

            /* We don't need to unswap relocations because this function is
             * called when linking is completed (so there are no relocations).
             */

            swap_section_64(sects, seg_hdr->nsects, target_order);
            swap_segment_command_64(seg_hdr, target_order);
            break;
        case LC_SYMTAB:
            symtab_hdr = (struct symtab_command *) load_hdr;
            symtab = (struct nlist_64 *) ((void *) (file + symtab_hdr->symoff));

            swap_nlist_64(symtab, symtab_hdr->nsyms, target_order);
            swap_symtab_command(symtab_hdr, target_order);

            break;
        default:
            swap_load_command(load_hdr, target_order);
            break;
        }
    }

    (void) swap_mach_header_64(mach_hdr, target_order);
}
#endif /* !KERNEL */
    
/*******************************************************************************
*******************************************************************************/
kxld_addr_t
kxld_align_address(kxld_addr_t address, u_int align)
{
    kxld_addr_t alignment = (1 << align);
    kxld_addr_t low_bits = 0;

    if (!align) return address;

    low_bits = (address) & (alignment - 1);
    if (low_bits) {
        address += (alignment - low_bits);
    }

    return address;
}

/*******************************************************************************
*******************************************************************************/
boolean_t
kxld_is_32_bit(cpu_type_t cputype)
{
    return !(cputype & CPU_ARCH_ABI64);
}

/*******************************************************************************
* Borrowed (and slightly modified) the libc implementation for the kernel 
* until the kernel has a supported strstr().
* Find the first occurrence of find in s.
*******************************************************************************/
const char *
kxld_strstr(const char *s, const char *find)
{
#if KERNEL
    char c, sc;
    size_t len;
    if (!s || !find)
        return s;
    if ((c = *find++) != 0) {
        len = strlen(find);
        do {
            do {
                if ((sc = *s++) == 0)
                    return (NULL);
            } while (sc != c);
        } while (strncmp(s, find, len) != 0);
        s--;
    }
    return s;
#else
    return strstr(s, find);
#endif /* KERNEL */
}

/*******************************************************************************
*******************************************************************************/
void
kxld_print_memory_report(void)
{
#if DEBUG
    kxld_log(kKxldLogLinking, kKxldLogExplicit, "kxld memory usage report:\n"
        "\tNumber of allocations:   %8lu\n"
        "\tNumber of frees:         %8lu\n"
        "\tAverage allocation size: %8lu\n"
        "\tTotal bytes allocated:   %8lu\n"
        "\tTotal bytes freed:       %8lu\n"
        "\tTotal bytes leaked:      %8lu",
        num_allocations, num_frees, bytes_allocated / num_allocations,
        bytes_allocated, bytes_freed, bytes_allocated - bytes_freed);
#endif
}

/*********************************************************************
*********************************************************************/
#if !KERNEL
boolean_t kxld_set_cross_link_page_size(kxld_size_t target_page_size)
{
    // verify radix 2
    if ((target_page_size != 0) && 
        ((target_page_size & (target_page_size - 1)) == 0)) {

        s_cross_link_enabled = TRUE;
        s_cross_link_page_size = target_page_size;

        return TRUE;   
    } else {
        return FALSE;
    }
}
#endif /* !KERNEL */

/*********************************************************************
*********************************************************************/
kxld_size_t kxld_get_effective_page_size(void)
{
#if KERNEL
    return PAGE_SIZE;
#else
    if (s_cross_link_enabled) {
        return s_cross_link_page_size;
    } else {
        return PAGE_SIZE;
    }
#endif /* KERNEL */
}

/*********************************************************************
*********************************************************************/
kxld_addr_t kxld_round_page_cross_safe(kxld_addr_t offset)
{
#if KERNEL
    return round_page(offset);
#else
    // assume s_cross_link_page_size is power of 2
    if (s_cross_link_enabled) {
        return (offset + (s_cross_link_page_size - 1)) & 
               (~(s_cross_link_page_size - 1));
    } else {
        return round_page(offset);
    }
#endif /* KERNEL */
}

#if SPLIT_KEXTS_DEBUG

void kxld_show_split_info(splitKextLinkInfo *info)
{
    kxld_log(kKxldLogLinking, kKxldLogErr,
             "splitKextLinkInfo: \n"
             "kextExecutable %p to %p kextSize %lu \n"
             "linkedKext %p to %p linkedKextSize %lu \n"
             "vmaddr_TEXT %p vmaddr_TEXT_EXEC %p "
             "vmaddr_DATA %p vmaddr_DATA_CONST %p "
             "vmaddr_LLVM_COV %p vmaddr_LINKEDIT %p",
             (void *) info->kextExecutable,
             (void *) (info->kextExecutable + info->kextSize),
             info->kextSize,
             (void*) info->linkedKext,
             (void*) (info->linkedKext + info->linkedKextSize),
             info->linkedKextSize,
             (void *) info->vmaddr_TEXT,
             (void *) info->vmaddr_TEXT_EXEC,
             (void *) info->vmaddr_DATA,
             (void *) info->vmaddr_DATA_CONST,
             (void *) info->vmaddr_LLVM_COV,
             (void *) info->vmaddr_LINKEDIT);
}

boolean_t isTargetKextName(const char * the_name)
{
    if (the_name && 0 == strcmp(the_name, KXLD_TARGET_KEXT)) {
        return(TRUE);
    }
    return(FALSE);
}
#endif

