xnu-4903.221.2.tar.gz

[apple/xnu.git] / libkern / kxld / kxld_object.c

/*
 * Copyright (c) 2009-2014 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 <string.h>
#include <sys/types.h>

#if KERNEL
    #include <libkern/kernel_mach_header.h>
    #include <mach/machine.h>
    #include <mach/vm_param.h>
    #include <mach-o/fat.h>
#else /* !KERNEL */
    /* Get machine.h from the kernel source so we can support all platforms
     * that the kernel supports. Otherwise we're at the mercy of the host.
     */
    #include "../../osfmk/mach/machine.h"

    #include <architecture/byte_order.h>
    #include <mach/mach_init.h>
    #include <mach-o/arch.h>
    #include <mach-o/swap.h>
#endif /* KERNEL */

#include <mach-o/loader.h>
#include <mach-o/nlist.h>
#include <mach-o/reloc.h>
#include <os/overflow.h>

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

#include "kxld_demangle.h"
#include "kxld_dict.h"
#include "kxld_reloc.h"
#include "kxld_sect.h"
#include "kxld_seg.h"
#include "kxld_srcversion.h"
#include "kxld_symtab.h"
#include "kxld_util.h"
#include "kxld_uuid.h"
#include "kxld_versionmin.h"
#include "kxld_vtable.h"
#include "kxld_splitinfolc.h"

#include "kxld_object.h"

extern boolean_t isSplitKext;
extern boolean_t isOldInterface;

/*******************************************************************************
* Data structures
*******************************************************************************/

struct kxld_object {
    u_char *file;       // used by old interface
    u_long size;        // used by old interface
    const char *name;
    uint32_t filetype;
    cpu_type_t cputype;
    cpu_subtype_t cpusubtype;
    KXLDArray segs;
    KXLDArray sects;
    KXLDArray extrelocs;
    KXLDArray locrelocs;
    KXLDRelocator relocator;
    KXLDuuid uuid;
    KXLDversionmin versionmin;
    KXLDsrcversion srcversion;
    KXLDSymtab *symtab;
    struct dysymtab_command *dysymtab_hdr;
    KXLDsplitinfolc splitinfolc;
    splitKextLinkInfo split_info;
    kxld_addr_t link_addr;
    u_long    output_buffer_size;
    boolean_t is_kernel;
    boolean_t is_final_image;
    boolean_t is_linked;
    boolean_t got_is_created;
#if KXLD_USER_OR_OBJECT
    KXLDArray *section_order;
#endif
#if KXLD_PIC_KEXTS
    boolean_t include_kaslr_relocs;
#endif
#if !KERNEL
    enum NXByteOrder host_order;
    enum NXByteOrder target_order;
#endif
};

/*******************************************************************************
* Prototypes
*******************************************************************************/

static kern_return_t get_target_machine_info(KXLDObject *object, 
    cpu_type_t cputype, cpu_subtype_t cpusubtype);
static kern_return_t get_macho_slice_for_arch(KXLDObject *object, 
    u_char *file, u_long size);

static u_long get_macho_header_size(const KXLDObject *object);
static u_long get_macho_data_size(const KXLDObject *object) __unused;

static kern_return_t init_from_execute(KXLDObject *object);
static kern_return_t init_from_final_linked_image(KXLDObject *object, 
    u_int *filetype_out, struct symtab_command **symtab_hdr_out);

static boolean_t target_supports_protected_segments(const KXLDObject *object)
    __attribute__((pure));
static void set_is_object_linked(KXLDObject *object);

#if KXLD_USER_OR_BUNDLE
static boolean_t target_supports_bundle(const KXLDObject *object) 
    __attribute((pure));
static kern_return_t init_from_bundle(KXLDObject *object);
static kern_return_t process_relocs_from_tables(KXLDObject *object);
static KXLDSeg *get_seg_by_base_addr(KXLDObject *object,
    kxld_addr_t base_addr);
static kern_return_t process_symbol_pointers(KXLDObject *object);
static void add_to_ptr(u_char *symptr, kxld_addr_t val, boolean_t is_32_bit);
#endif /* KXLD_USER_OR_BUNDLE */

#if KXLD_USER_OR_OBJECT
static boolean_t target_supports_object(const KXLDObject *object) 
    __attribute((pure));
static kern_return_t init_from_object(KXLDObject *object);
static kern_return_t process_relocs_from_sections(KXLDObject *object);
#endif /* KXLD_USER_OR_OBJECT */

#if KXLD_PIC_KEXTS
static boolean_t target_supports_slideable_kexts(const KXLDObject *object);
#endif  /* KXLD_PIC_KEXTS */


static kern_return_t export_macho_header(const KXLDObject *object, u_char *buf, 
    u_int ncmds, u_long *header_offset, u_long header_size);
#if KXLD_USER_OR_ILP32
static u_long get_macho_cmd_data_32(u_char *file, u_long offset, 
    u_int *filetype, u_int *ncmds);
static kern_return_t export_macho_header_32(const KXLDObject *object, 
    u_char *buf, u_int ncmds, u_long *header_offset, u_long header_size);
#endif /* KXLD_USER_OR_ILP32 */
#if KXLD_USER_OR_LP64
static u_long get_macho_cmd_data_64(u_char *file, u_long offset,
    u_int *filetype, u_int *ncmds);
static kern_return_t export_macho_header_64(const KXLDObject *object, 
    u_char *buf, u_int ncmds, u_long *header_offset, u_long header_size);
#endif /* KXLD_USER_OR_LP64 */

#if KXLD_USER_OR_GOT || KXLD_USER_OR_COMMON
static kern_return_t add_section(KXLDObject *object, KXLDSect **sect);
#endif /* KXLD_USER_OR_GOT || KXLD_USER_OR_COMMON */

#if KXLD_USER_OR_COMMON
static kern_return_t resolve_common_symbols(KXLDObject *object);
#endif /* KXLD_USER_OR_COMMON */

#if KXLD_USER_OR_GOT
static boolean_t target_has_got(const KXLDObject *object) __attribute__((pure));
static kern_return_t create_got(KXLDObject *object);
static kern_return_t populate_got(KXLDObject *object);
#endif /* KXLD_USER_OR_GOT */

static KXLDSym *get_mutable_sym(const KXLDObject *object, const KXLDSym *sym);

static kern_return_t populate_kmod_info(KXLDObject *object);

/*******************************************************************************
* Prototypes that may need to be exported
*******************************************************************************/
static boolean_t kxld_object_target_needs_swap(const KXLDObject *object __unused);
static KXLDSeg * kxld_object_get_seg_by_name(const KXLDObject *object, const char *segname);
static KXLDSect * kxld_object_get_sect_by_name(const KXLDObject *object, const char *segname,
    const char *sectname);

/*******************************************************************************
*******************************************************************************/
size_t 
kxld_object_sizeof(void)
{
    return sizeof(KXLDObject);
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_init_from_macho(KXLDObject *object, u_char *file, u_long size,
    const char *name, KXLDArray *section_order __unused, 
    cpu_type_t cputype, cpu_subtype_t cpusubtype, KXLDFlags flags __unused)
{
    kern_return_t       rval    = KERN_FAILURE;
    KXLDSeg           * seg     = NULL;
    u_int               i       = 0;
    u_char *            my_file;

    check(object);
    check(file);
    check(name);

    object->name = name;

#if KXLD_USER_OR_OBJECT
    object->section_order = section_order;
#endif
#if KXLD_PIC_KEXTS
    object->include_kaslr_relocs = ((flags & kKXLDFlagIncludeRelocs) == kKXLDFlagIncludeRelocs);
#endif
    
    /* Find the local architecture */

    rval = get_target_machine_info(object, cputype, cpusubtype);
    require_noerr(rval, finish);

    /* Find the Mach-O slice for the target architecture */

    rval = get_macho_slice_for_arch(object, file, size);
    require_noerr(rval, finish);

    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }
    
    /* Allocate the symbol table */

    if (!object->symtab) {
        object->symtab = kxld_alloc(kxld_symtab_sizeof());
        require_action(object->symtab, finish, rval=KERN_RESOURCE_SHORTAGE);
        bzero(object->symtab, kxld_symtab_sizeof());
    }

    /* Build the relocator */

    rval = kxld_relocator_init(&object->relocator,
                               my_file,
                               object->symtab, &object->sects,
                               object->cputype,
                               object->cpusubtype,
                               kxld_object_target_needs_swap(object));
    require_noerr(rval, finish);

    /* There are four types of Mach-O files that we can support:
     *   1) 32-bit MH_OBJECT      - Snow Leopard and earlier
     *   2) 32-bit MH_KEXT_BUNDLE - Lion and Later
     *   3) 64-bit MH_OBJECT      - Unsupported
     *   4) 64-bit MH_KEXT_BUNDLE - Snow Leopard and Later
     */

    if (kxld_object_is_32_bit(object)) {
        struct mach_header *mach_hdr = (struct mach_header *) ((void *) my_file);
        object->filetype = mach_hdr->filetype;
    } else {
        struct mach_header_64 *mach_hdr = (struct mach_header_64 *) ((void *) my_file);
        object->filetype = mach_hdr->filetype;
    }

    switch (object->filetype) {
#if KXLD_USER_OR_BUNDLE
    case MH_KEXT_BUNDLE:
        rval = init_from_bundle(object);
        require_noerr(rval, finish);
        break;
#endif /* KXLD_USER_OR_BUNDLE */
#if KXLD_USER_OR_OBJECT
    case MH_OBJECT:
        rval = init_from_object(object);
        require_noerr(rval, finish);
        break;
#endif /* KXLD_USER_OR_OBJECT */
    case MH_EXECUTE:
        object->is_kernel = TRUE;
        rval = init_from_execute(object);
        require_noerr(rval, finish);
        break;
    default:
        rval = KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr,
            kKxldLogFiletypeNotSupported, object->filetype);
        goto finish;
    }

    if (!kxld_object_is_kernel(object)) {
        for (i = 0; i < object->segs.nitems; ++i) {
            seg = kxld_array_get_item(&object->segs, i);
            kxld_seg_set_vm_protections(seg, 
                target_supports_protected_segments(object));
        }

        seg = kxld_object_get_seg_by_name(object, SEG_LINKEDIT);
        if (seg) {
            (void) kxld_seg_populate_linkedit(seg, object->symtab,
                kxld_object_is_32_bit(object)
#if KXLD_PIC_KEXTS
                , &object->locrelocs, &object->extrelocs,
                target_supports_slideable_kexts(object)
#endif
                , isOldInterface ? 0 : object->splitinfolc.datasize
                );
        }
    }
    
    (void) set_is_object_linked(object);

    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
 *******************************************************************************/
splitKextLinkInfo *
kxld_object_get_link_info(KXLDObject *object)
{
    check(object);
    
    return &object->split_info;
}


/*******************************************************************************
 *******************************************************************************/
void
kxld_object_set_link_info(KXLDObject *object, splitKextLinkInfo *link_info)
{
    check(object);
    check(link_info);

    object->split_info.vmaddr_TEXT = link_info->vmaddr_TEXT;
    object->split_info.vmaddr_TEXT_EXEC = link_info->vmaddr_TEXT_EXEC;
    object->split_info.vmaddr_DATA = link_info->vmaddr_DATA;
    object->split_info.vmaddr_DATA_CONST = link_info->vmaddr_DATA_CONST;
    object->split_info.vmaddr_LLVM_COV = link_info->vmaddr_LLVM_COV;
    object->split_info.vmaddr_LINKEDIT = link_info->vmaddr_LINKEDIT;

    return;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
get_target_machine_info(KXLDObject *object, cpu_type_t cputype __unused, 
    cpu_subtype_t cpusubtype __unused)
{
#if KERNEL

    /* Because the kernel can only link for its own architecture, we know what
     * the host and target architectures are at compile time, so we can use
     * a vastly simplified version of this function.
     */ 

    check(object);

#if   defined(__x86_64__)
    object->cputype = CPU_TYPE_X86_64;
/* FIXME: we need clang to provide a __x86_64h__ macro for the sub-type. Using
 * __AVX2__ is a temporary solution until this is available. */
#if   defined(__AVX2__)
    object->cpusubtype = CPU_SUBTYPE_X86_64_H;
#else
    object->cpusubtype = CPU_SUBTYPE_X86_64_ALL;
#endif
    return KERN_SUCCESS;
#elif defined(__arm__)
    object->cputype = CPU_TYPE_ARM;
    object->cpusubtype = CPU_SUBTYPE_ARM_ALL;
    return KERN_SUCCESS;
#elif defined(__arm64__)
    object->cputype = CPU_TYPE_ARM64;
    object->cpusubtype = CPU_SUBTYPE_ARM64_ALL;
    return KERN_SUCCESS;
#else 
    kxld_log(kKxldLogLinking, kKxldLogErr, 
        kKxldLogArchNotSupported, _mh_execute_header->cputype);
    return KERN_NOT_SUPPORTED;
#endif /* Supported architecture defines */


#else /* !KERNEL */

    /* User-space must look up the architecture it's running on and the target
     * architecture at run-time.
     */

    kern_return_t rval = KERN_FAILURE;
    const NXArchInfo *host_arch = NULL;

    check(object);

    host_arch = NXGetLocalArchInfo();
    require_action(host_arch, finish, rval=KERN_FAILURE);

    object->host_order = host_arch->byteorder;

    /* If the user did not specify a cputype, use the local architecture.
     */

    if (cputype) {
        object->cputype = cputype;
        object->cpusubtype = cpusubtype;
    } else {
        object->cputype = host_arch->cputype;
        object->target_order = object->host_order;

        switch (object->cputype) {
        case CPU_TYPE_I386:
            object->cpusubtype = CPU_SUBTYPE_I386_ALL;
            break;
        case CPU_TYPE_X86_64:
            object->cpusubtype = CPU_SUBTYPE_X86_64_ALL;
            break;
        case CPU_TYPE_ARM:
            object->cpusubtype = CPU_SUBTYPE_ARM_ALL;
            break;
        case CPU_TYPE_ARM64:
            object->cpusubtype = CPU_SUBTYPE_ARM64_ALL;
            break;
        default:
            object->cpusubtype = 0;
            break;
        }
    }

    /* Validate that we support the target architecture and record its 
     * endianness.
     */

    switch(object->cputype) {
    case CPU_TYPE_ARM:
    case CPU_TYPE_ARM64:
    case CPU_TYPE_I386:
    case CPU_TYPE_X86_64:
        object->target_order = NX_LittleEndian;
        break;
    default:
        rval = KERN_NOT_SUPPORTED;
        kxld_log(kKxldLogLinking, kKxldLogErr, 
            kKxldLogArchNotSupported, object->cputype);
        goto finish;
    }

    rval = KERN_SUCCESS;

finish:
    return rval;
#endif /* KERNEL */
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
get_macho_slice_for_arch(KXLDObject *object, u_char *file, u_long size)
{
    kern_return_t rval = KERN_FAILURE;
    struct mach_header *mach_hdr = NULL;
#if !KERNEL
    struct fat_header *fat = (struct fat_header *) ((void *) file);
    struct fat_arch *archs = (struct fat_arch *) &fat[1];
    boolean_t swap = FALSE;
#endif /* KERNEL */
    u_char *my_file = file;
    u_long my_file_size = size;
    
    check(object);
    check(file);
    check(size);

    /* We are assuming that we will never receive a fat file in the kernel */

#if !KERNEL
    require_action(size >= sizeof(*fat), finish, 
        rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

    /* The fat header is always big endian, so swap if necessary */
    if (fat->magic == FAT_CIGAM) {
        (void) swap_fat_header(fat, object->host_order);
        swap = TRUE;
    }

    if (fat->magic == FAT_MAGIC) {
        struct fat_arch *arch = NULL;
        u_long arch_size;
        boolean_t ovr = os_mul_and_add_overflow(fat->nfat_arch, sizeof(*archs), sizeof(*fat), &arch_size);

        require_action(!ovr && size >= arch_size,
            finish, 
            rval=KERN_FAILURE;
            kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

        /* Swap the fat_arch structures if necessary */
        if (swap) {
            (void) swap_fat_arch(archs, fat->nfat_arch, object->host_order);
        }

        /* Locate the Mach-O for the requested architecture */

        arch = NXFindBestFatArch(object->cputype, object->cpusubtype, archs, fat->nfat_arch);
        require_action(arch, finish, rval=KERN_FAILURE;
            kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogArchNotFound));
        require_action(size >= arch->offset + arch->size, finish, 
            rval=KERN_FAILURE;
            kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));

        my_file = my_file + arch->offset;
        my_file_size = arch->size;
    }
#endif /* !KERNEL */

    /* Swap the Mach-O's headers to this architecture if necessary */
    if (kxld_object_is_32_bit(object)) {
        rval = validate_and_swap_macho_32(my_file, my_file_size
#if !KERNEL
            , object->host_order
#endif /* !KERNEL */
            );
    } else {
            rval = validate_and_swap_macho_64(my_file, my_file_size
#if !KERNEL
            , object->host_order
#endif /* !KERNEL */
            );
    }
    require_noerr(rval, finish);

    mach_hdr = (struct mach_header *) ((void *) my_file);
    require_action(object->cputype == mach_hdr->cputype, finish,
        rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogTruncatedMachO));
    object->cpusubtype = mach_hdr->cpusubtype;  /* <rdar://problem/16008438> */

    if (isOldInterface) {
        object->file = my_file;
        object->size = my_file_size;
    }
    else {
        object->split_info.kextExecutable = my_file;
        object->split_info.kextSize = my_file_size;
    }

    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
init_from_final_linked_image(KXLDObject *object, u_int *filetype_out,
    struct symtab_command **symtab_hdr_out)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSeg *seg = NULL;
    KXLDSect *sect = NULL;
    struct load_command *cmd_hdr = NULL;
    struct symtab_command *symtab_hdr = NULL;
    struct uuid_command *uuid_hdr = NULL;
    struct version_min_command *versionmin_hdr = NULL;
    struct build_version_command *build_version_hdr = NULL;
    struct source_version_command *source_version_hdr = NULL;
    u_long base_offset = 0;
    u_long offset = 0;
    u_long sect_offset = 0;
    u_int filetype = 0;
    u_int i = 0;
    u_int j = 0;
    u_int segi = 0;
    u_int secti = 0;
    u_int nsegs = 0;
    u_int nsects = 0;
    u_int ncmds = 0;
    u_char *my_file;

    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }

    KXLD_3264_FUNC(kxld_object_is_32_bit(object), base_offset,
        get_macho_cmd_data_32, get_macho_cmd_data_64,
        my_file, offset, &filetype, &ncmds);

    /* First pass to count segments and sections */

    offset = base_offset;
    for (i = 0; i < ncmds; ++i, offset += cmd_hdr->cmdsize) {
        cmd_hdr = (struct load_command *) ((void *) (my_file + offset));

        switch(cmd_hdr->cmd) {
#if KXLD_USER_OR_ILP32
        case LC_SEGMENT:
            {
                struct segment_command *seg_hdr = 
                    (struct segment_command *) cmd_hdr;

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

                ++nsegs;
                nsects += seg_hdr->nsects;
            }
            break;
#endif /* KXLD_USER_OR_ILP32 */
#if KXLD_USER_OR_LP64
        case LC_SEGMENT_64:
            {
                struct segment_command_64 *seg_hdr = 
                    (struct segment_command_64 *) ((void *) cmd_hdr);

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

                ++nsegs;
                nsects += seg_hdr->nsects;
            }
            break;
#endif /* KXLD_USER_OR_LP64 */
        default:
            continue;
        }
    }

    /* Allocate the segments and sections */

    if (nsegs) {
        rval = kxld_array_init(&object->segs, sizeof(KXLDSeg), nsegs);
        require_noerr(rval, finish);

        rval = kxld_array_init(&object->sects, sizeof(KXLDSect), nsects);
        require_noerr(rval, finish);
    }

    /* Initialize the segments and sections */

    offset = base_offset;
    for (i = 0; i < ncmds; ++i, offset += cmd_hdr->cmdsize) {
        cmd_hdr = (struct load_command *) ((void *) (my_file + offset));
        seg = NULL;

        switch(cmd_hdr->cmd) {
#if KXLD_USER_OR_ILP32
        case LC_SEGMENT:
            {
                struct segment_command *seg_hdr =
                    (struct segment_command *) cmd_hdr;

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

                seg = kxld_array_get_item(&object->segs, segi++);

                rval = kxld_seg_init_from_macho_32(seg, seg_hdr);
                require_noerr(rval, finish);

                sect_offset = offset + sizeof(*seg_hdr);
            }
            break;
#endif /* KXLD_USER_OR_ILP32 */
#if KXLD_USER_OR_LP64
        case LC_SEGMENT_64:
            {
                struct segment_command_64 *seg_hdr = 
                    (struct segment_command_64 *) ((void *) cmd_hdr);

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

                seg = kxld_array_get_item(&object->segs, segi++);

                rval = kxld_seg_init_from_macho_64(seg, seg_hdr);
                require_noerr(rval, finish);

                sect_offset = offset + sizeof(*seg_hdr);
            }
            break;
#endif /* KXLD_USER_OR_LP64 */
        case LC_SYMTAB:
            symtab_hdr = (struct symtab_command *) cmd_hdr;
            break;
        case LC_UUID:
            uuid_hdr = (struct uuid_command *) cmd_hdr;
            kxld_uuid_init_from_macho(&object->uuid, uuid_hdr);
            break;
        case LC_VERSION_MIN_MACOSX:
        case LC_VERSION_MIN_IPHONEOS:
        case LC_VERSION_MIN_TVOS:
        case LC_VERSION_MIN_WATCHOS:
            versionmin_hdr = (struct version_min_command *) cmd_hdr;
            kxld_versionmin_init_from_macho(&object->versionmin, versionmin_hdr);
            break;
        case LC_BUILD_VERSION:
            build_version_hdr = (struct build_version_command *)cmd_hdr;
            kxld_versionmin_init_from_build_cmd(&object->versionmin, build_version_hdr);
            break;
        case LC_SOURCE_VERSION:
            source_version_hdr = (struct source_version_command *) (void *) cmd_hdr;
            kxld_srcversion_init_from_macho(&object->srcversion, source_version_hdr);
            break;
        case LC_DYSYMTAB:
            object->dysymtab_hdr = (struct dysymtab_command *) cmd_hdr;            
            rval = kxld_reloc_create_macho(&object->extrelocs, &object->relocator,
                (struct relocation_info *) ((void *) (my_file + object->dysymtab_hdr->extreloff)),
                object->dysymtab_hdr->nextrel);
            require_noerr(rval, finish);

            rval = kxld_reloc_create_macho(&object->locrelocs, &object->relocator,
                (struct relocation_info *) ((void *) (my_file + object->dysymtab_hdr->locreloff)),
                object->dysymtab_hdr->nlocrel);
            require_noerr(rval, finish);

            break;
        case LC_UNIXTHREAD:
        case LC_MAIN:
            /* Don't need to do anything with UNIXTHREAD or MAIN for the kernel */
            require_action(kxld_object_is_kernel(object), 
                finish, rval=KERN_FAILURE;
                kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
                    "LC_UNIXTHREAD/LC_MAIN segment is not valid in a kext."));
            break;
        case LC_SEGMENT_SPLIT_INFO:
                if (isSplitKext) {
                    struct linkedit_data_command *split_info_hdr = NULL;
                    split_info_hdr = (struct linkedit_data_command *) (void *) cmd_hdr;
                    kxld_splitinfolc_init_from_macho(&object->splitinfolc, split_info_hdr);
                }
            break;
        case LC_NOTE:
            /* binary blob of data */
            break;
        case LC_CODE_SIGNATURE:
        case LC_DYLD_INFO:
        case LC_DYLD_INFO_ONLY:
        case LC_FUNCTION_STARTS:
        case LC_DATA_IN_CODE:
        case LC_DYLIB_CODE_SIGN_DRS:
            /* Various metadata that might be stored in the linkedit segment */
            break;
        default:
            rval=KERN_FAILURE;
            kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
                "Invalid load command type in MH_KEXT_BUNDLE kext: %u.", cmd_hdr->cmd);
            goto finish;
        }

        if (seg) {

            /* Initialize the sections */
            for (j = 0; j < seg->sects.nitems; ++j, ++secti) {
                sect = kxld_array_get_item(&object->sects, secti);
                
                KXLD_3264_FUNC(kxld_object_is_32_bit(object), rval,
                               kxld_sect_init_from_macho_32, kxld_sect_init_from_macho_64,
                               sect, my_file, &sect_offset, secti, &object->relocator);
                require_noerr(rval, finish);

                /* Add the section to the segment.  This will also make sure
                 * that the sections and segments have the same segname.
                 */
                rval = kxld_seg_add_section(seg, sect);
                require_noerr(rval, finish);
            }
            rval = kxld_seg_finish_init(seg);
            require_noerr(rval, finish);
        }
    }

    if (filetype_out) *filetype_out = filetype;
    if (symtab_hdr_out) *symtab_hdr_out = symtab_hdr;
    object->is_final_image = TRUE;
    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
init_from_execute(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    struct symtab_command *symtab_hdr = NULL;
    u_int filetype = 0;
    KXLDSeg * kernel_linkedit_seg = NULL;  // used if running kernel
#if KXLD_USER_OR_OBJECT
    KXLDSeg *seg = NULL;
    KXLDSect *sect = NULL;
    KXLDSectionName *sname = NULL;
    u_int i = 0, j = 0, k = 0;
#endif /* KXLD_USER_OR_OBJECT */
    u_char *my_file;
    
    check(object);

    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }
    
    require_action(kxld_object_is_kernel(object), finish, rval=KERN_FAILURE);
    
    rval = init_from_final_linked_image(object, &filetype, &symtab_hdr);
    require_noerr(rval, finish);

    require_action(filetype == MH_EXECUTE, finish, rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO 
            "The kernel file is not of type MH_EXECUTE."));

   /* Initialize the symbol table. If this is the running kernel
    * we  will work from the in-memory linkedit segment;
    * otherwise we work from the whole mach-o image.
    */
#if KERNEL
    kernel_linkedit_seg = kxld_object_get_seg_by_name(object, SEG_LINKEDIT);
    require_action(kernel_linkedit_seg, finish, rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO));
#endif

    KXLD_3264_FUNC(kxld_object_is_32_bit(object), rval,
        kxld_symtab_init_from_macho_32, kxld_symtab_init_from_macho_64,
        object->symtab, symtab_hdr, my_file, kernel_linkedit_seg);
    require_noerr(rval, finish);

#if KXLD_USER_OR_OBJECT
    /* Save off the order of section names so that we can lay out kext 
     * sections for MH_OBJECT-based systems.
     */
    if (target_supports_object(object)) {

        rval = kxld_array_init(object->section_order, sizeof(KXLDSectionName), 
            object->sects.nitems);
        require_noerr(rval, finish);

        /* Copy the section names into the section_order array for future kext
         * section ordering.
         */
        for (i = 0, k = 0; i < object->segs.nitems; ++i) {
            seg = kxld_array_get_item(&object->segs, i);

            for (j = 0; j < seg->sects.nitems; ++j, ++k) {
                sect = *(KXLDSect **) kxld_array_get_item(&seg->sects, j);
                sname = kxld_array_get_item(object->section_order, k);

                strlcpy(sname->segname, sect->segname, sizeof(sname->segname));
                strlcpy(sname->sectname, sect->sectname, sizeof(sname->sectname));
            }
        }
    }
#endif /* KXLD_USER_OR_OBJECT */

    rval = KERN_SUCCESS;
finish:
    return rval;
}

#if KXLD_USER_OR_BUNDLE
/*******************************************************************************
*******************************************************************************/
static boolean_t
target_supports_bundle(const KXLDObject *object __unused)
{
    return TRUE;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t 
init_from_bundle(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    struct symtab_command *symtab_hdr = NULL;
    u_int filetype = 0;
    u_char *my_file;
    
    check(object);
   
    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }

    require_action(target_supports_bundle(object), finish,
        rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr,
            kKxldLogFiletypeNotSupported, MH_KEXT_BUNDLE));

    rval = init_from_final_linked_image(object, &filetype, &symtab_hdr);
    require_noerr(rval, finish);

    require_action(filetype == MH_KEXT_BUNDLE, finish,
        rval=KERN_FAILURE);

    KXLD_3264_FUNC(kxld_object_is_32_bit(object), rval,
        kxld_symtab_init_from_macho_32, kxld_symtab_init_from_macho_64,
        object->symtab, symtab_hdr, my_file,
        /* kernel_linkedit_seg */ NULL);
    require_noerr(rval, finish);

    rval = KERN_SUCCESS;
finish:
   return rval;
}
#endif /* KXLD_USER_OR_BUNDLE */

#if KXLD_USER_OR_OBJECT
/*******************************************************************************
*******************************************************************************/
static boolean_t target_supports_object(const KXLDObject *object)
{
    return (object->cputype == CPU_TYPE_I386);
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t 
init_from_object(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    struct load_command *cmd_hdr = NULL;
    struct symtab_command *symtab_hdr = NULL;
    struct uuid_command *uuid_hdr = NULL;
    KXLDSect *sect = NULL;
    u_long offset = 0;
    u_long sect_offset = 0;
    u_int filetype = 0;
    u_int ncmds = 0;
    u_int nsects = 0;
    u_int i = 0;
    boolean_t has_segment = FALSE;
    u_char *my_file;
    
    check(object);
   
    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }

    require_action(target_supports_object(object),
        finish, rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr,
            kKxldLogFiletypeNotSupported, MH_OBJECT));

    KXLD_3264_FUNC(kxld_object_is_32_bit(object), offset,
        get_macho_cmd_data_32, get_macho_cmd_data_64,
        my_file, offset, &filetype, &ncmds);

    require_action(filetype == MH_OBJECT, finish, rval=KERN_FAILURE);

    /* MH_OBJECTs use one unnamed segment to contain all of the sections.  We
     * loop over all of the load commands to initialize the structures we
     * expect.  Then, we'll use the unnamed segment to get to all of the
     * sections, and then use those sections to create the actual segments.
     */

    for (; i < ncmds; ++i, offset += cmd_hdr->cmdsize) {
        cmd_hdr = (struct load_command *) ((void *) (my_file + offset));

        switch(cmd_hdr->cmd) {
#if KXLD_USER_OR_ILP32
        case LC_SEGMENT:
            {
                struct segment_command *seg_hdr = 
                    (struct segment_command *) cmd_hdr;

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

                /* Ignore LINKEDIT segments */
                if (streq_safe(seg_hdr->segname, SEG_LINKEDIT, 
                        const_strlen(SEG_LINKEDIT))) 
                {
                    continue;
                }

                require_action(kxld_object_is_32_bit(object), finish, rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
                        "LC_SEGMENT in 64-bit kext."));
                require_action(!has_segment, finish, rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
                        "Multiple segments in an MH_OBJECT kext."));

                nsects = seg_hdr->nsects;
                sect_offset = offset + sizeof(*seg_hdr);
                has_segment = TRUE;
            }
            break;
#endif /* KXLD_USER_OR_ILP32 */
#if KXLD_USER_OR_LP64
        case LC_SEGMENT_64:
            {
                struct segment_command_64 *seg_hdr =
                    (struct segment_command_64 *) ((void *) cmd_hdr);

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

                /* Ignore LINKEDIT segments */
                if (streq_safe(seg_hdr->segname, SEG_LINKEDIT, 
                        const_strlen(SEG_LINKEDIT))) 
                {
                    continue;
                }

                require_action(!kxld_object_is_32_bit(object), finish, rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
                        "LC_SEGMENT_64 in a 32-bit kext."));
                require_action(!has_segment, finish, rval=KERN_FAILURE;
                    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
                        "Multiple segments in an MH_OBJECT kext."));

                nsects = seg_hdr->nsects;
                sect_offset = offset + sizeof(*seg_hdr);
                has_segment = TRUE;
            }
            break;
#endif /* KXLD_USER_OR_LP64 */
        case LC_SYMTAB:
            symtab_hdr = (struct symtab_command *) cmd_hdr;

            KXLD_3264_FUNC(kxld_object_is_32_bit(object), rval,
                kxld_symtab_init_from_macho_32, kxld_symtab_init_from_macho_64,
                object->symtab, symtab_hdr, my_file,
                /* kernel_linkedit_seg */ NULL);
            require_noerr(rval, finish);
            break;
        case LC_UUID:
            uuid_hdr = (struct uuid_command *) cmd_hdr;
            kxld_uuid_init_from_macho(&object->uuid, uuid_hdr);
            break;
        case LC_UNIXTHREAD:
        case LC_MAIN:
            /* Don't need to do anything with UNIXTHREAD or MAIN */
            break;
        case LC_CODE_SIGNATURE:
        case LC_DYLD_INFO:
        case LC_DYLD_INFO_ONLY:
        case LC_FUNCTION_STARTS:
        case LC_DATA_IN_CODE:
        case LC_DYLIB_CODE_SIGN_DRS:
            /* Various metadata that might be stored in the linkedit segment */
            break;
        case LC_NOTE:
            /* bag-of-bits carried with the binary: ignore */
            break;
        case LC_BUILD_VERSION:
            /* should be able to ignore build version commands */
            kxld_log(kKxldLogLinking, kKxldLogWarn,
                     "Ignoring LC_BUILD_VERSION (%u) in MH_OBJECT kext: (platform:%d)",
                     cmd_hdr->cmd, ((struct build_version_command *)cmd_hdr)->platform);
            break;
        case LC_VERSION_MIN_MACOSX:
        case LC_VERSION_MIN_IPHONEOS:
        case LC_VERSION_MIN_TVOS:
        case LC_VERSION_MIN_WATCHOS:
        case LC_SOURCE_VERSION:
            /* Not supported for object files, fall through */
        default:
            rval = KERN_FAILURE;
            kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
                "Invalid load command type in MH_OBJECT kext: %u.", cmd_hdr->cmd);
            goto finish;
        }
    }

    if (has_segment) {

        /* Get the number of sections from the segment and build the section index */

        rval = kxld_array_init(&object->sects, sizeof(KXLDSect), nsects);
        require_noerr(rval, finish);

        /* Loop over all of the sections to initialize the section index */

        for (i = 0; i < nsects; ++i) {
            sect = kxld_array_get_item(&object->sects, i);
            
            KXLD_3264_FUNC(kxld_object_is_32_bit(object), rval,
                           kxld_sect_init_from_macho_32, kxld_sect_init_from_macho_64,
                           sect, my_file, &sect_offset, i, &object->relocator);
            require_noerr(rval, finish);
        }

        /* Create special sections */

#if KXLD_USER_OR_GOT
        rval = create_got(object);
        require_noerr(rval, finish);
#endif /* KXLD_USER_OR_GOT */

#if KXLD_USER_OR_COMMON
        rval = resolve_common_symbols(object);
        require_noerr(rval, finish);
#endif /* KXLD_USER_OR_COMMON */

        /* Create the segments from the section index */

        rval = kxld_seg_create_seg_from_sections(&object->segs, &object->sects);
        require_noerr(rval, finish);

        rval = kxld_seg_finalize_object_segment(&object->segs, 
            object->section_order, get_macho_header_size(object));
        require_noerr(rval, finish);

        rval = kxld_seg_init_linkedit(&object->segs);
        require_noerr(rval, finish);
    }

    rval = KERN_SUCCESS;
finish:
    return rval;
}
#endif /* KXLD_USER_OR_OBJECT */

#if KXLD_USER_OR_ILP32
/*******************************************************************************
*******************************************************************************/
static u_long
get_macho_cmd_data_32(u_char *file, u_long offset, u_int *filetype, u_int *ncmds)
{
    struct mach_header *mach_hdr = (struct mach_header *) ((void *) (file + offset));

    if (filetype) *filetype = mach_hdr->filetype;
    if (ncmds) *ncmds = mach_hdr->ncmds;

    return sizeof(*mach_hdr);
}

#endif /* KXLD_USER_OR_ILP32 */

#if KXLD_USER_OR_LP64
/*******************************************************************************
*******************************************************************************/
static u_long
get_macho_cmd_data_64(u_char *file, u_long offset, u_int *filetype,  u_int *ncmds)
{
    struct mach_header_64 *mach_hdr = (struct mach_header_64 *) ((void *) (file + offset));

    if (filetype) *filetype = mach_hdr->filetype;
    if (ncmds) *ncmds = mach_hdr->ncmds;

    return sizeof(*mach_hdr);
}
#endif /* KXLD_USER_OR_LP64 */

/*******************************************************************************
*******************************************************************************/
static u_long
get_macho_header_size(const KXLDObject *object)
{
    KXLDSeg *seg = NULL;
    u_long header_size = 0;
    u_int i = 0;
    boolean_t   object_is_32_bit = kxld_object_is_32_bit(object);

    check(object);

    /* Mach, segment, symtab, and UUID headers */

    header_size += object_is_32_bit ? sizeof(struct mach_header) : sizeof(struct mach_header_64);

    for (i = 0; i < object->segs.nitems; ++i) {
        seg = kxld_array_get_item(&object->segs, i);
        header_size += kxld_seg_get_macho_header_size(seg, object_is_32_bit);
    }

    header_size += kxld_symtab_get_macho_header_size();

#if KXLD_PIC_KEXTS
    if (target_supports_slideable_kexts(object)) {
        header_size += kxld_reloc_get_macho_header_size();
    }
#endif	/* KXLD_PIC_KEXTS */

    if (object->uuid.has_uuid) {
        header_size += kxld_uuid_get_macho_header_size();
    }

    if (object->versionmin.has_versionmin) {
        header_size += kxld_versionmin_get_macho_header_size(&object->versionmin);
    }

    if (object->srcversion.has_srcversion) {
        header_size += kxld_srcversion_get_macho_header_size();
    }
    
    if (isSplitKext && object->splitinfolc.has_splitinfolc) {
        header_size += kxld_splitinfolc_get_macho_header_size();
    }
    
    return header_size;
}

/*******************************************************************************
*******************************************************************************/
static u_long
get_macho_data_size(const KXLDObject *object)
{
    KXLDSeg *seg = NULL;
    u_long data_size = 0;
    u_int i = 0;

    check(object);

    /* total all segment vmsize values */
    for (i = 0; i < object->segs.nitems; ++i) {
        seg = kxld_array_get_item(&object->segs, i);
        data_size += (u_long) kxld_seg_get_vmsize(seg);
    }

#if KXLD_PIC_KEXTS
    {
        /* ensure that when we eventually emit the final linked object, 
         * appending the __DYSYMTAB data after the __LINKEDIT data will
         * not overflow the space allocated for the __LINKEDIT segment
         */
        
        u_long  seg_vmsize = 0;
        u_long  symtab_size = 0;
        u_long  reloc_size = 0;
        
        /* get current __LINKEDIT sizes */
        seg = kxld_object_get_seg_by_name(object, SEG_LINKEDIT);
        
        seg_vmsize = (u_long) kxld_seg_get_vmsize(seg);
         
        /* get size of symbol table data that will eventually be dumped
         * into the __LINKEDIT segment
         */
        symtab_size = kxld_symtab_get_macho_data_size(object->symtab, kxld_object_is_32_bit(object));
        
        if (target_supports_slideable_kexts(object)) {
            /* get size of __DYSYMTAB relocation entries */
            reloc_size = kxld_reloc_get_macho_data_size(&object->locrelocs, &object->extrelocs);
        }
        
        /* combine, and ensure they'll both fit within the page(s)
         * allocated for the __LINKEDIT segment. If they'd overflow,
         * increase the vmsize appropriately so no overflow will occur
         */
        if ((symtab_size + reloc_size) > seg_vmsize) {
            u_long  overflow = (symtab_size + reloc_size) - seg_vmsize;
            data_size += kxld_round_page_cross_safe(overflow);
        }
    }
#endif  // KXLD_PIC_KEXTS

    return data_size;
}

/*******************************************************************************
*******************************************************************************/
boolean_t 
kxld_object_target_needs_swap(const KXLDObject *object __unused)
{
#if KERNEL
    return FALSE;
#else
    return (object->target_order != object->host_order);
#endif /* KERNEL */
}

/*******************************************************************************
*******************************************************************************/
KXLDSeg *
kxld_object_get_seg_by_name(const KXLDObject *object, const char *segname)
{
    KXLDSeg *seg = NULL;
    u_int i = 0;

    for (i = 0; i < object->segs.nitems; ++i) {
        seg = kxld_array_get_item(&object->segs, i);

        if (streq_safe(segname, seg->segname, sizeof(seg->segname))) break;

        seg = NULL;
    }

    return seg;
}

/*******************************************************************************
*******************************************************************************/
const KXLDRelocator * 
kxld_object_get_relocator(const KXLDObject * object)
{
    check(object);

    return &object->relocator;
}

/*******************************************************************************
*******************************************************************************/
KXLDSect *
kxld_object_get_sect_by_name(const KXLDObject *object, const char *segname, 
    const char *sectname)
{
    KXLDSect *sect = NULL;
    u_int i = 0;

    for (i = 0; i < object->sects.nitems; ++i) {
        sect = kxld_array_get_item(&object->sects, i);

        if (streq_safe(segname, sect->segname, sizeof(sect->segname)) && 
            streq_safe(sectname, sect->sectname, sizeof(sect->sectname))) 
        {
            break;
        }

        sect = NULL;
    }

    return sect;
}

/*******************************************************************************
*******************************************************************************/
const KXLDReloc * 
kxld_object_get_reloc_at_symbol(const KXLDObject *object, const KXLDSym *sym)
{
    const KXLDReloc *reloc = NULL;
    const KXLDSect *sect = NULL;
    uint32_t offset = 0;

    check(object);
    check(sym);

    sect = kxld_object_get_section_by_index(object, sym->sectnum);
    require(sect, finish);

    if (kxld_object_is_final_image(object)) {
        reloc = kxld_reloc_get_reloc_by_offset(&object->extrelocs, 
                                               sym->base_addr);
        if (!reloc) {
            reloc = kxld_reloc_get_reloc_by_offset(&object->locrelocs, 
                                                   sym->base_addr);
        }
    } else {
        offset = kxld_sym_get_section_offset(sym, sect);
        reloc = kxld_reloc_get_reloc_by_offset(&sect->relocs, offset);
    }

finish:
    return reloc;
}

/*******************************************************************************
*******************************************************************************/
const KXLDSym * 
kxld_object_get_symbol_of_reloc(const KXLDObject *object, 
    const KXLDReloc *reloc, const KXLDSect *sect)
{
    const KXLDSym *sym = NULL;
    u_char *my_file;
    
    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }
    
    if (kxld_object_is_final_image(object)) {
       sym = kxld_reloc_get_symbol(&object->relocator, reloc, my_file);
   } else {
       sym = kxld_reloc_get_symbol(&object->relocator, reloc, sect->data);
   }
    return sym;
}

/*******************************************************************************
*******************************************************************************/
const KXLDSect * 
kxld_object_get_section_by_index(const KXLDObject *object, u_int sectnum)
{
    KXLDSect *sect = NULL;
    
    check(object);

    if (sectnum < object->sects.nitems) {
        sect = kxld_array_get_item(&object->sects, sectnum);
    }

    return sect;
}

/*******************************************************************************
*******************************************************************************/
const KXLDArray  * 
kxld_object_get_extrelocs(const KXLDObject *object)
{
    const KXLDArray *rval = NULL;
    
    check(object);

    if (kxld_object_is_final_image(object)) {
        rval = &object->extrelocs;
    }

    return rval;
}

/*******************************************************************************
*******************************************************************************/
const KXLDSymtab *
kxld_object_get_symtab(const KXLDObject *object)
{
    check(object);

    return object->symtab;
}

#if KXLD_USER_OR_GOT || KXLD_USER_OR_COMMON
/*******************************************************************************
*******************************************************************************/
static kern_return_t
add_section(KXLDObject *object, KXLDSect **sect)
{
    kern_return_t rval = KERN_FAILURE;
    u_int nsects = object->sects.nitems;

    rval = kxld_array_resize(&object->sects, nsects + 1);
    require_noerr(rval, finish);

    *sect = kxld_array_get_item(&object->sects, nsects);

    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_GOT || KXLD_USER_OR_COMMON */

#if KXLD_USER_OR_COMMON
/*******************************************************************************
* If there are common symbols, calculate how much space they'll need
* and create/grow the __DATA __common section to accommodate them.
* Then, resolve them against that section.
*******************************************************************************/
static kern_return_t
resolve_common_symbols(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSymtabIterator iter;
    KXLDSym *sym = NULL;
    KXLDSect *sect = NULL;
    kxld_addr_t base_addr = 0;
    kxld_size_t size = 0;
    kxld_size_t total_size = 0;
    u_int align = 0;
    u_int max_align = 0;
    u_int sectnum = 0;

    if (!kxld_object_target_supports_common_symbols(object)) {
        rval = KERN_SUCCESS;
        goto finish;
    }

    /* Iterate over the common symbols to calculate their total aligned size */
    kxld_symtab_iterator_init(&iter, object->symtab, kxld_sym_is_common, FALSE);
    while ((sym = kxld_symtab_iterator_get_next(&iter))) {
        align = kxld_sym_get_common_align(sym);
        size = kxld_sym_get_common_size(sym);

        if (align > max_align) max_align = align;

        total_size = kxld_align_address(total_size, align) + size;
    }

    /* If there are common symbols, grow or create the __DATA __common section
     * to hold them.
     */
    if (total_size) {
        sect = kxld_object_get_sect_by_name(object, SEG_DATA, SECT_COMMON);
        if (sect) {
            base_addr = sect->base_addr + sect->size;

            kxld_sect_grow(sect, total_size, max_align);
        } else {
            base_addr = 0;

            rval = add_section(object, &sect);
            require_noerr(rval, finish);

            kxld_sect_init_zerofill(sect, SEG_DATA, SECT_COMMON, 
                total_size, max_align);
        }

        /* Resolve the common symbols against the new section */
        rval = kxld_array_get_index(&object->sects, sect, &sectnum);
        require_noerr(rval, finish);

        kxld_symtab_iterator_reset(&iter);
        while ((sym = kxld_symtab_iterator_get_next(&iter))) {
            align = kxld_sym_get_common_align(sym);
            size = kxld_sym_get_common_size(sym);

            base_addr = kxld_align_address(base_addr, align);
            kxld_sym_resolve_common(sym, sectnum, base_addr);

            base_addr += size;
        }
    }

    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_COMMON */

#if KXLD_USER_OR_GOT
/*******************************************************************************
*******************************************************************************/
static boolean_t
target_has_got(const KXLDObject *object)
{
    return FALSE:
}

/*******************************************************************************
* Create and initialize the Global Offset Table
*******************************************************************************/
static kern_return_t
create_got(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSect *sect = NULL;
    u_int ngots = 0;
    u_int i = 0;

    if (!target_has_got(object)) {
        rval = KERN_SUCCESS;
        goto finish;
    }

    for (i = 0; i < object->sects.nitems; ++i) {
        sect = kxld_array_get_item(&object->sects, i);
        ngots += kxld_sect_get_ngots(sect, &object->relocator, 
            object->symtab);
    }

    rval = add_section(object, &sect);
    require_noerr(rval, finish);

    rval = kxld_sect_init_got(sect, ngots);
    require_noerr(rval, finish);

    object->got_is_created = TRUE;
    rval = KERN_SUCCESS;

finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
populate_got(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSect *sect = NULL;
    u_int i = 0;

    if (!target_has_got(object) || !object->got_is_created) {
        rval = KERN_SUCCESS;
        goto finish;
    }

    for (i = 0; i < object->sects.nitems; ++i) {
        sect = kxld_array_get_item(&object->sects, i);
        if (streq_safe(sect->segname, KXLD_SEG_GOT, sizeof(KXLD_SEG_GOT)) &&
            streq_safe(sect->sectname, KXLD_SECT_GOT, sizeof(KXLD_SECT_GOT)))
        {
            kxld_sect_populate_got(sect, object->symtab,
                kxld_object_target_needs_swap(object));
            break;
        }
    }

    require_action(i < object->sects.nitems, finish, rval=KXLD_MISSING_GOT);

    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_GOT */

/*******************************************************************************
*******************************************************************************/
static boolean_t
target_supports_protected_segments(const KXLDObject *object)
{
    return (object->is_final_image && 
            (object->cputype == CPU_TYPE_X86_64 ||
             object->cputype == CPU_TYPE_ARM ||
             object->cputype == CPU_TYPE_ARM64));
}

/*******************************************************************************
*******************************************************************************/
static void
set_is_object_linked(KXLDObject *object)
{
    u_int i = 0;

    if (kxld_object_is_kernel(object)) {
        object->is_linked = TRUE;
        return;
    }

    if (object->is_final_image) {
        object->is_linked = !object->extrelocs.nitems;
        return;
    }

    object->is_linked = TRUE;
    for (i = 0; i < object->sects.nitems; ++i) {
        KXLDSect *sect = kxld_array_get_item(&object->sects, i);
        if (sect->relocs.nitems) {
            object->is_linked = FALSE;
            break;
        }
    }
}


/*******************************************************************************
*******************************************************************************/
void kxld_object_clear(KXLDObject *object)
{
    KXLDSeg *seg = NULL;
    KXLDSect *sect = NULL;
    u_int i;
    u_char *my_file;
    
    check(object);

    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }

#if !KERNEL
    if (kxld_object_is_kernel(object)) {
        unswap_macho(my_file, object->host_order, object->target_order);
    }
#endif /* !KERNEL */

    for (i = 0; i < object->segs.nitems; ++i) {
        seg = kxld_array_get_item(&object->segs, i);
        kxld_seg_clear(seg);
    }
    kxld_array_reset(&object->segs);

    for (i = 0; i < object->sects.nitems; ++i) {
        sect = kxld_array_get_item(&object->sects, i);
        kxld_sect_clear(sect);
    }
    kxld_array_reset(&object->sects);

    kxld_array_reset(&object->extrelocs);
    kxld_array_reset(&object->locrelocs);
    kxld_relocator_clear(&object->relocator);
    kxld_uuid_clear(&object->uuid);
    kxld_versionmin_clear(&object->versionmin);
    kxld_srcversion_clear(&object->srcversion);

    if (object->symtab) kxld_symtab_clear(object->symtab);

    if (isOldInterface) {
        object->file = NULL;
        object->size = 0;
    }
    else {
        kxld_splitinfolc_clear(&object->splitinfolc);
        object->split_info.kextExecutable = NULL;
        object->split_info.kextSize = 0;
    }
    object->filetype = 0;
    object->cputype = 0;
    object->cpusubtype = 0;
    object->is_kernel = FALSE;
    object->is_final_image = FALSE;
    object->is_linked = FALSE;
    object->got_is_created = FALSE;

#if KXLD_USER_OR_OBJECT
    object->section_order = NULL;
#endif
#if !KERNEL
    object->host_order = 0;
    object->target_order = 0;
#endif
}

/*******************************************************************************
*******************************************************************************/
void kxld_object_deinit(KXLDObject *object __unused)
{
    KXLDSeg *seg = NULL;
    KXLDSect *sect = NULL;
    u_int i;
    u_char *my_file;
    
    check(object);
    
    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }

#if !KERNEL
    if (my_file && kxld_object_is_kernel(object)) {
        unswap_macho(my_file, object->host_order, object->target_order);
    }
#endif /* !KERNEL */

    for (i = 0; i < object->segs.maxitems; ++i) {
        seg = kxld_array_get_slot(&object->segs, i);
        kxld_seg_deinit(seg);
    }
    kxld_array_deinit(&object->segs);

    for (i = 0; i < object->sects.maxitems; ++i) {
        sect = kxld_array_get_slot(&object->sects, i);
        kxld_sect_deinit(sect);
    }
    kxld_array_deinit(&object->sects);

    kxld_array_deinit(&object->extrelocs);
    kxld_array_deinit(&object->locrelocs);

    if (object->symtab) {
        kxld_symtab_deinit(object->symtab);
        kxld_free(object->symtab, kxld_symtab_sizeof());
    }

    bzero(object, sizeof(*object));
}

/*******************************************************************************
*******************************************************************************/
const u_char *
kxld_object_get_file(const KXLDObject *object)
{
    const u_char *my_file;
    
    check(object);

    if (isOldInterface) {
        my_file = object->file;
    }
    else {
        my_file = object->split_info.kextExecutable;
    }
    
    return my_file;
}

/*******************************************************************************
*******************************************************************************/
const char *
kxld_object_get_name(const KXLDObject *object)
{
    check(object);

    return object->name;
}

/*******************************************************************************
*******************************************************************************/
boolean_t 
kxld_object_is_32_bit(const KXLDObject *object)
{
    check(object);

    return kxld_is_32_bit(object->cputype);
}

/*******************************************************************************
*******************************************************************************/
boolean_t 
kxld_object_is_final_image(const KXLDObject *object)
{
    check(object);

    return object->is_final_image;
}

/*******************************************************************************
*******************************************************************************/
boolean_t 
kxld_object_is_kernel(const KXLDObject *object)
{
    check(object);

    return object->is_kernel;
}

/*******************************************************************************
*******************************************************************************/
boolean_t 
kxld_object_is_linked(const KXLDObject *object)
{
    check(object);

    return object->is_linked;
}

/*******************************************************************************
*******************************************************************************/
boolean_t
kxld_object_target_supports_strict_patching(const KXLDObject *object)
{
    check(object);

    return (object->cputype != CPU_TYPE_I386);
}

/*******************************************************************************
*******************************************************************************/
boolean_t
kxld_object_target_supports_common_symbols(const KXLDObject *object)
{
    check(object);

    return (object->cputype == CPU_TYPE_I386);
}


/*******************************************************************************
 *******************************************************************************/
void
kxld_object_get_vmsize_for_seg_by_name(const KXLDObject *object,
                                       const char *segname,
                                       u_long *vmsize)
{
    check(object);
    check(segname);
    check(vmsize);

    KXLDSeg *seg = NULL;
    u_long  my_size = 0;

    /* segment vmsize */
    seg = kxld_object_get_seg_by_name(object, segname);
    
    my_size = (u_long) kxld_seg_get_vmsize(seg);
    
#if KXLD_PIC_KEXTS
    if (kxld_seg_is_linkedit_seg(seg))
    {
        u_long  reloc_size = 0;
        
        if (target_supports_slideable_kexts(object)) {
            /* get size of __DYSYMTAB relocation entries */
            reloc_size = kxld_reloc_get_macho_data_size(&object->locrelocs, &object->extrelocs);
            my_size += reloc_size;
        }
    }
#endif
    
    *vmsize = my_size;
}

/*******************************************************************************
*******************************************************************************/
void
kxld_object_get_vmsize(const KXLDObject *object, u_long *header_size, 
    u_long *vmsize)
{
    check(object);
    check(header_size);
    check(vmsize);
    *header_size = 0;
    *vmsize = 0;

    /* vmsize is the padded header page(s) + segment vmsizes */

    *header_size = (object->is_final_image) ?
        0 : (u_long)kxld_round_page_cross_safe(get_macho_header_size(object));
    
    *vmsize = *header_size + get_macho_data_size(object);

}

/*******************************************************************************
 *******************************************************************************/
void
kxld_object_set_linked_object_size(KXLDObject *object, u_long vmsize)
{
    check(object);

    if (isOldInterface) {
        object->output_buffer_size = vmsize;	/* cache this for use later */
    }
    else {
        object->split_info.linkedKextSize = vmsize;
    }
    return;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_export_linked_object(const KXLDObject *object, 
                                 void *linked_object
                                 )
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSeg *seg = NULL;
    u_long size = 0;
    u_long header_size = 0;
    u_long header_offset = 0;
    u_long data_offset = 0;
    u_int ncmds = 0;
    u_int i = 0;
    boolean_t   is_32bit_object = kxld_object_is_32_bit(object);
    kxld_addr_t link_addr;
    u_char *my_linked_object;

    check(object);
    check(linked_object);
    
    if (isOldInterface) {
        size = object->output_buffer_size;
        link_addr = object->link_addr;
        my_linked_object = (u_char *) linked_object;
    }
    else {
        size = ((splitKextLinkInfo *)linked_object)->linkedKextSize;
        link_addr = ((splitKextLinkInfo *)linked_object)->vmaddr_TEXT;
        my_linked_object = ((splitKextLinkInfo *)linked_object)->linkedKext;
    }

    /* Calculate the size of the headers and data */

    header_size = get_macho_header_size(object);
    
    /* Copy data to the file */

    ncmds = object->segs.nitems + 1 /* LC_SYMTAB */;

#if KXLD_PIC_KEXTS
    /* don't write out a DYSYMTAB segment for targets that can't digest it
     */
    if (target_supports_slideable_kexts(object)) {
        ncmds++; /* dysymtab */
    }
#endif	/* KXLD_PIC_KEXTS */

    if (object->uuid.has_uuid == TRUE) {
        ncmds++;
    }

    if (object->versionmin.has_versionmin == TRUE) {
        ncmds++;
    }

    if (object->srcversion.has_srcversion == TRUE) {
        ncmds++;
    }
    
    if (isSplitKext && object->splitinfolc.has_splitinfolc) {
       ncmds++;
    }

    rval = export_macho_header(object, my_linked_object, ncmds, &header_offset, header_size);
    require_noerr(rval, finish);
    
    for (i = 0; i < object->segs.nitems; ++i) {
        seg = kxld_array_get_item(&object->segs, i);

        rval = kxld_seg_export_macho_to_vm(seg, my_linked_object, &header_offset,
                                           header_size, size, link_addr, is_32bit_object);
       require_noerr(rval, finish);
    }

    seg = kxld_object_get_seg_by_name(object, SEG_LINKEDIT);
    data_offset = (u_long) (seg->link_addr - link_addr);
    
    // data_offset is used to set the fileoff in the macho header load commands
    rval = kxld_symtab_export_macho(object->symtab,
                                    my_linked_object,
                                    &header_offset,
                                    header_size,
                                    &data_offset, size, is_32bit_object);
    require_noerr(rval, finish);

    // data_offset now points past the symbol tab and strings data in the linkedit
    // segment - (it was used to set new values for symoff and stroff)

#if KXLD_PIC_KEXTS
    if (target_supports_slideable_kexts(object)) {
        rval = kxld_reloc_export_macho(&object->relocator,
                                       &object->locrelocs,
                                       &object->extrelocs,
                                       my_linked_object,
                                       &header_offset,
                                       header_size,
                                       &data_offset, size);
        require_noerr(rval, finish);
    }
#endif	/* KXLD_PIC_KEXTS */

    if (object->uuid.has_uuid) {
        rval = kxld_uuid_export_macho(&object->uuid, my_linked_object, &header_offset, header_size);
        require_noerr(rval, finish);
    }

    if (object->versionmin.has_versionmin) {
        rval = kxld_versionmin_export_macho(&object->versionmin, my_linked_object, &header_offset, header_size);
        require_noerr(rval, finish);
    }

    if (object->srcversion.has_srcversion) {
        rval = kxld_srcversion_export_macho(&object->srcversion, my_linked_object, &header_offset, header_size);
        require_noerr(rval, finish);
    }

    if (isSplitKext && object->splitinfolc.has_splitinfolc) {
        rval = kxld_splitinfolc_export_macho(&object->splitinfolc,
                                             linked_object,
                                             &header_offset,
                                             header_size,
                                             &data_offset,
                                             size);
        require_noerr(rval, finish);
    }

#if !KERNEL
    unswap_macho(my_linked_object, object->host_order, object->target_order);
#endif /* KERNEL */

    rval = KERN_SUCCESS;

finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
export_macho_header(const KXLDObject *object, u_char *buf, u_int ncmds,
    u_long *header_offset, u_long header_size)
{
    kern_return_t rval = KERN_FAILURE;

    check(object);
    check(buf);
    check(header_offset);

    KXLD_3264_FUNC(kxld_object_is_32_bit(object), rval, 
        export_macho_header_32, export_macho_header_64, 
        object, buf, ncmds, header_offset, header_size);
    require_noerr(rval, finish);

    rval = KERN_SUCCESS;

finish:
   return rval;
}

#if KXLD_USER_OR_ILP32
/*******************************************************************************
*******************************************************************************/
static kern_return_t
export_macho_header_32(const KXLDObject *object, u_char *buf, u_int ncmds,
    u_long *header_offset, u_long header_size)
{
    kern_return_t rval = KERN_FAILURE;
    struct mach_header *mach = NULL;

    check(object);
    check(buf);
    check(header_offset);
    
    require_action(sizeof(*mach) <= header_size - *header_offset, finish,
        rval=KERN_FAILURE);
    mach = (struct mach_header *) ((void *) (buf + *header_offset));

    mach->magic = MH_MAGIC;
    mach->cputype = object->cputype;
    mach->cpusubtype = object->cpusubtype;
    mach->filetype = object->filetype;
    mach->ncmds = ncmds;
    mach->sizeofcmds = (uint32_t) (header_size - sizeof(*mach));
    mach->flags = MH_NOUNDEFS;

    *header_offset += sizeof(*mach);
    
    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_ILP32 */

#if KXLD_USER_OR_LP64
/*******************************************************************************
*******************************************************************************/
static kern_return_t
export_macho_header_64(const KXLDObject *object, u_char *buf, u_int ncmds,
    u_long *header_offset, u_long header_size)
{
    kern_return_t rval = KERN_FAILURE;
    struct mach_header_64 *mach = NULL;

    check(object);
    check(buf);
    check(header_offset);
    
    require_action(sizeof(*mach) <= header_size - *header_offset, finish,
        rval=KERN_FAILURE);
    mach = (struct mach_header_64 *) ((void *) (buf + *header_offset));
    
    mach->magic = MH_MAGIC_64;
    mach->cputype = object->cputype;
    mach->cpusubtype = object->cpusubtype;
    mach->filetype = object->filetype;
    mach->ncmds = ncmds;
    mach->sizeofcmds = (uint32_t) (header_size - sizeof(*mach));
    mach->flags = MH_NOUNDEFS;

    *header_offset += sizeof(*mach);
    
#if SPLIT_KEXTS_DEBUG
    {
        kxld_log(kKxldLogLinking, kKxldLogErr,
                 " %p >>> Start of macho header (size %lu) <%s>",
                 (void *) mach,
                 sizeof(*mach),
                 __func__);
        kxld_log(kKxldLogLinking, kKxldLogErr,
                 " %p <<< End of macho header <%s>",
                 (void *) ((u_char *)mach + sizeof(*mach)),
                 __func__);
    }
#endif
    
    rval = KERN_SUCCESS;

finish:
    return rval;
}
#endif /* KXLD_USER_OR_LP64 */

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_index_symbols_by_name(KXLDObject *object)
{
    return kxld_symtab_index_symbols_by_name(object->symtab);
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_index_cxx_symbols_by_value(KXLDObject *object)
{
    return kxld_symtab_index_cxx_symbols_by_value(object->symtab);
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_relocate(KXLDObject *object, kxld_addr_t link_address)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSeg *seg = NULL;
    u_int i = 0;

    check(object);

    object->link_addr = link_address;

    /* Relocate segments (which relocates the sections) */
    for (i = 0; i < object->segs.nitems; ++i) {
        seg = kxld_array_get_item(&object->segs, i);
        kxld_seg_relocate(seg, link_address);
    } // for...

    /* Relocate symbols */
    rval = kxld_symtab_relocate(object->symtab, &object->sects);
    require_noerr(rval, finish);

    rval = KERN_SUCCESS;
finish:
   return rval;
}

/*******************************************************************************
*******************************************************************************/
static KXLDSym *
get_mutable_sym(const KXLDObject *object, const KXLDSym *sym)
{
    KXLDSym *rval = NULL;
    kern_return_t result = KERN_FAILURE;
    u_int i = 0;

    result = kxld_symtab_get_sym_index(object->symtab, sym, &i);
    require_noerr(result, finish);

    rval = kxld_symtab_get_symbol_by_index(object->symtab, i);
    require_action(rval == sym, finish, rval=NULL);

finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_resolve_symbol(KXLDObject *object, 
    const KXLDSym *sym, kxld_addr_t addr)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSym *resolved_sym = NULL;

    resolved_sym = get_mutable_sym(object, sym);
    require_action(resolved_sym, finish, rval=KERN_FAILURE);

    rval = kxld_sym_resolve(resolved_sym, addr);
    require_noerr(rval, finish);

    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_patch_symbol(KXLDObject *object, const struct kxld_sym *sym)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSym *patched_sym = NULL;

    patched_sym = get_mutable_sym(object, sym);
    require_action(patched_sym, finish, rval=KERN_FAILURE);

    (void) kxld_sym_patch(patched_sym);
    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_add_symbol(KXLDObject *object, char *name, kxld_addr_t link_addr, 
    const KXLDSym **sym_out)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSym *sym = NULL;

    rval = kxld_symtab_add_symbol(object->symtab, name, link_addr, &sym);
    require_noerr(rval, finish);

    *sym_out = sym;
    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t 
kxld_object_process_relocations(KXLDObject *object, 
    const KXLDDict *patched_vtables)
{
    kern_return_t rval = KERN_FAILURE;

    (void) kxld_relocator_set_vtables(&object->relocator, patched_vtables);

    /* Process relocation entries and populate the global offset table.
     *
     * For final linked images: the relocation entries are contained in a couple
     * of tables hanging off the end of the symbol table.  The GOT has its own
     * section created by the linker; we simply need to fill it.
     *
     * For object files: the relocation entries are bound to each section.
     * The GOT, if it exists for the target architecture, is created by kxld,
     * and we must populate it according to our internal structures.
     */
    if (object->is_final_image) {
#if KXLD_USER_OR_BUNDLE
        rval = process_symbol_pointers(object);
        require_noerr(rval, finish);

        rval = process_relocs_from_tables(object);
        require_noerr(rval, finish);
#else
        require_action(FALSE, finish, rval=KERN_FAILURE);
#endif /* KXLD_USER_OR_BUNDLE */
    } else {
#if KXLD_USER_OR_GOT
        /* Populate GOT */
        rval = populate_got(object);
        require_noerr(rval, finish);
#endif /* KXLD_USER_OR_GOT */
#if KXLD_USER_OR_OBJECT
        rval = process_relocs_from_sections(object);
        require_noerr(rval, finish);
#else
        require_action(FALSE, finish, rval=KERN_FAILURE);
#endif /* KXLD_USER_OR_OBJECT */
    }

    /* Populate kmod info structure */
    rval = populate_kmod_info(object);
    require_noerr(rval, finish);
 
    rval = KERN_SUCCESS;
finish:
   return rval;
}

#if KXLD_USER_OR_BUNDLE

#if SPLIT_KEXTS_DEBUG
static boolean_t  kxld_show_ptr_value;
#endif

#define SECT_SYM_PTRS "__nl_symbol_ptr"

/*******************************************************************************
* Final linked images create an __nl_symbol_ptr section for the global offset
* table and for symbol pointer lookups in general.  Rather than use relocation
* entries, the linker creates an "indirect symbol table" which stores indexes
* into the symbol table corresponding to the entries of this section.  This
* function populates the section with the relocated addresses of those symbols.
*******************************************************************************/
static kern_return_t
process_symbol_pointers(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSect *sect = NULL;
    KXLDSym *sym = NULL;
    int32_t *symidx = NULL;
    u_char *symptr = NULL;
    u_long symptrsize = 0;
    u_int nsyms = 0;
    u_int firstsym = 0;
    u_int i = 0;

    check(object);

    require_action(object->is_final_image && object->dysymtab_hdr, 
        finish, rval=KERN_FAILURE);

    /* Get the __DATA,__nl_symbol_ptr section.  If it doesn't exist, we have
     * nothing to do.
     */
    
    sect = kxld_object_get_sect_by_name(object, SEG_DATA, SECT_SYM_PTRS);
    if (!sect || !(sect->flags & S_NON_LAZY_SYMBOL_POINTERS)) {
        rval = KERN_SUCCESS;
        goto finish;
    }

    /* Calculate the table offset and number of entries in the section */

    if (kxld_object_is_32_bit(object)) {
        symptrsize = sizeof(uint32_t);
    } else {
        symptrsize = sizeof(uint64_t);
    }

    nsyms = (u_int) (sect->size / symptrsize);
    firstsym = sect->reserved1;

    require_action(firstsym + nsyms <= object->dysymtab_hdr->nindirectsyms,
        finish, rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogMalformedMachO
            "firstsym + nsyms > object->dysymtab_hdr->nindirectsyms"));

    /* Iterate through the indirect symbol table and fill in the section of
     * symbol pointers.  There are three cases:
     *   1) A normal symbol - put its value directly in the table
     *   2) An INDIRECT_SYMBOL_LOCAL - symbols that are local and already have
     *      their offset from the start of the file in the section.  Simply
     *      add the file's link address to fill this entry.
     *   3) An INDIRECT_SYMBOL_ABS - prepopulated absolute symbols.  No
     *      action is required.
     */

    if (isOldInterface) {
        symidx = (int32_t *) ((void *) (object->file + object->dysymtab_hdr->indirectsymoff));
    }
    else {
        symidx = (int32_t *) ((void *) (object->split_info.kextExecutable + object->dysymtab_hdr->indirectsymoff));
    }

    symidx += firstsym;
    symptr = sect->data;
    for (i = 0; i < nsyms; ++i, ++symidx, symptr+=symptrsize) {
        if (*symidx & INDIRECT_SYMBOL_LOCAL) {
            if (*symidx & INDIRECT_SYMBOL_ABS) continue;

            if (isOldInterface) {
                add_to_ptr(symptr, object->link_addr, kxld_object_is_32_bit(object));
            }
            else {
                add_to_ptr(symptr, object->split_info.vmaddr_TEXT, kxld_object_is_32_bit(object));
            }
        } else {
            sym = kxld_symtab_get_symbol_by_index(object->symtab, *symidx);
            require_action(sym, finish, rval=KERN_FAILURE);
            
            if (isOldInterface) {
                add_to_ptr(symptr, sym->link_addr, kxld_object_is_32_bit(object));
            }
            else {
                add_to_ptr(symptr, object->split_info.vmaddr_TEXT, kxld_object_is_32_bit(object));
            }
        }
    }

    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
static KXLDSeg *
get_seg_by_base_addr(KXLDObject *object, kxld_addr_t base_addr)
{
    KXLDSeg *seg = NULL;
    kxld_addr_t start = 0;
    kxld_addr_t end = 0;
    u_int i = 0;

    for (i = 0; i < object->segs.nitems; ++i) {
        seg = kxld_array_get_item(&object->segs, i);
        start = seg->base_addr;
        end = seg->base_addr + seg->vmsize;

        if (start <= base_addr && base_addr < end) return seg;
    }

    return NULL;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
process_relocs_from_tables(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDReloc *reloc = NULL;
    KXLDSeg *seg = NULL;
    u_int i = 0;

    /* Process external relocations */
    for (i = 0; i < object->extrelocs.nitems; ++i) {
        reloc = kxld_array_get_item(&object->extrelocs, i);

        seg = get_seg_by_base_addr(object, reloc->address);
        require_action(seg, finish, rval=KERN_FAILURE);

        if (isOldInterface) {
            rval = kxld_relocator_process_table_reloc(&object->relocator, reloc,
                                                      seg, object->link_addr);
        }
        else {
            kxld_addr_t my_link_addr = object->split_info.vmaddr_TEXT;
            if (isSplitKext) {
                if (kxld_seg_is_text_exec_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_TEXT_EXEC;
                }
                else if (kxld_seg_is_data_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_DATA;
                }
                else if (kxld_seg_is_data_const_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_DATA_CONST;
                }
                else if (kxld_seg_is_llvm_cov_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_LLVM_COV;
                }
                else if (kxld_seg_is_linkedit_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_LINKEDIT;
                }
            }
            rval = kxld_relocator_process_table_reloc(&object->relocator,
                                                      reloc,
                                                      seg,
                                                      my_link_addr);
        }
        require_noerr(rval, finish);
    }

    /* Process local relocations */
    for (i = 0; i < object->locrelocs.nitems; ++i) {
        reloc = kxld_array_get_item(&object->locrelocs, i);

        seg = get_seg_by_base_addr(object, reloc->address);
        require_action(seg, finish, rval=KERN_FAILURE);
        
        if (isOldInterface) {
            rval = kxld_relocator_process_table_reloc(&object->relocator, reloc,
                                                      seg, object->link_addr);
        }
        else {
            kxld_addr_t my_link_addr = object->split_info.vmaddr_TEXT;
            if (isSplitKext) {
                if (kxld_seg_is_text_exec_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_TEXT_EXEC;
                }
                else if (kxld_seg_is_data_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_DATA;
                }
                else if (kxld_seg_is_data_const_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_DATA_CONST;
                }
                else if (kxld_seg_is_llvm_cov_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_LLVM_COV;
                }
                else if (kxld_seg_is_linkedit_seg(seg)) {
                    my_link_addr = object->split_info.vmaddr_LINKEDIT;
                }
            }
            rval = kxld_relocator_process_table_reloc(&object->relocator,
                                                      reloc,
                                                      seg,
                                                      my_link_addr);
        }
        require_noerr(rval, finish);
    }

    rval = KERN_SUCCESS;
finish:
    return rval;
}

/*******************************************************************************
*******************************************************************************/
static void
add_to_ptr(u_char *symptr, kxld_addr_t val, boolean_t is_32_bit)
{
    if (is_32_bit) {
        uint32_t *ptr = (uint32_t *) ((void *) symptr);
        
        *ptr += (uint32_t) val;
    } else {
        uint64_t *ptr = (uint64_t *) ((void *) symptr);
        
        *ptr += (uint64_t) val;
    }
    
#if SPLIT_KEXTS_DEBUG
    kxld_show_ptr_value = FALSE;
#endif

}
#endif /* KXLD_USER_OR_BUNDLE */

#if KXLD_USER_OR_OBJECT
/*******************************************************************************
*******************************************************************************/
static kern_return_t
process_relocs_from_sections(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSect *sect = NULL;
    u_int i = 0;

    for (i = 0; i < object->sects.nitems; ++i) {
        sect = kxld_array_get_item(&object->sects, i);
        rval = kxld_sect_process_relocs(sect, &object->relocator);
        require_noerr(rval, finish);
    }

    rval = KERN_SUCCESS;
finish:
    return rval;
}
#endif /* KXLD_USER_OR_OBJECT */

/*******************************************************************************
*******************************************************************************/
static kern_return_t
populate_kmod_info(KXLDObject *object)
{
    kern_return_t rval = KERN_FAILURE;
    KXLDSect *kmodsect = NULL;
    KXLDSym *kmodsym = NULL;
    kmod_info_t *kmod_info = NULL;
    u_long kmod_offset = 0;
    u_long header_size;
    u_long size;

    if (kxld_object_is_kernel(object)) {
        rval = KERN_SUCCESS;
        goto finish;
    }

    kxld_object_get_vmsize(object, &header_size, &size);

    kmodsym = kxld_symtab_get_locally_defined_symbol_by_name(object->symtab, 
        KXLD_KMOD_INFO_SYMBOL);
    require_action(kmodsym, finish, rval=KERN_FAILURE;
        kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogNoKmodInfo));
 
    kmodsect = kxld_array_get_item(&object->sects, kmodsym->sectnum);
    
    kmod_offset = (u_long) (kmodsym->base_addr -  kmodsect->base_addr);
    kmod_info = (kmod_info_t *) ((void *) (kmodsect->data + kmod_offset));

    if (kxld_object_is_32_bit(object)) {
        kmod_info_32_v1_t *kmod = (kmod_info_32_v1_t *) (kmod_info);

        if (isOldInterface) {
            kmod->address = (uint32_t) object->link_addr;
        }
        else {
            kmod->address = (uint32_t) object->split_info.vmaddr_TEXT;
        }

        kmod->size = (uint32_t) size;
        kmod->hdr_size = (uint32_t) header_size;

#if !KERNEL
        if (kxld_object_target_needs_swap(object)) {
            kmod->address = OSSwapInt32(kmod->address);
            kmod->size = OSSwapInt32(kmod->size);
            kmod->hdr_size = OSSwapInt32(kmod->hdr_size);
        }
#endif /* !KERNEL */
    } else {
        kmod_info_64_v1_t *kmod = (kmod_info_64_v1_t *) (kmod_info);
        
        if (isOldInterface) {
            kmod->address = object->link_addr;
        }
        else {
            kmod->address = object->split_info.vmaddr_TEXT;
        }

        kmod->size = size;
        kmod->hdr_size = header_size;

#if !KERNEL
        if (kxld_object_target_needs_swap(object)) {
            kmod->address = OSSwapInt64(kmod->address);
            kmod->size = OSSwapInt64(kmod->size);
            kmod->hdr_size = OSSwapInt64(kmod->hdr_size);
        }
#endif /* !KERNEL */
        
#if SPLIT_KEXTS_DEBUG
        {
            kxld_log(kKxldLogLinking, kKxldLogErr,
                     " kmodsect %p kmod_info %p = kmodsect->data %p + kmod_offset %lu <%s>",
                     (void *) kmodsect,
                     (void *) kmod_info,
                     (void *) kmodsect->data,
                     kmod_offset,
                     __func__);
            
            kxld_log(kKxldLogLinking, kKxldLogErr,
                     " kmod_info data: address %p size %llu hdr_size %llu start_addr %p stop_addr %p <%s>",
                     (void *) kmod->address,
                     kmod->size,
                     kmod->hdr_size,
                     (void *) kmod->start_addr,
                     (void *) kmod->stop_addr,
                     __func__);
        }
#endif

    }

    rval = KERN_SUCCESS;

finish:
    return rval;
}

#if KXLD_PIC_KEXTS
/*******************************************************************************
 *******************************************************************************/
static boolean_t
target_supports_slideable_kexts(const KXLDObject *object)
{
    check(object);

    return (object->cputype != CPU_TYPE_I386 && object->include_kaslr_relocs);
}
#endif  /* KXLD_PIC_KEXTS */