FreeBSD/Linux Kernel Cross Reference
sys/libsa/load.c

     /*
      * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
      *
      * @APPLE_LICENSE_HEADER_START@
      * 
      * The contents of this file constitute Original Code as defined in and
      * are subject to the Apple Public Source License Version 1.1 (the
      * "License").  You may not use this file except in compliance with the
      * License.  Please obtain a copy of the License at
     * http://www.apple.com/publicsource and read it before using this file.
     * 
     * This 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 OR NON-INFRINGEMENT.  Please see the
     * License for the specific language governing rights and limitations
     * under the License.
     * 
     * @APPLE_LICENSE_HEADER_END@
     */
     
    /***************
    * HEADERS
    ***************/
    #ifndef KERNEL
    
    #include <CoreFoundation/CoreFoundation.h>
    
    #include <libc.h>
    #include <stdlib.h>
    #include <stdarg.h>
    #include <stdio.h>
    #include <string.h>
    #include <unistd.h>
    
    #include <sys/stat.h>
    #include <sys/file.h>
    #include <sys/param.h>
    #include <sys/types.h>
    #include <sys/mman.h>
    
    #include <mach/mach_types.h>
    #include <mach/mach.h>
    #include <mach/mach_init.h>
    #include <mach/mach_error.h>
    #include <mach/mach_host.h>
    #include <mach/mach_port.h>
    #include <mach-o/kld.h>
    #include <mach-o/arch.h>
    #include <mach-o/fat.h>
    #include <mach-o/loader.h>
    #include <mach-o/nlist.h>
    #include <kern/kern_types.h>
    #include <kern/kalloc.h>
    #include <libkern/OSByteOrder.h>
    
    #include "vers_rsrc.h"
    
    #else
    
    #include <mach-o/kld.h>
    #include <mach-o/loader.h>
    #include <mach-o/nlist.h>
    #include <libsa/vers_rsrc.h>
    
    #endif /* not KERNEL */
    
    #include "load.h"
    #include "dgraph.h"
    #include "kld_patch.h"
    
    /***************
    * MACROS
    ***************/
    
    #ifndef KERNEL
    
    #define PRIV_EXT
    
    #else
    
    #define PRIV_EXT  __private_extern__
    
    #ifdef DEBUG
    #define LOG_DELAY(x)    IODelay((x) * 1000000)
    #define VTYELLOW  "\033[33m"
    #define VTRESET   "\033[0m"
    #else
    #define LOG_DELAY()
    #define VTYELLOW
    #define VTRESET
    #endif /* DEBUG */
    
    #endif /* not KERNEL */
    
    /***************
    * FUNCTION PROTOS
    ***************/
   
   #ifdef KERNEL
   extern kern_return_t
   kmod_create_internal(
               kmod_info_t *info,
               kmod_t *id);
   
   extern kern_return_t
   kmod_destroy_internal(kmod_t id);
   
   extern kern_return_t
   kmod_start_or_stop(
       kmod_t id,
       int start,
       kmod_args_t *data,
       mach_msg_type_number_t *dataCount);
   
   extern kern_return_t kmod_retain(kmod_t id);
   extern kern_return_t kmod_release(kmod_t id);
   
   extern struct mach_header _mh_execute_header;
   #endif /* KERNEL */
   
   
   // Used to pass info between kld library and callbacks
   static dgraph_entry_t * G_current_load_entry = NULL;
   
   #ifndef KERNEL
   static mach_port_t G_kernel_port = PORT_NULL;
   static mach_port_t G_kernel_priv_port = PORT_NULL;
   static int G_syms_only;
   
   static kload_error
   register_prelink(dgraph_entry_t * entry,
                       kmod_info_t * local_kmod_info, vm_offset_t kernel_kmod_info);
   
   struct PrelinkState
   {
       kmod_info_t modules[1];
   };
   struct PrelinkState *   G_prelink;
   CFMutableDataRef        G_prelink_data;
   CFMutableDataRef        G_prelink_dependencies;
   
   #endif /* not KERNEL */
   
   // used by dgraph.c so can't be static
   kload_log_level log_level = 0;
   
   #ifndef KERNEL
   static void __kload_null_log(const char * format, ...);
   static void __kload_null_err_log(const char * format, ...);
   static int __kload_null_approve(int default_answer, const char * format, ...);
   static int __kload_null_veto(int default_answer, const char * format, ...);
   static const char * __kload_null_input(const char * format, ...);
   
   void (*__kload_log_func)(const char * format, ...) =
       &__kload_null_log;
   void (*__kload_err_log_func)(const char * format, ...) = &__kload_null_err_log;
   int (*__kload_approve_func)(int default_answer,
       const char * format, ...) = &__kload_null_approve;
   int (*__kload_veto_func)(int default_answer,
       const char * format, ...) = &__kload_null_veto;
   const char * (*__kload_input_func)(const char * format, ...) =
       &__kload_null_input;
   #endif /* not KERNEL */
   
   static unsigned long __kload_linkedit_address(
       unsigned long size,
       unsigned long headers_size);
   static void __kload_clean_up_entry(dgraph_entry_t * entry);
   static void __kload_clear_kld_globals(void);
   static kload_error __kload_patch_dgraph(dgraph_t * dgraph
   #ifndef KERNEL
       ,
       const char * kernel_file
   #endif /* not KERNEL */
       );
   static kload_error __kload_load_modules(dgraph_t * dgraph
   #ifndef KERNEL
       ,
       const char * kernel_file,
       const char * patch_file, const char * patch_dir,
       const char * symbol_file, const char * symbol_dir,
       int do_load, int do_start_kmod, int do_prelink,
       int interactive_level,
       int ask_overwrite_symbols, int overwrite_symbols
   #endif /* not KERNEL */
       );
   
   static kload_error __kload_check_module_loaded(
       dgraph_t * dgraph,
       dgraph_entry_t * entry,
   #ifndef KERNEL
       kmod_info_t * kmod_list,
   #endif /* not KERNEL */
       int log_if_already);
   
   static kload_error __kload_load_module(dgraph_t * dgraph,
       dgraph_entry_t * entry,
       int is_root
   #ifndef KERNEL
       ,
       const char * symbol_file,
       const char * symbol_dir,
       int do_load,
       int interactive_level,
       int ask_overwrite_symbols,
       int overwrite_symbols
   #endif /* not KERNEL */
       );
   static kload_error __kload_set_module_dependencies(dgraph_entry_t * entry);
   static kload_error __kload_start_module(dgraph_entry_t * entry);
   
   #ifndef KERNEL
   static kload_error __kload_output_patches(
       dgraph_t * dgraph,
       const char * patch_file,
       const char * patch_dir,
       int ask_overwrite_symbols,
       int overwrite_symbols);
   
   Boolean _IOReadBytesFromFile(CFAllocatorRef alloc, const char *path, void **bytes,
                                   CFIndex *length, CFIndex maxLength);
   Boolean _IOWriteBytesToFile(const char *path, const void *bytes, CFIndex length);
   
   #endif /* not KERNEL */
   
   /*******************************************************************************
   *
   *******************************************************************************/
   PRIV_EXT
   kload_error kload_load_dgraph(dgraph_t * dgraph
   #ifndef KERNEL
       ,
       const char * kernel_file,
       const char * patch_file, const char * patch_dir,
       const char * symbol_file, const char * symbol_dir,
       int do_load, int do_start_kmod, int do_prelink,
       int interactive_level,
       int ask_overwrite_symbols, int overwrite_symbols
   #endif /* not KERNEL */
       )
   {
       kload_error result = kload_error_none;
       int one_has_address = 0;
       int one_lacks_address = 0;
       unsigned int i;
   #ifndef KERNEL
       int syms_only;
   
       syms_only = (!do_load) && (symbol_dir || symbol_file);
   
       if (log_level >= kload_log_level_load_details) {
           kload_log_message("loading dependency graph:" KNL);
           dgraph_log(dgraph);
       }
   
       if (syms_only && log_level >= kload_log_level_load_details) {
           kload_log_message("loading for symbol generation only" KNL);
       }
   
      /*****
       * If we're not loading and have no request to emit a symbol
       * or patch file, there's nothing to do!
       */
       if (!do_load && !symbol_dir && !symbol_file &&
           !patch_dir && !patch_file) {
   
           if (syms_only && log_level >= kload_log_level_load_details) {
               kload_log_message("loader has no work to do" KNL);
           }
   
           result = kload_error_none;  // fixme: should this be USAGE error?
           goto finish;
       }
   
      /*****
       * If we're doing symbols only, then all entries in the dgraph must
       * have addresses assigned, or none must.
       */
       if (syms_only) {
           if (log_level >= kload_log_level_load_details) {
               kload_log_message("checking whether modules have addresses assigned" KNL);
           }
           for (i = 0; i < dgraph->length; i++) {
               struct dgraph_entry_t * entry = dgraph->load_order[i];
               if (entry->is_kernel_component) {
                   continue;
               }
               if (entry->loaded_address != 0) {
                   one_has_address = 1;
               } else {
                   one_lacks_address = 1;
               }
           }
       }
   #endif /* not KERNEL */
   
       if (one_has_address && one_lacks_address) {
           kload_log_error(
               "either all modules must have addresses set to nonzero values or "
               "none must" KNL);
           result = kload_error_invalid_argument;
           goto finish;
       }
   
   #ifndef KERNEL
      /* we need the priv port to check/load modules in the kernel.
       */
       if (PORT_NULL == G_kernel_priv_port) {
           G_kernel_priv_port = mach_host_self();  /* if we are privileged */
       }
   #endif /* not KERNEL */
   
   /*****
    * In the kernel, ALWAYS get load addresses of existing loaded kmods.
    */
   #ifndef KERNEL
      /*****
       * If we don't have addresses, then get them from the kernel.
       */
       if (!one_has_address && !do_prelink && (do_load || symbol_file || symbol_dir)) {
   #endif /* not KERNEL */
           if (log_level >= kload_log_level_load_details) {
               kload_log_message("getting module addresses from kernel" KNL);
           }
   #ifndef KERNEL
           result = kload_set_load_addresses_from_kernel(dgraph, kernel_file,
               do_load);
   #else
           result = kload_set_load_addresses_from_kernel(dgraph);
   #endif /* not KERNEL */
           if (result == kload_error_already_loaded) {
   
   #ifndef KERNEL
               if (do_load) {
                   goto finish;
               }
   #else
               goto finish;
   #endif /* not KERNEL */
   
           } else if (result != kload_error_none) {
               kload_log_error("can't check load addresses of modules" KNL);
               goto finish;
           }
   #ifndef KERNEL
       }
   #endif /* not KERNEL */
   
   #ifndef KERNEL
      /*****
       * At this point, if we're doing symbols only, it's an error to not
       * have a load address for every module.
       */
       if (syms_only && !do_prelink) {
           if (log_level >= kload_log_level_load_details) {
               kload_log_message("checking that all modules have addresses assigned" KNL);
           }
           for (i = 0; i < dgraph->length; i++) {
               struct dgraph_entry_t * entry = dgraph->load_order[i];
               if (entry->is_kernel_component) {
                   continue;
               }
               if (!entry->loaded_address) {
                   kload_log_error(
                       "missing load address during symbol generation: %s" KNL,
                       entry->name);
                   result = kload_error_unspecified;
                   goto finish;
               }
          }
       }
   
       if (do_prelink)
       {
           void *          bytes;
           CFIndex        length;
           CFAllocatorRef alloc;
   
           // We need a real allocator to pass to _IOReadBytesFromFile
           alloc = CFRetain(CFAllocatorGetDefault());
           if (_IOReadBytesFromFile(alloc, "prelinkstate", &bytes, &length, 0))
           {
               G_prelink_data = CFDataCreateMutable(alloc, 0);
               CFDataAppendBytes(G_prelink_data, (UInt8 *) bytes, length);
               CFAllocatorDeallocate(alloc, bytes);
           }
           G_prelink_dependencies = CFDataCreateMutable(alloc, 0);
           if (_IOReadBytesFromFile(alloc, "prelinkdependencies", &bytes, &length, 0))
           {
               CFDataAppendBytes(G_prelink_dependencies, (UInt8 *) bytes, length);
               CFAllocatorDeallocate(alloc, bytes);
           }
           CFRelease(alloc);
   
           if (!G_prelink_data) {
               kload_log_error(
                   "can't get load address for prelink %s" KNL, kernel_file);
               result = kload_error_link_load;
               goto finish;
           }
           else
               G_prelink = (struct PrelinkState *) CFDataGetMutableBytePtr(G_prelink_data);
       }
       else
           G_prelink = 0;
   #endif /* not KERNEL */
   
   #ifndef KERNEL
   
       result = __kload_load_modules(dgraph, kernel_file,
           patch_file, patch_dir, symbol_file, symbol_dir,
           do_load, do_start_kmod, do_prelink, interactive_level,
           ask_overwrite_symbols, overwrite_symbols);
   #else
       result = __kload_load_modules(dgraph);
   #endif /* not KERNEL */
   
   finish:
   
   #ifndef KERNEL
      /* Dispose of the host port to prevent security breaches and port
       * leaks. We don't care about the kern_return_t value of this
       * call for now as there's nothing we can do if it fails.
       */
       if (PORT_NULL != G_kernel_priv_port) {
           mach_port_deallocate(mach_task_self(), G_kernel_priv_port);
           G_kernel_priv_port = PORT_NULL;
       }
   #endif /* not KERNEL */
   
       for (i = 0; i < dgraph->length; i++) {
           dgraph_entry_t * current_entry = dgraph->graph[i];
           __kload_clean_up_entry(current_entry);
       }
   
   #ifndef KERNEL
       if (G_prelink)
       {
           SInt32       length;
           const void * bytes;
           Boolean      success;
   
           length = CFDataGetLength(G_prelink_data);
           bytes = (0 == length) ? (const void *)"" : CFDataGetBytePtr(G_prelink_data);
           success = _IOWriteBytesToFile("prelinkstate", bytes, length);
           if (!success)
           {
               kload_log_error("write prelinkstate" KNL);
               result = kload_error_link_load;
           }
           length = CFDataGetLength(G_prelink_dependencies);
           bytes = (0 == length) ? (const void *)"" : CFDataGetBytePtr(G_prelink_dependencies);
           success = _IOWriteBytesToFile("prelinkdependencies", bytes, length);
           if (!success)
           {
               kload_log_error("write prelinkdependencies" KNL);
               result = kload_error_link_load;
           }
       }
   #endif /* not KERNEL */
   
       return result;
   }
   
   #ifndef KERNEL
   /*******************************************************************************
   * This function claims the option flags d and D for object file dependencies
   * and in-kernel dependencies, respectively.
   *******************************************************************************/
   kload_error kload_load_with_arglist(
       int argc, char **argv,
       const char * kernel_file,
       const char * patch_file, const char * patch_dir,
       const char * symbol_file, const char * symbol_dir,
       int do_load, int do_start_kmod,
       int interactive_level,
       int ask_overwrite_symbols, int overwrite_symbols)
   {
       kload_error result = kload_error_none;
       dgraph_error_t dgraph_result;
       int syms_only = (!do_load) && (symbol_file || symbol_dir);
   
       static dgraph_t dependency_graph;
   
      /* Zero out fields in dependency graph for proper error handling later.
       */
       bzero(&dependency_graph, sizeof(dependency_graph));
   
       dgraph_result = dgraph_init_with_arglist(&dependency_graph,
           syms_only, "-d", "-D", argc, argv);
       if (dgraph_result == dgraph_error) {
           kload_log_error("error processing dependency list" KNL);
           result = kload_error_unspecified;
           goto finish;
       } else if (dgraph_result == dgraph_invalid) {
           // anything to print here, or did init call print something?
           result = kload_error_invalid_argument;
           goto finish;
       }
   
       result = kload_load_dgraph(&dependency_graph, kernel_file,
           patch_file, patch_dir, symbol_file, symbol_dir,
           do_load, do_start_kmod, false /* do_prelink */, interactive_level,
           ask_overwrite_symbols, overwrite_symbols);
   
   finish:
       return result;
   }
   #endif /* not KERNEL */
   /*******************************************************************************
   * This function can only operate on 32 bit mach object file symbol table
   * entries.
   *******************************************************************************/
   static
   kload_error __kload_keep_symbols(dgraph_entry_t * entry)
   {
       struct mach_header *        hdr;
       struct segment_command *    seg;
       struct nlist *              sym;
       struct symtab_command *     symcmd;
       unsigned long               idx, ncmds;
       vm_size_t                   size;
       vm_address_t                mem;
   
       if (entry->symbols)
           return kload_error_none;
   
       hdr   = entry->linked_image;
       ncmds = hdr->ncmds;
       seg   = (struct segment_command *)(hdr + 1);
       for (idx = 0;
               idx < ncmds;
               idx++, seg = (struct segment_command *)(((vm_offset_t)seg) + seg->cmdsize))
       {
           if (LC_SYMTAB == seg->cmd)
               break;
       }
       if (idx >= ncmds)
       {
           kload_log_error("no LC_SYMTAB" KNL);
           return kload_error_unspecified;
       }
   
       symcmd = (struct symtab_command *) seg;
   
       struct load_cmds {
           struct mach_header     hdr;
           struct segment_command seg;
           struct symtab_command  symcmd;
       };
       struct load_cmds * cmd;
       unsigned int symtabsize;
   
       symtabsize = symcmd->stroff + symcmd->strsize - symcmd->symoff;
   
       size = sizeof(struct load_cmds) + symtabsize;
   
       mem = (vm_offset_t) malloc(size);
   
       cmd = (struct load_cmds *) mem;
       sym = (struct nlist *) (cmd + 1);
   
       cmd->hdr    = *hdr;
       cmd->symcmd = *symcmd;
       bcopy((const void *) (((vm_offset_t) hdr) + symcmd->symoff), 
               sym,
               symtabsize);
   
       hdr                 = (struct mach_header *) mem;
       cmd->hdr.ncmds      = 2;
       cmd->hdr.sizeofcmds = sizeof(struct load_cmds) - sizeof(struct mach_header);
       cmd->hdr.flags     &= ~MH_INCRLINK;
   
       cmd->symcmd.stroff -= (symcmd->symoff - sizeof(struct load_cmds));
       cmd->symcmd.symoff  = sizeof(struct load_cmds);
   
       cmd->seg.cmd        = LC_SEGMENT;
       cmd->seg.cmdsize    = sizeof(struct segment_command);
       strcpy(cmd->seg.segname, SEG_LINKEDIT);
       cmd->seg.vmaddr     = 0;
       cmd->seg.vmsize     = 0;
       cmd->seg.fileoff    = cmd->symcmd.symoff;
       cmd->seg.filesize   = symtabsize;
       cmd->seg.maxprot    = 7;
       cmd->seg.initprot   = 1;
       cmd->seg.nsects     = 0;
       cmd->seg.flags      = 0;
   
       sym = (struct nlist *) (cmd + 1);
       for (idx = 0; idx < symcmd->nsyms; idx++, sym++)
       {
           if ( (sym->n_type & N_STAB) != 0)
           {
               sym->n_type = N_ABS;
               sym->n_desc  = 0;
               sym->n_value = sym->n_un.n_strx;
               sym->n_un.n_strx = 0;
               sym->n_sect = NO_SECT;
           }
           else if ( (sym->n_type & N_TYPE) == N_SECT)
           {
               sym->n_sect = NO_SECT;
               sym->n_type = (sym->n_type & ~N_TYPE) | N_ABS;
           }
       }
       if (log_level >= kload_log_level_load_details)
       {
           kload_log_message("__kload_keep_symbols %s, nsyms %ld, 0x%x bytes" KNL, 
                               entry->name, symcmd->nsyms, size);
       }
   
       entry->symbols        = mem;
       entry->symbols_malloc = mem;
       entry->symbols_length = size;
   
       return kload_error_none;
   }
   
   
   /*******************************************************************************
   * This function can only operate on 32 bit mach object files
   *******************************************************************************/
   static
   kload_error __kload_make_opaque_basefile(dgraph_t * dgraph, struct mach_header * hdr)
   {
       struct segment_command *    seg;
       struct segment_command *    data_seg;
       struct segment_command *    text_seg;
       struct section *            sec;
       unsigned int                j;
       vm_offset_t                 offset;
       unsigned long               idx, ncmds;
       vm_size_t                   size;
       vm_address_t                mem, out;
       static vm_address_t         keep_base_image;
       static vm_size_t            keep_base_size;
   
       if (dgraph->opaque_base_image)
           return kload_error_none;
   
       if (keep_base_image)
       {
           dgraph->opaque_base_image  = keep_base_image;
           dgraph->opaque_base_length = keep_base_size;
           return kload_error_none;
       }
   
       data_seg = text_seg = NULL;
       ncmds = hdr->ncmds;
       seg = (struct segment_command *)(hdr + 1);
       for (idx = 0;
               idx < ncmds;
               idx++, seg = (struct segment_command *)(((vm_offset_t)seg) + seg->cmdsize))
       {
           if (LC_SEGMENT != seg->cmd)
               continue;
           if (!strcmp(SEG_TEXT, seg->segname))
               text_seg = seg;
           else if (!strcmp(SEG_DATA, seg->segname))
               data_seg = seg;
       }
       if (!text_seg || !data_seg)
       {
           kload_log_error("no SEG_TEXT or SEG_DATA" KNL);
           return kload_error_unspecified;
       }
   
       size = sizeof(struct mach_header) + text_seg->cmdsize + data_seg->cmdsize;
       mem = (vm_offset_t) malloc(size);
   
       out = mem;
       bcopy(hdr, (void *) out, sizeof(struct mach_header));
       hdr = (struct mach_header *) out;
       out += sizeof(struct mach_header);
   
       bcopy(text_seg, (void *) out, text_seg->cmdsize);
       text_seg = (struct segment_command *) out;
       out += text_seg->cmdsize;
   
       bcopy(data_seg, (void *) out, data_seg->cmdsize);
       data_seg = (struct segment_command *) out;
       out += data_seg->cmdsize;
   
       hdr->ncmds = 2;
       hdr->sizeofcmds = text_seg->cmdsize + data_seg->cmdsize;
   
       offset = hdr->sizeofcmds;
   
       text_seg->fileoff  = offset;
       text_seg->filesize = 0;
   
       sec = (struct section *)(text_seg + 1);
       for (j = 0; j < text_seg->nsects; j++, sec++)
       {
   //      sec->addr   = (unsigned long) addr;
           sec->size   = 0;
           sec->offset = offset;
           sec->nreloc = 0;
       }
   
       data_seg->fileoff  = offset;
       data_seg->filesize = 0;
   
       sec = (struct section *)(data_seg + 1);
       for (j = 0; j < data_seg->nsects; j++, sec++)
       {
   //      sec->addr   = (unsigned long) addr;
           sec->size   = 0;
           sec->offset = offset;
           sec->nreloc = 0;
       }
   
       dgraph->opaque_base_image  = mem;
       dgraph->opaque_base_length = size;
       keep_base_image            = mem;
       keep_base_size             = size;
   
       return kload_error_none;
   }
   
   /*******************************************************************************
   *
   *******************************************************************************/
   static
   kload_error __kload_load_modules(dgraph_t * dgraph
   #ifndef KERNEL
       ,
       const char * kernel_file,
       const char * patch_file,
       const char * patch_dir,
       const char * symbol_file,
       const char * symbol_dir,
       int do_load,
       int do_start_kmod,
       int do_prelink,
       int interactive_level,
       int ask_overwrite_symbols,
       int overwrite_symbols
   #endif /* not KERNEL */
       )
   {
       kload_error result = kload_error_none;
   #ifndef KERNEL
       long int kernel_size = 0;
       kern_return_t mach_result = KERN_SUCCESS;
   #endif /* not KERNEL */
       char * kernel_base_addr = 0;
       int kld_result;
       Boolean cleanup_kld_loader = false;
       unsigned int i;
   
      /* We have to map all object files to get their CFBundleIdentifier
       * names.
       */
   #ifndef KERNEL
       result = kload_map_dgraph(dgraph, kernel_file);
   #else
       result = kload_map_dgraph(dgraph);
   #endif /* not KERNEL */
       if (result != kload_error_none) {
           kload_log_error("error mapping object files" KNL);
           goto finish;
       }
   
   #ifndef KERNEL
       result = __kload_patch_dgraph(dgraph, kernel_file);
   #else
       result = __kload_patch_dgraph(dgraph);
   #endif /* not KERNEL */
       if (result != kload_error_none) {
           // FIXME: print an error message here?
           goto finish;
       }
   
   #ifndef KERNEL
       // FIXME: check error return
       __kload_output_patches(dgraph, patch_file, patch_dir,
           ask_overwrite_symbols, overwrite_symbols);
   
      /*****
       * If we're not loading or writing symbols, we're done.
       */
       if (!do_load && !do_prelink && !symbol_file && !symbol_dir) {
           goto finish;
       }
   
       if (do_load && PORT_NULL == G_kernel_port) {
           mach_result = task_for_pid(mach_task_self(), 0, &G_kernel_port);
           if (mach_result != KERN_SUCCESS) {
               kload_log_error("unable to get kernel task port: %s" KNL,
                   mach_error_string(mach_result));
               kload_log_error("you must be running as root to load "
                   "modules into the kernel" KNL);
               result = kload_error_kernel_permission;
               goto finish;
           }
       }
   #endif /* not KERNEL */
   
       kld_address_func(&__kload_linkedit_address);
   
   #ifndef KERNEL
       G_syms_only = (!do_load) && (symbol_file || symbol_dir || patch_dir);
   
       kernel_base_addr = kld_file_getaddr(kernel_file, &kernel_size);
       if (!kernel_base_addr) {
           kload_log_error(
               "can't get load address for kernel %s" KNL, kernel_file);
           result = kload_error_link_load;
           goto finish;
       }
   #else /* KERNEL */
   
       const char * kernel_file = "(kernel)";
       kernel_base_addr = (char *) &_mh_execute_header;
   
   #endif /* not KERNEL */
   
       kld_result = true;
       if (dgraph->has_symbol_sets)
       {
           result = __kload_make_opaque_basefile(dgraph, (struct mach_header *) kernel_base_addr);
           if (result != kload_error_none) {
               kload_log_error("can't construct opaque base image from %s" KNL, kernel_file);
               goto finish;
           }
   
           kld_result = kld_load_basefile_from_memory(kernel_file,
                               (char *)  dgraph->opaque_base_image, 
                                          dgraph->opaque_base_length);
       }
   #ifndef KERNEL
       else
           kld_result = kld_load_basefile_from_memory(kernel_file,
                               (char *)  kernel_base_addr, kernel_size);
   #endif /* not KERNEL */
   
       if (!kld_result) {
           kload_log_error("can't link base image %s" KNL, kernel_file);
           result = kload_error_link_load;
           goto finish;
       }
   
       cleanup_kld_loader = true;
       char opaque_now = false;
   
       for (i = 0; i < dgraph->length; i++) {
           dgraph_entry_t * current_entry = dgraph->load_order[i];
   
           opaque_now |= current_entry->opaque_link;
   
           if (kOpaqueLink & opaque_now)
           {
               unsigned int k, j;
   
               if (log_level >= kload_log_level_load_details)
               {
                   kload_log_message("opaque link for %s" KNL, current_entry->name);
               }
   
               kld_set_link_options(KLD_STRIP_ALL);        // KLD_STRIP_NONE
   
               if (dgraph->have_loaded_symbols)
               {
                   kld_unload_all(1);
                   if (kRawKernelLink & current_entry->opaque_link) {
   #ifndef KERNEL
                       kld_result = kld_load_basefile_from_memory(kernel_file,
                                                          (char *)  kernel_base_addr, kernel_size);
   #endif
                   } else {
                       kld_result = kld_load_basefile_from_memory(kernel_file,
                                                           (char *)  dgraph->opaque_base_image, 
                                                                       dgraph->opaque_base_length);
                       dgraph->have_loaded_symbols = false;
                   }
                   if (!kld_result) {
                       kload_log_error("can't link base image %s" KNL, kernel_file);
                       result = kload_error_link_load;
                       goto finish;
                   }
               }
   
               for (j = 0; j < i; j++)
               {
   
                   dgraph_entry_t * image_dep = dgraph->load_order[j];
   
                   if (current_entry->opaque_link)
                   {
                       for (k = 0;
                           (k < current_entry->num_dependencies)
                           && (current_entry->dependencies[k] != image_dep);
                           k++)    {}
       
                       if (k == current_entry->num_dependencies)
                           continue;
                   }
   
                   if (!current_entry->opaque_link && image_dep->opaques)
                   {
                       // kpi not on direct dependency list
                       continue;
                   }
                   if (kRawKernelLink & image_dep->opaques)
                   {
                       // raw kernel already in base image
                       continue;
                   }
   
                   if (!image_dep->symbols)
                   {
                       kload_log_error("internal error; no dependent symbols" KNL);
                       result = kload_error_link_load;
                       goto finish;
                   }
                   else
                   {
                       struct mach_header * kld_header;
   
   #ifndef KERNEL
                       kld_result = kld_load_from_memory(&kld_header, image_dep->name,
                               (char *) image_dep->symbols, image_dep->symbols_length, NULL);
   #else
                       kld_result = kld_load_from_memory(&kld_header, image_dep->name,
                               (char *) image_dep->symbols, image_dep->symbols_length);
   #endif /* not KERNEL */
                       if (!kld_result) {
                           kload_log_error("can't link dependent image %s" KNL, image_dep->name);
                           result = kload_error_link_load;
                           goto finish;
                       }
                       kld_forget_symbol("_kmod_info");
                       dgraph->have_loaded_symbols = true;
                   }
               }
           } /* opaque_now */
   
           if (dgraph->has_opaque_links
   #ifndef KERNEL
               || symbol_file || symbol_dir
   #endif
               )
               kld_set_link_options(KLD_STRIP_NONE);
           else
               kld_set_link_options(KLD_STRIP_ALL);
   
   #ifndef KERNEL
           result = __kload_load_module(dgraph, current_entry,
               (current_entry == dgraph->root),
               symbol_file, symbol_dir, do_load,
               interactive_level, ask_overwrite_symbols, overwrite_symbols);
   #else
           result = __kload_load_module(dgraph, current_entry,
               (current_entry == dgraph->root));
   #endif /* not KERNEL */
           if (result != kload_error_none) {
               goto finish;
           }
   
           if (dgraph->has_opaque_links && (current_entry != dgraph->root))
           {
               if (!(kRawKernelLink & current_entry->opaques)) {
                   result = __kload_keep_symbols(current_entry);
               }
               if (result != kload_error_none) {
                   kload_log_error("__kload_keep_symbols() failed for module %s" KNL,
                       current_entry->name);
                   goto finish;
               }
           }
   
   #ifndef KERNEL
           if (do_load && current_entry->do_load) {
   #else
           if (current_entry->do_load) {
   #endif /* not KERNEL */
               result = __kload_set_module_dependencies(current_entry);
               if ( ! (result == kload_error_none ||
                       result == kload_error_already_loaded) ) {
                   goto finish;
               }
   
   #ifndef KERNEL
               if ( (interactive_level == 1 && current_entry == dgraph->root) ||
                    (interactive_level == 2) ) {
   
                   int approve = (*__kload_approve_func)(1,
                       "\nStart module %s (ansering no will abort the load)",
                       current_entry->name);
   
                   if (approve > 0) {
                       do_start_kmod = true; // override 'cause user said so
                   } else {
                       kern_return_t mach_result;
                       if (approve < 0) {
                            kload_log_message("error reading user response; "
                              "destroying loaded module" KNL);
                      } else {
                           kload_log_message("user canceled module start; "
                              "destroying loaded module" KNL);
                      }
                      mach_result = kmod_destroy(G_kernel_priv_port, current_entry->kmod_id);
                      if (mach_result != KERN_SUCCESS) {
                          kload_log_error("kmod_destroy() failed" KNL);
                      }
                      if (approve < 0) {
                          result = kload_error_unspecified;
                          goto finish;
                      } else {
                          result = kload_error_user_abort;
                          goto finish;
                      }
                  }
              }
  #endif /* not KERNEL */
  
  #ifndef KERNEL
              if (current_entry != dgraph->root ||
                  (current_entry == dgraph->root && do_start_kmod)) {
  #endif /* not KERNEL */
  
                  result = __kload_start_module(current_entry);
                  if ( ! (result == kload_error_none ||
                          result == kload_error_already_loaded) ) {
                      goto finish;
  #ifndef KERNEL
                  } else if (interactive_level ||
                             log_level >= kload_log_level_load_details) {
  #else
                  } else if (log_level >= kload_log_level_load_details) {
  #endif /* not KERNEL */
  
                       kload_log_message("started module %s" KNL,
                          current_entry->name);
                  } /* log_level */
  #ifndef KERNEL
              } /* current_entry... */
  #endif /* not KERNEL */
  
  
  #ifndef KERNEL
          } /* if do_load */
  #else
          } /* if do_load */
  #endif /* not KERNEL */
      } /* for i, dgraph->length */
  
  finish:
  
  #ifndef KERNEL
     /* Dispose of the kernel port to prevent security breaches and port
      * leaks. We don't care about the kern_return_t value of this
      * call for now as there's nothing we can do if it fails.
      */
      if (PORT_NULL != G_kernel_port) {
          mach_port_deallocate(mach_task_self(), G_kernel_port);
          G_kernel_port = PORT_NULL;
      }
  #endif /* not KERNEL */
  
      if (cleanup_kld_loader) {
          kld_unload_all(1);
      }
  
      return result;
  }
  
  
  /*******************************************************************************
  *
  *******************************************************************************/
  
  #ifndef KERNEL
  #define __KLOAD_SYMBOL_EXTENSION   ".sym"
  #endif /* not KERNEL */
  
  static
  kload_error __kload_load_module(dgraph_t * dgraph,
      dgraph_entry_t * entry,
  #ifdef KERNEL
      __unused int is_root
  #else   /* not KERNEL */
      int is_root,
      const char * symbol_file,
      const char * symbol_dir,
      int do_load,
      int interactive_level,
      int ask_overwrite_symbols,
      int overwrite_symbols
      #endif /* not KERNEL */
      )
  {
      kload_error result = kload_error_none;
  
      int kld_result;
      int mach_result;
      struct mach_header * kld_header;
      const char * kmod_symbol = "_kmod_info";
      unsigned long kernel_kmod_info;
      kmod_info_t * local_kmod_info = NULL;
      char * dest_address = 0;
  #ifndef KERNEL
      char * allocated_filename = NULL;
      char * symbol_filename = NULL;
      int file_check;
      vm_address_t vm_buffer = 0;
  #endif /* not KERNEL */
  
     /* A kernel component is by nature already linked and loaded and has
      * no work to be done upon it.
      */
      if (entry->is_kernel_component && !entry->is_symbol_set) {
          result = kload_error_none;
          goto finish;
      }
  
      G_current_load_entry = entry;
  
      if (log_level >= kload_log_level_load_basic) {
  #ifndef KERNEL
          if (do_load) {
  #endif /* not KERNEL */
              kload_log_message("link/loading file %s" KNL, entry->name);
  #ifndef KERNEL
          } else {
              kload_log_message("linking file %s" KNL, entry->name);
          }
  #endif /* not KERNEL */
      }
  
  #ifndef KERNEL
      if (entry->link_output_file != entry->name) {
          symbol_filename = entry->link_output_file;
      }
  
      if (symbol_filename) {
          file_check = kload_file_exists(symbol_filename);
          if (file_check < 0) {
              kload_log_error("error checking existence of file %s" KNL,
                  symbol_filename);
          } else if (file_check > 0 && !overwrite_symbols) {
  
              if (!ask_overwrite_symbols) {
                  kload_log_message("symbol file %s exists; not overwriting" KNL,
                      symbol_filename);
                  symbol_filename = NULL;
              } else {
                  int approve = (*__kload_approve_func)(1,
                      "\nSymbol file %s exists; overwrite", symbol_filename);
  
                  if (approve < 0) {
                      result = kload_error_unspecified;
                      goto finish;
                  } else if (approve == 0) {
                      if (allocated_filename) free(allocated_filename);
                      allocated_filename = NULL;
                      symbol_filename = NULL;
                  }
              }
          }
      }
  
      if (symbol_filename &&
          (interactive_level ||
           log_level >= kload_log_level_basic) ) {
  
          kload_log_message("writing symbol file %s" KNL, symbol_filename);
      }
  
      if (do_load) {
          if (interactive_level && entry->loaded_address) {
              kload_log_message(
                  "module %s is already loaded as %s at address 0x%08x" KNL,
                  entry->name, entry->expected_kmod_name,
                  entry->loaded_address);
          } else if ( (interactive_level == 1 && is_root) ||
               (interactive_level == 2) ) {
  
              int approve = (*__kload_approve_func)(1,
                  "\nLoad module %s", entry->name);
  
              if (approve < 0) {
                  result = kload_error_unspecified;
                  goto finish;
              } else if (approve == 0) {
                  result = kload_error_user_abort;
                  goto finish;
              }
          }
      }
  #endif /* not KERNEL */
  
      entry->object = kld_file_getaddr(entry->name, &entry->object_length);
      if (!entry->object) {
          kload_log_error("kld_file_getaddr() failed for module %s" KNL,
              entry->name);
          __kload_clear_kld_globals();
          result = kload_error_link_load;
          goto finish;
      }
  
      if (entry->is_symbol_set) {
          entry->symbols        = (vm_address_t) entry->object;
          entry->symbols_length = entry->object_length;
  
  #ifndef KERNEL
          if (symbol_filename) {
              if (!_IOWriteBytesToFile(symbol_filename, (void *) entry->symbols, entry->symbols_length)) {
                  kload_log_error("write symbol file failed for module %s" KNL,
                      entry->name);
                  __kload_clear_kld_globals();
                  result = kload_error_link_load;
                  goto finish;
              }
              symbol_filename = 0;
              if (G_prelink && (entry->name != entry->link_output_file))
              {
                  kload_log_error("prelink %s %s %s" KNL,
                      entry->name, entry->link_output_file, entry->expected_kmod_name);
                  register_prelink(entry, NULL, NULL);
              }
          }
  #endif /* not KERNEL */
          if (entry->opaques) {
              result = kload_error_none;
              goto finish;
          }
      }
  
  #ifndef KERNEL
      kld_result = kld_load_from_memory(&kld_header, entry->name,
              entry->object, entry->object_length, symbol_filename);
  #else
      kld_result = kld_load_from_memory(&kld_header, entry->name,
              entry->object, entry->object_length);
  #endif /* not KERNEL */
  
  #ifndef KERNEL
      fflush(stdout);
      fflush(stderr);
  #endif /* not KERNEL */
  
      dgraph->have_loaded_symbols = true;
  
      if (!kld_result || !entry->kernel_load_address) {
          kload_log_error("kld_load_from_memory() failed for module %s" KNL,
              entry->name);
          __kload_clear_kld_globals();
          entry->need_cleanup = 1;
          result = kload_error_link_load;
          goto finish;
      }
  
      if (entry->is_symbol_set) {
          result = kload_error_none;
          goto finish;
      }
  
      entry->linked_image = kld_header;
      entry->linked_image_length = -1;    // unknown!
  
  /* If we're in the kernel and not loading (as when handling an
   * already-loaded dependency), we don't need to waste any CPU
   * cycles looking up the kmod_info struct.
   */
  #ifdef KERNEL
      if (entry->do_load) {
  #endif /* KERNEL */
  
      kld_result = kld_lookup(kmod_symbol, &kernel_kmod_info);
      if (!kld_result) {
          kload_log_error("kld_lookup(\"%s\") failed for module %s" KNL,
              kmod_symbol, entry->name);
          entry->need_cleanup = 1;
          result = kload_error_link_load;
          goto finish;
      }
  
  #ifdef KERNEL
      }
  #endif /* KERNEL */
  
      kld_result = kld_forget_symbol(kmod_symbol);
  #ifndef KERNEL
      fflush(stdout);
      fflush(stderr);
  #endif /* not KERNEL */
      if (!kld_result) {
          kload_log_error("kld_forget_symbol(\"%s\") failed for module %s" KNL,
              kmod_symbol, entry->name);
          entry->need_cleanup = 1;
          result = kload_error_link_load;
          goto finish;
      }
  
  /* This section is always done in userland, but in kernel space
   * only if we're loading the kext, because what we have in kernel
   * space for an already-loaded kext is the kext itself, which
   * must not be touched again after it's been loaded and started.
   */
  #ifdef KERNEL
      if (entry->do_load)
  #endif /* KERNEL */
      {
  
  
     /* Get the linked image's kmod_info by translating from the
      * destined kernel-space address at kernel_kmod_info to an
      * offset from kld_header.
      */
      local_kmod_info = (kmod_info_t *)((unsigned long)kernel_kmod_info -
          (unsigned long)G_current_load_entry->kernel_load_address +
          (unsigned long)kld_header);
  
     /* Stamp the bundle ID and version from the entry over anything
      * resident inside the kmod.
      */
      bzero(local_kmod_info->name, sizeof(local_kmod_info->name));
      strcpy(local_kmod_info->name, entry->expected_kmod_name);
  
      bzero(local_kmod_info->version, sizeof(local_kmod_info->version));
      strcpy(local_kmod_info->version, entry->expected_kmod_vers);
  
      if (log_level >= kload_log_level_details) {
          kload_log_message("kmod name: %s" KNL, local_kmod_info->name);
          kload_log_message("kmod start @ 0x%x (offset 0x%lx)" KNL,
             (vm_address_t)local_kmod_info->start,
             (unsigned long)local_kmod_info->start - (unsigned long)G_current_load_entry->kernel_load_address);
          kload_log_message("kmod stop @ 0x%x (offset 0x%lx)" KNL,
             (vm_address_t)local_kmod_info->stop,
             (unsigned long)local_kmod_info->stop - (unsigned long)G_current_load_entry->kernel_load_address);
      }
  
      if (!local_kmod_info->start || !local_kmod_info->start) {
          kload_log_error(
              "error for module file %s; start or stop address is zero" KNL,
              entry->name);
          entry->need_cleanup = 1;
          result = kload_error_link_load;
          goto finish;
      }
  
     /* Record link info into kmod_info struct, rounding the hdr_size
      * to fit the adjustment that was made in __kload_linkedit_address().
      */
      if (entry->kernel_alloc_address) {
          local_kmod_info->address = entry->kernel_alloc_address;
      } else {
          local_kmod_info->address = entry->loaded_address;
      }
      local_kmod_info->size = entry->kernel_alloc_size;
      local_kmod_info->hdr_size = round_page(entry->kernel_hdr_size);
  
      }
  
  #ifndef KERNEL
      if (G_prelink && (entry->name != entry->link_output_file))
      {
          register_prelink(entry, local_kmod_info, kernel_kmod_info);
      }
  
      if (do_load && entry->do_load) {
          mach_result = vm_allocate(mach_task_self(), &vm_buffer,
              entry->kernel_alloc_size, VM_FLAGS_ANYWHERE);
          if (mach_result != KERN_SUCCESS) {
              kload_log_error("unable to vm_allocate() copy buffer" KNL);
              entry->need_cleanup = 1;
              result = kload_error_no_memory;  // FIXME: kernel error?
              goto finish;
          }
  
          dest_address = (char *)vm_buffer;
  
          memcpy(dest_address, kld_header, entry->kernel_hdr_size);
          memcpy(dest_address + round_page(entry->kernel_hdr_size),
                 (void *)((unsigned long)kld_header + entry->kernel_hdr_size),
                 entry->kernel_load_size - entry->kernel_hdr_size);
  
          mach_result = vm_write(G_kernel_port, entry->kernel_alloc_address,
              vm_buffer, entry->kernel_alloc_size);
          if (mach_result != KERN_SUCCESS) {
              kload_log_error("unable to write module to kernel memory" KNL);
              entry->need_cleanup = 1;
              result = kload_error_kernel_error;
              goto finish;
          }
  
          mach_result = kmod_create(G_kernel_priv_port,
              (vm_address_t)kernel_kmod_info, &(entry->kmod_id));
  
  #else
      if (entry->do_load) {
          dest_address = (char *)entry->kernel_alloc_address;
          memcpy(dest_address, kld_header, entry->kernel_hdr_size);
          memcpy(dest_address + round_page(entry->kernel_hdr_size),
                 (void *)((unsigned long)kld_header + entry->kernel_hdr_size),
                 entry->kernel_load_size - entry->kernel_hdr_size);
  
         /* We've written data & instructions into kernel memory, so flush
          * the data cache and invalidate the instruction cache.
          */
          flush_dcache(entry->kernel_alloc_address, entry->kernel_alloc_size, false);
          invalidate_icache(entry->kernel_alloc_address, entry->kernel_alloc_size, false);
  
          mach_result = kmod_create_internal(
              (kmod_info_t *)kernel_kmod_info, &(entry->kmod_id));
  
  #endif /* not KERNEL */
  
          if (mach_result != KERN_SUCCESS) {
              kload_log_error("unable to register module with kernel" KNL);
              entry->need_cleanup = 1;
              result = kload_error_kernel_error;
              goto finish;
          }
  
  #ifndef KERNEL
          if (interactive_level || log_level >= kload_log_level_load_basic) {
  #else
          if (log_level >= kload_log_level_load_basic) {
  #endif /* not KERNEL */
              kload_log_message(
                  "module %s created as # %d at address 0x%x, size %ld" KNL,
                  entry->expected_kmod_name, entry->kmod_id,
                  entry->kernel_alloc_address,
                  entry->kernel_alloc_size);
  
  #ifndef KERNEL
          }
  #else
          }
  #endif /* not KERNEL */
  
  #ifndef KERNEL
          if (interactive_level) {
              kload_log_message(
                  "You can now break to the debugger and set breakpoints "
                  " for this extension." KNL);
          }
  #endif /* not KERNEL */
  
  #ifndef KERNEL
      }
  #else
      }
  #endif /* not KERNEL */
  
  finish:
  
  #ifndef KERNEL
      if (allocated_filename) {
          free(allocated_filename);
      }
      if (vm_buffer) {
          vm_deallocate(mach_task_self(), vm_buffer, entry->kernel_alloc_size);
      }
  #endif /* not KERNEL */
      __kload_clear_kld_globals();
  
      return result;
  }
  
  /*******************************************************************************
  *******************************************************************************/
  
  #ifndef KERNEL
  static kload_error
  register_prelink(dgraph_entry_t * entry, 
                      kmod_info_t * local_kmod_info, vm_offset_t kernel_kmod_info)
  {
      CFIndex i, j, depoffset;
      Boolean exists;
      kmod_info_t desc;
  
      depoffset = CFDataGetLength(G_prelink_dependencies) / sizeof(CFIndex);
  
      for (i = 0; i < entry->num_dependencies; i++)
      {
          exists = false;
          for (j = 1; (j < (1 + G_prelink->modules[0].id)); j++)
          {
              exists = (0 == strcmp(entry->dependencies[i]->expected_kmod_name,
                                      G_prelink->modules[j].name));
              if (exists)
                  break;
          }
          if (!exists)
          {
              bzero(&desc, sizeof(desc));
              strcpy(desc.name, entry->dependencies[i]->expected_kmod_name);
  
              if (log_level >= kload_log_level_basic) {
                  kload_log_message("[%d] (dep)\n    %s" KNL, 
                                      G_prelink->modules[0].id + 1, desc.name);
              }
              G_prelink->modules[0].id++;
              CFDataAppendBytes(G_prelink_data, (UInt8 *) &desc, sizeof(desc));
              G_prelink = (struct PrelinkState *) CFDataGetMutableBytePtr(G_prelink_data);
          }
  
          G_prelink->modules[0].reference_count++;
          OSWriteBigInt32(&j, 0, j);
          CFDataAppendBytes(G_prelink_dependencies, (UInt8 *) &j, sizeof(j));
      }
      if (log_level >= kload_log_level_basic) {
          kload_log_message("[%d] 0x%08x info 0x%08x\n    %s,\n    %s" KNL, 
                              G_prelink->modules[0].id + 1, entry->kernel_load_address,
                              kernel_kmod_info, entry->link_output_file, entry->name);
      }
  
      if (local_kmod_info)
          desc = *local_kmod_info;
      else
      {
          bzero(&desc, sizeof(desc));
          desc.size = entry->symbols_length;
      }
  
      desc.id = kernel_kmod_info;
      desc.reference_count = entry->num_dependencies;
      desc.reference_list  = (kmod_reference_t *) depoffset;
  
      /* Stamp the bundle ID and version from the entry over anything
      * resident inside the kmod.
      */
      bzero(desc.name, sizeof(local_kmod_info->name));
      strcpy(desc.name, entry->expected_kmod_name);
      bzero(desc.version, sizeof(local_kmod_info->version));
      strcpy(desc.version, entry->expected_kmod_vers);
  
      G_prelink->modules[0].id++;
      CFDataAppendBytes(G_prelink_data, (UInt8 *) &desc, sizeof(desc));
      G_prelink = (struct PrelinkState *) CFDataGetMutableBytePtr(G_prelink_data);
  
      return kload_error_none;
  }
  
  #endif
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  #ifndef KERNEL
  kload_error kload_map_dgraph(
      dgraph_t * dgraph,
      const char * kernel_file)
  #else
  kload_error kload_map_dgraph(
      dgraph_t * dgraph)
  #endif /* not KERNEL */
  {
      kload_error result = kload_error_none;
      unsigned int i;
  
      if (log_level >= kload_log_level_load_details) {
  #ifndef KERNEL
          kload_log_message("mapping the kernel file %s" KNL, kernel_file);
  #else
          kload_log_message("mapping the kernel" KNL);
  #endif /* not KERNEL */
      }
  
  #ifndef KERNEL
      if (!kld_file_map(kernel_file)) {
          result = kload_error_link_load;
          goto finish;
      }
  #endif /* not KERNEL */
  
      for (i = 0; i < dgraph->length; i++) {
          dgraph_entry_t * entry = dgraph->load_order[i];
  
          if (entry->is_kernel_component && !entry->is_symbol_set) {
              continue;
          }
  
          result = kload_map_entry(entry);
          if (result != kload_error_none) {
              goto finish;
          }
      }
  
  finish:
      return result;
  
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  kload_error kload_map_entry(dgraph_entry_t * entry)
  {
      kload_error result = kload_error_none;
  
      if (entry->is_kernel_component && !entry->is_symbol_set) {
          kload_log_error("attempt to map kernel component %s" KNL, entry->name);
          result = kload_error_invalid_argument;
          goto finish;
      }
  
      if (log_level >= kload_log_level_load_details) {
          kload_log_message("mapping module file %s" KNL, entry->name);
      }
  
      if (kld_file_getaddr(entry->name, NULL)) {
          if (log_level >= kload_log_level_load_details) {
              kload_log_message("module file %s is already mapped" KNL, entry->name);
          }
          result = kload_error_none;
          goto finish;
      }
  
  #ifndef KERNEL
      if (!kld_file_map(entry->name)) {
  #else
      if (!kld_file_map(entry->name, entry->object, entry->object_length,
           entry->object_is_kmem)) {
  #endif /* not KERNEL */
          kload_log_error("error mapping module file %s" KNL, entry->name);
  
          result = kload_error_link_load;
          goto finish;
  #ifndef KERNEL
      }
  #else
      }
  #endif /* not KERNEL */
  
      entry->is_mapped = true;
      
     /* Clear these bits now, as the kld patch module now owns the info
      * and it is subject to change. We reset them in the entry from the
      * kld patch module as needed.
      */
      entry->object = 0;
      entry->object_length = 0;
  #ifdef KERNEL
      entry->object_is_kmem = false;
  #endif /* KERNEL */
  
      // FIXME: Stop using this symbol; have the info passed in by
      // FIXME: ...the kext management library.
  #ifndef KERNEL
      if (!entry->is_kernel_component && !kld_file_lookupsymbol(entry->name, "_kmod_info")) {
          kload_log_error("%s does not not contain kernel extension code" KNL,
              entry->name);
          result = kload_error_executable_bad;
          goto finish;
      }
  #endif /* not KERNEL */
  
  finish:
      return result;
  }
  
  #ifndef KERNEL
  /*******************************************************************************
  *
  *******************************************************************************/
  kload_error kload_request_load_addresses(
      dgraph_t * dgraph,
      const char * kernel_file)
  {
      kload_error result = kload_error_none;
      int i;
      const char * user_response = NULL;  // must free
      int scan_result;
      unsigned int address;
  
     /* We have to map all object files to get their CFBundleIdentifier
      * names.
      */
      result = kload_map_dgraph(dgraph, kernel_file);
      if (result != kload_error_none) {
          kload_log_error("error mapping object files" KNL);
          goto finish;
      }
  
      // fixme: this shouldn't be printf, should it?
      printf("enter the hexadecimal load addresses for these modules:\n");
  
      for (i = 0; i < dgraph->length; i++) {
          dgraph_entry_t * entry = dgraph->load_order[i];
  
          if (!entry) {
              result = kload_error_unspecified;
              goto finish;
          }
  
          if (entry->is_kernel_component) {
              continue;
          }
  
          if (!entry->is_mapped) {
              result = kload_error_unspecified;
              goto finish;
          }
  
          user_response = __kload_input_func("%s:",
              entry->expected_kmod_name);
          if (!user_response) {
              result = kload_error_unspecified;
              goto finish;
          }
          scan_result = sscanf(user_response, "%x", &address);
          if (scan_result < 1 || scan_result == EOF) {
              result = kload_error_unspecified;
              goto finish;
          }
          entry->loaded_address = address;
      }
  
  finish:
      return result;
  
  }
  
  /*******************************************************************************
  * addresses is a NULL-terminated list of string of the form "module_id@address"
  *******************************************************************************/
  kload_error kload_set_load_addresses_from_args(
      dgraph_t * dgraph,
      const char * kernel_file,
      char ** addresses)
  {
      kload_error result = kload_error_none;
      int i, j;
  
  
     /* We have to map all object files to get their CFBundleIdentifier
      * names.
      */
      result = kload_map_dgraph(dgraph, kernel_file);
      if (result != kload_error_none) {
          kload_log_error("error mapping object files" KNL);
          goto finish;
      }
  
     /*****
      * Run through and assign all addresses to their relevant module
      * entries.
      */
      for (i = 0; i < dgraph->length; i++) {
          dgraph_entry_t * entry = dgraph->load_order[i];
  
          if (!entry) {
              result = kload_error_unspecified;
              goto finish;
          }
  
          if (entry->is_kernel_component) {
              continue;
          }
  
          if (!entry->is_mapped) {
              result = kload_error_unspecified;
              goto finish;
          }
  
          for (j = 0; addresses[j]; j++) {
              char * this_addr = addresses[j];
              char * address_string = NULL;
              unsigned int address;
              unsigned int module_namelen = strlen(entry->expected_kmod_name);
  
              if (!this_addr) {
                  result = kload_error_unspecified;
                  goto finish;
              }
  
              if (strncmp(this_addr, entry->expected_kmod_name, module_namelen)) {
                  continue;
              }
              if (this_addr[module_namelen] != '@') {
                  continue;
              }
  
              address_string = index(this_addr, '@');
              if (!address_string) {
                  result = kload_error_unspecified;
                  goto finish;
              }
              address_string++;
              address = strtoul(address_string, NULL, 16);
              entry->loaded_address = address;
          }
      }
  
     /*****
      * Now that we've done that see that all non-kernel modules do have
      * addresses set. If even one doesn't, we can't complete the link
      * relocation of symbols, so return a usage error.
      */
      for (i = 0; i < dgraph->length; i++) {
          dgraph_entry_t * entry = dgraph->load_order[i];
  
          if (entry->is_kernel_component) {
              continue;
          }
  
          if (!entry->loaded_address) {
              result = kload_error_invalid_argument;
              goto finish;
          }
      }
  
  finish:
      return result;
  
  }
  
  /*******************************************************************************
  * This function requires G_kernel_priv_port to be set before it will work.
  *******************************************************************************/
  kload_error kload_set_load_addresses_from_kernel(
      dgraph_t * dgraph,
      const char * kernel_file,
      int do_load)
  {
      kload_error result = kload_error_none;
      int mach_result;
      kmod_info_t * loaded_modules = NULL;
      int           loaded_bytecount = 0;
      unsigned int i;
  
  
     /*****
      * We have to map the dgraph's modules before checking whether they've
      * been loaded.
      */
      result = kload_map_dgraph(dgraph, kernel_file);
      if (result != kload_error_none) {
          kload_log_error("can't map module files" KNL);
          goto finish;
      }
  
  
     /* First clear all the load addresses.
      */
      for (i = 0; i < dgraph->length; i++) {
          struct dgraph_entry_t * entry = dgraph->load_order[i];
          entry->loaded_address = 0;
      }
  
      mach_result = kmod_get_info(G_kernel_priv_port,
              (void *)&loaded_modules, &loaded_bytecount);
      if (mach_result != KERN_SUCCESS) {
          kload_log_error("kmod_get_info() failed" KNL);
          result = kload_error_kernel_error;
          goto finish;
      }
  
     /*****
      * Find out which modules have already been loaded & verify
      * that loaded versions are same as requested.
      */
      for (i = 0; i < dgraph->length; i++) {
          kload_error cresult;
          dgraph_entry_t * current_entry = dgraph->load_order[i];
  
         /* If necessary, check whether the current module is already loaded.
          * (We already did the root module above.)
          */
          cresult = __kload_check_module_loaded(dgraph, current_entry,
              loaded_modules, do_load);
          if ( ! (cresult == kload_error_none ||
                  cresult == kload_error_already_loaded) ) {
              goto finish;
          }
          if (current_entry == dgraph->root &&
              cresult == kload_error_already_loaded) {
  
              result = cresult;
          }
      }
  
  finish:
  
      if (loaded_modules) {
          vm_deallocate(mach_task_self(), (vm_address_t)loaded_modules,
              loaded_bytecount);
          loaded_modules = 0;
      }
  
      return result;
  }
  
  #else
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  kload_error kload_set_load_addresses_from_kernel(
      dgraph_t * dgraph)
  {
      kload_error result = kload_error_none;
  #ifndef KERNEL
      int mach_result;
      kmod_info_t * loaded_modules = NULL;
      int           loaded_bytecount = 0;
  #endif /* not KERNEL */
      unsigned int i;
  
  
     /*****
      * We have to map the dgraph's modules before checking whether they've
      * been loaded.
      */
      result = kload_map_dgraph(dgraph);
      if (result != kload_error_none) {
          kload_log_error("can't map module files" KNL);
          goto finish;
      }
  
  
     /* First clear all the load addresses.
      */
      for (i = 0; i < dgraph->length; i++) {
          struct dgraph_entry_t * entry = dgraph->load_order[i];
          entry->loaded_address = 0;
      }
  
     /*****
      * Find out which modules have already been loaded & verify
      * that loaded versions are same as requested.
      */
      for (i = 0; i < dgraph->length; i++) {
          kload_error cresult;
          dgraph_entry_t * current_entry = dgraph->load_order[i];
  
         /* If necessary, check whether the current module is already loaded.
          * (We already did the root module above.)
          */
          cresult = __kload_check_module_loaded(dgraph, current_entry, false);
          if ( ! (cresult == kload_error_none ||
                  cresult == kload_error_already_loaded) ) {
              goto finish;
          }
          if (current_entry == dgraph->root &&
              cresult == kload_error_already_loaded) {
  
              result = cresult;
          }
      }
  
  finish:
  
      return result;
  }
  #endif /* not KERNEL */
  
  /*******************************************************************************
  *
  *******************************************************************************/
  #ifdef KERNEL
  extern kern_return_t kmod_load_from_cache(const char * kmod_name);
  #endif /* KERNEL */
  
  static kmod_info_t * __kload_find_kmod_info(const char * kmod_name
  #ifndef KERNEL
      ,
      kmod_info_t * kmod_list
  #endif /* not KERNEL */
      )
  {
  #ifndef KERNEL
      unsigned int i;
  
      for (i = 0; ; i++) {
          kmod_info_t * current_kmod = &(kmod_list[i]);
          if (0 == strcmp(current_kmod->name, kmod_name)) {
              return current_kmod;
          }
          if (kmod_list[i].next == 0) {
              break;
          }
      }
      return NULL;
  #else
      kmod_info_t * info;
      info = kmod_lookupbyname_locked(kmod_name);
      if (!info && (KERN_SUCCESS == kmod_load_from_cache(kmod_name))) {
          info = kmod_lookupbyname_locked(kmod_name);
      }
      return info;
  #endif /* not KERNEL */
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  static
  kload_error __kload_check_module_loaded(
      dgraph_t * dgraph,
      dgraph_entry_t * entry,
  #ifndef KERNEL
      kmod_info_t * kmod_list,
  #endif /* not KERNEL */
      int log_if_already)
  {
      kload_error result = kload_error_none;
      const char * kmod_name;
      kmod_info_t * current_kmod = 0;
  
      VERS_version entry_vers;
      VERS_version loaded_vers;
  
      if (false && entry->is_kernel_component) {
          kmod_name = entry->name;
      } else {
          kmod_name = entry->expected_kmod_name;
          if (log_level >= kload_log_level_load_details) {
              kload_log_message("checking whether module file %s is already loaded" KNL,
                  kmod_name);
          }
      }
  
  #ifndef KERNEL
      current_kmod = __kload_find_kmod_info(kmod_name, kmod_list);
  #else
      current_kmod = __kload_find_kmod_info(kmod_name);
  #endif /* not KERNEL */
  
      if (!current_kmod) {
          goto finish;
      }
  
      entry->do_load = 0;
      entry->kmod_id = current_kmod->id;
      entry->loaded_address = current_kmod->address;
  
      if (entry->is_kernel_component) {
          goto finish;
      }
  
      if (log_level >= kload_log_level_load_details) {
          kload_log_message("module file %s is loaded; checking status" KNL,
              kmod_name);
      }
  
      // We really want to move away from having this info in a kmod....
      //
      loaded_vers = VERS_parse_string(current_kmod->version);
      if (loaded_vers < 0) {
          kload_log_error(
              "can't parse version string \"%s\" of loaded module %s" KNL,
              current_kmod->version,
              current_kmod->name);
          result = kload_error_unspecified;
          goto finish;
      }
  
      entry_vers = VERS_parse_string(entry->expected_kmod_vers);
      if (entry_vers < 0) {
          kload_log_error(
              "can't parse version string \"%s\" of module file %s" KNL,
              entry->expected_kmod_name,
              kmod_name);
          result = kload_error_unspecified;
          goto finish;
      }
  
      if (loaded_vers != entry_vers) {
          kload_log_error(
              "loaded version %s of module %s differs from "
              "requested version %s" KNL,
              current_kmod->version,
              current_kmod->name,
              entry->expected_kmod_name);
          if (entry == dgraph->root) {
              result = kload_error_loaded_version_differs;
          } else {
              result = kload_error_dependency_loaded_version_differs;
          }
          goto finish;
      } else {
  
          if (log_if_already && log_level >=
                  kload_log_level_load_basic) {
  
              kload_log_message(
                  "module %s (identifier %s) is already loaded" KNL,
                  entry->name, kmod_name);
          }
          result = kload_error_already_loaded;
          goto finish;
      }
  
  finish:
  #ifdef KERNEL
      // Do this ONLY if in the kernel!
      if (current_kmod) {
          kfree(current_kmod, sizeof(kmod_info_t));
      }
  #endif /* KERNEL */
      return result;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  kload_error __kload_patch_dgraph(dgraph_t * dgraph
  #ifndef KERNEL
      ,
      const char * kernel_file
  #endif /* not KERNEL */
      )
  {
      kload_error result = kload_error_none;
      unsigned int i;
  
  #ifndef KERNEL
      if (!kld_file_merge_OSObjects(kernel_file)) {
          result = kload_error_link_load;
          goto finish;
      }
  #endif /* not KERNEL */
  
      for (i = 0; i < dgraph->length; i++) {
          dgraph_entry_t * current_entry = dgraph->load_order[i];
  
         /* The kernel has already been patched.
          */
          if (current_entry->is_kernel_component) {
              continue;
          }
  
          if (log_level >= kload_log_level_load_details) {
              kload_log_message("patching C++ code in module %s" KNL,
                  current_entry->name);
          }
  
  #ifndef KERNEL
         /* In userland, we call the patch function for all kmods,
          * loaded or not, because we don't have all the info that
          * the kernel environment has.
          */
          if (!kld_file_patch_OSObjects(current_entry->name)) {
              result = kload_error_link_load;   // FIXME: need a "patch" error?
              goto finish;
          }
  #else
         /* In the kernel, we call the merge function for already-loaded
          * kmods, since the kld patch environment retains info for kmods
          * that have already been patched. The patch function does a little
          * more work, and is only for kmods that haven't been processed yet.
          * NOTE: We are depending here on kload_check_module_loaded()
          * having been called, which is guaranteed by kload_load_dgraph()
          * is used, but not by its subroutines (such as
          * __kload_load_modules()).
          */
          if (current_entry->loaded_address) {
              if (!kld_file_merge_OSObjects(current_entry->name)) {
                  result = kload_error_link_load;   // FIXME: need a "patch" error?
                  goto finish;
              }
          } else {
              if (!kld_file_patch_OSObjects(current_entry->name)) {
                  result = kload_error_link_load;   // FIXME: need a "patch" error?
                  goto finish;
              }
          }
  #endif /* not KERNEL */
  
      }
  
      if (!kld_file_prepare_for_link()) {
          result = kload_error_link_load;   // FIXME: need more specific error?
          goto finish;
      }
  
  finish:
      return result;
  }
  
  #ifndef KERNEL
  /*******************************************************************************
  *
  *******************************************************************************/
  #define __KLOAD_PATCH_EXTENSION ".patch"
  
  kload_error __kload_output_patches(
      dgraph_t * dgraph,
      const char * patch_file,
      const char * patch_dir,
      int ask_overwrite_symbols,
      int overwrite_symbols)
  {
      kload_error result = kload_error_none;
      unsigned int i;
      char * allocated_filename = NULL;
      char * patch_filename = NULL;
      int file_check;
      int output_patch;
  
      if (patch_dir) {
  
          for (i = 0; i < dgraph->length; i++) {
  
              struct dgraph_entry_t * entry = dgraph->load_order[i];
              unsigned long length;
  
              if (entry->is_kernel_component) {
                  continue;
              }
  
              length = strlen(patch_dir) +
                  strlen(entry->expected_kmod_name) +
                  strlen(__KLOAD_PATCH_EXTENSION) +
                  1 + 1 ;   // 1 for '/' added, 1 for terminating null
              if (length >= MAXPATHLEN) {
                  kload_log_error(
                      "output filename \"%s/%s%s\" would be too long" KNL,
                      patch_dir, entry->expected_kmod_name,
                      __KLOAD_PATCH_EXTENSION);
                  result = kload_error_invalid_argument;
                  goto finish;
              }
  
              allocated_filename = (char *)malloc(length);
              if (! allocated_filename) {
                  kload_log_error("malloc failure" KNL);
                  result = kload_error_no_memory;
                  goto finish;
              }
  
              patch_filename = allocated_filename;
              strcpy(patch_filename, patch_dir);
              strcat(patch_filename, "/");
              strcat(patch_filename, entry->expected_kmod_name);
              strcat(patch_filename, __KLOAD_PATCH_EXTENSION);
  
              output_patch = 1;
              file_check = kload_file_exists(patch_filename);
  
              if (file_check < 0) {
                  kload_log_error("error checking existence of file %s" KNL,
                      patch_filename);
              } else if (file_check > 0 && !overwrite_symbols) {
                  if (!ask_overwrite_symbols) {
                      kload_log_error(
                          "patch file %s exists; not overwriting" KNL,
                          patch_filename);
                      output_patch = 0;
                  } else {
                      int approve = (*__kload_approve_func)(1,
                          "\nPatch file %s exists; overwrite", patch_filename);
  
                      if (approve < 0) {
                          result = kload_error_unspecified;
                          goto finish;
                      } else {
                          output_patch = approve;
                      }
                  }
              }
  
              if (output_patch) {
                  if (log_level >= kload_log_level_basic) {
                      kload_log_message("writing patch file %s" KNL, patch_filename);
                  }
                  kld_file_debug_dump(entry->name, patch_filename);
              }
  
              if (allocated_filename) free(allocated_filename);
              allocated_filename = NULL;
          }
  
      } else if (patch_file) {
          output_patch = 1;
          file_check = kload_file_exists(patch_file);
  
          if (file_check < 0) {
              kload_log_error("error checking existence of file %s" KNL,
                  patch_file);
          } else if (file_check > 0 && !overwrite_symbols) {
              if (!ask_overwrite_symbols) {
                  kload_log_error("patch file %s exists; not overwriting" KNL,
                      patch_filename);
                  output_patch = 0;
              } else {
                  int approve = (*__kload_approve_func)(1,
                      "\nPatch file %s exists; overwrite", patch_filename);
  
                  if (approve < 0) {
                      result = kload_error_unspecified;
                      goto finish;
                  } else {
                      output_patch = approve;
                  }
              }
          }
  
          if (output_patch) {
              if (log_level >= kload_log_level_basic) {
                  kload_log_message("writing patch file %s" KNL, patch_filename);
              }
              kld_file_debug_dump(dgraph->root->name, patch_file);
          }
      }
  
  finish:
      if (allocated_filename) free(allocated_filename);
  
      return result;
  }
  #endif /* not KERNEL */
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  kload_error __kload_set_module_dependencies(dgraph_entry_t * entry) {
      kload_error result = kload_error_none;
      int mach_result;
  #ifndef KERNEL
      void * kmod_control_args = 0;
      int num_args = 0;
  #endif /* not KERNEL */
      kmod_t packed_id;
      unsigned int i;
      dgraph_entry_t * current_dep = NULL;
  
      if (!entry->do_load) {
          result = kload_error_already_loaded;
          goto finish;
      }
  
      for (i = 0; i < entry->num_dependencies; i++) {
          current_dep = entry->dependencies[i];
  
          if (log_level >= kload_log_level_load_details) {
              kload_log_message("adding reference from %s (%d) to %s (%d)" KNL,
                  entry->expected_kmod_name, entry->kmod_id,
                  current_dep->expected_kmod_name, current_dep->kmod_id);
          }
  
          packed_id = KMOD_PACK_IDS(entry->kmod_id, current_dep->kmod_id);
  #ifndef KERNEL
          mach_result = kmod_control(G_kernel_priv_port,
                  packed_id, KMOD_CNTL_RETAIN, &kmod_control_args, &num_args);
  #else
          mach_result = kmod_retain(packed_id);
  #endif /* not KERNEL */
          if (mach_result != KERN_SUCCESS) {
              kload_log_error(
                  "kmod retain failed for %s; destroying kmod" KNL,
                  entry->expected_kmod_name);
  #ifndef KERNEL
              mach_result = kmod_destroy(G_kernel_priv_port, entry->kmod_id);
  #else
              mach_result = kmod_destroy_internal(entry->kmod_id);
  #endif /* not KERNEL */
              if (mach_result != KERN_SUCCESS) {
                  kload_log_error("kmod destroy failed" KNL);
              }
              result = kload_error_link_load;
              goto finish;
          }
      }
  
      if (log_level >= kload_log_level_load_basic) {
          kload_log_message("module # %d reference counts incremented" KNL,
              entry->kmod_id);
      }
  
  finish:
      return result;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  kload_error __kload_start_module(dgraph_entry_t * entry) {
      kload_error result = kload_error_none;
      int mach_result;
  #ifndef KERNEL
      void * kmod_control_args = 0;
      int num_args = 0;
  #endif /* not KERNEL */
  
      if (!entry->do_load) {
          result = kload_error_already_loaded;
          goto finish;
      }
  
  #ifndef KERNEL
      mach_result = kmod_control(G_kernel_priv_port,
              entry->kmod_id, KMOD_CNTL_START, &kmod_control_args, &num_args);
  #else
      mach_result = kmod_start_or_stop(entry->kmod_id, 1, 0, 0);
  #endif /* not KERNEL */
  
      if (mach_result != KERN_SUCCESS) {
          kload_log_error(
              "kmod_control/start failed for %s; destroying kmod" KNL,
              entry->expected_kmod_name);
  #ifndef KERNEL
          mach_result = kmod_destroy(G_kernel_priv_port, entry->kmod_id);
  #else
          mach_result = kmod_destroy_internal(entry->kmod_id);
  #endif /* not KERNEL */
          if (mach_result != KERN_SUCCESS) {
              kload_log_error("kmod destroy failed" KNL);
          }
          result = kload_error_link_load;
          goto finish;
      }
  
      if (log_level >= kload_log_level_load_basic) {
          kload_log_message("module # %d started" KNL,
             entry->kmod_id);
      }
  
  finish:
      return result;
  }
  
  /*******************************************************************************
  *******************************************************************************/
  
  /*******************************************************************************
  * This function can only operate on 32 bit mach object file symbol table
  * graphs represented by G_current_load_entry.
  *******************************************************************************/
  static
  unsigned long __kload_linkedit_address(
      unsigned long size,
      unsigned long headers_size)
  {
      unsigned long round_segments_size;
      unsigned long round_headers_size;
      unsigned long round_size;
      int mach_result;
      const struct machOMapping {
          struct mach_header h;
          struct segment_command seg[1];
      } *machO;
  
      if (!G_current_load_entry) {
          return 0;
      }
  
      // the actual size allocated by kld_load_from_memory()
      G_current_load_entry->kernel_load_size = size;
  
      round_headers_size = round_page(headers_size);
      round_segments_size = round_page(size - headers_size);
      round_size = round_headers_size + round_segments_size;
  
      G_current_load_entry->kernel_alloc_size = round_size;
  
      // will need to be rounded *after* load/link
      G_current_load_entry->kernel_hdr_size = headers_size;
      G_current_load_entry->kernel_hdr_pad = round_headers_size - headers_size;
      
      if (G_current_load_entry->loaded_address) {
          G_current_load_entry->kernel_load_address =
              G_current_load_entry->loaded_address +
              G_current_load_entry->kernel_hdr_pad;
          if (log_level >= kload_log_level_load_basic) {
              kload_log_message(
                  "using %s load address 0x%x (0x%x with header pad)" KNL,
                  G_current_load_entry->kmod_id ? "existing" : "provided",
                  G_current_load_entry->loaded_address,
                  G_current_load_entry->kernel_load_address);
          }
          return G_current_load_entry->kernel_load_address;
      }
  
      machO = (const struct machOMapping *) G_current_load_entry->object;
      if (machO->seg[0].vmaddr)
      {
          G_current_load_entry->loaded_address = trunc_page(machO->seg[0].vmaddr - machO->seg[0].fileoff);
  
          G_current_load_entry->kernel_load_address = G_current_load_entry->loaded_address 
                  + G_current_load_entry->kernel_hdr_pad;
  
          return G_current_load_entry->kernel_load_address;
      }
  
  #ifndef KERNEL
      if (G_prelink) {
          G_current_load_entry->kernel_alloc_address = G_prelink->modules[0].address;
          G_prelink->modules[0].address += round_page(G_current_load_entry->kernel_alloc_size);
          mach_result = KERN_SUCCESS;
          
      } else if (G_syms_only) {
          kload_log_error(
              "internal error; asked to allocate kernel memory" KNL);
          // FIXME: no provision for cleanup here
          return kload_error_unspecified;
  
      } else
  #endif /* not KERNEL */
  
      {
  #ifndef KERNEL
          mach_result = vm_allocate(G_kernel_port,
                  &G_current_load_entry->kernel_alloc_address,
                  G_current_load_entry->kernel_alloc_size, VM_FLAGS_ANYWHERE);
  #else
          mach_result = vm_allocate(kernel_map,
              &G_current_load_entry->kernel_alloc_address,
              G_current_load_entry->kernel_alloc_size, VM_FLAGS_ANYWHERE);
  #endif /* not KERNEL */
      }
  
      if (mach_result != KERN_SUCCESS) {
          kload_log_error("can't allocate kernel memory" KNL);
          // FIXME: no provision for cleanup here
          return kload_error_kernel_error;
      }
  
      if (log_level >= kload_log_level_load_basic) {
          kload_log_message("allocated %ld bytes in kernel space at 0x%x" KNL,
              G_current_load_entry->kernel_alloc_size,
              G_current_load_entry->kernel_alloc_address);
      }
  
      G_current_load_entry->kernel_load_address =
          G_current_load_entry->kernel_alloc_address +
          G_current_load_entry->kernel_hdr_pad;
  
      G_current_load_entry->loaded_address = G_current_load_entry->kernel_alloc_address;
  
      if (log_level >= kload_log_level_load_basic) {
          kload_log_message(
              "using load address of 0x%x" KNL,
              G_current_load_entry->kernel_alloc_address);
      }
  
      return G_current_load_entry->kernel_load_address;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  static
  void __kload_clear_kld_globals(void) {
      G_current_load_entry = NULL;
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  static
  void __kload_clean_up_entry(dgraph_entry_t * entry) {
      int mach_result;
  
      if (entry->need_cleanup && entry->kernel_alloc_address) {
  #ifndef KERNEL
          if (G_prelink) {
  
              if ((entry->kernel_alloc_address + entry->kernel_alloc_size) == G_prelink->modules[0].address) {
                  G_prelink->modules[0].address = entry->kernel_alloc_address;
              } else {
                  kload_log_error(
                      "bad free load address of 0x%x (last 0x%x)" KNL,
                      entry->kernel_alloc_address, G_prelink->modules[0].address);
              }
          } else {
              mach_result = vm_deallocate(G_kernel_port, entry->kernel_alloc_address,
                  entry->kernel_alloc_size);
          }
  #else
          mach_result = vm_deallocate(kernel_map, entry->kernel_alloc_address,
              entry->kernel_alloc_size);
  #endif /* not KERNEL */
          entry->kernel_alloc_address = 0;
      }
      return;
  }
  
  #ifndef KERNEL
  /*******************************************************************************
  *
  *******************************************************************************/
  int kload_file_exists(const char * path)
  {
      int result = 0;  // assume it doesn't exist
      struct stat stat_buf;
  
      if (stat(path, &stat_buf) == 0) {
          result = 1;  // the file does exist; we don't care beyond that
          goto finish;
      }
  
      switch (errno) {
        case ENOENT:
          result = 0;  // the file doesn't exist
          goto finish;
          break;
        default:
          result = -1;  // unknown error
          goto finish;
          break;
      }
  
  finish:
      return result;
  }
  #endif /* not KERNEL */
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  void kload_set_log_level(kload_log_level level)
  {
      log_level = level;
      return;
  }
  
  #ifndef KERNEL
  /*******************************************************************************
  *
  *******************************************************************************/
  void kload_set_log_function(
      void (*func)(const char * format, ...))
  {
      if (!func) {
          __kload_log_func = &__kload_null_log;
      } else {
          __kload_log_func = func;
      }
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  void kload_set_error_log_function(
      void (*func)(const char * format, ...))
  {
      if (!func) {
          __kload_err_log_func = &__kload_null_err_log;
      } else {
          __kload_err_log_func = func;
      }
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  void kload_set_user_approve_function(
      int (*func)(int default_answer, const char * format, ...))
  {
      if (!func) {
          __kload_approve_func = &__kload_null_approve;
      } else {
          __kload_approve_func = func;
      }
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  void kload_set_user_veto_function(
      int (*func)(int default_answer, const char * format, ...))
  {
      if (!func) {
          __kload_veto_func = &__kload_null_veto;
      } else {
          __kload_veto_func = func;
      }
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  void kload_set_user_input_function(
      const char * (*func)(const char * format, ...))
  {
      if (!func) {
          __kload_input_func = &__kload_null_input;
      } else {
          __kload_input_func = func;
      }
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  void kload_log_message(const char * format, ...)
  {
      va_list ap;
      char fake_buffer[2];
      int output_length;
      char * output_string;
  
      if (log_level <= kload_log_level_silent) {
          return;
      }
  
      va_start(ap, format);
      output_length = vsnprintf(fake_buffer, 1, format, ap);
      va_end(ap);
  
      output_string = (char *)malloc(output_length + 1);
      if (!output_string) {
          return;
      }
  
      va_start(ap, format);
      vsprintf(output_string, format, ap);
      va_end(ap);
  
      __kload_log_func(output_string);
      free(output_string);
  
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  PRIV_EXT
  void kload_log_error(const char * format, ...)
  {
      va_list ap;
      char fake_buffer[2];
      int output_length;
      char * output_string;
  
      if (log_level <= kload_log_level_silent) {
          return;
      }
  
      va_start(ap, format);
      output_length = vsnprintf(fake_buffer, 1, format, ap);
      va_end(ap);
  
      output_string = (char *)malloc(output_length + 1);
      if (!output_string) {
          return;
      }
  
      va_start(ap, format);
      vsprintf(output_string, format, ap);
      va_end(ap);
  
      __kload_err_log_func(output_string);
      free(output_string);
  
      return;
  }
  /*******************************************************************************
  *
  *******************************************************************************/
  void __kload_null_log(const char * format, ...)
  {
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  void __kload_null_err_log(const char * format, ...)
  {
      return;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  int __kload_null_approve(int default_answer, const char * format, ...)
  {
      return 0;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  int __kload_null_veto(int default_answer, const char * format, ...)
  {
      return 1;
  }
  
  /*******************************************************************************
  *
  *******************************************************************************/
  const char * __kload_null_input(const char * format, ...)
  {
      return NULL;
  }
  
  /*******************************************************************************
  * The kld_patch.c module uses this function, if defined, to print errors. In
  * the kernel this function is defined in libsa/misc.c.
  *******************************************************************************/
  void kld_error_vprintf(const char * format, va_list ap) {
      if (log_level <= kload_log_level_silent) return;
      vfprintf(stderr, format, ap);
      return;
  }
  
  #endif /* not KERNEL */

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