unexmacosx.c 42.5 KB
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/* Dump Emacs in Mach-O format for use on Mac OS X.
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   Copyright (C) 2001-2013 Free Software Foundation, Inc.
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This file is part of GNU Emacs.

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GNU Emacs is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
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along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
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/* Contributed by Andrew Choi (akochoi@mac.com).  */

/* Documentation note.

   Consult the following documents/files for a description of the
   Mach-O format: the file loader.h, man pages for Mach-O and ld, old
   NEXTSTEP documents of the Mach-O format.  The tool otool dumps the
   mach header (-h option) and the load commands (-l option) in a
   Mach-O file.  The tool nm on Mac OS X displays the symbol table in
   a Mach-O file.  For examples of unexec for the Mach-O format, see
   the file unexnext.c in the GNU Emacs distribution, the file
   unexdyld.c in the Darwin port of GNU Emacs 20.7, and unexdyld.c in
   the Darwin port of XEmacs 21.1.  Also the Darwin Libc source
   contains the source code for malloc_freezedry and malloc_jumpstart.
   Read that to see what they do.  This file was written completely
   from scratch, making use of information from the above sources.  */

/* The Mac OS X implementation of unexec makes use of Darwin's `zone'
   memory allocator.  All calls to malloc, realloc, and free in Emacs
   are redirected to unexec_malloc, unexec_realloc, and unexec_free in
   this file.  When temacs is run, all memory requests are handled in
   the zone EmacsZone.  The Darwin memory allocator library calls
   maintain the data structures to manage this zone.  Dumping writes
   its contents to data segments of the executable file.  When emacs
   is run, the loader recreates the contents of the zone in memory.
   However since the initialization routine of the zone memory
   allocator is run again, this `zone' can no longer be used as a
   heap.  That is why emacs uses the ordinary malloc system call to
   allocate memory.  Also, when a block of memory needs to be
   reallocated and the new size is larger than the old one, a new
   block must be obtained by malloc and the old contents copied to
   it.  */

/* Peculiarity of the Mach-O files generated by ld in Mac OS X
   (possible causes of future bugs if changed).

   The file offset of the start of the __TEXT segment is zero.  Since
   the Mach header and load commands are located at the beginning of a
   Mach-O file, copying the contents of the __TEXT segment from the
   input file overwrites them in the output file.  Despite this,
   unexec works fine as written below because the segment load command
   for __TEXT appears, and is therefore processed, before all other
   load commands except the segment load command for __PAGEZERO, which
   remains unchanged.

   Although the file offset of the start of the __TEXT segment is
   zero, none of the sections it contains actually start there.  In
   fact, the earliest one starts a few hundred bytes beyond the end of
   the last load command.  The linker option -headerpad controls the
   minimum size of this padding.  Its setting can be changed in
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   s/darwin.h.  A value of 0x690, e.g., leaves room for 30 additional
   load commands for the newly created __DATA segments (at 56 bytes
   each).  Unexec fails if there is not enough room for these new
   segments.
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   The __TEXT segment contains the sections __text, __cstring,
   __picsymbol_stub, and __const and the __DATA segment contains the
   sections __data, __la_symbol_ptr, __nl_symbol_ptr, __dyld, __bss,
   and __common.  The other segments do not contain any sections.
   These sections are copied from the input file to the output file,
   except for __data, __bss, and __common, which are dumped from
   memory.  The types of the sections __bss and __common are changed
   from S_ZEROFILL to S_REGULAR.  Note that the number of sections and
   their relative order in the input and output files remain
   unchanged.  Otherwise all n_sect fields in the nlist records in the
   symbol table (specified by the LC_SYMTAB load command) will have to
   be changed accordingly.
*/

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/* config.h #define:s malloc/realloc/free and then includes stdlib.h.
   We want the undefined versions, but if config.h includes stdlib.h
   with the #define:s in place, the prototypes will be wrong and we get
   warnings.  To prevent that, include stdlib.h before config.h.  */

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#include <stdlib.h>
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#include <config.h>
#undef malloc
#undef realloc
#undef free
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#include "unexec.h"

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#include <stdio.h>
#include <fcntl.h>
#include <stdarg.h>
#include <sys/types.h>
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#include <unistd.h>
#include <mach/mach.h>
#include <mach-o/loader.h>
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#include <mach-o/reloc.h>
#if defined (__ppc__)
#include <mach-o/ppc/reloc.h>
#endif
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#ifdef HAVE_MALLOC_MALLOC_H
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#include <malloc/malloc.h>
#else
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#include <objc/malloc.h>
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#endif

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#include <assert.h>

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/* LC_DATA_IN_CODE is not defined in mach-o/loader.h on OS X 10.7.
   But it is used if we build with "Command Line Tools for Xcode 4.5
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   (OS X Lion) - September 2012".  */
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#ifndef LC_DATA_IN_CODE
#define LC_DATA_IN_CODE 0x29 /* table of non-instructions in __text */
#endif

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#ifdef _LP64
#define mach_header			mach_header_64
#define segment_command			segment_command_64
#undef  VM_REGION_BASIC_INFO_COUNT
#define VM_REGION_BASIC_INFO_COUNT	VM_REGION_BASIC_INFO_COUNT_64
#undef  VM_REGION_BASIC_INFO
#define VM_REGION_BASIC_INFO		VM_REGION_BASIC_INFO_64
#undef  LC_SEGMENT
#define LC_SEGMENT			LC_SEGMENT_64
#define vm_region			vm_region_64
#define section				section_64
#undef MH_MAGIC
#define MH_MAGIC			MH_MAGIC_64
#endif
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#define VERBOSE 1

/* Size of buffer used to copy data from the input file to the output
   file in function unexec_copy.  */
#define UNEXEC_COPY_BUFSZ 1024

/* Regions with memory addresses above this value are assumed to be
   mapped to dynamically loaded libraries and will not be dumped.  */
#define VM_DATA_TOP (20 * 1024 * 1024)

/* Type of an element on the list of regions to be dumped.  */
struct region_t {
  vm_address_t address;
  vm_size_t size;
  vm_prot_t protection;
  vm_prot_t max_protection;

  struct region_t *next;
};

/* Head and tail of the list of regions to be dumped.  */
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static struct region_t *region_list_head = 0;
static struct region_t *region_list_tail = 0;
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/* Pointer to array of load commands.  */
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static struct load_command **lca;
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/* Number of load commands.  */
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static int nlc;
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/* The highest VM address of segments loaded by the input file.
   Regions with addresses beyond this are assumed to be allocated
   dynamically and thus require dumping.  */
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static vm_address_t infile_lc_highest_addr = 0;
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/* The lowest file offset used by the all sections in the __TEXT
   segments.  This leaves room at the beginning of the file to store
   the Mach-O header.  Check this value against header size to ensure
   the added load commands for the new __DATA segments did not
   overwrite any of the sections in the __TEXT segment.  */
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static unsigned long text_seg_lowest_offset = 0x10000000;
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/* Mach header.  */
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static struct mach_header mh;
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/* Offset at which the next load command should be written.  */
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static unsigned long curr_header_offset = sizeof (struct mach_header);
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/* Offset at which the next segment should be written.  */
static unsigned long curr_file_offset = 0;

static unsigned long pagesize;
#define ROUNDUP_TO_PAGE_BOUNDARY(x)	(((x) + pagesize - 1) & ~(pagesize - 1))
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static int infd, outfd;
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static int in_dumped_exec = 0;
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static malloc_zone_t *emacs_zone;
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/* file offset of input file's data segment */
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static off_t data_segment_old_fileoff = 0;
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static struct segment_command *data_segment_scp;
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/* Read N bytes from infd into memory starting at address DEST.
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   Return true if successful, false otherwise.  */
static int
unexec_read (void *dest, size_t n)
{
  return n == read (infd, dest, n);
}

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/* Write COUNT bytes from memory starting at address SRC to outfd
   starting at offset DEST.  Return true if successful, false
   otherwise.  */
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static int
unexec_write (off_t dest, const void *src, size_t count)
{
  if (lseek (outfd, dest, SEEK_SET) != dest)
    return 0;

  return write (outfd, src, count) == count;
}

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/* Write COUNT bytes of zeros to outfd starting at offset DEST.
   Return true if successful, false otherwise.  */
static int
unexec_write_zero (off_t dest, size_t count)
{
  char buf[UNEXEC_COPY_BUFSZ];
  ssize_t bytes;

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  memset (buf, 0, UNEXEC_COPY_BUFSZ);
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  if (lseek (outfd, dest, SEEK_SET) != dest)
    return 0;

  while (count > 0)
    {
      bytes = count > UNEXEC_COPY_BUFSZ ? UNEXEC_COPY_BUFSZ : count;
      if (write (outfd, buf, bytes) != bytes)
	return 0;
      count -= bytes;
    }

  return 1;
}

/* Copy COUNT bytes from starting offset SRC in infd to starting
   offset DEST in outfd.  Return true if successful, false
   otherwise.  */
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static int
unexec_copy (off_t dest, off_t src, ssize_t count)
{
  ssize_t bytes_read;
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  ssize_t bytes_to_read;
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  char buf[UNEXEC_COPY_BUFSZ];

  if (lseek (infd, src, SEEK_SET) != src)
    return 0;

  if (lseek (outfd, dest, SEEK_SET) != dest)
    return 0;

  while (count > 0)
    {
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      bytes_to_read = count > UNEXEC_COPY_BUFSZ ? UNEXEC_COPY_BUFSZ : count;
      bytes_read = read (infd, buf, bytes_to_read);
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      if (bytes_read <= 0)
	return 0;
      if (write (outfd, buf, bytes_read) != bytes_read)
	return 0;
      count -= bytes_read;
    }

  return 1;
}

/* Debugging and informational messages routines.  */

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static _Noreturn void
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unexec_error (const char *format, ...)
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{
  va_list ap;

  va_start (ap, format);
  fprintf (stderr, "unexec: ");
  vfprintf (stderr, format, ap);
  fprintf (stderr, "\n");
  va_end (ap);
  exit (1);
}

static void
print_prot (vm_prot_t prot)
{
  if (prot == VM_PROT_NONE)
    printf ("none");
  else
    {
      putchar (prot & VM_PROT_READ ? 'r' : ' ');
      putchar (prot & VM_PROT_WRITE ? 'w' : ' ');
      putchar (prot & VM_PROT_EXECUTE ? 'x' : ' ');
      putchar (' ');
    }
}

static void
print_region (vm_address_t address, vm_size_t size, vm_prot_t prot,
	      vm_prot_t max_prot)
{
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  printf ("%#10lx %#8lx ", (long) address, (long) size);
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  print_prot (prot);
  putchar (' ');
  print_prot (max_prot);
  putchar ('\n');
}

static void
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print_region_list (void)
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{
  struct region_t *r;

  printf ("   address     size prot maxp\n");

  for (r = region_list_head; r; r = r->next)
    print_region (r->address, r->size, r->protection, r->max_protection);
}

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static void
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print_regions (void)
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{
  task_t target_task = mach_task_self ();
  vm_address_t address = (vm_address_t) 0;
  vm_size_t size;
  struct vm_region_basic_info info;
  mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT;
  mach_port_t object_name;

  printf ("   address     size prot maxp\n");

  while (vm_region (target_task, &address, &size, VM_REGION_BASIC_INFO,
		    (vm_region_info_t) &info, &info_count, &object_name)
	 == KERN_SUCCESS && info_count == VM_REGION_BASIC_INFO_COUNT)
    {
      print_region (address, size, info.protection, info.max_protection);

      if (object_name != MACH_PORT_NULL)
	mach_port_deallocate (target_task, object_name);
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      address += size;
    }
}

/* Build the list of regions that need to be dumped.  Regions with
   addresses above VM_DATA_TOP are omitted.  Adjacent regions with
   identical protection are merged.  Note that non-writable regions
   cannot be omitted because they some regions created at run time are
   read-only.  */
static void
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build_region_list (void)
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{
  task_t target_task = mach_task_self ();
  vm_address_t address = (vm_address_t) 0;
  vm_size_t size;
  struct vm_region_basic_info info;
  mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT;
  mach_port_t object_name;
  struct region_t *r;

#if VERBOSE
  printf ("--- List of All Regions ---\n");
  printf ("   address     size prot maxp\n");
#endif

  while (vm_region (target_task, &address, &size, VM_REGION_BASIC_INFO,
		    (vm_region_info_t) &info, &info_count, &object_name)
	 == KERN_SUCCESS && info_count == VM_REGION_BASIC_INFO_COUNT)
    {
      /* Done when we reach addresses of shared libraries, which are
	 loaded in high memory.  */
      if (address >= VM_DATA_TOP)
	break;

#if VERBOSE
      print_region (address, size, info.protection, info.max_protection);
#endif

      /* If a region immediately follows the previous one (the one
	 most recently added to the list) and has identical
	 protection, merge it with the latter.  Otherwise create a
	 new list element for it.  */
      if (region_list_tail
	  && info.protection == region_list_tail->protection
	  && info.max_protection == region_list_tail->max_protection
	  && region_list_tail->address + region_list_tail->size == address)
	{
	  region_list_tail->size += size;
	}
      else
	{
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	  r = malloc (sizeof *r);
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	  if (!r)
	    unexec_error ("cannot allocate region structure");
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	  r->address = address;
	  r->size = size;
	  r->protection = info.protection;
	  r->max_protection = info.max_protection;
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	  r->next = 0;
	  if (region_list_head == 0)
	    {
	      region_list_head = r;
	      region_list_tail = r;
	    }
	  else
	    {
	      region_list_tail->next = r;
	      region_list_tail = r;
	    }
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	  /* Deallocate (unused) object name returned by
	     vm_region.  */
	  if (object_name != MACH_PORT_NULL)
	    mach_port_deallocate (target_task, object_name);
	}
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      address += size;
    }

  printf ("--- List of Regions to be Dumped ---\n");
  print_region_list ();
}


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#define MAX_UNEXEC_REGIONS 800
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static int num_unexec_regions;
typedef struct {
  vm_range_t range;
  vm_size_t filesize;
} unexec_region_info;
static unexec_region_info unexec_regions[MAX_UNEXEC_REGIONS];
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static void
unexec_regions_recorder (task_t task, void *rr, unsigned type,
			 vm_range_t *ranges, unsigned num)
{
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  vm_address_t p;
  vm_size_t filesize;

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  while (num && num_unexec_regions < MAX_UNEXEC_REGIONS)
    {
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      /* Subtract the size of trailing null bytes from filesize.  It
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	 can be smaller than vmsize in segment commands.  In such a
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	 case, trailing bytes are initialized with zeros.  */
      for (p = ranges->address + ranges->size; p > ranges->address; p--)
      	if (*(((char *) p)-1))
      	  break;
      filesize = p - ranges->address;
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      unexec_regions[num_unexec_regions].filesize = filesize;
      unexec_regions[num_unexec_regions++].range = *ranges;
      printf ("%#10lx (sz: %#8lx/%#8lx)\n", (long) (ranges->address),
	      (long) filesize, (long) (ranges->size));
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      ranges++; num--;
    }
}

static kern_return_t
unexec_reader (task_t task, vm_address_t address, vm_size_t size, void **ptr)
{
  *ptr = (void *) address;
  return KERN_SUCCESS;
}

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static void
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find_emacs_zone_regions (void)
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{
  num_unexec_regions = 0;

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  emacs_zone->introspect->enumerator (mach_task_self (), 0,
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				      MALLOC_PTR_REGION_RANGE_TYPE
				      | MALLOC_ADMIN_REGION_RANGE_TYPE,
				      (vm_address_t) emacs_zone,
				      unexec_reader,
				      unexec_regions_recorder);
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  if (num_unexec_regions == MAX_UNEXEC_REGIONS)
    unexec_error ("find_emacs_zone_regions: too many regions");
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}

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static int
unexec_regions_sort_compare (const void *a, const void *b)
{
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  vm_address_t aa = ((unexec_region_info *) a)->range.address;
  vm_address_t bb = ((unexec_region_info *) b)->range.address;
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  if (aa < bb)
    return -1;
  else if (aa > bb)
    return 1;
  else
    return 0;
}

static void
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unexec_regions_merge (void)
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{
  int i, n;
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  unexec_region_info r;
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  vm_size_t padsize;
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  qsort (unexec_regions, num_unexec_regions, sizeof (unexec_regions[0]),
	 &unexec_regions_sort_compare);
  n = 0;
  r = unexec_regions[0];
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  padsize = r.range.address & (pagesize - 1);
  if (padsize)
    {
      r.range.address -= padsize;
      r.range.size += padsize;
      r.filesize += padsize;
    }
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  for (i = 1; i < num_unexec_regions; i++)
    {
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      if (r.range.address + r.range.size == unexec_regions[i].range.address
	  && r.range.size - r.filesize < 2 * pagesize)
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	{
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	  r.filesize = r.range.size + unexec_regions[i].filesize;
	  r.range.size += unexec_regions[i].range.size;
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	}
      else
	{
	  unexec_regions[n++] = r;
	  r = unexec_regions[i];
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	  padsize = r.range.address & (pagesize - 1);
	  if (padsize)
	    {
	      if ((unexec_regions[n-1].range.address
		   + unexec_regions[n-1].range.size) == r.range.address)
		unexec_regions[n-1].range.size -= padsize;

	      r.range.address -= padsize;
	      r.range.size += padsize;
	      r.filesize += padsize;
	    }
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	}
    }
  unexec_regions[n++] = r;
  num_unexec_regions = n;
}

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/* More informational messages routines.  */

static void
print_load_command_name (int lc)
{
  switch (lc)
    {
    case LC_SEGMENT:
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#ifndef _LP64
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      printf ("LC_SEGMENT       ");
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#else
      printf ("LC_SEGMENT_64    ");
#endif
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      break;
    case LC_LOAD_DYLINKER:
      printf ("LC_LOAD_DYLINKER ");
      break;
    case LC_LOAD_DYLIB:
      printf ("LC_LOAD_DYLIB    ");
      break;
    case LC_SYMTAB:
      printf ("LC_SYMTAB        ");
      break;
    case LC_DYSYMTAB:
      printf ("LC_DYSYMTAB      ");
      break;
    case LC_UNIXTHREAD:
      printf ("LC_UNIXTHREAD    ");
      break;
    case LC_PREBOUND_DYLIB:
      printf ("LC_PREBOUND_DYLIB");
      break;
    case LC_TWOLEVEL_HINTS:
      printf ("LC_TWOLEVEL_HINTS");
      break;
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#ifdef LC_UUID
    case LC_UUID:
      printf ("LC_UUID          ");
      break;
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#endif
#ifdef LC_DYLD_INFO
    case LC_DYLD_INFO:
      printf ("LC_DYLD_INFO     ");
      break;
    case LC_DYLD_INFO_ONLY:
      printf ("LC_DYLD_INFO_ONLY");
      break;
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#endif
#ifdef LC_VERSION_MIN_MACOSX
    case LC_VERSION_MIN_MACOSX:
      printf ("LC_VERSION_MIN_MACOSX");
      break;
#endif
#ifdef LC_FUNCTION_STARTS
    case LC_FUNCTION_STARTS:
      printf ("LC_FUNCTION_STARTS");
      break;
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#endif
#ifdef LC_MAIN
    case LC_MAIN:
      printf ("LC_MAIN          ");
      break;
#endif
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#ifdef LC_DATA_IN_CODE
    case LC_DATA_IN_CODE:
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      printf ("LC_DATA_IN_CODE  ");
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      break;
#endif
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#ifdef LC_SOURCE_VERSION
    case LC_SOURCE_VERSION:
      printf ("LC_SOURCE_VERSION");
      break;
#endif
#ifdef LC_DYLIB_CODE_SIGN_DRS
    case LC_DYLIB_CODE_SIGN_DRS:
      printf ("LC_DYLIB_CODE_SIGN_DRS");
      break;
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#endif
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    default:
      printf ("unknown          ");
    }
}

static void
print_load_command (struct load_command *lc)
{
  print_load_command_name (lc->cmd);
  printf ("%8d", lc->cmdsize);

  if (lc->cmd == LC_SEGMENT)
    {
      struct segment_command *scp;
      struct section *sectp;
      int j;

      scp = (struct segment_command *) lc;
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      printf (" %-16.16s %#10lx %#8lx\n",
	      scp->segname, (long) (scp->vmaddr), (long) (scp->vmsize));
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      sectp = (struct section *) (scp + 1);
      for (j = 0; j < scp->nsects; j++)
	{
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	  printf ("                           %-16.16s %#10lx %#8lx\n",
		  sectp->sectname, (long) (sectp->addr), (long) (sectp->size));
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	  sectp++;
	}
    }
  else
    printf ("\n");
}

/* Read header and load commands from input file.  Store the latter in
   the global array lca.  Store the total number of load commands in
   global variable nlc.  */
static void
674
read_load_commands (void)
675
{
676
  int i;
677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698

  if (!unexec_read (&mh, sizeof (struct mach_header)))
    unexec_error ("cannot read mach-o header");

  if (mh.magic != MH_MAGIC)
    unexec_error ("input file not in Mach-O format");

  if (mh.filetype != MH_EXECUTE)
    unexec_error ("input Mach-O file is not an executable object file");

#if VERBOSE
  printf ("--- Header Information ---\n");
  printf ("Magic = 0x%08x\n", mh.magic);
  printf ("CPUType = %d\n", mh.cputype);
  printf ("CPUSubType = %d\n", mh.cpusubtype);
  printf ("FileType = 0x%x\n", mh.filetype);
  printf ("NCmds = %d\n", mh.ncmds);
  printf ("SizeOfCmds = %d\n", mh.sizeofcmds);
  printf ("Flags = 0x%08x\n", mh.flags);
#endif

  nlc = mh.ncmds;
699
  lca = malloc (nlc * sizeof *lca);
700

701 702 703 704 705 706 707
  for (i = 0; i < nlc; i++)
    {
      struct load_command lc;
      /* Load commands are variable-size: so read the command type and
	 size first and then read the rest.  */
      if (!unexec_read (&lc, sizeof (struct load_command)))
        unexec_error ("cannot read load command");
708
      lca[i] = malloc (lc.cmdsize);
709 710 711 712 713 714
      memcpy (lca[i], &lc, sizeof (struct load_command));
      if (!unexec_read (lca[i] + 1, lc.cmdsize - sizeof (struct load_command)))
        unexec_error ("cannot read content of load command");
      if (lc.cmd == LC_SEGMENT)
	{
	  struct segment_command *scp = (struct segment_command *) lca[i];
715

716 717 718 719 720 721 722 723 724 725 726 727 728 729 730
	  if (scp->vmaddr + scp->vmsize > infile_lc_highest_addr)
	    infile_lc_highest_addr = scp->vmaddr + scp->vmsize;

	  if (strncmp (scp->segname, SEG_TEXT, 16) == 0)
	    {
	      struct section *sectp = (struct section *) (scp + 1);
	      int j;

	      for (j = 0; j < scp->nsects; j++)
		if (sectp->offset < text_seg_lowest_offset)
		  text_seg_lowest_offset = sectp->offset;
	    }
	}
    }

731 732
  printf ("Highest address of load commands in input file: %#8lx\n",
	  (unsigned long)infile_lc_highest_addr);
733

734
  printf ("Lowest offset of all sections in __TEXT segment: %#8lx\n",
735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757
	  text_seg_lowest_offset);

  printf ("--- List of Load Commands in Input File ---\n");
  printf ("# cmd              cmdsize name                address     size\n");

  for (i = 0; i < nlc; i++)
    {
      printf ("%1d ", i);
      print_load_command (lca[i]);
    }
}

/* Copy a LC_SEGMENT load command other than the __DATA segment from
   the input file to the output file, adjusting the file offset of the
   segment and the file offsets of sections contained in it.  */
static void
copy_segment (struct load_command *lc)
{
  struct segment_command *scp = (struct segment_command *) lc;
  unsigned long old_fileoff = scp->fileoff;
  struct section *sectp;
  int j;

758
  scp->fileoff = curr_file_offset;
759 760 761 762

  sectp = (struct section *) (scp + 1);
  for (j = 0; j < scp->nsects; j++)
    {
763
      sectp->offset += curr_file_offset - old_fileoff;
764 765 766
      sectp++;
    }

767 768 769
  printf ("Writing segment %-16.16s @ %#8lx (%#8lx/%#8lx @ %#10lx)\n",
	  scp->segname, (long) (scp->fileoff), (long) (scp->filesize),
	  (long) (scp->vmsize), (long) (scp->vmaddr));
770 771 772

  if (!unexec_copy (scp->fileoff, old_fileoff, scp->filesize))
    unexec_error ("cannot copy segment from input to output file");
773 774
  curr_file_offset += ROUNDUP_TO_PAGE_BOUNDARY (scp->filesize);

775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798
  if (!unexec_write (curr_header_offset, lc, lc->cmdsize))
    unexec_error ("cannot write load command to header");

  curr_header_offset += lc->cmdsize;
}

/* Copy a LC_SEGMENT load command for the __DATA segment in the input
   file to the output file.  We assume that only one such segment load
   command exists in the input file and it contains the sections
   __data, __bss, __common, __la_symbol_ptr, __nl_symbol_ptr, and
   __dyld.  The first three of these should be dumped from memory and
   the rest should be copied from the input file.  Note that the
   sections __bss and __common contain no data in the input file
   because their flag fields have the value S_ZEROFILL.  Dumping these
   from memory makes it necessary to adjust file offset fields in
   subsequently dumped load commands.  Then, create new __DATA segment
   load commands for regions on the region list other than the one
   corresponding to the __DATA segment in the input file.  */
static void
copy_data_segment (struct load_command *lc)
{
  struct segment_command *scp = (struct segment_command *) lc;
  struct section *sectp;
  int j;
799 800 801 802 803 804 805 806
  unsigned long header_offset, old_file_offset;

  /* The new filesize of the segment is set to its vmsize because data
     blocks for segments must start at region boundaries.  Note that
     this may leave unused locations at the end of the segment data
     block because the total of the sizes of all sections in the
     segment is generally smaller than vmsize.  */
  scp->filesize = scp->vmsize;
807

808 809 810
  printf ("Writing segment %-16.16s @ %#8lx (%#8lx/%#8lx @ %#10lx)\n",
	  scp->segname, curr_file_offset, (long)(scp->filesize),
	  (long)(scp->vmsize), (long) (scp->vmaddr));
811 812 813 814 815 816 817 818 819

  /* Offsets in the output file for writing the next section structure
     and segment data block, respectively.  */
  header_offset = curr_header_offset + sizeof (struct segment_command);

  sectp = (struct section *) (scp + 1);
  for (j = 0; j < scp->nsects; j++)
    {
      old_file_offset = sectp->offset;
820
      sectp->offset = sectp->addr - scp->vmaddr + curr_file_offset;
821 822 823 824 825 826 827
      /* The __data section is dumped from memory.  The __bss and
	 __common sections are also dumped from memory but their flag
	 fields require changing (from S_ZEROFILL to S_REGULAR).  The
	 other three kinds of sections are just copied from the input
	 file.  */
      if (strncmp (sectp->sectname, SECT_DATA, 16) == 0)
	{
828 829 830 831 832 833 834 835 836 837 838 839 840 841
	  extern char my_edata[];
	  unsigned long my_size;

	  /* The __data section is basically dumped from memory.  But
	     initialized data in statically linked libraries are
	     copied from the input file.  In particular,
	     add_image_hook.names and add_image_hook.pointers stored
	     by libarclite_macosx.a, are restored so that they will be
	     reinitialized when the dumped binary is executed.  */
	  my_size = (unsigned long)my_edata - sectp->addr;
	  if (!(sectp->addr <= (unsigned long)my_edata
		&& my_size <= sectp->size))
	    unexec_error ("my_edata is not in section %s", SECT_DATA);
	  if (!unexec_write (sectp->offset, (void *) sectp->addr, my_size))
842
	    unexec_error ("cannot write section %s", SECT_DATA);
843 844 845
	  if (!unexec_copy (sectp->offset + my_size, old_file_offset + my_size,
			    sectp->size - my_size))
	    unexec_error ("cannot copy section %s", SECT_DATA);
846 847 848
	  if (!unexec_write (header_offset, sectp, sizeof (struct section)))
	    unexec_error ("cannot write section %s's header", SECT_DATA);
	}
849
      else if (strncmp (sectp->sectname, SECT_COMMON, 16) == 0)
850 851 852
	{
	  sectp->flags = S_REGULAR;
	  if (!unexec_write (sectp->offset, (void *) sectp->addr, sectp->size))
853
	    unexec_error ("cannot write section %.16s", sectp->sectname);
854
	  if (!unexec_write (header_offset, sectp, sizeof (struct section)))
855
	    unexec_error ("cannot write section %.16s's header", sectp->sectname);
856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872
	}
      else if (strncmp (sectp->sectname, SECT_BSS, 16) == 0)
	{
	  extern char *my_endbss_static;
	  unsigned long my_size;

	  sectp->flags = S_REGULAR;

	  /* Clear uninitialized local variables in statically linked
	     libraries.  In particular, function pointers stored by
	     libSystemStub.a, which is introduced in Mac OS X 10.4 for
	     binary compatibility with respect to long double, are
	     cleared so that they will be reinitialized when the
	     dumped binary is executed on other versions of OS.  */
	  my_size = (unsigned long)my_endbss_static - sectp->addr;
	  if (!(sectp->addr <= (unsigned long)my_endbss_static
		&& my_size <= sectp->size))
873
	    unexec_error ("my_endbss_static is not in section %.16s",
874 875
			  sectp->sectname);
	  if (!unexec_write (sectp->offset, (void *) sectp->addr, my_size))
876
	    unexec_error ("cannot write section %.16s", sectp->sectname);
877 878
	  if (!unexec_write_zero (sectp->offset + my_size,
				  sectp->size - my_size))
879
	    unexec_error ("cannot write section %.16s", sectp->sectname);
880
	  if (!unexec_write (header_offset, sectp, sizeof (struct section)))
881
	    unexec_error ("cannot write section %.16s's header", sectp->sectname);
882 883 884
	}
      else if (strncmp (sectp->sectname, "__la_symbol_ptr", 16) == 0
	       || strncmp (sectp->sectname, "__nl_symbol_ptr", 16) == 0
885
	       || strncmp (sectp->sectname, "__got", 16) == 0
886
	       || strncmp (sectp->sectname, "__la_sym_ptr2", 16) == 0
887
	       || strncmp (sectp->sectname, "__dyld", 16) == 0
888
	       || strncmp (sectp->sectname, "__const", 16) == 0
889 890
	       || strncmp (sectp->sectname, "__cfstring", 16) == 0
	       || strncmp (sectp->sectname, "__gcc_except_tab", 16) == 0
891
	       || strncmp (sectp->sectname, "__program_vars", 16) == 0
892 893
	       || strncmp (sectp->sectname, "__mod_init_func", 16) == 0
	       || strncmp (sectp->sectname, "__mod_term_func", 16) == 0
894
	       || strncmp (sectp->sectname, "__objc_", 7) == 0)
895 896
	{
	  if (!unexec_copy (sectp->offset, old_file_offset, sectp->size))
897
	    unexec_error ("cannot copy section %.16s", sectp->sectname);
898
	  if (!unexec_write (header_offset, sectp, sizeof (struct section)))
899
	    unexec_error ("cannot write section %.16s's header", sectp->sectname);
900 901
	}
      else
902 903
	unexec_error ("unrecognized section %.16s in __DATA segment",
		      sectp->sectname);
904

905 906 907
      printf ("        section %-16.16s at %#8lx - %#8lx (sz: %#8lx)\n",
	      sectp->sectname, (long) (sectp->offset),
	      (long) (sectp->offset + sectp->size), (long) (sectp->size));
908 909 910 911 912

      header_offset += sizeof (struct section);
      sectp++;
    }

913 914
  curr_file_offset += ROUNDUP_TO_PAGE_BOUNDARY (scp->filesize);

915 916 917 918 919 920 921
  if (!unexec_write (curr_header_offset, scp, sizeof (struct segment_command)))
    unexec_error ("cannot write header of __DATA segment");
  curr_header_offset += lc->cmdsize;

  /* Create new __DATA segment load commands for regions on the region
     list that do not corresponding to any segment load commands in
     the input file.
922
  */
923 924 925
  for (j = 0; j < num_unexec_regions; j++)
    {
      struct segment_command sc;
926

927 928 929
      sc.cmd = LC_SEGMENT;
      sc.cmdsize = sizeof (struct segment_command);
      strncpy (sc.segname, SEG_DATA, 16);
930 931
      sc.vmaddr = unexec_regions[j].range.address;
      sc.vmsize = unexec_regions[j].range.size;
932
      sc.fileoff = curr_file_offset;
933
      sc.filesize = unexec_regions[j].filesize;
934 935 936 937
      sc.maxprot = VM_PROT_READ | VM_PROT_WRITE;
      sc.initprot = VM_PROT_READ | VM_PROT_WRITE;
      sc.nsects = 0;
      sc.flags = 0;
938

939 940 941
      printf ("Writing segment %-16.16s @ %#8lx (%#8lx/%#8lx @ %#10lx)\n",
	      sc.segname, (long) (sc.fileoff), (long) (sc.filesize),
	      (long) (sc.vmsize), (long) (sc.vmaddr));
942

943
      if (!unexec_write (sc.fileoff, (void *) sc.vmaddr, sc.filesize))
944
	unexec_error ("cannot write new __DATA segment");
945
      curr_file_offset += ROUNDUP_TO_PAGE_BOUNDARY (sc.filesize);
946

947 948 949 950 951 952 953 954 955 956
      if (!unexec_write (curr_header_offset, &sc, sc.cmdsize))
	unexec_error ("cannot write new __DATA segment's header");
      curr_header_offset += sc.cmdsize;
      mh.ncmds++;
    }
}

/* Copy a LC_SYMTAB load command from the input file to the output
   file, adjusting the file offset fields.  */
static void
957
copy_symtab (struct load_command *lc, long delta)
958 959 960 961 962 963 964 965 966 967 968 969 970 971
{
  struct symtab_command *stp = (struct symtab_command *) lc;

  stp->symoff += delta;
  stp->stroff += delta;

  printf ("Writing LC_SYMTAB command\n");

  if (!unexec_write (curr_header_offset, lc, lc->cmdsize))
    unexec_error ("cannot write symtab command to header");

  curr_header_offset += lc->cmdsize;
}

972 973
/* Fix up relocation entries. */
static void
974
unrelocate (const char *name, off_t reloff, int nrel, vm_address_t base)
975 976 977 978 979
{
  int i, unreloc_count;
  struct relocation_info reloc_info;
  struct scattered_relocation_info *sc_reloc_info
    = (struct scattered_relocation_info *) &reloc_info;
980
  vm_address_t location;
981 982 983 984 985 986 987 988 989 990 991 992 993

  for (unreloc_count = 0, i = 0; i < nrel; i++)
    {
      if (lseek (infd, reloff, L_SET) != reloff)
	unexec_error ("unrelocate: %s:%d cannot seek to reloc_info", name, i);
      if (!unexec_read (&reloc_info, sizeof (reloc_info)))
	unexec_error ("unrelocate: %s:%d cannot read reloc_info", name, i);
      reloff += sizeof (reloc_info);

      if (sc_reloc_info->r_scattered == 0)
	switch (reloc_info.r_type)
	  {
	  case GENERIC_RELOC_VANILLA:
994
	    location = base + reloc_info.r_address;
995 996 997
	    if (location >= data_segment_scp->vmaddr
		&& location < (data_segment_scp->vmaddr
			       + data_segment_scp->vmsize))
998 999
	      {
		off_t src_off = data_segment_old_fileoff
1000
		  + (location - data_segment_scp->vmaddr);
1001
		off_t dst_off = data_segment_scp->fileoff
1002
		  + (location - data_segment_scp->vmaddr);
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032

		if (!unexec_copy (dst_off, src_off, 1 << reloc_info.r_length))
		  unexec_error ("unrelocate: %s:%d cannot copy original value",
				name, i);
		unreloc_count++;
	      }
	    break;
	  default:
	    unexec_error ("unrelocate: %s:%d cannot handle type = %d",
			  name, i, reloc_info.r_type);
	  }
      else
	switch (sc_reloc_info->r_type)
	  {
#if defined (__ppc__)
	  case PPC_RELOC_PB_LA_PTR:
	    /* nothing to do for prebound lazy pointer */
	    break;
#endif
	  default:
	    unexec_error ("unrelocate: %s:%d cannot handle scattered type = %d",
			  name, i, sc_reloc_info->r_type);
	  }
    }

  if (nrel > 0)
    printf ("Fixed up %d/%d %s relocation entries in data segment.\n",
	    unreloc_count, nrel, name);
}

1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
#if __ppc64__
/* Rebase r_address in the relocation table.  */
static void
rebase_reloc_address (off_t reloff, int nrel, long linkedit_delta, long diff)
{
  int i;
  struct relocation_info reloc_info;
  struct scattered_relocation_info *sc_reloc_info
    = (struct scattered_relocation_info *) &reloc_info;

  for (i = 0; i < nrel; i++, reloff += sizeof (reloc_info))
    {
      if (lseek (infd, reloff - linkedit_delta, L_SET)
	  != reloff - linkedit_delta)
	unexec_error ("rebase_reloc_table: cannot seek to reloc_info");
      if (!unexec_read (&reloc_info, sizeof (reloc_info)))
	unexec_error ("rebase_reloc_table: cannot read reloc_info");

      if (sc_reloc_info->r_scattered == 0
	  && reloc_info.r_type == GENERIC_RELOC_VANILLA)
	{
	  reloc_info.r_address -= diff;
	  if (!unexec_write (reloff, &reloc_info, sizeof (reloc_info)))
	    unexec_error ("rebase_reloc_table: cannot write reloc_info");
	}
    }
}
#endif

1062 1063 1064
/* Copy a LC_DYSYMTAB load command from the input file to the output
   file, adjusting the file offset fields.  */
static void
1065
copy_dysymtab (struct load_command *lc, long delta)
1066 1067
{
  struct dysymtab_command *dstp = (struct dysymtab_command *) lc;
1068
  vm_address_t base;
1069

1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099
#ifdef _LP64
#if __ppc64__
  {
    int i;

    base = 0;
    for (i = 0; i < nlc; i++)
      if (lca[i]->cmd == LC_SEGMENT)
	{
	  struct segment_command *scp = (struct segment_command *) lca[i];

	  if (scp->vmaddr + scp->vmsize > 0x100000000
	      && (scp->initprot & VM_PROT_WRITE) != 0)
	    {
	      base = data_segment_scp->vmaddr;
	      break;
	    }
	}
  }
#else
  /* First writable segment address.  */
  base = data_segment_scp->vmaddr;
#endif
#else
  /* First segment address in the file (unless MH_SPLIT_SEGS set). */
  base = 0;
#endif

  unrelocate ("local", dstp->locreloff, dstp->nlocrel, base);
  unrelocate ("external", dstp->extreloff, dstp->nextrel, base);
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117

  if (dstp->nextrel > 0) {
    dstp->extreloff += delta;
  }

  if (dstp->nlocrel > 0) {
    dstp->locreloff += delta;
  }

  if (dstp->nindirectsyms > 0)
    dstp->indirectsymoff += delta;

  printf ("Writing LC_DYSYMTAB command\n");

  if (!unexec_write (curr_header_offset, lc, lc->cmdsize))
    unexec_error ("cannot write symtab command to header");

  curr_header_offset += lc->cmdsize;
1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140

#if __ppc64__
  /* Check if the relocation base needs to be changed.  */
  if (base == 0)
    {
      vm_address_t newbase = 0;
      int i;

      for (i = 0; i < num_unexec_regions; i++)
	if (unexec_regions[i].range.address + unexec_regions[i].range.size
	    > 0x100000000)
	  {
	    newbase = data_segment_scp->vmaddr;
	    break;
	  }

      if (newbase)
	{
	  rebase_reloc_address (dstp->locreloff, dstp->nlocrel, delta, newbase);
	  rebase_reloc_address (dstp->extreloff, dstp->nextrel, delta, newbase);
	}
    }
#endif
1141 1142
}

1143 1144 1145
/* Copy a LC_TWOLEVEL_HINTS load command from the input file to the output
   file, adjusting the file offset fields.  */
static void
1146
copy_twolevelhints (struct load_command *lc, long delta)
1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161
{
  struct twolevel_hints_command *tlhp = (struct twolevel_hints_command *) lc;

  if (tlhp->nhints > 0) {
    tlhp->offset += delta;
  }

  printf ("Writing LC_TWOLEVEL_HINTS command\n");

  if (!unexec_write (curr_header_offset, lc, lc->cmdsize))
    unexec_error ("cannot write two level hint command to header");

  curr_header_offset += lc->cmdsize;
}

1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191
#ifdef LC_DYLD_INFO
/* Copy a LC_DYLD_INFO(_ONLY) load command from the input file to the output
   file, adjusting the file offset fields.  */
static void
copy_dyld_info (struct load_command *lc, long delta)
{
  struct dyld_info_command *dip = (struct dyld_info_command *) lc;

  if (dip->rebase_off > 0)
    dip->rebase_off += delta;
  if (dip->bind_off > 0)
    dip->bind_off += delta;
  if (dip->weak_bind_off > 0)
    dip->weak_bind_off += delta;
  if (dip->lazy_bind_off > 0)
    dip->lazy_bind_off += delta;
  if (dip->export_off > 0)
    dip->export_off += delta;

  printf ("Writing ");
  print_load_command_name (lc->cmd);
  printf (" command\n");

  if (!unexec_write (curr_header_offset, lc, lc->cmdsize))
    unexec_error ("cannot write dyld info command to header");

  curr_header_offset += lc->cmdsize;
}
#endif

1192
#ifdef LC_FUNCTION_STARTS
1193 1194 1195
/* Copy a LC_FUNCTION_STARTS/LC_DATA_IN_CODE/LC_DYLIB_CODE_SIGN_DRS
   load command from the input file to the output file, adjusting the
   data offset field.  */
1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214
static void
copy_linkedit_data (struct load_command *lc, long delta)
{
  struct linkedit_data_command *ldp = (struct linkedit_data_command *) lc;

  if (ldp->dataoff > 0)
    ldp->dataoff += delta;

  printf ("Writing ");
  print_load_command_name (lc->cmd);
  printf (" command\n");

  if (!unexec_write (curr_header_offset, lc, lc->cmdsize))
    unexec_error ("cannot write linkedit data command to header");

  curr_header_offset += lc->cmdsize;
}
#endif

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/* Copy other kinds of load commands from the input file to the output
   file, ones that do not require adjustments of file offsets.  */
static void
copy_other (struct load_command *lc)
{
  printf ("Writing ");
  print_load_command_name (lc->cmd);
  printf (" command\n");

  if (!unexec_write (curr_header_offset, lc, lc->cmdsize))
    unexec_error ("cannot write symtab command to header");

  curr_header_offset += lc->cmdsize;
}

/* Loop through all load commands and dump them.  Then write the Mach
   header.  */
static void
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dump_it (void)
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{
  int i;
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  long linkedit_delta = 0;
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  printf ("--- Load Commands written to Output File ---\n");

  for (i = 0; i < nlc; i++)
    switch (lca[i]->cmd)
      {
      case LC_SEGMENT:
	{
	  struct segment_command *scp = (struct segment_command *) lca[i];
	  if (strncmp (scp->segname, SEG_DATA, 16) == 0)
	    {
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	      /* save data segment file offset and segment_command for
		 unrelocate */
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	      if (data_segment_old_fileoff)
		unexec_error ("cannot handle multiple DATA segments"
			      " in input file");
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	      data_segment_old_fileoff = scp->fileoff;
	      data_segment_scp = scp;

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	      copy_data_segment (lca[i]);
	    }
	  else
	    {
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	      if (strncmp (scp->segname, SEG_LINKEDIT, 16) == 0)
		{
		  if (linkedit_delta)
		    unexec_error ("cannot handle multiple LINKEDIT segments"
				  " in input file");
		  linkedit_delta = curr_file_offset - scp->fileoff;
		}

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	      copy_segment (lca[i]);
	    }
	}
	break;
      case LC_SYMTAB:
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	copy_symtab (lca[i], linkedit_delta);
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	break;
      case LC_DYSYMTAB:
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	copy_dysymtab (lca[i], linkedit_delta);
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	break;
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      case LC_TWOLEVEL_HINTS:
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	copy_twolevelhints (lca[i], linkedit_delta);
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	break;
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#ifdef LC_DYLD_INFO
      case LC_DYLD_INFO:
      case LC_DYLD_INFO_ONLY:
	copy_dyld_info (lca[i], linkedit_delta);
	break;
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#endif
#ifdef LC_FUNCTION_STARTS
      case LC_FUNCTION_STARTS:
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#ifdef LC_DATA_IN_CODE
      case LC_DATA_IN_CODE:
#endif
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#ifdef LC_DYLIB_CODE_SIGN_DRS
      case LC_DYLIB_CODE_SIGN_DRS:
#endif
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	copy_linkedit_data (lca[i], linkedit_delta);
	break;
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#endif
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      default:
	copy_other (lca[i]);
	break;
      }

  if (curr_header_offset > text_seg_lowest_offset)
    unexec_error ("not enough room for load commands for new __DATA segments");

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  printf ("%ld unused bytes follow Mach-O header\n",
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	  text_seg_lowest_offset - curr_header_offset);

  mh.sizeofcmds = curr_header_offset - sizeof (struct mach_header);
  if (!unexec_write (0, &mh, sizeof (struct mach_header)))
    unexec_error ("cannot write final header contents");
}

/* Take a snapshot of Emacs and make a Mach-O format executable file
   from it.  The file names of the output and input files are outfile
   and infile, respectively.  The three other parameters are
   ignored.  */
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void
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unexec (const char *outfile, const char *infile)
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{
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  if (in_dumped_exec)
    unexec_error ("Unexec from a dumped executable is not supported.");

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  pagesize = getpagesize ();
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  infd = open (infile, O_RDONLY, 0);
  if (infd < 0)
    {
      unexec_error ("cannot open input file `%s'", infile);
    }
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  outfd = open (outfile, O_WRONLY | O_TRUNC | O_CREAT, 0755);
  if (outfd < 0)
    {
      close (infd);
      unexec_error ("cannot open output file `%s'", outfile);
    }

  build_region_list ();
  read_load_commands ();

  find_emacs_zone_regions ();
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  unexec_regions_merge ();
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  in_dumped_exec = 1;

  dump_it ();

  close (outfd);
}


void
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unexec_init_emacs_zone (void)
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{
  emacs_zone = malloc_create_zone (0, 0);
  malloc_set_zone_name (emacs_zone, "EmacsZone");
}

YAMAMOTO Mitsuharu's avatar
YAMAMOTO Mitsuharu committed
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#ifndef MACOSX_MALLOC_MULT16
#define MACOSX_MALLOC_MULT16 1
#endif

typedef struct unexec_malloc_header {
  union {
    char c[8];
    size_t size;
  } u;
} unexec_malloc_header_t;

#if MACOSX_MALLOC_MULT16

#define ptr_in_unexec_regions(p) ((((vm_address_t) (p)) & 8) != 0)

#else

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int
ptr_in_unexec_regions (void *ptr)
{
  int i;

  for (i = 0; i < num_unexec_regions; i++)