macosx-nat-dyld-process.c   [plain text]

/* Mac OS X support for GDB, the GNU debugger.
   Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2004
   Free Software Foundation, Inc.

   Contributed by Apple Computer, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "cached-symfile.h"
#include "macosx-nat-dyld-info.h"
#include "macosx-nat-dyld-path.h"
#include "macosx-nat-dyld-io.h"
#include "macosx-nat-dyld.h"
#include "macosx-nat-inferior.h"
#include "macosx-nat-mutils.h"
#include "macosx-nat-dyld-process.h"

#include "defs.h"
#include "inferior.h"
#include "symfile.h"
#include "symtab.h"
#include "gdbcmd.h"
#include "objfiles.h"
#include "mach-o.h"
#include "gdbcore.h"
#include "gdb_regex.h"
#include "gdb-stabs.h"
#include "gdb_assert.h"
#include "interps.h"
#include "objc-lang.h"

#include <mach-o/nlist.h>
#include <mach-o/loader.h>
#include <mach-o/dyld_debug.h>

#ifdef USE_MMALLOC
#include "mmprivate.h"
#endif

#define MAPPED_SYMFILES (USE_MMALLOC && HAVE_MMAP)

#include <sys/mman.h>
#include <string.h>

extern int dyld_preload_libraries_flag;
extern int dyld_filter_events_flag;
extern int dyld_always_read_from_memory_flag;
extern char *dyld_symbols_prefix;
extern int dyld_load_dyld_symbols_flag;
extern int dyld_load_dyld_shlib_symbols_flag;
extern int dyld_load_cfm_shlib_symbols_flag;
extern int dyld_print_basenames_flag;
extern int dyld_reload_on_downgrade_flag;
extern char *dyld_load_rules;
extern char *dyld_minimal_load_rules;

#if WITH_CFM
extern int inferior_auto_start_cfm_flag;
#endif /* WITH_CFM */

extern macosx_inferior_status *macosx_status;

static int
dyld_print_status ()
{
  /* do not print status dots when executing MI */
  return !ui_out_is_mi_like_p (uiout);
}

void
dyld_add_inserted_libraries (struct dyld_objfile_info *info,
                             const struct dyld_path_info *d)
{
  const char *s1, *s2;

  CHECK_FATAL (info != NULL);
  CHECK_FATAL (d != NULL);

  s1 = d->insert_libraries;
  if (s1 == NULL)
    {
      return;
    }

  while (*s1 != '\0')
    {

      struct dyld_objfile_entry *e = NULL;

      s2 = strchr (s1, ':');
      if (s2 == NULL)
        {
          s2 = strchr (s1, '\0');
        }
      CHECK_FATAL (s2 != NULL);

      e = dyld_objfile_entry_alloc (info);

      e->user_name = savestring (s1, (s2 - s1));
      e->reason = dyld_reason_init;

      s1 = s2;
      while (*s1 == ':')
        {
          s1++;
        }
    }
}

void
dyld_add_image_libraries (struct dyld_objfile_info *info, bfd *abfd)
{
  struct mach_o_data_struct *mdata = NULL;
  unsigned int i;

  CHECK_FATAL (info != NULL);

  if (abfd == NULL)
    {
      return;
    }

  if (!bfd_mach_o_valid (abfd))
    {
      return;
    }

  mdata = abfd->tdata.mach_o_data;

  if (mdata == NULL)
    {
      dyld_debug ("dyld_add_image_libraries: mdata == NULL\n");
      return;
    }

  for (i = 0; i < mdata->header.ncmds; i++)
    {
      struct bfd_mach_o_load_command *cmd = &mdata->commands[i];
      switch (cmd->type)
        {
        case BFD_MACH_O_LC_LOAD_WEAK_DYLIB:
        case BFD_MACH_O_LC_LOAD_DYLINKER:
        case BFD_MACH_O_LC_LOAD_DYLIB:
          {

            struct dyld_objfile_entry *e = NULL;
            char *name = NULL;

            switch (cmd->type)
              {
              case BFD_MACH_O_LC_LOAD_DYLINKER:
                {
                  bfd_mach_o_dylinker_command *dcmd = &cmd->command.dylinker;

                  name = xmalloc (dcmd->name_len + 1);

                  bfd_seek (abfd, dcmd->name_offset, SEEK_SET);
                  if (bfd_bread (name, dcmd->name_len, abfd) !=
                      dcmd->name_len)
                    {
                      warning
                        ("Unable to find library name for LC_LOAD_DYLINKER command; ignoring");
                      xfree (name);
                      continue;
                    }
                  break;
                }
              case BFD_MACH_O_LC_LOAD_DYLIB:
              case BFD_MACH_O_LC_LOAD_WEAK_DYLIB:
                {
                  bfd_mach_o_dylib_command *dcmd = &cmd->command.dylib;

                  name = xmalloc (dcmd->name_len + 1);

                  bfd_seek (abfd, dcmd->name_offset, SEEK_SET);
                  if (bfd_bread (name, dcmd->name_len, abfd) !=
                      dcmd->name_len)
                    {
                      warning
                        ("Unable to find library name for LC_LOAD_DYLIB or LC_LOAD_WEAK_DYLIB command; ignoring");
                      xfree (name);
                      continue;
                    }
                  break;
                }
              default:
                abort ();
              }

            if (name[0] == '\0')
              {
                warning
                  ("No image name specified by LC_LOAD command; ignoring");
                xfree (name);
                name = NULL;
              }

            e = dyld_objfile_entry_alloc (info);

            /* We have to run realpath on the text name here because
               some makefiles build the library with one name, then
               copy it to another.  For instance, they will build
               libfoo.2.dylib, but install the actual binary as
               libfoo.2.1.dylib, and then link libfoo.2.dylib back
               to this.  That means the load command refers to a
               file that exists (as a link) but isn't the same as
               what gets loaded.  If we canonicalize everything to
               the real file, then we won't get fooled by this.  */

            {
              char buf[PATH_MAX];

              if (realpath (name, buf) != NULL)
                {
                  xfree (name);
                  name = xstrdup (buf);
                }
            }
            e->text_name = name;
            e->text_name_valid = 1;
            e->reason = dyld_reason_init;

            switch (cmd->type)
              {
              case BFD_MACH_O_LC_LOAD_DYLINKER:
                e->prefix = dyld_symbols_prefix;
                break;
              case BFD_MACH_O_LC_LOAD_DYLIB:
                break;
              case BFD_MACH_O_LC_LOAD_WEAK_DYLIB:
                e->reason |= dyld_reason_weak_mask;
                break;
              default:
                abort ();
              };
          }
        default:
          break;
        }
    }
}

void
dyld_resolve_filename_image (const struct macosx_dyld_thread_status *s,
                             struct dyld_objfile_entry *e)
{
  struct mach_header header;
  CHECK_FATAL (e->allocated);
  if (e->image_name_valid)
    {
      return;
    }

  if (!e->dyld_valid)
    {
      return;
    }

  target_read_memory (e->dyld_addr, (char *) &header,
                      sizeof (struct mach_header));

  switch (header.filetype)
    {
    case MH_DYLINKER:
    case MH_DYLIB:
      break;
    case MH_BUNDLE:
      break;
    default:
      return;
    }
  e->image_name = dyld_find_dylib_name (header.ncmds, e->dyld_addr);

  if (e->image_name == NULL)
    {
      dyld_debug ("Unable to determine filename for loaded object "
                  "(no LC_ID load command)\n");
    }
  else
    {
      dyld_debug ("Determined filename for loaded object from image\n");
      e->image_name_valid = 1;
    }
}

/* Assuming a Mach header starts at ADDR, and has NCMDS, look for the
   dylib name, and return a malloc'ed string containing the name */

char *
dyld_find_dylib_name (CORE_ADDR addr, unsigned int ncmds)
{
  CORE_ADDR curpos;
  unsigned int i;
  char *image_name = NULL;

  curpos = ((unsigned long) addr) + sizeof (struct mach_header);
  for (i = 0; i < ncmds; i++)
    {

      struct load_command cmd;
      struct dylib_command dcmd;
      struct dylinker_command dlcmd;
      char name[256];

      target_read_memory (curpos, (char *) &cmd,
                          sizeof (struct load_command));
      if (cmd.cmd == LC_ID_DYLIB)
        {
          target_read_memory (curpos, (char *) &dcmd,
                              sizeof (struct dylib_command));
          target_read_memory (curpos + dcmd.dylib.name.offset, name, 256);
          image_name = savestring (name, strlen (name));
          break;
        }
      else if (cmd.cmd == LC_ID_DYLINKER)
        {
          target_read_memory (curpos, (char *) &dlcmd,
                              sizeof (struct dylinker_command));
          target_read_memory (curpos + dlcmd.name.offset, name, 256);
          image_name = savestring (name, strlen (name));
          break;
        }

      curpos += cmd.cmdsize;
    }
  return image_name;
}

void
dyld_resolve_filenames (const struct macosx_dyld_thread_status *s,
                        struct dyld_objfile_info *new)
{
  unsigned int i;

  CHECK_FATAL (s != NULL);
  CHECK_FATAL (new != NULL);

  for (i = 0; i < new->nents; i++)
    {
      struct dyld_objfile_entry *e = &new->entries[i];
      if (!e->allocated)
        {
          continue;
        }
      if (e->dyld_name_valid)
        {
          continue;
        }
      dyld_resolve_filename_image (s, e);
    }
}

static CORE_ADDR
library_offset (struct dyld_objfile_entry *e)
{
  CHECK_FATAL (e != NULL);
  if (e->image_addr_valid && e->dyld_valid)
    {
      CHECK_FATAL (e->dyld_addr ==
                   ((e->image_addr + e->dyld_slide) & 0xffffffff)); /* FIXME: 64bit ? */
    }

  if (e->dyld_valid)
    {
      return e->dyld_addr;
    }
  else if (e->image_addr_valid)
    {
      return e->image_addr;
    }
  else
    {
      return 0;
    }
}

unsigned int
dyld_parse_load_level (const char *s)
{
  if (strcmp (s, "all") == 0)
    {
      return OBJF_SYM_ALL;
    }
  else if (strcmp (s, "container") == 0)
    {
      return OBJF_SYM_CONTAINER;
    }
  else if (strcmp (s, "extern") == 0)
    {
      return OBJF_SYM_EXTERN;
    }
  else if (strcmp (s, "none") == 0)
    {
      return OBJF_SYM_NONE;
    }
  else
    {
      warning ("unknown setting \"%s\"; using \"none\"\n", s);
      return OBJF_SYM_NONE;
    }
}

int
dyld_resolve_load_flag (const struct dyld_path_info *d,
                        struct dyld_objfile_entry *e, const char *rules)
{
  const char *name = NULL;
  const char *leaf = NULL;

  char **prules = NULL;
  char **trule = NULL;
  int nrules = 0;
  int crule = 0;

  name = dyld_entry_string (e, 1);

  if (name == NULL)
    return OBJF_SYM_NONE;

  leaf = strrchr (name, '/');
  leaf = ((leaf != NULL) ? leaf : name);

  if (rules != NULL)
    {
      prules = buildargv (rules);
      if (prules == NULL)
        {
          warning ("unable to parse load rules");
          return OBJF_SYM_NONE;
        }
    }

  nrules = 0;

  if (prules != NULL)
    {
      for (trule = prules; *trule != NULL; trule++)
        {
          nrules++;
        }
    }

  if ((nrules % 3) != 0)
    {
      warning
        ("unable to parse load-rules (number of rule clauses must be a "
         "multiple of 3)");
      return OBJF_SYM_NONE;
    }
  nrules /= 3;

  for (crule = 0; crule < nrules; crule++)
    {

      char *matchreason = prules[crule * 3];
      char *matchname = prules[(crule * 3) + 1];
      char *setting = prules[(crule * 3) + 2];

      const char *reason = NULL;
      const char *name = NULL;

      regex_t reasonbuf;
      regex_t namebuf;

      int ret;

      switch (e->reason & dyld_reason_type_mask)
        {
        case dyld_reason_user:
          reason = "user";
          break;
        case dyld_reason_init:
          reason = "dyld";
          break;
        case dyld_reason_executable:
          reason = "exec";
          break;
        case dyld_reason_dyld:
          reason = "dyld";
          break;
        case dyld_reason_cfm:
          reason = "cfm";
          break;
        default:
          reason = "INVALID";
          break;
        }

      if (e->objfile)
        {
          if (e->loaded_from_memory)
            {
              name = "memory";
            }
          else
            {
              name = e->loaded_name;
            }
        }
      else
        {
          name = dyld_entry_filename (e, d, DYLD_ENTRY_FILENAME_LOADED);
          if (name == NULL)
            {
              if (!(e->reason & dyld_reason_weak_mask))
                {
                  warning ("Unable to resolve \"%s\"; not loading.", name);
                }
              return OBJF_SYM_NONE;
            }
        }

      ret = regcomp (&reasonbuf, matchreason, REG_NOSUB);
      if (ret != 0)
        {
          warning ("unable to compile regular expression \"%s\"",
                   matchreason);
          continue;
        }

      ret = regcomp (&namebuf, matchname, REG_NOSUB);
      if (ret != 0)
        {
          warning ("unable to compile regular expression \"%s\"",
                   matchreason);
          continue;
        }

      ret = regexec (&reasonbuf, reason, 0, 0, 0);
      if (ret != 0)
        continue;

      ret = regexec (&namebuf, name, 0, 0, 0);
      if (ret != 0)
        continue;

      return dyld_parse_load_level (setting);
    }

  return -1;
}

int
dyld_minimal_load_flag (const struct dyld_path_info *d,
                        struct dyld_objfile_entry *e)
{
  int ret = dyld_resolve_load_flag (d, e, dyld_minimal_load_rules);
  return (ret >= 0) ? ret : OBJF_SYM_NONE;
}

int
dyld_default_load_flag (const struct dyld_path_info *d,
                        struct dyld_objfile_entry *e)
{
  int ret = dyld_resolve_load_flag (d, e, dyld_load_rules);
  if (ret >= 0)
    return ret;

  if (e->reason != dyld_reason_cfm)
    {
      if (dyld_load_dyld_shlib_symbols_flag)
        return OBJF_SYM_ALL;
    }
  else
    {
      if (dyld_load_cfm_shlib_symbols_flag)
        return OBJF_SYM_ALL;
    }

  return OBJF_SYM_NONE;
}

void
dyld_load_library (const struct dyld_path_info *d,
                   struct dyld_objfile_entry *e)
{
  int read_from_memory = 0;
  const char *name = NULL;

  CHECK_FATAL (e->allocated);

  if (e->abfd)
    {
      return;
    }
  if (e->objfile)
    {
      return;
    }
  if (e->loaded_error)
    {
      return;
    }

  if (e->reason & dyld_reason_executable_mask)
    {
      CHECK_FATAL (e->objfile == symfile_objfile);
    }

  if (e->reason == dyld_reason_cfm)
    {
      read_from_memory = 1;
    }

  if (dyld_always_read_from_memory_flag)
    {
      read_from_memory = 1;
    }

  if (!read_from_memory)
    {
      name = dyld_entry_filename (e, d, DYLD_ENTRY_FILENAME_LOADED);
      if (name == NULL)
        {
          char *s = dyld_entry_string (e, 1);
          warning ("No image filename available for %s.", s);
          xfree (s);
          read_from_memory = 1;
        }
    }

  if (!read_from_memory)
    {
      CHECK_FATAL (name != NULL);
      e->abfd = symfile_bfd_open_safe (name, 0);
      if (e->abfd == NULL)
        {
          char *s = dyld_entry_string (e, 1);
          warning ("Unable to read symbols from %s.", s);
          xfree (s);
        }
      else
        {
          e->loaded_name = bfd_get_filename (e->abfd);
          e->loaded_from_memory = 0;
        }
    }

  if (read_from_memory && !e->dyld_valid)
    {
      char *s = dyld_entry_string (e, dyld_print_basenames_flag);
      warning
        ("Unable to read symbols from %s (not yet mapped into memory); skipping",
         s);
      return;
    }

  if (read_from_memory && e->dyld_valid)
    {
      CHECK_FATAL (e->abfd == NULL);
      e->abfd =
        inferior_bfd (name, e->dyld_addr, e->dyld_slide, e->dyld_length);
      e->loaded_memaddr = e->dyld_addr;
      e->loaded_from_memory = 1;
    }

  if (e->abfd == NULL)
    {
      char *s = dyld_entry_string (e, 1);
      e->loaded_error = 1;
      warning ("Unable to read symbols from %s; skipping.", s);
      xfree (s);
      return;
    }

  if (e->reason & dyld_reason_image_mask)
    {
      asection *text_sect =
        bfd_get_section_by_name (e->abfd, "LC_SEGMENT.__TEXT");
      if (text_sect != NULL)
        {
          e->image_addr = bfd_section_vma (e->abfd, text_sect);
          e->image_addr_valid = 1;
        }
    }

  if (e->reason & dyld_reason_executable_mask)
    {
      symfile_objfile = e->objfile;
    }
}

void
dyld_load_libraries (const struct dyld_path_info *d,
                     struct dyld_objfile_info *result)
{
  int i;
  CHECK_FATAL (result != NULL);

  for (i = 0; i < result->nents; i++)
    {
      struct dyld_objfile_entry *e = &result->entries[i];
      if (!e->allocated)
        {
          continue;
        }
      if (e->load_flag < 0)
        {
          e->load_flag =
            dyld_default_load_flag (d, e) | dyld_minimal_load_flag (d, e);
        }
      if (e->load_flag)
        {
          dyld_load_library (d, e);
        }
    }
}

void
dyld_symfile_loaded_hook (struct objfile *o)
{
#if WITH_CFM

  if (strstr (o->name, "CarbonCore") == NULL)
    return;

  struct minimal_symbol *hooksym =
    lookup_minimal_symbol ("gPCFMInfoHooks", NULL, NULL);
  struct minimal_symbol *system =
    lookup_minimal_symbol ("gPCFMSystemUniverse", NULL, NULL);
  struct minimal_symbol *context =
    lookup_minimal_symbol ("gPCFMContextUniverse", NULL, NULL);
  struct cfm_parser *parser = &macosx_status->cfm_status.parser;
  CORE_ADDR offset = 0;

  if ((hooksym == NULL) || (system == NULL) || (context == NULL))
    return;

  offset = SYMBOL_VALUE_ADDRESS (context) - SYMBOL_VALUE_ADDRESS (system);

  if (offset == 88)
    {
      parser->version = 3;
      parser->universe_length = 88;
      parser->universe_container_offset = 48;
      parser->universe_connection_offset = 60;
      parser->universe_closure_offset = 72;
      parser->connection_length = 68;
      parser->connection_next_offset = 0;
      parser->connection_container_offset = 28;
      parser->container_length = 176;
      parser->container_address_offset = 24;
      parser->container_length_offset = 28;
      parser->container_fragment_name_offset = 44;
      parser->container_section_count_offset = 100;
      parser->container_sections_offset = 104;
      parser->section_length = 24;
      parser->section_total_length_offset = 12;
      parser->instance_length = 24;
      parser->instance_address_offset = 12;
      macosx_status->cfm_status.breakpoint_offset = 956;
    }
  else if (offset == 104)
    {
      parser->version = 2;
      parser->universe_length = 104;
      parser->universe_container_offset = 52;
      parser->universe_connection_offset = 68;
      parser->universe_closure_offset = 84;
      parser->connection_length = 72;
      parser->connection_next_offset = 0;
      parser->connection_container_offset = 32;
      parser->container_length = 176;
      parser->container_address_offset = 28;
      parser->container_length_offset = 36;
      parser->container_fragment_name_offset = 44;
      parser->container_section_count_offset = 100;
      parser->container_sections_offset = 104;
      parser->section_length = 24;
      parser->section_total_length_offset = 12;
      parser->instance_length = 24;
      parser->instance_address_offset = 12;
      macosx_status->cfm_status.breakpoint_offset = 864;
    }
  else if (offset == 120)
    {
      parser->version = 1;
      parser->universe_length = 120;
      parser->universe_container_offset = 68;
      parser->universe_connection_offset = 84;
      parser->universe_closure_offset = 100;
      parser->connection_length = 84;
      parser->connection_next_offset = 0;
      parser->connection_container_offset = 36;
      parser->container_length = 172;
      parser->container_address_offset = 28;
      parser->container_length_offset = 32;
      parser->container_fragment_name_offset = 40;
      parser->container_section_count_offset = 96;
      parser->container_sections_offset = 100;
      parser->section_length = 24;
      parser->section_total_length_offset = 12;
      parser->instance_length = 24;
      parser->instance_address_offset = 12;
      macosx_status->cfm_status.breakpoint_offset = 864;
    }
  else
    {
      warning ("unable to determine CFM version; disabling CFM support");
      parser->version = 0;
      return;
    }

  macosx_status->cfm_status.info_api_cookie = SYMBOL_VALUE_ADDRESS (hooksym);
  dyld_debug ("Found gPCFMInfoHooks in CarbonCore: 0x%s with version %d\n",
              paddr_nz (SYMBOL_VALUE_ADDRESS (hooksym)), parser->version);

  if (inferior_auto_start_cfm_flag)
    macosx_cfm_thread_create (&macosx_status->cfm_status,
                              macosx_status->task);

#endif /* WITH_CFM */
}

void
dyld_load_symfile (struct dyld_objfile_entry *e)
{
  struct section_addr_info *addrs;
  unsigned int i;

  if (e->loaded_error)
    {
      return;
    }

  CHECK_FATAL (e->allocated);

  if (e->reason & dyld_reason_executable_mask)
    {
      CHECK_FATAL (e->objfile == symfile_objfile);
    }

  if (e->dyld_valid)
    {
      e->loaded_addr = e->dyld_addr;
      e->loaded_addrisoffset = 0;
    }
  else if (e->image_addr_valid)
    {
      e->loaded_addr = e->image_addr;
      e->loaded_addrisoffset = 0;
    }
  else
    {
      e->loaded_addr = e->dyld_slide;
      e->loaded_addrisoffset = 1;
    }

  if (e->objfile != NULL)
    {
      struct section_offsets *new_offsets =
        (struct section_offsets *)
        xmalloc (SIZEOF_N_SECTION_OFFSETS (e->objfile->num_sections));
      tell_breakpoints_objfile_changed (e->objfile);
      tell_objc_msgsend_cacher_objfile_changed (e->objfile);
      for (i = 0; i < e->objfile->num_sections; i++)
        {
          new_offsets->offsets[i] = e->dyld_slide;
        }
      if (info_verbose)
        printf_filtered ("Relocating symbols from %s...", e->objfile->name);
      gdb_flush (gdb_stdout);
#if MAPPED_SYMFILES
      mmalloc_protect (e->objfile->md, PROT_READ | PROT_WRITE);
#endif
      objfile_relocate (e->objfile, new_offsets);
#if MAPPED_SYMFILES
      mmalloc_protect (e->objfile->md, PROT_READ);
#endif
      xfree (new_offsets);
      if (info_verbose)
        printf_filtered ("done\n");

    }
  else
    {

      CHECK_FATAL (e->abfd != NULL);

      addrs = alloc_section_addr_info (bfd_count_sections (e->abfd));

      for (i = 0; i < addrs->num_sections; i++)
        {
          addrs->other[i].name = NULL;
          addrs->other[i].addr = e->dyld_slide;
          addrs->other[i].sectindex = 0;
        }

      addrs->addrs_are_offsets = 1;

      e->objfile =
        symbol_file_add_bfd_safe (e->abfd, 0, addrs, 0, 0, e->load_flag, 0,
                                  e->prefix);
      e->abfd = NULL;

      if (e->objfile == NULL)
        {
          e->loaded_error = 1;
          return;
        }

      e->loaded_name = e->objfile->name;
      /* CHECK_FATAL (e->objfile->obfd == e->abfd); */


      /* If we are loading the library for the first time, check to see
         if it has a __DATA.__commpage section, and if so, process the
         contents of that section as if it were a separate objfile.
         This objfile will not get relocated along with the parent
         library, which is appropriate since the commpage never moves in
         memory. */

      const char *segname = "LC_SEGMENT.__DATA.__commpage";
      asection *commsec;

      commsec = bfd_get_section_by_name (e->objfile->obfd, segname);
      if (commsec != NULL)
        {
          char *buf;
          bfd_size_type len;
          char *bfdname;

          len = bfd_section_size (e->objfile->obfd, commsec);
          buf = xmalloc (len * sizeof (char));
          bfdname = xmalloc (strlen (e->objfile->obfd->filename) + 128);

          sprintf (bfdname, "%s[%s]", e->objfile->obfd->filename, segname);

          if (bfd_get_section_contents
              (e->objfile->obfd, commsec, buf, 0, len) != TRUE)
            warning ("unable to read commpage data");

          e->commpage_bfd = bfd_memopenr (bfdname, NULL, buf, len);

          if (!bfd_check_format (e->commpage_bfd, bfd_object))
            {
              bfd_close (e->commpage_bfd);
              e->commpage_bfd = NULL;
            }

          if (e->commpage_bfd != NULL)
            e->commpage_objfile =
              symbol_file_add_bfd_safe (e->commpage_bfd, 0, 0, 0, 0,
                                        e->load_flag, 0, e->prefix);

          e->commpage_bfd = NULL;
        }
    }

  dyld_symfile_loaded_hook (e->objfile);

  if (e->reason & dyld_reason_executable_mask)
    {
      CHECK_FATAL ((symfile_objfile == NULL)
                   || (symfile_objfile == e->objfile));
      symfile_objfile = e->objfile;
      return;
    }
}

void
dyld_load_symfiles (struct dyld_objfile_info *result)
{
  int i;
  int first = 1;
  CHECK_FATAL (result != NULL);

  for (i = 0; i < result->nents; i++)
    {

      struct dyld_objfile_entry *e = &result->entries[i];
      char load_char;

      if (!e->allocated)
        {
          continue;
        }
      if (e->loaded_error)
        {
          continue;
        }
      if (e->abfd == NULL && e->objfile == NULL)
        {
          continue;
        }
      if (e->objfile != NULL)
        {
          if (e->dyld_valid && e->loaded_addr == e->dyld_addr
              && !e->loaded_addrisoffset)
            continue;
          if (e->dyld_valid && e->loaded_addr == e->dyld_slide
              && e->loaded_addrisoffset)
            continue;
          if (e->image_addr_valid && e->loaded_addr == e->image_addr
              && !e->loaded_addrisoffset)
            continue;
          if (!e->dyld_valid && !e->image_addr_valid)
            continue;
        }

      load_char = (e->objfile != NULL) ? '+' : '.';
      if (first && !info_verbose && dyld_print_status ())
        {
          first = 0;
          printf_filtered ("Reading symbols for shared libraries ");
          gdb_flush (gdb_stdout);
        }
      dyld_load_symfile (e);
      if (!info_verbose && dyld_print_status ())
        {
          printf_filtered ("%c", load_char);
          gdb_flush (gdb_stdout);
        }
    }

  if (!first && !info_verbose && dyld_print_status ())
    {
      printf_filtered (" done\n");
      gdb_flush (gdb_stdout);
    }
}

/* Look up the objfile for a given shared library entry.  If no
   objfile is currently allocated, or if the objfile has been removed
   by a lower level of GDB, return NULL. */

struct objfile *
dyld_lookup_objfile_safe (struct dyld_objfile_entry *e)
{
  struct objfile *o, *temp;

  ALL_OBJFILES_SAFE (o, temp)
    if (e->objfile == o)
      return o;

  return NULL;
}

int
dyld_objfile_allocated (struct objfile *o)
{
  struct objfile *objfile, *temp;

  ALL_OBJFILES_SAFE (objfile, temp)
  {
    if (o == objfile)
      {
        return 1;
      }
  }
  return 0;
}

void
dyld_purge_objfiles (struct dyld_objfile_info *info)
{
  struct dyld_objfile_entry *e;
  unsigned int i;

  DYLD_ALL_OBJFILE_INFO_ENTRIES (info, e, i)
    if (e->objfile != NULL)
      if (dyld_lookup_objfile_safe (e) == NULL)
        dyld_remove_objfile (e);
}

/* Return the dyld_objfile_entry for a given objfile.  If no
   dyld_objfile_entry claims the specified objfile, return NULL. */

struct dyld_objfile_entry *
dyld_lookup_objfile_entry (struct dyld_objfile_info *info, struct objfile *o)
{
  unsigned int i;
  struct dyld_objfile_entry *e;

  DYLD_ALL_OBJFILE_INFO_ENTRIES (info, e, i)
    if (e->objfile == o)
      return e;

  return NULL;
}

/* dyld_should_reload_objfile_for_flags: Checks whether the
   load level of the objfile in the dyld_objfile_entry E needs
   to be reloaded.  We always say a upgrade should be done.  But
   if it is a cached symfile, or dyld_reload_on_downgrade_flag
   is true, then reject downgrades.  */

enum dyld_reload_result
dyld_should_reload_objfile_for_flags (struct dyld_objfile_entry *e)
{

  /* For cached symbol files, don't reload if the cached file
     contains *more* symbols than the request being made. */
  if (e->objfile->flags & OBJF_MAPPED)
    {
      if (e->load_flag & ~e->objfile->symflags)
        return DYLD_UPGRADE;
      else
        return DYLD_NO_CHANGE;
    }
  else
    {
      /* For regular symbol files, reload if there is any difference
         in the requested symbols at all if dyld_reload_on_downgrade_flag
         is set.  Otherwise, only reload on upgrade. */
      if (e->load_flag == e->objfile->symflags)
        return DYLD_NO_CHANGE;
      else if (e->load_flag & ~e->objfile->symflags)
        return DYLD_UPGRADE;
      else
        {
          if (dyld_reload_on_downgrade_flag)
            return DYLD_DOWNGRADE;
          else
            return DYLD_NO_CHANGE;
        }
    }
}

/* Called when an objfile is to be freed.
   If a corresponding dyld_objfile_entry exists, we must free that
   as well so the dyld-level structures and the high-level objfile
   structures stay in sync.

   It would be nice if we got a notification from dyld about a dylib/bundle
   being unloaded and handled that correctly.  But as of today, we're not,
   so Fix and Continue is reduced to doing it by hand.  */

void
remove_objfile_from_dyld_records (struct objfile *obj)
{
  struct dyld_objfile_info *info = &macosx_status->dyld_status.current_info;
  struct dyld_objfile_entry *e;
  int i;

  DYLD_ALL_OBJFILE_INFO_ENTRIES (info, e, i)
    if (e->objfile == obj)
      dyld_remove_objfile (e);
}

/* Returns 1 if the objfile OBJ is actually in memory right now.
   A better name might be "dyld_is_objfile_resident".

   If we the OBJ objfile record exists because of a program's load command,
   or it was loaded when the program was running but the inferior has exited
   (has been target_mourn_inferior'ed), we return 0.  */

int
dyld_is_objfile_loaded (struct objfile *obj)
{
  struct dyld_objfile_entry *e;
  int i;
  struct macosx_dyld_thread_status *status = &macosx_status->dyld_status;

  if (obj == NULL)
    return 0;

  /* A SYMS_ONLY_OBJFILE is an objfile added by the user, either with
     add-symbol-file or "sharedlibrary specify-symbol-file"; it shadows
     an actually loaded & resident objfile, but breakpoints will be
     associated with the syms-only-objfile.  So under the theory that
     users don't add-symbol-file things which haven't been loaded yet,
     set breakpoints in this unconditionally.  */
  if (obj->syms_only_objfile == 1)
    return 1;

  DYLD_ALL_OBJFILE_INFO_ENTRIES (&status->current_info, e, i)
    if (e->objfile == obj || e->commpage_objfile == obj)
      if (e->dyld_name != NULL
          || (e->dyld_addr != 0 && e->dyld_addr != INVALID_ADDRESS))
        return 1;

  return 0;
}

void
dyld_remove_objfile (struct dyld_objfile_entry *e)
{
  char *s = NULL;

  CHECK_FATAL (e->allocated);

  if (e->reason & dyld_reason_executable_mask)
    CHECK_FATAL (e->objfile == symfile_objfile);

  if (e->objfile == NULL)
    {
      return;
    }

  CHECK_FATAL (dyld_objfile_allocated (e->objfile));

  s = dyld_entry_string (e, dyld_print_basenames_flag);
  if (info_verbose)
    {
      printf_filtered ("Removing symbols for %s\n", s);
    }
  xfree (s);
  gdb_flush (gdb_stdout);

  free_objfile (e->objfile);
  e->objfile = NULL;

  if (e->abfd != NULL)
    bfd_close (e->abfd);
  e->abfd = NULL;

  if (e->commpage_objfile != NULL)
    {
      /* The commpage objfile is read when symbols for the main library
         are ready for the first time; it needs to be freed along with
         the main objfile. */

      free_objfile (e->commpage_objfile);
      e->commpage_objfile = NULL;

      if (e->commpage_bfd != NULL)
        bfd_close (e->commpage_bfd);
      e->commpage_bfd = NULL;
    }

  e->loaded_name = NULL;
  e->loaded_memaddr = 0;
  gdb_flush (gdb_stdout);

  if (e->reason & dyld_reason_executable_mask)
    {
      symfile_objfile = e->objfile;
    }
}

void
dyld_remove_objfiles (const struct dyld_path_info *d,
                      struct dyld_objfile_info *result)
{
  unsigned int i;
  unsigned int first = 1;
  struct dyld_objfile_entry *e;
  CHECK_FATAL (result != NULL);

  DYLD_ALL_OBJFILE_INFO_ENTRIES (result, e, i)
    {
      int should_reload = 0;

      if (!e->allocated)
        {
          continue;
        }
      if (e->load_flag < 0)
        {
          e->load_flag =
            dyld_default_load_flag (d, e) | dyld_minimal_load_flag (d, e);
        }

      if (e->reason & dyld_reason_executable_mask)
        CHECK_FATAL (e->objfile == symfile_objfile);

      if (e->objfile != NULL)
        {
          if (e->user_name != NULL
              && strcmp (e->user_name, e->objfile->name) != 0)
            should_reload = 1;

          if (dyld_should_reload_objfile_for_flags (e))
            should_reload = 1;
        }

      if (should_reload)
        {
          dyld_remove_objfile (e);
          if (first && !info_verbose && dyld_print_status ())
            {
              first = 0;
              printf_filtered ("Removing symbols for unused shared libraries ");
              gdb_flush (gdb_stdout);
            }
          if (!info_verbose && dyld_print_status ())
            {
              printf_filtered (".");
              gdb_flush (gdb_stdout);
            }
        }
    }
  if (!first && !info_verbose && dyld_print_status ())
    {
      printf_filtered (" done\n");
      gdb_flush (gdb_stdout);
    }
}

static int
dyld_libraries_similar (struct dyld_objfile_entry *f,
                        struct dyld_objfile_entry *l)
{
  const char *fname = NULL;
  const char *lname = NULL;

  const char *fbase = NULL;
  const char *lbase = NULL;
  unsigned int flen = 0;
  unsigned int llen = 0;

  CHECK_FATAL (f != NULL);
  CHECK_FATAL (l != NULL);

  if (library_offset (f) != 0 && library_offset (l) != 0)
    {
      return (library_offset (f) == library_offset (l));
    }

  fname = dyld_entry_filename (f, NULL, DYLD_ENTRY_FILENAME_LOADED);
  lname = dyld_entry_filename (l, NULL, DYLD_ENTRY_FILENAME_LOADED);

  if (lname != NULL && fname != NULL)
    {

      int f_is_framework, f_is_bundle;
      int l_is_framework, l_is_bundle;

      dyld_library_basename (fname, &fbase, &flen, &f_is_framework,
                             &f_is_bundle);
      dyld_library_basename (lname, &lbase, &llen, &l_is_framework,
                             &l_is_bundle);

      if (flen != llen || strncmp (fbase, lbase, llen) != 0)
        {
          xfree ((char *) fbase);
          xfree ((char *) lbase);
          return 0;
        }

      xfree ((char *) fbase);
      xfree ((char *) lbase);

      if (f_is_framework != l_is_framework)
        return 0;

      if (f_is_bundle != l_is_bundle)
        return 0;

      return 1;
    }

  return 0;
}

/* Do dyld_objfile_entry's F and L have the same filename?
   Or in other words, are they the same dylib/bundle/executable/etc ?  */

int
dyld_libraries_compatible (struct dyld_path_info *d,
                           struct dyld_objfile_entry *f,
                           struct dyld_objfile_entry *l)
{
  const char *fname = NULL;
  const char *lname = NULL;

  CHECK_FATAL (f != NULL);
  CHECK_FATAL (l != NULL);

  /* If either prefix is non-NULL, then they must both be the same string. */

  if (f->prefix != NULL || l->prefix != NULL)
    {
      if (f->prefix == NULL || l->prefix == NULL)
        return 0;
      if (strcmp (f->prefix, l->prefix) != 0)
        return 0;
    }

  fname = dyld_entry_filename (f, d, DYLD_ENTRY_FILENAME_LOADED);
  lname = dyld_entry_filename (l, d, DYLD_ENTRY_FILENAME_LOADED);

  /* If either filename is non-NULL, then they must both be the same string. */

  if (fname != NULL || lname != NULL)
    {
      if (fname == NULL || lname == NULL)
        return 0;
      if (strcmp (fname, lname) != 0)
        return 0;
    }

  if (dyld_always_read_from_memory_flag)
    {
      if (f->loaded_from_memory != l->loaded_from_memory)
        {
          return 0;
        }
    }

  return 1;
}

/* Move the load data (whatever distinction that is -- not all the
   fields are moved) from the SRC dyld_objfile_entry into DEST.
   Upon completion, SRC won't have any of its load data fields set.  */

void
dyld_objfile_move_load_data (struct dyld_objfile_entry *src,
                             struct dyld_objfile_entry *dest)
{
  gdb_assert (dest->abfd == NULL);
  gdb_assert (dest->commpage_bfd == NULL);

  gdb_assert (src->objfile == dest->objfile || dest->objfile == NULL);
  gdb_assert (dest->commpage_objfile == NULL);

  dest->abfd = src->abfd;
  dest->objfile = src->objfile;

  dest->commpage_bfd = src->commpage_bfd;
  dest->commpage_objfile = src->commpage_objfile;

  /* FIXME: This used to test dest->load_flag < 0, but you are moving
     the data from src -> dest, so it seems odd to see if dest->load_flag
     was set...  */
  if (src->load_flag >= 0)
    {
      dest->load_flag = src->load_flag;
    }

  dest->prefix = src->prefix;
  dest->loaded_name = src->loaded_name;
  dest->loaded_memaddr = src->loaded_memaddr;
  dest->loaded_addr = src->loaded_addr;
  dest->loaded_offset = src->loaded_offset;
  dest->loaded_addrisoffset = src->loaded_addrisoffset;
  dest->loaded_from_memory = src->loaded_from_memory;
  dest->loaded_error = src->loaded_error;

  src->objfile = NULL;
  src->abfd = NULL;

  src->commpage_bfd = NULL;
  src->commpage_objfile = NULL;

  src->load_flag = -1;

  src->loaded_name = NULL;
  src->loaded_memaddr = 0;
  src->loaded_addr = 0;
  src->loaded_offset = 0;
  src->loaded_addrisoffset = 0;
  src->loaded_from_memory = 0;
  src->loaded_error = 0;
}

void
dyld_check_discarded (struct dyld_objfile_info *info)
{
  unsigned int j;
  for (j = 0; j < info->nents; j++)
    {
      struct dyld_objfile_entry *e = &info->entries[j];
      if (e->abfd == NULL && e->objfile == NULL && !e->loaded_error)
        {
          dyld_objfile_entry_clear (e);
        }
    }
}

/* We're adding NEWENT to the list of dylib/bundle/etcs loaded in the
   inferior in a little while.  Look through the existing entries
   in OLDINFOS and see if we had one for this dylib/bundle/etc
   already.  If so, copy over the load data into NEWENT and clear
   them from the old entry in OLDINFOS.  (I think the old entry is
   marked as obsolete over in the purge_shlib function or something.)  */

void
dyld_merge_shlib (const struct macosx_dyld_thread_status *s,
                  struct dyld_path_info *d,
                  struct dyld_objfile_info *oldinfos,
                  struct dyld_objfile_entry *newent)
{
  int i;
  struct dyld_objfile_entry *oldent;

  DYLD_ALL_OBJFILE_INFO_ENTRIES (oldinfos, oldent, i)
    if (dyld_libraries_compatible (d, newent, oldent))
    {
      dyld_objfile_move_load_data (oldent, newent);
      if (newent->reason & dyld_reason_executable_mask)
        symfile_objfile = newent->objfile;
      return;
    }

  DYLD_ALL_OBJFILE_INFO_ENTRIES (oldinfos, oldent, i)
    if ((newent->reason & dyld_reason_image_mask)
        && dyld_libraries_similar (newent, oldent) && oldent->objfile != NULL)
    {
      dyld_objfile_move_load_data (oldent, newent);
      if (newent->reason & dyld_reason_executable_mask)
        symfile_objfile = newent->objfile;
      return;
    }
}

/* Go through all the dyld_objfile_entry's in OBJINFO, looking for
   other entries that are for the same file image as NEW.

   When gdb starts with an app before launching, it creates
   dyld_objfile_entry's for all the dylibs it finds in the app's
   load commands.  Then when the app executes, we get notifications
   from dyld when the dylibs/bundles/etc actually load.  So at that
   point we want to toss the pre-execution speculative dyld_objfile_entry
   and standardize on the actually-seen image file.

   That's one instance where we'll be using this function.  */

void
dyld_prune_shlib (struct dyld_objfile_info *obj_info,
                  struct dyld_objfile_entry *new)
{
  struct dyld_objfile_entry *o;
  unsigned int i;

  DYLD_ALL_OBJFILE_INFO_ENTRIES (obj_info, o, i)
  {
    if ((o->reason & dyld_reason_executable_mask)
        && (new->reason & dyld_reason_executable_mask))
      {
        if (o->objfile != NULL && o->objfile != new->objfile)
          {
            tell_breakpoints_objfile_changed (o->objfile);
            tell_objc_msgsend_cacher_objfile_changed (o->objfile);
          }
        dyld_objfile_entry_clear (o);
        continue;
      }

    if (dyld_libraries_similar (o, new))
      {
        if (o->objfile != NULL)
          {
            tell_breakpoints_objfile_changed (o->objfile);
            tell_objc_msgsend_cacher_objfile_changed (o->objfile);
          }
        dyld_remove_objfile (o);
        dyld_objfile_entry_clear (o);
      }
  }
}

void
dyld_merge_shlibs (const struct macosx_dyld_thread_status *s,
                   struct dyld_path_info *d,
                   struct dyld_objfile_info *old,
                   struct dyld_objfile_info *new)
{
  struct dyld_objfile_entry *n = NULL;
  struct dyld_objfile_entry *o = NULL;
  unsigned int i;

  CHECK_FATAL (old != NULL);
  CHECK_FATAL (new != NULL);
  CHECK_FATAL (old != new);

  dyld_resolve_filenames (s, new);

  DYLD_ALL_OBJFILE_INFO_ENTRIES (new, n, i)
    if (n->objfile == NULL)
      dyld_merge_shlib (s, d, old, n);

  DYLD_ALL_OBJFILE_INFO_ENTRIES (new, n, i)
    dyld_prune_shlib (old, n);

  DYLD_ALL_OBJFILE_INFO_ENTRIES (old, o, i)
  {
    struct dyld_objfile_entry *e = NULL;
    e = dyld_objfile_entry_alloc (new);
    *e = *o;

    e->reason |= dyld_reason_cached_mask;

    dyld_objfile_entry_clear (o);
  }
}

static void
dyld_shlibs_updated (struct dyld_objfile_info *info)
{
  dyld_objfile_info_pack (info);
  update_section_tables_dyld (info);
  update_current_target ();
  reread_symbols ();
  breakpoint_update ();
  re_enable_breakpoints_in_shlibs (0);
}

void
dyld_update_shlibs (struct dyld_path_info *d, struct dyld_objfile_info *result)
{
  CHECK_FATAL (result != NULL);

  dyld_debug ("dyld_update_shlibs: updating shared library information\n");

  dyld_remove_objfiles (d, result);
  dyld_load_libraries (d, result);
  dyld_load_symfiles (result);

  dyld_shlibs_updated (result);
}

void
dyld_purge_cached_libraries (struct dyld_objfile_info *info)
{
  unsigned int i;
  CHECK_FATAL (info != NULL);

  for (i = 0; i < info->nents; i++)
    {
      struct dyld_objfile_entry *e = &info->entries[i];
      if (!e->allocated)
        {
          continue;
        }
      if (e->reason & dyld_reason_cached_mask)
        {
          dyld_remove_objfile (e);
          dyld_objfile_entry_clear (e);
        }
    }

  dyld_shlibs_updated (info);
}

void
_initialize_macosx_nat_dyld_process ()
{
}