gdb/build-id.c - gdb

Functions defined

Source code

  1. /* build-id-related functions.

  3.    Copyright (C) 1991-2015 Free Software Foundation, Inc.

  5.    This file is part of GDB.

  7.    This program is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3 of the License, or
  10.    (at your option) any later version.

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

  17.    You should have received a copy of the GNU General Public License
  18.    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

  20. #include "defs.h"
  21. #include "bfd.h"
  22. #include "elf-bfd.h"
  23. #include "gdb_bfd.h"
  24. #include "build-id.h"
  25. #include "gdb_vecs.h"
  26. #include "symfile.h"
  27. #include "objfiles.h"
  28. #include "filenames.h"

  30. /* See build-id.h.  */

  32. const struct elf_build_id *
  33. ‌build_id_bfd_get (bfd *abfd)
  34. {
  35.   if (!bfd_check_format (abfd, bfd_object)
  36.       || bfd_get_flavour (abfd) != bfd_target_elf_flavour
  37.       /* Although this is ELF_specific, it is safe to do in generic
  38.          code because it does not rely on any ELF-specific symbols at
  39.          link time, and if the ELF code is not available in BFD, then
  40.          ABFD will not have the ELF flavour.  */
  41.       || elf_tdata (abfd)->build_id == NULL)
  42.     return NULL;

  44.   return elf_tdata (abfd)->build_id;
  45. }

  47. /* See build-id.h.  */

  49. int
  50. ‌build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
  51. {
  52.   const struct elf_build_id *found;
  53.   int retval = 0;

  55.   found = build_id_bfd_get (abfd);

  57.   if (found == NULL)
  58.     warning (_("File \"%s\" has no build-id, file skipped"),
  59.              bfd_get_filename (abfd));
  60.   else if (found->size != check_len
  61.            || memcmp (found->data, check, found->size) != 0)
  62.     warning (_("File \"%s\" has a different build-id, file skipped"),
  63.              bfd_get_filename (abfd));
  64.   else
  65.     retval = 1;

  67.   return retval;
  68. }

  70. /* See build-id.h.  */

  72. bfd *
  73. ‌build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
  74. {
  75.   char *link, *debugdir;
  76.   VEC (char_ptr) *debugdir_vec;
  77.   struct cleanup *back_to;
  78.   int ix;
  79.   bfd *abfd = NULL;

  81.   /* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */
  82.   link = alloca (strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1
  83.                  + 2 * build_id_len + (sizeof ".debug" - 1) + 1);

  85.   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
  86.      cause "/.build-id/..." lookups.  */

  88.   debugdir_vec = dirnames_to_char_ptr_vec (debug_file_directory);
  89.   back_to = make_cleanup_free_char_ptr_vec (debugdir_vec);

  91.   for (ix = 0; VEC_iterate (char_ptr, debugdir_vec, ix, debugdir); ++ix)
  92.     {
  93.       size_t debugdir_len = strlen (debugdir);
  94.       const gdb_byte *data = build_id;
  95.       size_t size = build_id_len;
  96.       char *s;
  97.       char *filename = NULL;

  99.       memcpy (link, debugdir, debugdir_len);
  100.       s = &link[debugdir_len];
  101.       s += sprintf (s, "/.build-id/");
  102.       if (size > 0)
  103.         {
  104.           size--;
  105.           s += sprintf (s, "%02x", (unsigned) *data++);
  106.         }
  107.       if (size > 0)
  108.         *s++ = '/';
  109.       while (size-- > 0)
  110.         s += sprintf (s, "%02x", (unsigned) *data++);
  111.       strcpy (s, ".debug");

  113.       /* lrealpath() is expensive even for the usually non-existent files.  */
  114.       if (access (link, F_OK) == 0)
  115.         filename = lrealpath (link);

  117.       if (filename == NULL)
  118.         continue;

  120.       /* We expect to be silent on the non-existing files.  */
  121.       abfd = gdb_bfd_open_maybe_remote (filename);
  122.       if (abfd == NULL)
  123.         continue;

  125.       if (build_id_verify (abfd, build_id_len, build_id))
  126.         break;

  128.       gdb_bfd_unref (abfd);
  129.       abfd = NULL;
  130.     }

  132.   do_cleanups (back_to);
  133.   return abfd;
  134. }

  136. /* See build-id.h.  */

  138. char *
  139. ‌find_separate_debug_file_by_buildid (struct objfile *objfile)
  140. {
  141.   const struct elf_build_id *build_id;

  143.   build_id = build_id_bfd_get (objfile->obfd);
  144.   if (build_id != NULL)
  145.     {
  146.       bfd *abfd;

  148.       abfd = build_id_to_debug_bfd (build_id->size, build_id->data);
  149.       /* Prevent looping on a stripped .debug file.  */
  150.       if (abfd != NULL
  151.           && filename_cmp (bfd_get_filename (abfd),
  152.                            objfile_name (objfile)) == 0)
  153.         {
  154.           warning (_("\"%s\": separate debug info file has no debug info"),
  155.                    bfd_get_filename (abfd));
  156.           gdb_bfd_unref (abfd);
  157.         }
  158.       else if (abfd != NULL)
  159.         {
  160.           char *result = xstrdup (bfd_get_filename (abfd));

  162.           gdb_bfd_unref (abfd);
  163.           return result;
  164.         }
  165.     }
  166.   return NULL;
  167. }