gdb/build-id.c

   1 /* build-id-related functions.
   2
   3    Copyright (C) 1991-2018 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   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.
  11
  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.
  16
  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/>.  */
  19
  20 #include "defs.h"
  21 #include "bfd.h"
  22 #include "gdb_bfd.h"
  23 #include "build-id.h"
  24 #include "gdb_vecs.h"
  25 #include "symfile.h"
  26 #include "objfiles.h"
  27 #include "filenames.h"
  28 #include "gdbcore.h"
  29
  30 /* See build-id.h.  */
  31
  32 const struct bfd_build_id *
  33 build_id_bfd_get (bfd *abfd)
  34 {
  35   if (!bfd_check_format (abfd, bfd_object))
  36     return NULL;
  37
  38   if (abfd->build_id != NULL)
  39     return abfd->build_id;
  40
  41   /* No build-id */
  42   return NULL;
  43 }
  44
  45 /* See build-id.h.  */
  46
  47 int
  48 build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
  49 {
  50   const struct bfd_build_id *found;
  51   int retval = 0;
  52
  53   found = build_id_bfd_get (abfd);
  54
  55   if (found == NULL)
  56     warning (_("File \"%s\" has no build-id, file skipped"),
  57              bfd_get_filename (abfd));
  58   else if (found->size != check_len
  59            || memcmp (found->data, check, found->size) != 0)
  60     warning (_("File \"%s\" has a different build-id, file skipped"),
  61              bfd_get_filename (abfd));
  62   else
  63     retval = 1;
  64
  65   return retval;
  66 }
  67
  68 /* See build-id.h.  */
  69
  70 gdb_bfd_ref_ptr
  71 build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
  72 {
  73   char *link, *debugdir;
  74   int ix;
  75   gdb_bfd_ref_ptr abfd;
  76   int alloc_len;
  77
  78   /* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */
  79   alloc_len = (strlen (debug_file_directory)
  80                + (sizeof "/.build-id/" - 1) + 1
  81                + 2 * build_id_len + (sizeof ".debug" - 1) + 1);
  82   link = (char *) alloca (alloc_len);
  83
  84   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
  85      cause "/.build-id/..." lookups.  */
  86
  87   std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec
  88     = dirnames_to_char_ptr_vec (debug_file_directory);
  89
  90   for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec)
  91     {
  92       size_t debugdir_len = strlen (debugdir.get ());
  93       const gdb_byte *data = build_id;
  94       size_t size = build_id_len;
  95       char *s;
  96
  97       memcpy (link, debugdir.get (), debugdir_len);
  98       s = &link[debugdir_len];
  99       s += sprintf (s, "/.build-id/");
 100       if (size > 0)
 101         {
 102           size--;
 103           s += sprintf (s, "%02x", (unsigned) *data++);
 104         }
 105       if (size > 0)
 106         *s++ = '/';
 107       while (size-- > 0)
 108         s += sprintf (s, "%02x", (unsigned) *data++);
 109       strcpy (s, ".debug");
 110
 111       if (separate_debug_file_debug)
 112         printf_unfiltered (_("  Trying %s\n"), link);
 113
 114       /* lrealpath() is expensive even for the usually non-existent files.  */
 115       gdb::unique_xmalloc_ptr<char> filename;
 116       if (access (link, F_OK) == 0)
 117         filename.reset (lrealpath (link));
 118
 119       if (filename == NULL)
 120         continue;
 121
 122       /* We expect to be silent on the non-existing files.  */
 123       abfd = gdb_bfd_open (filename.get (), gnutarget, -1);
 124
 125       if (abfd == NULL)
 126         continue;
 127
 128       if (build_id_verify (abfd.get(), build_id_len, build_id))
 129         break;
 130
 131       abfd.release ();
 132     }
 133
 134   return abfd;
 135 }
 136
 137 /* See build-id.h.  */
 138
 139 std::string
 140 find_separate_debug_file_by_buildid (struct objfile *objfile)
 141 {
 142   const struct bfd_build_id *build_id;
 143
 144   build_id = build_id_bfd_get (objfile->obfd);
 145   if (build_id != NULL)
 146     {
 147       if (separate_debug_file_debug)
 148         printf_unfiltered (_("\nLooking for separate debug info (build-id) for "
 149                              "%s\n"), objfile_name (objfile));
 150
 151       gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
 152                                                    build_id->data));
 153       /* Prevent looping on a stripped .debug file.  */
 154       if (abfd != NULL
 155           && filename_cmp (bfd_get_filename (abfd.get ()),
 156                            objfile_name (objfile)) == 0)
 157         warning (_("\"%s\": separate debug info file has no debug info"),
 158                  bfd_get_filename (abfd.get ()));
 159       else if (abfd != NULL)
 160         return std::string (bfd_get_filename (abfd.get ()));
 161     }
 162
 163   return std::string ();
 164 }