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   gdb_bfd_ref_ptr abfd;
  74
  75   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
  76      cause "/.build-id/..." lookups.  */
  77
  78   std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec
  79     = dirnames_to_char_ptr_vec (debug_file_directory);
  80
  81   for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec)
  82     {
  83       const gdb_byte *data = build_id;
  84       size_t size = build_id_len;
  85
  86       std::string link = debugdir.get ();
  87       link += "/.build-id/";
  88
  89       if (size > 0)
  90         {
  91           size--;
  92           string_appendf (link, "%02x/", (unsigned) *data++);
  93         }
  94
  95       while (size-- > 0)
  96         string_appendf (link, "%02x", (unsigned) *data++);
  97
  98       link += ".debug";
  99
 100       if (separate_debug_file_debug)
 101         {
 102           printf_unfiltered (_("  Trying %s..."), link.c_str ());
 103           gdb_flush (gdb_stdout);
 104         }
 105
 106       /* lrealpath() is expensive even for the usually non-existent files.  */
 107       gdb::unique_xmalloc_ptr<char> filename;
 108       if (access (link.c_str (), F_OK) == 0)
 109         filename.reset (lrealpath (link.c_str ()));
 110
 111       if (filename == NULL)
 112         {
 113           if (separate_debug_file_debug)
 114             printf_unfiltered (_(" no, unable to compute real path\n"));
 115
 116           continue;
 117         }
 118
 119       /* We expect to be silent on the non-existing files.  */
 120       abfd = gdb_bfd_open (filename.get (), gnutarget, -1);
 121
 122       if (abfd == NULL)
 123         {
 124           if (separate_debug_file_debug)
 125             printf_unfiltered (_(" no, unable to open.\n"));
 126
 127           continue;
 128         }
 129
 130       if (build_id_verify (abfd.get(), build_id_len, build_id))
 131         {
 132           if (separate_debug_file_debug)
 133             printf_unfiltered (_(" yes!\n"));
 134
 135           break;
 136         }
 137       else
 138         {
 139           if (separate_debug_file_debug)
 140             printf_unfiltered (_(" no, build-id does not match.\n"));
 141         }
 142
 143       abfd.release ();
 144     }
 145
 146   return abfd;
 147 }
 148
 149 /* See build-id.h.  */
 150
 151 std::string
 152 find_separate_debug_file_by_buildid (struct objfile *objfile)
 153 {
 154   const struct bfd_build_id *build_id;
 155
 156   build_id = build_id_bfd_get (objfile->obfd);
 157   if (build_id != NULL)
 158     {
 159       if (separate_debug_file_debug)
 160         printf_unfiltered (_("\nLooking for separate debug info (build-id) for "
 161                              "%s\n"), objfile_name (objfile));
 162
 163       gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
 164                                                    build_id->data));
 165       /* Prevent looping on a stripped .debug file.  */
 166       if (abfd != NULL
 167           && filename_cmp (bfd_get_filename (abfd.get ()),
 168                            objfile_name (objfile)) == 0)
 169         warning (_("\"%s\": separate debug info file has no debug info"),
 170                  bfd_get_filename (abfd.get ()));
 171       else if (abfd != NULL)
 172         return std::string (bfd_get_filename (abfd.get ()));
 173     }
 174
 175   return std::string ();
 176 }