gdb/build-id.c

   1 /* build-id-related functions.
   2
   3    Copyright (C) 1991-2017 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   VEC (char_ptr) *debugdir_vec;
  75   struct cleanup *back_to;
  76   int ix;
  77   gdb_bfd_ref_ptr abfd;
  78   int alloc_len;
  79
  80   /* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */
  81   alloc_len = (strlen (debug_file_directory)
  82                + (sizeof "/.build-id/" - 1) + 1
  83                + 2 * build_id_len + (sizeof ".debug" - 1) + 1);
  84   link = (char *) alloca (alloc_len);
  85
  86   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
  87      cause "/.build-id/..." lookups.  */
  88
  89   debugdir_vec = dirnames_to_char_ptr_vec (debug_file_directory);
  90   back_to = make_cleanup_free_char_ptr_vec (debugdir_vec);
  91
  92   for (ix = 0; VEC_iterate (char_ptr, debugdir_vec, ix, debugdir); ++ix)
  93     {
  94       size_t debugdir_len = strlen (debugdir);
  95       const gdb_byte *data = build_id;
  96       size_t size = build_id_len;
  97       char *s;
  98       char *filename = NULL;
  99       struct cleanup *inner;
 100
 101       memcpy (link, debugdir, debugdir_len);
 102       s = &link[debugdir_len];
 103       s += sprintf (s, "/.build-id/");
 104       if (size > 0)
 105         {
 106           size--;
 107           s += sprintf (s, "%02x", (unsigned) *data++);
 108         }
 109       if (size > 0)
 110         *s++ = '/';
 111       while (size-- > 0)
 112         s += sprintf (s, "%02x", (unsigned) *data++);
 113       strcpy (s, ".debug");
 114
 115       if (separate_debug_file_debug)
 116         printf_unfiltered (_("  Trying %s\n"), link);
 117
 118       /* lrealpath() is expensive even for the usually non-existent files.  */
 119       if (access (link, F_OK) == 0)
 120         filename = lrealpath (link);
 121
 122       if (filename == NULL)
 123         continue;
 124
 125       /* We expect to be silent on the non-existing files.  */
 126       inner = make_cleanup (xfree, filename);
 127       abfd = gdb_bfd_open (filename, gnutarget, -1);
 128       do_cleanups (inner);
 129
 130       if (abfd == NULL)
 131         continue;
 132
 133       if (build_id_verify (abfd.get(), build_id_len, build_id))
 134         break;
 135
 136       abfd.release ();
 137     }
 138
 139   do_cleanups (back_to);
 140   return abfd;
 141 }
 142
 143 /* See build-id.h.  */
 144
 145 char *
 146 find_separate_debug_file_by_buildid (struct objfile *objfile)
 147 {
 148   const struct bfd_build_id *build_id;
 149
 150   build_id = build_id_bfd_get (objfile->obfd);
 151   if (build_id != NULL)
 152     {
 153       if (separate_debug_file_debug)
 154         printf_unfiltered (_("\nLooking for separate debug info (build-id) for "
 155                              "%s\n"), objfile_name (objfile));
 156
 157       gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
 158                                                    build_id->data));
 159       /* Prevent looping on a stripped .debug file.  */
 160       if (abfd != NULL
 161           && filename_cmp (bfd_get_filename (abfd.get ()),
 162                            objfile_name (objfile)) == 0)
 163         warning (_("\"%s\": separate debug info file has no debug info"),
 164                  bfd_get_filename (abfd.get ()));
 165       else if (abfd != NULL)
 166         return xstrdup (bfd_get_filename (abfd.get ()));
 167     }
 168   return NULL;
 169 }