gdb/build-id.c

   1 /* build-id-related functions.
   2
   3    Copyright (C) 1991-2024 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 "bfd.h"
  21 #include "gdb_bfd.h"
  22 #include "build-id.h"
  23 #include "gdbsupport/gdb_vecs.h"
  24 #include "symfile.h"
  25 #include "objfiles.h"
  26 #include "filenames.h"
  27 #include "gdbcore.h"
  28 #include "cli/cli-style.h"
  29
  30 /* See build-id.h.  */
  31
  32 const struct bfd_build_id *
  33 build_id_bfd_get (bfd *abfd)
  34 {
  35   /* Dynamic objfiles such as ones created by JIT reader API
  36      have no underlying bfd structure (that is, objfile->obfd
  37      is NULL).  */
  38   if (abfd == nullptr)
  39     return nullptr;
  40
  41   if (!bfd_check_format (abfd, bfd_object)
  42       && !bfd_check_format (abfd, bfd_core))
  43     return NULL;
  44
  45   if (abfd->build_id != NULL)
  46     return abfd->build_id;
  47
  48   /* No build-id */
  49   return NULL;
  50 }
  51
  52 /* See build-id.h.  */
  53
  54 int
  55 build_id_verify (bfd *abfd, size_t check_len, const bfd_byte *check)
  56 {
  57   const struct bfd_build_id *found;
  58   int retval = 0;
  59
  60   found = build_id_bfd_get (abfd);
  61
  62   if (found == NULL)
  63     warning (_("File \"%ps\" has no build-id, file skipped"),
  64              styled_string (file_name_style.style (),
  65                             bfd_get_filename (abfd)));
  66   else if (found->size != check_len
  67            || memcmp (found->data, check, found->size) != 0)
  68     warning (_("File \"%ps\" has a different build-id, file skipped"),
  69              styled_string (file_name_style.style (),
  70                             bfd_get_filename (abfd)));
  71   else
  72     retval = 1;
  73
  74   return retval;
  75 }
  76
  77 /* Helper for build_id_to_debug_bfd.  LINK is a path to a potential
  78    build-id-based separate debug file, potentially a symlink to the real file.
  79    If the file exists and matches BUILD_ID, return a BFD reference to it.  */
  80
  81 static gdb_bfd_ref_ptr
  82 build_id_to_debug_bfd_1 (const std::string &link, size_t build_id_len,
  83                          const bfd_byte *build_id)
  84 {
  85   if (separate_debug_file_debug)
  86     {
  87       gdb_printf (gdb_stdlog, _("  Trying %s..."), link.c_str ());
  88       gdb_flush (gdb_stdlog);
  89     }
  90
  91   /* lrealpath() is expensive even for the usually non-existent files.  */
  92   gdb::unique_xmalloc_ptr<char> filename_holder;
  93   const char *filename = nullptr;
  94   if (is_target_filename (link))
  95     filename = link.c_str ();
  96   else if (access (link.c_str (), F_OK) == 0)
  97     {
  98       filename_holder.reset (lrealpath (link.c_str ()));
  99       filename = filename_holder.get ();
 100     }
 101
 102   if (filename == NULL)
 103     {
 104       if (separate_debug_file_debug)
 105         gdb_printf (gdb_stdlog,
 106                     _(" no, unable to compute real path\n"));
 107
 108       return {};
 109     }
 110
 111   /* We expect to be silent on the non-existing files.  */
 112   gdb_bfd_ref_ptr debug_bfd = gdb_bfd_open (filename, gnutarget);
 113
 114   if (debug_bfd == NULL)
 115     {
 116       if (separate_debug_file_debug)
 117         gdb_printf (gdb_stdlog, _(" no, unable to open.\n"));
 118
 119       return {};
 120     }
 121
 122   if (!build_id_verify (debug_bfd.get(), build_id_len, build_id))
 123     {
 124       if (separate_debug_file_debug)
 125         gdb_printf (gdb_stdlog, _(" no, build-id does not match.\n"));
 126
 127       return {};
 128     }
 129
 130   if (separate_debug_file_debug)
 131     gdb_printf (gdb_stdlog, _(" yes!\n"));
 132
 133   return debug_bfd;
 134 }
 135
 136 /* Common code for finding BFDs of a given build-id.  This function
 137    works with both debuginfo files (SUFFIX == ".debug") and executable
 138    files (SUFFIX == "").  */
 139
 140 static gdb_bfd_ref_ptr
 141 build_id_to_bfd_suffix (size_t build_id_len, const bfd_byte *build_id,
 142                         const char *suffix)
 143 {
 144   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
 145      cause "/.build-id/..." lookups.  */
 146
 147   std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec
 148     = dirnames_to_char_ptr_vec (debug_file_directory.c_str ());
 149
 150   for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec)
 151     {
 152       const gdb_byte *data = build_id;
 153       size_t size = build_id_len;
 154
 155       /* Compute where the file named after the build-id would be.
 156
 157          If debugdir is "/usr/lib/debug" and the build-id is abcdef, this will
 158          give "/usr/lib/debug/.build-id/ab/cdef.debug".  */
 159       std::string link = debugdir.get ();
 160       link += "/.build-id/";
 161
 162       if (size > 0)
 163         {
 164           size--;
 165           string_appendf (link, "%02x/", (unsigned) *data++);
 166         }
 167
 168       while (size-- > 0)
 169         string_appendf (link, "%02x", (unsigned) *data++);
 170
 171       link += suffix;
 172
 173       gdb_bfd_ref_ptr debug_bfd
 174         = build_id_to_debug_bfd_1 (link, build_id_len, build_id);
 175       if (debug_bfd != NULL)
 176         return debug_bfd;
 177
 178       /* Try to look under the sysroot as well.  If the sysroot is
 179          "/the/sysroot", it will give
 180          "/the/sysroot/usr/lib/debug/.build-id/ab/cdef.debug".  */
 181
 182       if (!gdb_sysroot.empty ())
 183         {
 184           link = gdb_sysroot + link;
 185           debug_bfd = build_id_to_debug_bfd_1 (link, build_id_len, build_id);
 186           if (debug_bfd != NULL)
 187             return debug_bfd;
 188         }
 189     }
 190
 191   return {};
 192 }
 193
 194 /* See build-id.h.  */
 195
 196 gdb_bfd_ref_ptr
 197 build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
 198 {
 199   return build_id_to_bfd_suffix (build_id_len, build_id, ".debug");
 200 }
 201
 202 /* See build-id.h.  */
 203
 204 gdb_bfd_ref_ptr
 205 build_id_to_exec_bfd (size_t build_id_len, const bfd_byte *build_id)
 206 {
 207   return build_id_to_bfd_suffix (build_id_len, build_id, "");
 208 }
 209
 210 /* See build-id.h.  */
 211
 212 std::string
 213 find_separate_debug_file_by_buildid (struct objfile *objfile,
 214                                      deferred_warnings *warnings)
 215 {
 216   const struct bfd_build_id *build_id;
 217
 218   build_id = build_id_bfd_get (objfile->obfd.get ());
 219   if (build_id != NULL)
 220     {
 221       if (separate_debug_file_debug)
 222         gdb_printf (gdb_stdlog,
 223                     _("\nLooking for separate debug info (build-id) for "
 224                       "%s\n"), objfile_name (objfile));
 225
 226       gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
 227                                                    build_id->data));
 228       /* Prevent looping on a stripped .debug file.  */
 229       if (abfd != NULL
 230           && filename_cmp (bfd_get_filename (abfd.get ()),
 231                            objfile_name (objfile)) == 0)
 232         {
 233           if (separate_debug_file_debug)
 234             gdb_printf (gdb_stdlog, "\"%s\": separate debug info file has no "
 235                         "debug info", bfd_get_filename (abfd.get ()));
 236           warnings->warn (_("\"%ps\": separate debug info file has no "
 237                             "debug info"),
 238                           styled_string (file_name_style.style (),
 239                                          bfd_get_filename (abfd.get ())));
 240         }
 241       else if (abfd != NULL)
 242         return std::string (bfd_get_filename (abfd.get ()));
 243     }
 244
 245   return std::string ();
 246 }