gdb/build-id.c

   1 /* build-id-related functions.
   2
   3    Copyright (C) 1991-2023 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 "gdbsupport/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   /* Dynamic objfiles such as ones created by JIT reader API
  36      have no underlaying 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 \"%s\" has no build-id, file skipped"),
  64              bfd_get_filename (abfd));
  65   else if (found->size != check_len
  66            || memcmp (found->data, check, found->size) != 0)
  67     warning (_("File \"%s\" has a different build-id, file skipped"),
  68              bfd_get_filename (abfd));
  69   else
  70     retval = 1;
  71
  72   return retval;
  73 }
  74
  75 /* Helper for build_id_to_debug_bfd.  LINK is a path to a potential
  76    build-id-based separate debug file, potentially a symlink to the real file.
  77    If the file exists and matches BUILD_ID, return a BFD reference to it.  */
  78
  79 static gdb_bfd_ref_ptr
  80 build_id_to_debug_bfd_1 (const std::string &link, size_t build_id_len,
  81                          const bfd_byte *build_id)
  82 {
  83   if (separate_debug_file_debug)
  84     {
  85       gdb_printf (gdb_stdlog, _("  Trying %s..."), link.c_str ());
  86       gdb_flush (gdb_stdlog);
  87     }
  88
  89   /* lrealpath() is expensive even for the usually non-existent files.  */
  90   gdb::unique_xmalloc_ptr<char> filename_holder;
  91   const char *filename = nullptr;
  92   if (startswith (link, TARGET_SYSROOT_PREFIX))
  93     filename = link.c_str ();
  94   else if (access (link.c_str (), F_OK) == 0)
  95     {
  96       filename_holder.reset (lrealpath (link.c_str ()));
  97       filename = filename_holder.get ();
  98     }
  99
 100   if (filename == NULL)
 101     {
 102       if (separate_debug_file_debug)
 103         gdb_printf (gdb_stdlog,
 104                     _(" no, unable to compute real path\n"));
 105
 106       return {};
 107     }
 108
 109   /* We expect to be silent on the non-existing files.  */
 110   gdb_bfd_ref_ptr debug_bfd = gdb_bfd_open (filename, gnutarget);
 111
 112   if (debug_bfd == NULL)
 113     {
 114       if (separate_debug_file_debug)
 115         gdb_printf (gdb_stdlog, _(" no, unable to open.\n"));
 116
 117       return {};
 118     }
 119
 120   if (!build_id_verify (debug_bfd.get(), build_id_len, build_id))
 121     {
 122       if (separate_debug_file_debug)
 123         gdb_printf (gdb_stdlog, _(" no, build-id does not match.\n"));
 124
 125       return {};
 126     }
 127
 128   if (separate_debug_file_debug)
 129     gdb_printf (gdb_stdlog, _(" yes!\n"));
 130
 131   return debug_bfd;
 132 }
 133
 134 /* Common code for finding BFDs of a given build-id.  This function
 135    works with both debuginfo files (SUFFIX == ".debug") and executable
 136    files (SUFFIX == "").  */
 137
 138 static gdb_bfd_ref_ptr
 139 build_id_to_bfd_suffix (size_t build_id_len, const bfd_byte *build_id,
 140                         const char *suffix)
 141 {
 142   /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will
 143      cause "/.build-id/..." lookups.  */
 144
 145   std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec
 146     = dirnames_to_char_ptr_vec (debug_file_directory.c_str ());
 147
 148   for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec)
 149     {
 150       const gdb_byte *data = build_id;
 151       size_t size = build_id_len;
 152
 153       /* Compute where the file named after the build-id would be.
 154
 155          If debugdir is "/usr/lib/debug" and the build-id is abcdef, this will
 156          give "/usr/lib/debug/.build-id/ab/cdef.debug".  */
 157       std::string link = debugdir.get ();
 158       link += "/.build-id/";
 159
 160       if (size > 0)
 161         {
 162           size--;
 163           string_appendf (link, "%02x/", (unsigned) *data++);
 164         }
 165
 166       while (size-- > 0)
 167         string_appendf (link, "%02x", (unsigned) *data++);
 168
 169       link += suffix;
 170
 171       gdb_bfd_ref_ptr debug_bfd
 172         = build_id_to_debug_bfd_1 (link, build_id_len, build_id);
 173       if (debug_bfd != NULL)
 174         return debug_bfd;
 175
 176       /* Try to look under the sysroot as well.  If the sysroot is
 177          "/the/sysroot", it will give
 178          "/the/sysroot/usr/lib/debug/.build-id/ab/cdef.debug".  */
 179
 180       if (!gdb_sysroot.empty ())
 181         {
 182           link = gdb_sysroot + link;
 183           debug_bfd = build_id_to_debug_bfd_1 (link, build_id_len, build_id);
 184           if (debug_bfd != NULL)
 185             return debug_bfd;
 186         }
 187     }
 188
 189   return {};
 190 }
 191
 192 /* See build-id.h.  */
 193
 194 gdb_bfd_ref_ptr
 195 build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id)
 196 {
 197   return build_id_to_bfd_suffix (build_id_len, build_id, ".debug");
 198 }
 199
 200 /* See build-id.h.  */
 201
 202 gdb_bfd_ref_ptr
 203 build_id_to_exec_bfd (size_t build_id_len, const bfd_byte *build_id)
 204 {
 205   return build_id_to_bfd_suffix (build_id_len, build_id, "");
 206 }
 207
 208 /* See build-id.h.  */
 209
 210 std::string
 211 find_separate_debug_file_by_buildid (struct objfile *objfile,
 212                                      std::vector<std::string> *warnings_vector)
 213 {
 214   const struct bfd_build_id *build_id;
 215
 216   build_id = build_id_bfd_get (objfile->obfd.get ());
 217   if (build_id != NULL)
 218     {
 219       if (separate_debug_file_debug)
 220         gdb_printf (gdb_stdlog,
 221                     _("\nLooking for separate debug info (build-id) for "
 222                       "%s\n"), objfile_name (objfile));
 223
 224       gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size,
 225                                                    build_id->data));
 226       /* Prevent looping on a stripped .debug file.  */
 227       if (abfd != NULL
 228           && filename_cmp (bfd_get_filename (abfd.get ()),
 229                            objfile_name (objfile)) == 0)
 230         {
 231           std::string msg
 232             = string_printf (_("\"%s\": separate debug info file has no "
 233                                "debug info"), bfd_get_filename (abfd.get ()));
 234           if (separate_debug_file_debug)
 235             gdb_printf (gdb_stdlog, "%s", msg.c_str ());
 236           warnings_vector->emplace_back (std::move (msg));
 237         }
 238       else if (abfd != NULL)
 239         return std::string (bfd_get_filename (abfd.get ()));
 240     }
 241
 242   return std::string ();
 243 }