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