1 /* build-id-related functions. 2 3 Copyright (C) 1991-2019 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 "common/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 /* Helper for build_id_to_debug_bfd. LINK is a path to a potential 69 build-id-based separate debug file, potentially a symlink to the real file. 70 If the file exists and matches BUILD_ID, return a BFD reference to it. */ 71 72 static gdb_bfd_ref_ptr 73 build_id_to_debug_bfd_1 (const std::string &link, size_t build_id_len, 74 const bfd_byte *build_id) 75 { 76 if (separate_debug_file_debug) 77 { 78 printf_unfiltered (_(" Trying %s..."), link.c_str ()); 79 gdb_flush (gdb_stdout); 80 } 81 82 /* lrealpath() is expensive even for the usually non-existent files. */ 83 gdb::unique_xmalloc_ptr<char> filename; 84 if (access (link.c_str (), F_OK) == 0) 85 filename.reset (lrealpath (link.c_str ())); 86 87 if (filename == NULL) 88 { 89 if (separate_debug_file_debug) 90 printf_unfiltered (_(" no, unable to compute real path\n")); 91 92 return {}; 93 } 94 95 /* We expect to be silent on the non-existing files. */ 96 gdb_bfd_ref_ptr debug_bfd = gdb_bfd_open (filename.get (), gnutarget, -1); 97 98 if (debug_bfd == NULL) 99 { 100 if (separate_debug_file_debug) 101 printf_unfiltered (_(" no, unable to open.\n")); 102 103 return {}; 104 } 105 106 if (!build_id_verify (debug_bfd.get(), build_id_len, build_id)) 107 { 108 if (separate_debug_file_debug) 109 printf_unfiltered (_(" no, build-id does not match.\n")); 110 111 return {}; 112 } 113 114 if (separate_debug_file_debug) 115 printf_unfiltered (_(" yes!\n")); 116 117 return debug_bfd; 118 } 119 120 /* See build-id.h. */ 121 122 gdb_bfd_ref_ptr 123 build_id_to_debug_bfd (size_t build_id_len, const bfd_byte *build_id) 124 { 125 /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will 126 cause "/.build-id/..." lookups. */ 127 128 std::vector<gdb::unique_xmalloc_ptr<char>> debugdir_vec 129 = dirnames_to_char_ptr_vec (debug_file_directory); 130 131 for (const gdb::unique_xmalloc_ptr<char> &debugdir : debugdir_vec) 132 { 133 const gdb_byte *data = build_id; 134 size_t size = build_id_len; 135 136 /* Compute where the file named after the build-id would be. 137 138 If debugdir is "/usr/lib/debug" and the build-id is abcdef, this will 139 give "/usr/lib/debug/.build-id/ab/cdef.debug". */ 140 std::string link = debugdir.get (); 141 link += "/.build-id/"; 142 143 if (size > 0) 144 { 145 size--; 146 string_appendf (link, "%02x/", (unsigned) *data++); 147 } 148 149 while (size-- > 0) 150 string_appendf (link, "%02x", (unsigned) *data++); 151 152 link += ".debug"; 153 154 gdb_bfd_ref_ptr debug_bfd 155 = build_id_to_debug_bfd_1 (link, build_id_len, build_id); 156 if (debug_bfd != NULL) 157 return debug_bfd; 158 159 /* Try to look under the sysroot as well. If the sysroot is 160 "/the/sysroot", it will give 161 "/the/sysroot/usr/lib/debug/.build-id/ab/cdef.debug". 162 163 Don't do it if the sysroot is the target system ("target:"). It 164 could work in theory, but the lrealpath in build_id_to_debug_bfd_1 165 only works with local paths. */ 166 if (strcmp (gdb_sysroot, TARGET_SYSROOT_PREFIX) != 0) 167 { 168 link = gdb_sysroot + link; 169 debug_bfd = build_id_to_debug_bfd_1 (link, build_id_len, build_id); 170 if (debug_bfd != NULL) 171 return debug_bfd; 172 } 173 } 174 175 return {}; 176 } 177 178 /* See build-id.h. */ 179 180 std::string 181 find_separate_debug_file_by_buildid (struct objfile *objfile) 182 { 183 const struct bfd_build_id *build_id; 184 185 build_id = build_id_bfd_get (objfile->obfd); 186 if (build_id != NULL) 187 { 188 if (separate_debug_file_debug) 189 printf_unfiltered (_("\nLooking for separate debug info (build-id) for " 190 "%s\n"), objfile_name (objfile)); 191 192 gdb_bfd_ref_ptr abfd (build_id_to_debug_bfd (build_id->size, 193 build_id->data)); 194 /* Prevent looping on a stripped .debug file. */ 195 if (abfd != NULL 196 && filename_cmp (bfd_get_filename (abfd.get ()), 197 objfile_name (objfile)) == 0) 198 warning (_("\"%s\": separate debug info file has no debug info"), 199 bfd_get_filename (abfd.get ())); 200 else if (abfd != NULL) 201 return std::string (bfd_get_filename (abfd.get ())); 202 } 203 204 return std::string (); 205 } 206