1 /* Find an ELF file for a module from its build ID.
2 Copyright (C) 2007-2010, 2014, 2015 Red Hat, Inc.
3 This file is part of elfutils.
5 This file is free software; you can redistribute it and/or modify
6 it under the terms of either
8 * the GNU Lesser General Public License as published by the Free
9 Software Foundation; either version 3 of the License, or (at
10 your option) any later version
14 * the GNU General Public License as published by the Free
15 Software Foundation; either version 2 of the License, or (at
16 your option) any later version
18 or both in parallel, as here.
20 elfutils is distributed in the hope that it will be useful, but
21 WITHOUT ANY WARRANTY; without even the implied warranty of
22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 General Public License for more details.
25 You should have received copies of the GNU General Public License and
26 the GNU Lesser General Public License along with this program. If
27 not, see <http://www.gnu.org/licenses/>. */
42 __libdwfl_open_by_build_id (Dwfl_Module *mod, bool debug, char **file_name,
43 const size_t id_len, const uint8_t *id)
45 /* We don't handle very short or really large build-ids. We need at
46 at least 3 and allow for up to 64 (normally ids are 20 long). */
47 #define MIN_BUILD_ID_BYTES 3
48 #define MAX_BUILD_ID_BYTES 64
49 if (id_len < MIN_BUILD_ID_BYTES || id_len > MAX_BUILD_ID_BYTES)
51 __libdwfl_seterrno (DWFL_E_WRONG_ID_ELF);
55 /* Search debuginfo_path directories' .build-id/ subdirectories. */
57 char id_name[sizeof "/.build-id/" + 1 + MAX_BUILD_ID_BYTES * 2
58 + sizeof ".debug" - 1];
59 strcpy (id_name, "/.build-id/");
60 int n = snprintf (&id_name[sizeof "/.build-id/" - 1],
61 4, "%02" PRIx8 "/", (uint8_t) id[0]);
63 for (size_t i = 1; i < id_len; ++i)
65 n = snprintf (&id_name[sizeof "/.build-id/" - 1 + 3 + (i - 1) * 2],
66 3, "%02" PRIx8, (uint8_t) id[i]);
70 strcpy (&id_name[sizeof "/.build-id/" - 1 + 3 + (id_len - 1) * 2],
73 const Dwfl_Callbacks *const cb = mod->dwfl->callbacks;
74 char *path = strdup ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
75 ?: DEFAULT_DEBUGINFO_PATH);
82 while (fd < 0 && (dir = strsep (&paths, ":")) != NULL)
84 if (dir[0] == '+' || dir[0] == '-')
87 /* Only absolute directory names are useful to us. */
91 size_t dirlen = strlen (dir);
92 char *name = malloc (dirlen + sizeof id_name);
93 if (unlikely (name == NULL))
95 memcpy (mempcpy (name, dir, dirlen), id_name, sizeof id_name);
97 fd = TEMP_FAILURE_RETRY (open (name, O_RDONLY));
100 if (*file_name != NULL)
102 *file_name = realpath (name, NULL);
103 if (*file_name == NULL)
114 /* If we simply found nothing, clear errno. If we had some other error
115 with the file, report that. Possibly this should treat other errors
116 like ENOENT too. But ignoring all errors could mask some that should
118 if (fd < 0 && errno == ENOENT)
126 __libdwfl_open_mod_by_build_id (Dwfl_Module *mod, bool debug, char **file_name)
128 /* If *FILE_NAME was primed into the module, leave it there
129 as the fallback when we have nothing to offer. */
131 if (mod->build_id_len <= 0)
134 const size_t id_len = mod->build_id_len;
135 const uint8_t *id = mod->build_id_bits;
137 return __libdwfl_open_by_build_id (mod, debug, file_name, id_len, id);
141 dwfl_build_id_find_elf (Dwfl_Module *mod,
142 void **userdata __attribute__ ((unused)),
143 const char *modname __attribute__ ((unused)),
144 Dwarf_Addr base __attribute__ ((unused)),
145 char **file_name, Elf **elfp)
148 if (mod->is_executable
149 && mod->dwfl->user_core != NULL
150 && mod->dwfl->user_core->executable_for_core != NULL)
152 /* When dwfl_core_file_report was called with a non-NULL executable file
153 name this callback will replace the Dwfl_Module main.name with the
154 recorded executable file when MOD was identified as main executable
155 (which then triggers opening and reporting of the executable). */
156 const char *executable = mod->dwfl->user_core->executable_for_core;
157 int fd = open (executable, O_RDONLY);
160 *file_name = strdup (executable);
161 if (*file_name != NULL)
167 int fd = __libdwfl_open_mod_by_build_id (mod, false, file_name);
170 Dwfl_Error error = __libdw_open_file (&fd, elfp, true, false);
171 if (error != DWFL_E_NOERROR)
172 __libdwfl_seterrno (error);
173 else if (__libdwfl_find_build_id (mod, false, *elfp) == 2)
175 /* This is a backdoor signal to short-circuit the ID refresh. */
176 mod->main.valid = true;
181 /* This file does not contain the ID it should! */
190 else if (errno == 0 && mod->build_id_len > 0)
191 /* Setting this with no file yet loaded is a marker that
192 the build ID is authoritative even if we also know a
193 putative *FILE_NAME. */
194 mod->main.valid = true;
198 INTDEF (dwfl_build_id_find_elf)