1 /* Standard find_debuginfo callback for libdwfl.
2 Copyright (C) 2005-2010, 2014 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/>. */
37 /* Try to open64 [DIR/][SUBDIR/]DEBUGLINK, return file descriptor or -1.
38 On success, *DEBUGINFO_FILE_NAME has the malloc'd name of the open file. */
40 try_open (const struct stat64 *main_stat,
41 const char *dir, const char *subdir, const char *debuglink,
42 char **debuginfo_file_name)
45 if (dir == NULL && subdir == NULL)
47 fname = strdup (debuglink);
51 else if ((subdir == NULL ? asprintf (&fname, "%s/%s", dir, debuglink)
52 : dir == NULL ? asprintf (&fname, "%s/%s", subdir, debuglink)
53 : asprintf (&fname, "%s/%s/%s", dir, subdir, debuglink)) < 0)
57 int fd = TEMP_FAILURE_RETRY (open64 (fname, O_RDONLY));
60 else if (fstat64 (fd, &st) == 0
61 && st.st_ino == main_stat->st_ino
62 && st.st_dev == main_stat->st_dev)
64 /* This is the main file by another name. Don't look at it again. */
70 *debuginfo_file_name = fname;
75 /* Return true iff the FD's contents CRC matches DEBUGLINK_CRC. */
77 check_crc (int fd, GElf_Word debuglink_crc)
80 return (__libdwfl_crc32_file (fd, &file_crc) == 0
81 && file_crc == debuglink_crc);
85 validate (Dwfl_Module *mod, int fd, bool check, GElf_Word debuglink_crc)
87 /* For alt debug files always check the build-id from the Dwarf and alt. */
93 ssize_t build_id_len = INTUSE(dwelf_dwarf_gnu_debugaltlink) (mod->dw,
98 /* We need to open an Elf handle on the file so we can check its
99 build ID note for validation. Backdoor the handle into the
100 module data structure since we had to open it early anyway. */
101 Dwfl_Error error = __libdw_open_file (&fd, &mod->alt_elf,
103 if (error != DWFL_E_NOERROR)
104 __libdwfl_seterrno (error);
107 const void *alt_build_id;
108 ssize_t alt_len = INTUSE(dwelf_elf_gnu_build_id) (mod->alt_elf,
110 if (alt_len > 0 && alt_len == build_id_len
111 && memcmp (build_id, alt_build_id, alt_len) == 0)
116 elf_end (mod->alt_elf);
126 /* If we have a build ID, check only that. */
127 if (mod->build_id_len > 0)
129 /* We need to open an Elf handle on the file so we can check its
130 build ID note for validation. Backdoor the handle into the
131 module data structure since we had to open it early anyway. */
133 mod->debug.valid = false;
134 Dwfl_Error error = __libdw_open_file (&fd, &mod->debug.elf, false, false);
135 if (error != DWFL_E_NOERROR)
136 __libdwfl_seterrno (error);
137 else if (likely (__libdwfl_find_build_id (mod, false,
138 mod->debug.elf) == 2))
139 /* Also backdoor the gratuitous flag. */
140 mod->debug.valid = true;
144 elf_end (mod->debug.elf);
145 mod->debug.elf = NULL;
150 return mod->debug.valid;
153 return !check || check_crc (fd, debuglink_crc);
157 find_debuginfo_in_path (Dwfl_Module *mod, const char *file_name,
158 const char *debuglink_file, GElf_Word debuglink_crc,
159 char **debuginfo_file_name)
161 bool cancheck = debuglink_crc != (GElf_Word) 0;
163 const char *file_basename = file_name == NULL ? NULL : basename (file_name);
164 if (debuglink_file == NULL)
166 /* For a alt debug multi file we need a name, for a separate debug
167 name we may be able to fall back on file_basename.debug. */
168 if (file_basename == NULL || mod->dw != NULL)
174 size_t len = strlen (file_basename);
175 char *localname = alloca (len + sizeof ".debug");
176 memcpy (localname, file_basename, len);
177 memcpy (&localname[len], ".debug", sizeof ".debug");
178 debuglink_file = localname;
182 /* Look for a file named DEBUGLINK_FILE in the directories
183 indicated by the debug directory path setting. */
185 const Dwfl_Callbacks *const cb = mod->dwfl->callbacks;
186 char *path = strdupa ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
187 ?: DEFAULT_DEBUGINFO_PATH);
189 /* A leading - or + in the whole path sets whether to check file CRCs. */
190 bool defcheck = true;
191 if (path[0] == '-' || path[0] == '+')
193 defcheck = path[0] == '+';
197 /* XXX dev/ino should be cached in struct dwfl_file. */
198 struct stat64 main_stat;
199 if (unlikely ((mod->main.fd != -1 ? fstat64 (mod->main.fd, &main_stat)
200 : file_name != NULL ? stat64 (file_name, &main_stat)
203 main_stat.st_dev = 0;
204 main_stat.st_ino = 0;
207 char *file_dirname = (file_basename == file_name ? NULL
208 : strndupa (file_name, file_basename - 1 - file_name));
210 while ((p = strsep (&path, ":")) != NULL)
212 /* A leading - or + says whether to check file CRCs for this element. */
213 bool check = defcheck;
214 if (*p == '+' || *p == '-')
216 check = check && cancheck;
218 const char *dir, *subdir, *file;
222 /* An empty entry says to try the main file's directory. */
225 file = debuglink_file;
228 /* An absolute path says to look there for a subdirectory
229 named by the main file's absolute directory. This cannot
230 be applied to a relative file name. For alt debug files
231 it means to look for the basename file in that dir or the
232 .dwz subdir (see below). */
234 && (file_dirname == NULL || file_dirname[0] != '/'))
239 subdir = file_dirname + 1;
240 file = debuglink_file;
245 file = basename (debuglink_file);
249 /* A relative path says to try a subdirectory of that name
250 in the main file's directory. */
253 file = debuglink_file;
258 int fd = try_open (&main_stat, dir, subdir, file, &fname);
264 /* If we are looking for the alt file also try the .dwz subdir.
265 But only if this is the empty or absolute path. */
266 if (mod->dw != NULL && (p[0] == '\0' || p[0] == '/'))
268 fd = try_open (&main_stat, dir, ".dwz",
269 basename (file), &fname);
272 if (errno != ENOENT && errno != ENOTDIR)
283 if (validate (mod, fd, check, debuglink_crc))
285 *debuginfo_file_name = fname;
298 dwfl_standard_find_debuginfo (Dwfl_Module *mod,
299 void **userdata __attribute__ ((unused)),
300 const char *modname __attribute__ ((unused)),
301 GElf_Addr base __attribute__ ((unused)),
302 const char *file_name,
303 const char *debuglink_file,
304 GElf_Word debuglink_crc,
305 char **debuginfo_file_name)
307 /* First try by build ID if we have one. If that succeeds or fails
308 other than just by finding nothing, that's all we do. */
309 const unsigned char *bits;
311 if (INTUSE(dwfl_module_build_id) (mod, &bits, &vaddr) > 0)
313 /* Dropping most arguments means we cannot rely on them in
314 dwfl_build_id_find_debuginfo. But leave it that way since
315 some user code out there also does this, so we'll have to
317 int fd = INTUSE(dwfl_build_id_find_debuginfo) (mod,
320 debuginfo_file_name);
322 /* Did the build_id callback find something or report an error?
323 Then we are done. Otherwise fallback on path based search. */
325 || (mod->dw == NULL && mod->debug.elf != NULL)
326 || (mod->dw != NULL && mod->alt_elf != NULL)
331 /* Failing that, search the path by name. */
332 int fd = find_debuginfo_in_path (mod, file_name,
333 debuglink_file, debuglink_crc,
334 debuginfo_file_name);
336 if (fd < 0 && errno == 0)
338 /* If FILE_NAME is a symlink, the debug file might be associated
339 with the symlink target name instead. */
341 char *canon = canonicalize_file_name (file_name);
342 if (canon != NULL && strcmp (file_name, canon))
343 fd = find_debuginfo_in_path (mod, canon,
344 debuglink_file, debuglink_crc,
345 debuginfo_file_name);
351 INTDEF (dwfl_standard_find_debuginfo)