Branch data Line data Source code
1 : : /* Find an ELF file for a module from its build ID.
2 : : Copyright (C) 2007-2010, 2014, 2015, 2019 Red Hat, Inc.
3 : : This file is part of elfutils.
4 : :
5 : : This file is free software; you can redistribute it and/or modify
6 : : it under the terms of either
7 : :
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
11 : :
12 : : or
13 : :
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
17 : :
18 : : or both in parallel, as here.
19 : :
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.
24 : :
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/>. */
28 : :
29 : : #ifdef HAVE_CONFIG_H
30 : : # include <config.h>
31 : : #endif
32 : :
33 : : #include "libdwflP.h"
34 : : #include <inttypes.h>
35 : : #include <fcntl.h>
36 : : #include "system.h"
37 : :
38 : :
39 : : int
40 : : internal_function
41 : 300 : __libdwfl_open_by_build_id (Dwfl_Module *mod, bool debug, char **file_name,
42 : : const size_t id_len, const uint8_t *id)
43 : : {
44 : : /* We don't handle very short or really large build-ids. We need at
45 : : at least 3 and allow for up to 64 (normally ids are 20 long). */
46 : : #define MIN_BUILD_ID_BYTES 3
47 : : #define MAX_BUILD_ID_BYTES 64
48 [ - + - + ]: 300 : if (id_len < MIN_BUILD_ID_BYTES || id_len > MAX_BUILD_ID_BYTES)
49 : : {
50 : 0 : bad_id:
51 : 0 : __libdwfl_seterrno (DWFL_E_WRONG_ID_ELF);
52 : 0 : return -1;
53 : : }
54 : :
55 : : /* Search debuginfo_path directories' .build-id/ subdirectories. */
56 : :
57 : : char id_name[sizeof "/.build-id/" + 1 + MAX_BUILD_ID_BYTES * 2
58 : : + sizeof ".debug" - 1];
59 : 300 : strcpy (id_name, "/.build-id/");
60 : 300 : int n = snprintf (&id_name[sizeof "/.build-id/" - 1],
61 : 300 : 4, "%02" PRIx8 "/", (uint8_t) id[0]);
62 [ - + ]: 300 : if (n != 3)
63 : 0 : goto bad_id;;
64 [ + + ]: 6000 : for (size_t i = 1; i < id_len; ++i)
65 : : {
66 : 5700 : n = snprintf (&id_name[sizeof "/.build-id/" - 1 + 3 + (i - 1) * 2],
67 : 5700 : 3, "%02" PRIx8, (uint8_t) id[i]);
68 [ - + ]: 5700 : if (n != 2)
69 : 0 : goto bad_id;
70 : : }
71 [ + + ]: 300 : if (debug)
72 : 254 : strcpy (&id_name[sizeof "/.build-id/" - 1 + 3 + (id_len - 1) * 2],
73 : : ".debug");
74 : :
75 : 300 : const Dwfl_Callbacks *const cb = mod->dwfl->callbacks;
76 [ + + + + ]: 300 : char *path = strdup ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
77 : : ?: DEFAULT_DEBUGINFO_PATH);
78 [ - + ]: 300 : if (path == NULL)
79 : 0 : return -1;
80 : :
81 : 300 : int fd = -1;
82 : : char *dir;
83 : 300 : char *paths = path;
84 [ + - + + ]: 1172 : while (fd < 0 && (dir = strsep (&paths, ":")) != NULL)
85 : : {
86 [ + - - + ]: 872 : if (dir[0] == '+' || dir[0] == '-')
87 : 0 : ++dir;
88 : :
89 : : /* Only absolute directory names are useful to us. */
90 [ + + ]: 872 : if (dir[0] != '/')
91 : 584 : continue;
92 : :
93 : 288 : size_t dirlen = strlen (dir);
94 : 288 : char *name = malloc (dirlen + sizeof id_name);
95 [ - + ]: 288 : if (unlikely (name == NULL))
96 : 0 : break;
97 : 288 : memcpy (mempcpy (name, dir, dirlen), id_name, sizeof id_name);
98 : :
99 [ + - - + ]: 288 : fd = TEMP_FAILURE_RETRY (open (name, O_RDONLY));
100 [ - + ]: 288 : if (fd >= 0)
101 : : {
102 [ # # ]: 0 : if (*file_name != NULL)
103 : 0 : free (*file_name);
104 : 0 : *file_name = realpath (name, NULL);
105 [ # # ]: 0 : if (*file_name == NULL)
106 : : {
107 : 0 : *file_name = name;
108 : 0 : name = NULL;
109 : : }
110 : : }
111 : 288 : free (name);
112 : : }
113 : :
114 : 300 : free (path);
115 : :
116 : : /* If we simply found nothing, clear errno. If we had some other error
117 : : with the file, report that. Possibly this should treat other errors
118 : : like ENOENT too. But ignoring all errors could mask some that should
119 : : be reported. */
120 [ + - + + ]: 300 : if (fd < 0 && errno == ENOENT)
121 : 288 : errno = 0;
122 : :
123 : 300 : return fd;
124 : : }
125 : :
126 : : int
127 : : internal_function
128 : 256 : __libdwfl_open_mod_by_build_id (Dwfl_Module *mod, bool debug, char **file_name)
129 : : {
130 : : /* If *FILE_NAME was primed into the module, leave it there
131 : : as the fallback when we have nothing to offer. */
132 : 256 : errno = 0;
133 [ - + ]: 256 : if (mod->build_id_len <= 0)
134 : 0 : return -1;
135 : :
136 : 256 : const size_t id_len = mod->build_id_len;
137 : 256 : const uint8_t *id = mod->build_id_bits;
138 : :
139 : 256 : return __libdwfl_open_by_build_id (mod, debug, file_name, id_len, id);
140 : : }
141 : :
142 : : int
143 : 70 : dwfl_build_id_find_elf (Dwfl_Module *mod,
144 : : void **userdata __attribute__ ((unused)),
145 : : const char *modname __attribute__ ((unused)),
146 : : Dwarf_Addr base __attribute__ ((unused)),
147 : : char **file_name, Elf **elfp)
148 : : {
149 : 70 : *elfp = NULL;
150 [ + + ]: 70 : if (mod->is_executable
151 [ + - ]: 26 : && mod->dwfl->user_core != NULL
152 [ + + ]: 26 : && mod->dwfl->user_core->executable_for_core != NULL)
153 : : {
154 : : /* When dwfl_core_file_report was called with a non-NULL executable file
155 : : name this callback will replace the Dwfl_Module main.name with the
156 : : recorded executable file when MOD was identified as main executable
157 : : (which then triggers opening and reporting of the executable). */
158 : 24 : const char *executable = mod->dwfl->user_core->executable_for_core;
159 : 24 : int fd = open (executable, O_RDONLY);
160 [ + - ]: 24 : if (fd >= 0)
161 : : {
162 : 24 : *file_name = strdup (executable);
163 [ + - ]: 24 : if (*file_name != NULL)
164 : 24 : return fd;
165 : : else
166 : 0 : close (fd);
167 : : }
168 : : }
169 : 46 : int fd = __libdwfl_open_mod_by_build_id (mod, false, file_name);
170 [ - + ]: 46 : if (fd >= 0)
171 : : {
172 : 0 : Dwfl_Error error = __libdw_open_file (&fd, elfp, true, false);
173 [ # # ]: 0 : if (error != DWFL_E_NOERROR)
174 : 0 : __libdwfl_seterrno (error);
175 [ # # ]: 0 : else if (__libdwfl_find_build_id (mod, false, *elfp) == 2)
176 : : {
177 : : /* This is a backdoor signal to short-circuit the ID refresh. */
178 : 0 : mod->main.valid = true;
179 : 0 : return fd;
180 : : }
181 : : else
182 : : {
183 : : /* This file does not contain the ID it should! */
184 : 0 : elf_end (*elfp);
185 : 0 : *elfp = NULL;
186 : 0 : close (fd);
187 : 0 : fd = -1;
188 : : }
189 : 0 : free (*file_name);
190 : 0 : *file_name = NULL;
191 : : }
192 : : else
193 : : {
194 : : #ifdef ENABLE_LIBDEBUGINFOD
195 : : /* If all else fails and a build-id is available, query the
196 : : debuginfo-server if enabled. */
197 [ + - + - ]: 46 : if (fd < 0 && mod->build_id_len > 0)
198 : 46 : fd = __libdwfl_debuginfod_find_executable (mod->dwfl,
199 : 46 : mod->build_id_bits,
200 : 46 : mod->build_id_len);
201 : : #endif
202 : : }
203 : :
204 [ + - + - : 46 : if (fd < 0 && errno == 0 && mod->build_id_len > 0)
+ - ]
205 : : /* Setting this with no file yet loaded is a marker that
206 : : the build ID is authoritative even if we also know a
207 : : putative *FILE_NAME. */
208 : 46 : mod->main.valid = true;
209 : :
210 : 46 : return fd;
211 : : }
212 : : INTDEF (dwfl_build_id_find_elf)
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