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 <unistd.h>
37 : : #include "system.h"
38 : :
39 : :
40 : : int
41 : : internal_function
42 : 120 : __libdwfl_open_by_build_id (Dwfl_Module *mod, bool debug, char **file_name,
43 : : const size_t id_len, const uint8_t *id)
44 : : {
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 [ - + ]: 120 : if (id_len < MIN_BUILD_ID_BYTES || id_len > MAX_BUILD_ID_BYTES)
50 : : {
51 : 0 : bad_id:
52 : 0 : __libdwfl_seterrno (DWFL_E_WRONG_ID_ELF);
53 : 0 : return -1;
54 : : }
55 : :
56 : : /* Search debuginfo_path directories' .build-id/ subdirectories. */
57 : :
58 : 120 : char id_name[sizeof "/.build-id/" + 1 + MAX_BUILD_ID_BYTES * 2
59 : : + sizeof ".debug" - 1];
60 [ - + ]: 120 : strcpy (id_name, "/.build-id/");
61 : 360 : int n = snprintf (&id_name[sizeof "/.build-id/" - 1],
62 [ - + ]: 120 : 4, "%02" PRIx8 "/", (uint8_t) id[0]);
63 [ - + ]: 120 : if (n != 3)
64 : : goto bad_id;;
65 [ + + ]: 2400 : for (size_t i = 1; i < id_len; ++i)
66 : : {
67 : 4560 : n = snprintf (&id_name[sizeof "/.build-id/" - 1 + 3 + (i - 1) * 2],
68 [ - + ][ - + ]: 4560 : 3, "%02" PRIx8, (uint8_t) id[i]);
69 [ - + ]: 2280 : if (n != 2)
70 : : goto bad_id;
71 : : }
72 [ + + ]: 120 : if (debug)
73 : 106 : strcpy (&id_name[sizeof "/.build-id/" - 1 + 3 + (id_len - 1) * 2],
74 : : ".debug");
75 : :
76 : 120 : const Dwfl_Callbacks *const cb = mod->dwfl->callbacks;
77 [ + + ][ + + ]: 120 : char *path = strdup ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
78 : : ?: DEFAULT_DEBUGINFO_PATH);
79 [ + - ]: 120 : if (path == NULL)
80 : : return -1;
81 : :
82 : 120 : int fd = -1;
83 : 120 : char *dir;
84 : 120 : char *paths = path;
85 [ + + ][ + + ]: 474 : while (fd < 0 && (dir = strsep (&paths, ":")) != NULL)
86 : : {
87 [ - + ]: 354 : if (dir[0] == '+' || dir[0] == '-')
88 : 0 : ++dir;
89 : :
90 : : /* Only absolute directory names are useful to us. */
91 [ + + ]: 354 : if (dir[0] != '/')
92 : : continue;
93 : :
94 : 118 : size_t dirlen = strlen (dir);
95 : 118 : char *name = malloc (dirlen + sizeof id_name);
96 [ + - ]: 118 : if (unlikely (name == NULL))
97 : : break;
98 : 236 : memcpy (mempcpy (name, dir, dirlen), id_name, sizeof id_name);
99 : :
100 [ + + ][ - + ]: 118 : fd = TEMP_FAILURE_RETRY (open (name, O_RDONLY));
101 [ + + ]: 118 : if (fd >= 0)
102 : : {
103 [ - + ]: 9 : if (*file_name != NULL)
104 : 0 : free (*file_name);
105 [ - + ]: 9 : *file_name = realpath (name, NULL);
106 [ - + ]: 9 : if (*file_name == NULL)
107 : : {
108 : 0 : *file_name = name;
109 : 0 : name = NULL;
110 : : }
111 : : }
112 : 118 : free (name);
113 : : }
114 : :
115 : 120 : free (path);
116 : :
117 : : /* If we simply found nothing, clear errno. If we had some other error
118 : : with the file, report that. Possibly this should treat other errors
119 : : like ENOENT too. But ignoring all errors could mask some that should
120 : : be reported. */
121 [ + + ][ + + ]: 120 : if (fd < 0 && errno == ENOENT)
122 : 109 : errno = 0;
123 : :
124 : : return fd;
125 : : }
126 : :
127 : : int
128 : : internal_function
129 : 107 : __libdwfl_open_mod_by_build_id (Dwfl_Module *mod, bool debug, char **file_name)
130 : : {
131 : : /* If *FILE_NAME was primed into the module, leave it there
132 : : as the fallback when we have nothing to offer. */
133 : 107 : errno = 0;
134 [ + - ]: 107 : if (mod->build_id_len <= 0)
135 : : return -1;
136 : :
137 : 107 : const size_t id_len = mod->build_id_len;
138 : 107 : const uint8_t *id = mod->build_id_bits;
139 : :
140 : 107 : return __libdwfl_open_by_build_id (mod, debug, file_name, id_len, id);
141 : : }
142 : :
143 : : int
144 : 26 : dwfl_build_id_find_elf (Dwfl_Module *mod,
145 : : void **userdata __attribute__ ((unused)),
146 : : const char *modname __attribute__ ((unused)),
147 : : Dwarf_Addr base __attribute__ ((unused)),
148 : : char **file_name, Elf **elfp)
149 : : {
150 : 26 : *elfp = NULL;
151 [ + + ]: 26 : if (mod->is_executable
152 [ + - ]: 12 : && mod->dwfl->user_core != NULL
153 [ + - ]: 12 : && mod->dwfl->user_core->executable_for_core != NULL)
154 : : {
155 : : /* When dwfl_core_file_report was called with a non-NULL executable file
156 : : name this callback will replace the Dwfl_Module main.name with the
157 : : recorded executable file when MOD was identified as main executable
158 : : (which then triggers opening and reporting of the executable). */
159 : 12 : const char *executable = mod->dwfl->user_core->executable_for_core;
160 : 12 : int fd = open (executable, O_RDONLY);
161 [ + - ]: 12 : if (fd >= 0)
162 : : {
163 : 12 : *file_name = strdup (executable);
164 [ - + ]: 12 : if (*file_name != NULL)
165 : : return fd;
166 : : else
167 : 0 : close (fd);
168 : : }
169 : : }
170 : 14 : int fd = __libdwfl_open_mod_by_build_id (mod, false, file_name);
171 [ - + ]: 14 : if (fd >= 0)
172 : : {
173 : 0 : Dwfl_Error error = __libdw_open_file (&fd, elfp, true, false);
174 [ # # ]: 0 : if (error != DWFL_E_NOERROR)
175 : 0 : __libdwfl_seterrno (error);
176 [ # # ]: 0 : else if (__libdwfl_find_build_id (mod, false, *elfp) == 2)
177 : : {
178 : : /* This is a backdoor signal to short-circuit the ID refresh. */
179 : 0 : mod->main.valid = true;
180 : 0 : return fd;
181 : : }
182 : : else
183 : : {
184 : : /* This file does not contain the ID it should! */
185 : 0 : elf_end (*elfp);
186 : 0 : *elfp = NULL;
187 : 0 : close (fd);
188 : 0 : fd = -1;
189 : : }
190 : 0 : free (*file_name);
191 : 0 : *file_name = NULL;
192 : : }
193 : : else
194 : : {
195 : : #ifdef ENABLE_LIBDEBUGINFOD
196 : : /* If all else fails and a build-id is available, query the
197 : : debuginfo-server if enabled. */
198 [ + - ]: 14 : if (fd < 0 && mod->build_id_len > 0)
199 : 14 : fd = __libdwfl_debuginfod_find_executable (mod->dwfl,
200 : 14 : mod->build_id_bits,
201 : : mod->build_id_len);
202 : : #endif
203 : : }
204 : :
205 [ + - ][ + - ]: 14 : if (fd < 0 && errno == 0 && mod->build_id_len > 0)
[ + - ]
206 : : /* Setting this with no file yet loaded is a marker that
207 : : the build ID is authoritative even if we also know a
208 : : putative *FILE_NAME. */
209 : 14 : mod->main.valid = true;
210 : :
211 : : return fd;
212 : : }
213 : : INTDEF (dwfl_build_id_find_elf)
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