Branch data Line data Source code
1 : : /* Find an ELF file for a module from its build ID.
2 : : Copyright (C) 2007-2010 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 : : #include "libdwflP.h"
30 : : #include <inttypes.h>
31 : : #include <fcntl.h>
32 : : #include <unistd.h>
33 : :
34 : :
35 : : int
36 : : internal_function
37 : 46 : __libdwfl_open_by_build_id (Dwfl_Module *mod, bool debug, char **file_name)
38 : : {
39 : : /* If *FILE_NAME was primed into the module, leave it there
40 : : as the fallback when we have nothing to offer. */
41 : 46 : errno = 0;
42 [ + - ]: 46 : if (mod->build_id_len <= 0)
43 : : return -1;
44 : :
45 : 46 : const size_t id_len = mod->build_id_len;
46 : 46 : const uint8_t *id = mod->build_id_bits;
47 : :
48 : : /* Search debuginfo_path directories' .build-id/ subdirectories. */
49 : :
50 : 46 : char id_name[sizeof "/.build-id/" + 1 + id_len * 2 + sizeof ".debug" - 1];
51 : 46 : strcpy (id_name, "/.build-id/");
52 : 46 : int n = snprintf (&id_name[sizeof "/.build-id/" - 1],
53 : 46 : 4, "%02" PRIx8 "/", (uint8_t) id[0]);
54 [ + - ]: 46 : assert (n == 3);
55 [ + + ]: 920 : for (size_t i = 1; i < id_len; ++i)
56 : : {
57 : 874 : n = snprintf (&id_name[sizeof "/.build-id/" - 1 + 3 + (i - 1) * 2],
58 : 874 : 3, "%02" PRIx8, (uint8_t) id[i]);
59 [ - + ]: 874 : assert (n == 2);
60 : : }
61 [ + + ]: 46 : if (debug)
62 : 38 : strcpy (&id_name[sizeof "/.build-id/" - 1 + 3 + (id_len - 1) * 2],
63 : : ".debug");
64 : :
65 : 46 : const Dwfl_Callbacks *const cb = mod->dwfl->callbacks;
66 [ + - ][ - + ]: 46 : char *path = strdupa ((cb->debuginfo_path ? *cb->debuginfo_path : NULL)
67 : : ?: DEFAULT_DEBUGINFO_PATH);
68 : :
69 : 46 : int fd = -1;
70 : : char *dir;
71 [ + + ][ + + ]: 359 : while (fd < 0 && (dir = strsep (&path, ":")) != NULL)
72 : : {
73 [ - + ]: 138 : if (dir[0] == '+' || dir[0] == '-')
74 : 0 : ++dir;
75 : :
76 : : /* Only absolute directory names are useful to us. */
77 [ + + ]: 138 : if (dir[0] != '/')
78 : 92 : continue;
79 : :
80 : 46 : size_t dirlen = strlen (dir);
81 : 46 : char *name = malloc (dirlen + sizeof id_name);
82 [ + - ]: 46 : if (unlikely (name == NULL))
83 : : break;
84 : 46 : memcpy (mempcpy (name, dir, dirlen), id_name, sizeof id_name);
85 : :
86 [ + + ][ - + ]: 46 : fd = TEMP_FAILURE_RETRY (open64 (name, O_RDONLY));
87 [ + + ]: 46 : if (fd >= 0)
88 : : {
89 [ - + ]: 9 : if (*file_name != NULL)
90 : 0 : free (*file_name);
91 : 9 : *file_name = canonicalize_file_name (name);
92 [ - + ]: 9 : if (*file_name == NULL)
93 : : {
94 : 0 : *file_name = name;
95 : 0 : name = NULL;
96 : : }
97 : : }
98 : 138 : free (name);
99 : : }
100 : :
101 : : /* If we simply found nothing, clear errno. If we had some other error
102 : : with the file, report that. Possibly this should treat other errors
103 : : like ENOENT too. But ignoring all errors could mask some that should
104 : : be reported. */
105 [ + + ][ + - ]: 46 : if (fd < 0 && errno == ENOENT)
106 : 46 : errno = 0;
107 : :
108 : : return fd;
109 : : }
110 : :
111 : : int
112 : 8 : dwfl_build_id_find_elf (Dwfl_Module *mod,
113 : : void **userdata __attribute__ ((unused)),
114 : : const char *modname __attribute__ ((unused)),
115 : : Dwarf_Addr base __attribute__ ((unused)),
116 : : char **file_name, Elf **elfp)
117 : : {
118 : 8 : *elfp = NULL;
119 : 8 : int fd = __libdwfl_open_by_build_id (mod, false, file_name);
120 [ - + ]: 8 : if (fd >= 0)
121 : : {
122 : 0 : Dwfl_Error error = __libdw_open_file (&fd, elfp, true, false);
123 [ # # ]: 0 : if (error != DWFL_E_NOERROR)
124 : 0 : __libdwfl_seterrno (error);
125 [ # # ]: 0 : else if (__libdwfl_find_build_id (mod, false, *elfp) == 2)
126 : : {
127 : : /* This is a backdoor signal to short-circuit the ID refresh. */
128 : 0 : mod->main.valid = true;
129 : 0 : return fd;
130 : : }
131 : : else
132 : : {
133 : : /* This file does not contain the ID it should! */
134 : 0 : elf_end (*elfp);
135 : 0 : *elfp = NULL;
136 : 0 : close (fd);
137 : 0 : fd = -1;
138 : : }
139 : 0 : free (*file_name);
140 : 0 : *file_name = NULL;
141 : : }
142 [ + - ][ + - ]: 8 : else if (errno == 0 && mod->build_id_len > 0)
143 : : /* Setting this with no file yet loaded is a marker that
144 : : the build ID is authoritative even if we also know a
145 : : putative *FILE_NAME. */
146 : 8 : mod->main.valid = true;
147 : :
148 : 8 : return fd;
149 : : }
150 : : INTDEF (dwfl_build_id_find_elf)
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