1 /* Find path of executable.
2 Copyright (C) 1998-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <assert.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <unistd.h>
23 #include <sys/param.h>
24 #include <ldsodefs.h>
25 #include <sysdep.h>
26
27 #include <dl-dst.h>
28
29 /* On Linux >= 2.1 systems which have the dcache implementation we can get
30 the path of the application from the /proc/self/exe symlink. Try this
31 first and fall back on the generic method if necessary. */
32
33 const char *
_dl_get_origin(void)34 _dl_get_origin (void)
35 {
36 char linkval[PATH_MAX];
37 char *result;
38 int len;
39
40 len = INTERNAL_SYSCALL_CALL (readlink, "/proc/self/exe", linkval,
41 sizeof (linkval));
42 if (! INTERNAL_SYSCALL_ERROR_P (len) && len > 0 && linkval[0] != '[')
43 {
44 /* We can use this value. */
45 assert (linkval[0] == '/');
46 while (len > 1 && linkval[len - 1] != '/')
47 --len;
48 result = (char *) malloc (len + 1);
49 if (result == NULL)
50 result = (char *) -1;
51 else if (len == 1)
52 memcpy (result, "/", 2);
53 else
54 *((char *) __mempcpy (result, linkval, len - 1)) = '\0';
55 }
56 else
57 {
58 result = (char *) -1;
59 /* We use the environment variable LD_ORIGIN_PATH. If it is set make
60 a copy and strip out trailing slashes. */
61 if (GLRO(dl_origin_path) != NULL)
62 {
63 size_t len = strlen (GLRO(dl_origin_path));
64 result = (char *) malloc (len + 1);
65 if (result == NULL)
66 result = (char *) -1;
67 else
68 {
69 char *cp = __mempcpy (result, GLRO(dl_origin_path), len);
70 while (cp > result + 1 && cp[-1] == '/')
71 --cp;
72 *cp = '\0';
73 }
74 }
75 }
76
77 return result;
78 }
79