1/* Find path of executable.
2 Copyright (C) 1998-2018 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
19
20#include <assert.h>
21#include <stdlib.h>
22#include <string.h>
23#include <unistd.h>
24#include <sys/param.h>
25#include <ldsodefs.h>
26#include <sysdep.h>
27
28#include <dl-dst.h>
29
30/* On Linux >= 2.1 systems which have the dcache implementation we can get
31 the path of the application from the /proc/self/exe symlink. Try this
32 first and fall back on the generic method if necessary. */
33
34const char *
35_dl_get_origin (void)
36{
37 char linkval[PATH_MAX];
38 char *result;
39 int len;
40 INTERNAL_SYSCALL_DECL (err);
41
42 len = INTERNAL_SYSCALL (readlink, err, 3, "/proc/self/exe", linkval,
43 sizeof (linkval));
44 if (! INTERNAL_SYSCALL_ERROR_P (len, err) && len > 0 && linkval[0] != '[')
45 {
46 /* We can use this value. */
47 assert (linkval[0] == '/');
48 while (len > 1 && linkval[len - 1] != '/')
49 --len;
50 result = (char *) malloc (len + 1);
51 if (result == NULL)
52 result = (char *) -1;
53 else if (len == 1)
54 memcpy (result, "/", 2);
55 else
56 *((char *) __mempcpy (result, linkval, len - 1)) = '\0';
57 }
58 else
59 {
60 result = (char *) -1;
61 /* We use the environment variable LD_ORIGIN_PATH. If it is set make
62 a copy and strip out trailing slashes. */
63 if (GLRO(dl_origin_path) != NULL)
64 {
65 size_t len = strlen (GLRO(dl_origin_path));
66 result = (char *) malloc (len + 1);
67 if (result == NULL)
68 result = (char *) -1;
69 else
70 {
71 char *cp = __mempcpy (result, GLRO(dl_origin_path), len);
72 while (cp > result + 1 && cp[-1] == '/')
73 --cp;
74 *cp = '\0';
75 }
76 }
77 }
78
79 return result;
80}
81