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/* Find path of executable.
Copyright (C) 1998-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/param.h>
#include <ldsodefs.h>
#include <sysdep.h>
#include <dl-dst.h>
/* On Linux >= 2.1 systems which have the dcache implementation we can get
the path of the application from the /proc/self/exe symlink. Try this
first and fall back on the generic method if necessary. */
const char *
_dl_get_origin (void)
{
char linkval[PATH_MAX];
char *result;
int len;
INTERNAL_SYSCALL_DECL (err);
len = INTERNAL_SYSCALL (readlinkat, err, 4, AT_FDCWD, "/proc/self/exe",
linkval, sizeof (linkval));
if (! INTERNAL_SYSCALL_ERROR_P (len, err) && len > 0 && linkval[0] != '[')
{
/* We can use this value. */
assert (linkval[0] == '/');
while (len > 1 && linkval[len - 1] != '/')
--len;
result = (char *) malloc (len + 1);
if (result == NULL)
result = (char *) -1;
else if (len == 1)
memcpy (result, "/", 2);
else
*((char *) __mempcpy (result, linkval, len - 1)) = '\0';
}
else
{
result = (char *) -1;
/* We use the environment variable LD_ORIGIN_PATH. If it is set make
a copy and strip out trailing slashes. */
if (GLRO(dl_origin_path) != NULL)
{
size_t len = strlen (GLRO(dl_origin_path));
result = (char *) malloc (len + 1);
if (result == NULL)
result = (char *) -1;
else
{
char *cp = __mempcpy (result, GLRO(dl_origin_path), len);
while (cp > result + 1 && cp[-1] == '/')
--cp;
*cp = '\0';
}
}
}
return result;
}
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