glibc/sysdeps/unix/sysv/linux/dl-origin.c

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/* Find path of executable.
Copyright (C) 1998, 1999 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>
#include <elf/ldsodefs.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. */
extern const char *_dl_origin_path;
const char *
_dl_get_origin (void)
{
char linkval[PATH_MAX];
char *result;
if (readlink ("/proc/self/exe", linkval, PATH_MAX) != -1
&& linkval[0] != '[')
{
/* We can use this value. */
char *last_slash = strrchr (linkval, '/');
result = (char *) malloc (last_slash - linkval + 1);
if (result == NULL)
result = (char *) -1;
else if (last_slash == linkval)
memcpy (result, "/", 2);
else
*((char *) __mempcpy (result, linkval, last_slash - linkval)) = '\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 (_dl_origin_path != NULL)
{
size_t len = strlen (_dl_origin_path);
result = malloc (len + 1);
if (result == NULL)
result = (char *) -1;
else
{
char *cp = __mempcpy (result, _dl_origin_path, len);
while (cp > result + 1 && cp[-1] == '/')
--cp;
*cp = '\0';
}
}
}
return result;
}