glibc/sysdeps/generic/dl-origin.h

/* Find path of executable.
   Copyright (C) 1998 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.  */

/* Generally it is not possible to implement this.  We have to fall
   back on a solution where the user provides the information.  */
extern const char *_dl_origin_path;

static inline const char *
get_origin (void)
{
  char *result = (char *) -1;
  /* We use te 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 && cp[-1] == '/')
	    --cp;
	  *cp = '\0';
	}
    }

  return result;
}