sysdeps/unix/sysv/linux/dl-origin.h

   1 /* Find path of executable.
   2    Copyright (C) 1998 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 /* On Linux >= 2.1 systems which have the dcache implementation we can get
  22    the path of the application from the /proc/self/exe symlink.  Try this
  23    first and fall back on the generic method if necessary.  */
  24 extern const char *_dl_origin_path;
  25
  26 static inline const char *
  27 get_origin (void)
  28 {
  29   char linkval[PATH_MAX];
  30   char *result;
  31
  32   if (readlink ("/proc/self/exe", linkval, PATH_MAX) != -1
  33       && linkval[0] != '[')
  34     {
  35       /* We can use this value.  */
  36       char *last_slash = strrchr (linkval, '/');
  37       result = (char *) malloc (last_slash - linkval + 1);
  38       if (result == NULL)
  39         result = (char *) -1;
  40       else if (last_slash == linkval)
  41         memcpy (result, "/", 2);
  42       else
  43         *((char *) __mempcpy (result, linkval, last_slash - linkval)) = '\0';
  44     }
  45   else
  46     {
  47       result = (char *) -1;
  48       /* We use the environment variable LD_ORIGIN_PATH.  If it is set make
  49          a copy and strip out trailing slashes.  */
  50       if (_dl_origin_path != NULL)
  51         {
  52           size_t len = strlen (_dl_origin_path);
  53           result = malloc (len + 1);
  54           if (result == NULL)
  55             result = (char *) -1;
  56           else
  57             {
  58               char *cp = __mempcpy (result, _dl_origin_path, len);
  59               while (cp > result + 1 && cp[-1] == '/')
  60                 --cp;
  61               *cp = '\0';
  62             }
  63         }
  64     }
  65
  66   return result;
  67 }