lib/xgetcwd.c

   1 /* xgetcwd.c -- return current directory with unlimited length
   2    Copyright (C) 1992 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include <config.h>
  22 #endif
  23
  24 #include <stdio.h>
  25 #include <errno.h>
  26 #ifndef errno
  27 extern int errno;
  28 #endif
  29 #include <sys/types.h>
  30 #include "pathmax.h"
  31
  32 #ifndef HAVE_GETCWD
  33 #define getcwd(buf, max) getwd (buf)
  34 #else
  35 char *getcwd ();
  36 #endif
  37
  38 /* Amount to increase buffer size by in each try. */
  39 #define PATH_INCR 32
  40
  41 char *xmalloc ();
  42 char *xrealloc ();
  43 void free ();
  44
  45 /* Return the current directory, newly allocated, arbitrarily long.
  46    Return NULL and set errno on error. */
  47
  48 char *
  49 xgetcwd ()
  50 {
  51   char *cwd;
  52   char *ret;
  53   unsigned path_max;
  54
  55   errno = 0;
  56   path_max = (unsigned) PATH_MAX;
  57   path_max += 2;                /* The getcwd docs say to do this. */
  58
  59   cwd = xmalloc (path_max);
  60
  61   errno = 0;
  62   while ((ret = getcwd (cwd, path_max)) == NULL && errno == ERANGE)
  63     {
  64       path_max += PATH_INCR;
  65       cwd = xrealloc (cwd, path_max);
  66       errno = 0;
  67     }
  68
  69   if (ret == NULL)
  70     {
  71       int save_errno = errno;
  72       free (cwd);
  73       errno = save_errno;
  74       return NULL;
  75     }
  76   return cwd;
  77 }