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 char *getwd ();
  34 #define getcwd(buf, max) getwd (buf)
  35 #else
  36 char *getcwd ();
  37 #endif
  38
  39 /* Amount to increase buffer size by in each try. */
  40 #define PATH_INCR 32
  41
  42 char *xmalloc ();
  43 char *xrealloc ();
  44 void free ();
  45
  46 /* Return the current directory, newly allocated, arbitrarily long.
  47    Return NULL and set errno on error. */
  48
  49 char *
  50 xgetcwd ()
  51 {
  52   char *cwd;
  53   char *ret;
  54   unsigned path_max;
  55
  56   errno = 0;
  57   path_max = (unsigned) PATH_MAX;
  58   path_max += 2;                /* The getcwd docs say to do this. */
  59
  60   cwd = xmalloc (path_max);
  61
  62   errno = 0;
  63   while ((ret = getcwd (cwd, path_max)) == NULL && errno == ERANGE)
  64     {
  65       path_max += PATH_INCR;
  66       cwd = xrealloc (cwd, path_max);
  67       errno = 0;
  68     }
  69
  70   if (ret == NULL)
  71     {
  72       int save_errno = errno;
  73       free (cwd);
  74       errno = save_errno;
  75       return NULL;
  76     }
  77   return cwd;
  78 }