lib/xgetcwd.c

   1 /* xgetcwd.c -- return current directory with unlimited length
   2    Copyright (C) 1992, 1996 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 Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.  */
  19
  20 #if 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
  30 #include <sys/types.h>
  31 #include "pathmax.h"
  32
  33 #if HAVE_GETCWD
  34 char *getcwd ();
  35 #else
  36 char *getwd ();
  37 # define getcwd(Buf, Max) getwd (Buf)
  38 #endif
  39
  40 /* Amount to increase buffer size by in each try. */
  41 #define PATH_INCR 32
  42
  43 char *xmalloc ();
  44 char *xrealloc ();
  45 void free ();
  46
  47 /* Return the current directory, newly allocated, arbitrarily long.
  48    Return NULL and set errno on error. */
  49
  50 char *
  51 xgetcwd ()
  52 {
  53   char *cwd;
  54   char *ret;
  55   unsigned path_max;
  56
  57   errno = 0;
  58   path_max = (unsigned) PATH_MAX;
  59   path_max += 2;                /* The getcwd docs say to do this. */
  60
  61   cwd = xmalloc (path_max);
  62
  63   errno = 0;
  64   while ((ret = getcwd (cwd, path_max)) == NULL && errno == ERANGE)
  65     {
  66       path_max += PATH_INCR;
  67       cwd = xrealloc (cwd, path_max);
  68       errno = 0;
  69     }
  70
  71   if (ret == NULL)
  72     {
  73       int save_errno = errno;
  74       free (cwd);
  75       errno = save_errno;
  76       return NULL;
  77     }
  78   return cwd;
  79 }