lib/save-cwd.c

   1 /* save-cwd.c -- Save and restore current working directory.
   2    Copyright (C) 1995, 1997, 1998 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 Jim Meyering <meyering@na-net.ornl.gov>.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include "config.h"
  22 #endif
  23
  24 #include <stdio.h>
  25
  26 #ifdef STDC_HEADERS
  27 # include <stdlib.h>
  28 #endif
  29
  30 #if HAVE_UNISTD_H
  31 # include <unistd.h>
  32 #endif
  33
  34 #if HAVE_FCNTL_H
  35 # include <fcntl.h>
  36 #else
  37 # include <sys/file.h>
  38 #endif
  39
  40 #include <errno.h>
  41 #ifndef errno
  42 extern int errno;
  43 #endif
  44
  45 #include "save-cwd.h"
  46 #include "error.h"
  47
  48 char *xgetcwd PARAMS ((void));
  49
  50 /* Record the location of the current working directory in CWD so that
  51    the program may change to other directories and later use restore_cwd
  52    to return to the recorded location.  This function may allocate
  53    space using malloc (via xgetcwd) or leave a file descriptor open;
  54    use free_cwd to perform the necessary free or close.  Upon failure,
  55    no memory is allocated, any locally opened file descriptors are
  56    closed;  return non-zero -- in that case, free_cwd need not be
  57    called, but doing so is ok.  Otherwise, return zero.  */
  58
  59 int
  60 save_cwd (struct saved_cwd *cwd)
  61 {
  62   static int have_working_fchdir = 1;
  63
  64   cwd->desc = -1;
  65   cwd->name = NULL;
  66
  67   if (have_working_fchdir)
  68     {
  69 #if HAVE_FCHDIR
  70       cwd->desc = open (".", O_RDONLY);
  71       if (cwd->desc < 0)
  72         {
  73           error (0, errno, "cannot open current directory");
  74           return 1;
  75         }
  76
  77 # if __sun__ || sun
  78       /* On SunOS 4, fchdir returns EINVAL if accounting is enabled,
  79          so we have to fall back to chdir.  */
  80       if (fchdir (cwd->desc))
  81         {
  82           if (errno == EINVAL)
  83             {
  84               close (cwd->desc);
  85               cwd->desc = -1;
  86               have_working_fchdir = 0;
  87             }
  88           else
  89             {
  90               error (0, errno, "current directory");
  91               close (cwd->desc);
  92               cwd->desc = -1;
  93               return 1;
  94             }
  95         }
  96 # endif /* __sun__ || sun */
  97 #else
  98 # define fchdir(x) (abort (), 0)
  99       have_working_fchdir = 0;
 100 #endif
 101     }
 102
 103   if (!have_working_fchdir)
 104     {
 105       cwd->name = xgetcwd ();
 106       if (cwd->name == NULL)
 107         {
 108           error (0, errno, "cannot get current directory");
 109           return 1;
 110         }
 111     }
 112   return 0;
 113 }
 114
 115 /* Change to recorded location, CWD, in directory hierarchy.
 116    If "saved working directory", NULL))
 117    */
 118
 119 int
 120 restore_cwd (const struct saved_cwd *cwd, const char *dest, const char *from)
 121 {
 122   int fail = 0;
 123   if (cwd->desc >= 0)
 124     {
 125       if (fchdir (cwd->desc))
 126         {
 127           error (0, errno, "cannot return to %s%s%s",
 128                  (dest ? dest : "saved working directory"),
 129                  (from ? " from " : ""),
 130                  (from ? from : ""));
 131           fail = 1;
 132         }
 133     }
 134   else if (chdir (cwd->name) < 0)
 135     {
 136       error (0, errno, "%s", cwd->name);
 137       fail = 1;
 138     }
 139   return fail;
 140 }
 141
 142 void
 143 free_cwd (struct saved_cwd *cwd)
 144 {
 145   if (cwd->desc >= 0)
 146     close (cwd->desc);
 147   if (cwd->name)
 148     free (cwd->name);
 149 }