contrib/tar/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 #ifndef O_DIRECTORY
  46 # define O_DIRECTORY 0
  47 #endif
  48
  49 #include "save-cwd.h"
  50 #include "error.h"
  51
  52 char *xgetcwd PARAMS ((void));
  53
  54 /* Record the location of the current working directory in CWD so that
  55    the program may change to other directories and later use restore_cwd
  56    to return to the recorded location.  This function may allocate
  57    space using malloc (via xgetcwd) or leave a file descriptor open;
  58    use free_cwd to perform the necessary free or close.  Upon failure,
  59    no memory is allocated, any locally opened file descriptors are
  60    closed;  return non-zero -- in that case, free_cwd need not be
  61    called, but doing so is ok.  Otherwise, return zero.  */
  62
  63 int
  64 save_cwd (struct saved_cwd *cwd)
  65 {
  66   static int have_working_fchdir = 1;
  67
  68   cwd->desc = -1;
  69   cwd->name = NULL;
  70
  71   if (have_working_fchdir)
  72     {
  73 #if HAVE_FCHDIR
  74       cwd->desc = open (".", O_RDONLY | O_DIRECTORY);
  75       if (cwd->desc < 0)
  76         {
  77           error (0, errno, "cannot open current directory");
  78           return 1;
  79         }
  80
  81 # if __sun__ || sun
  82       /* On SunOS 4, fchdir returns EINVAL if accounting is enabled,
  83          so we have to fall back to chdir.  */
  84       if (fchdir (cwd->desc))
  85         {
  86           if (errno == EINVAL)
  87             {
  88               close (cwd->desc);
  89               cwd->desc = -1;
  90               have_working_fchdir = 0;
  91             }
  92           else
  93             {
  94               error (0, errno, "current directory");
  95               close (cwd->desc);
  96               cwd->desc = -1;
  97               return 1;
  98             }
  99         }
 100 # endif /* __sun__ || sun */
 101 #else
 102 # define fchdir(x) (abort (), 0)
 103       have_working_fchdir = 0;
 104 #endif
 105     }
 106
 107   if (!have_working_fchdir)
 108     {
 109       cwd->name = xgetcwd ();
 110       if (cwd->name == NULL)
 111         {
 112           error (0, errno, "cannot get current directory");
 113           return 1;
 114         }
 115     }
 116   return 0;
 117 }
 118
 119 /* Change to recorded location, CWD, in directory hierarchy.
 120    If "saved working directory", NULL))
 121    */
 122
 123 int
 124 restore_cwd (const struct saved_cwd *cwd, const char *dest, const char *from)
 125 {
 126   int fail = 0;
 127   if (cwd->desc >= 0)
 128     {
 129       if (fchdir (cwd->desc))
 130         {
 131           error (0, errno, "cannot return to %s%s%s",
 132                  (dest ? dest : "saved working directory"),
 133                  (from ? " from " : ""),
 134                  (from ? from : ""));
 135           fail = 1;
 136         }
 137     }
 138   else if (chdir (cwd->name) < 0)
 139     {
 140       error (0, errno, "%s", cwd->name);
 141       fail = 1;
 142     }
 143   return fail;
 144 }
 145
 146 void
 147 free_cwd (struct saved_cwd *cwd)
 148 {
 149   if (cwd->desc >= 0)
 150     close (cwd->desc);
 151   if (cwd->name)
 152     free (cwd->name);
 153 }