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/* save-cwd.c -- Save and restore current working directory.
Copyright (C) 1995, 1997, 1998, 2003, 2004 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Written by Jim Meyering. */
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include "save-cwd.h"
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#if HAVE_UNISTD_H
# include <unistd.h>
#endif
#if HAVE_FCNTL_H
# include <fcntl.h>
#else
# include <sys/file.h>
#endif
#include <errno.h>
#include "chdir-long.h"
#include "xgetcwd.h"
/* Record the location of the current working directory in CWD so that
the program may change to other directories and later use restore_cwd
to return to the recorded location. This function may allocate
space using malloc (via xgetcwd) or leave a file descriptor open;
use free_cwd to perform the necessary free or close. Upon failure,
no memory is allocated, any locally opened file descriptors are
closed; return non-zero -- in that case, free_cwd need not be
called, but doing so is ok. Otherwise, return zero.
The `raison d'etre' for this interface is that some systems lack
support for fchdir, and getcwd is not robust or as efficient.
So, we prefer to use the open/fchdir approach, but fall back on
getcwd if necessary. Some systems lack fchdir altogether: OS/2,
Cygwin (as of March 2003), SCO Xenix. At least SunOS 4 and Irix 5.3
provide the function, yet it doesn't work for partitions on which
auditing is enabled. */
int
save_cwd (struct saved_cwd *cwd)
{
#if !HAVE_FCHDIR
# undef fchdir
# define fchdir(x) (abort (), 0)
bool have_working_fchdir = false;
bool fchdir_needs_testing = false;
#elif (__sgi || __sun)
static bool have_working_fchdir = true;
bool fchdir_needs_testing = true;
#else
bool have_working_fchdir = true;
bool fchdir_needs_testing = false;
#endif
cwd->desc = -1;
cwd->name = NULL;
if (have_working_fchdir)
{
cwd->desc = open (".", O_RDONLY);
if (cwd->desc < 0)
{
cwd->desc = open (".", O_WRONLY);
if (cwd->desc < 0)
{
cwd->name = xgetcwd ();
return cwd->name ? 0 : -1;
}
}
/* On SunOS 4 and IRIX 5.3, fchdir returns EINVAL when auditing
is enabled, so we have to fall back to chdir. */
if (fchdir_needs_testing && fchdir (cwd->desc) != 0)
{
int saved_errno = errno;
close (cwd->desc);
cwd->desc = -1;
if (saved_errno != EINVAL)
{
errno = saved_errno;
return -1;
}
have_working_fchdir = false;
}
}
if (!have_working_fchdir)
{
cwd->name = xgetcwd ();
if (cwd->name == NULL)
return -1;
}
return 0;
}
/* Change to recorded location, CWD, in directory hierarchy.
Upon failure, return -1 (errno is set by chdir or fchdir).
Upon success, return zero. */
int
restore_cwd (const struct saved_cwd *cwd)
{
if (0 <= cwd->desc)
return fchdir (cwd->desc);
else
return chdir_long (cwd->name);
}
void
free_cwd (struct saved_cwd *cwd)
{
if (cwd->desc >= 0)
close (cwd->desc);
if (cwd->name)
free (cwd->name);
}
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