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- /* save-cwd.c -- Save and restore current working directory.
- Copyright (C) 1995, 1997-1998, 2003-2006, 2009-2021 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 3 of the License, 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, see <https://www.gnu.org/licenses/>. */
- /* Written by Jim Meyering. */
- #include <config.h>
- #include "save-cwd.h"
- #include <errno.h>
- #include <fcntl.h>
- #include <stdbool.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include "chdir-long.h"
- #include "unistd--.h"
- #if GNULIB_FCNTL_SAFER
- # include "fcntl--.h"
- #else
- # define GNULIB_FCNTL_SAFER 0
- #endif
- /* 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 getcwd) 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 the working directory
- is sometimes inaccessible, and getcwd is not robust or as efficient.
- So, we prefer to use the open/fchdir approach, but fall back on
- getcwd if necessary. This module works for most cases with just
- the getcwd-lgpl module, but to be truly robust, use the getcwd module.
- Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin,
- SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it
- doesn't work for partitions on which auditing is enabled. If
- you're still using an obsolete system with these problems, please
- send email to the maintainer of this code. */
- int
- save_cwd (struct saved_cwd *cwd)
- {
- cwd->name = NULL;
- cwd->desc = open (".", O_SEARCH | O_CLOEXEC);
- if (!GNULIB_FCNTL_SAFER)
- cwd->desc = fd_safer_flag (cwd->desc, O_CLOEXEC);
- if (cwd->desc < 0)
- {
- cwd->name = getcwd (NULL, 0);
- return cwd->name ? 0 : -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);
- free (cwd->name);
- }
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