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110 lines
3.2 KiB
C
110 lines
3.2 KiB
C
/* save-cwd.c -- Save and restore current working directory.
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Copyright (C) 1995, 1997, 1998, 2003, 2004, 2005 Free Software
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Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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/* Written by Jim Meyering. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "save-cwd.h"
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#include <errno.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "chdir-long.h"
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#include "fcntl--.h"
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#include "xgetcwd.h"
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/* On systems without the fchdir function (WOE), pretend that open
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always returns -1 so that save_cwd resorts to using xgetcwd.
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Since chdir_long requires fchdir, use chdir instead. */
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#if !HAVE_FCHDIR
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# undef open
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# define open(File, Flags) (-1)
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# undef fchdir
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# define fchdir(Fd) (abort (), -1)
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# undef chdir_long
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# define chdir_long(Dir) chdir (Dir)
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#endif
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/* Record the location of the current working directory in CWD so that
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the program may change to other directories and later use restore_cwd
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to return to the recorded location. This function may allocate
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space using malloc (via xgetcwd) or leave a file descriptor open;
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use free_cwd to perform the necessary free or close. Upon failure,
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no memory is allocated, any locally opened file descriptors are
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closed; return non-zero -- in that case, free_cwd need not be
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called, but doing so is ok. Otherwise, return zero.
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The `raison d'etre' for this interface is that the working directory
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is sometimes inaccessible, and getcwd is not robust or as efficient.
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So, we prefer to use the open/fchdir approach, but fall back on
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getcwd if necessary.
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Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin,
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SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it
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doesn't work for partitions on which auditing is enabled. If
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you're still using an obsolete system with these problems, please
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send email to the maintainer of this code. */
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int
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save_cwd (struct saved_cwd *cwd)
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{
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cwd->name = NULL;
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cwd->desc = open (".", O_RDONLY);
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if (cwd->desc < 0)
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{
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cwd->desc = open (".", O_WRONLY);
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if (cwd->desc < 0)
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{
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cwd->name = xgetcwd ();
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return cwd->name ? 0 : -1;
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}
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}
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return 0;
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}
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/* Change to recorded location, CWD, in directory hierarchy.
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Upon failure, return -1 (errno is set by chdir or fchdir).
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Upon success, return zero. */
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int
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restore_cwd (const struct saved_cwd *cwd)
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{
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if (0 <= cwd->desc)
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return fchdir (cwd->desc);
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else
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return chdir_long (cwd->name);
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}
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void
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free_cwd (struct saved_cwd *cwd)
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{
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if (cwd->desc >= 0)
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close (cwd->desc);
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if (cwd->name)
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free (cwd->name);
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}
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