1/* save-cwd.c -- Save and restore current working directory. 2 3 Copyright (C) 1995, 1997, 1998, 2003, 2004, 2005, 2006 Free 4 Software Foundation, Inc. 5 6 This program is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program; if not, write to the Free Software Foundation, 18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 19 20/* Written by Jim Meyering. */ 21 22#include <config.h> 23 24#include "save-cwd.h" 25 26#include <errno.h> 27#include <stdbool.h> 28#include <stdio.h> 29#include <stdlib.h> 30#include <unistd.h> 31 32#include "chdir-long.h" 33#include "fcntl--.h" 34#include "xgetcwd.h" 35 36/* On systems without the fchdir function (WOE), pretend that open 37 always returns -1 so that save_cwd resorts to using xgetcwd. 38 Since chdir_long requires fchdir, use chdir instead. */ 39#if !HAVE_FCHDIR 40# undef open 41# define open(File, Flags) (-1) 42# undef fchdir 43# define fchdir(Fd) (abort (), -1) 44# undef chdir_long 45# define chdir_long(Dir) chdir (Dir) 46#endif 47 48/* Record the location of the current working directory in CWD so that 49 the program may change to other directories and later use restore_cwd 50 to return to the recorded location. This function may allocate 51 space using malloc (via xgetcwd) or leave a file descriptor open; 52 use free_cwd to perform the necessary free or close. Upon failure, 53 no memory is allocated, any locally opened file descriptors are 54 closed; return non-zero -- in that case, free_cwd need not be 55 called, but doing so is ok. Otherwise, return zero. 56 57 The `raison d'etre' for this interface is that the working directory 58 is sometimes inaccessible, and getcwd is not robust or as efficient. 59 So, we prefer to use the open/fchdir approach, but fall back on 60 getcwd if necessary. 61 62 Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin, 63 SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it 64 doesn't work for partitions on which auditing is enabled. If 65 you're still using an obsolete system with these problems, please 66 send email to the maintainer of this code. */ 67 68int 69save_cwd (struct saved_cwd *cwd) 70{ 71 cwd->name = NULL; 72 73 cwd->desc = open (".", O_RDONLY); 74 if (cwd->desc < 0) 75 { 76 cwd->name = xgetcwd (); 77 return cwd->name ? 0 : -1; 78 } 79 80 return 0; 81} 82 83/* Change to recorded location, CWD, in directory hierarchy. 84 Upon failure, return -1 (errno is set by chdir or fchdir). 85 Upon success, return zero. */ 86 87int 88restore_cwd (const struct saved_cwd *cwd) 89{ 90 if (0 <= cwd->desc) 91 return fchdir (cwd->desc); 92 else 93 return chdir_long (cwd->name); 94} 95 96void 97free_cwd (struct saved_cwd *cwd) 98{ 99 if (cwd->desc >= 0) 100 close (cwd->desc); 101 if (cwd->name) 102 free (cwd->name); 103} 104