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 3 of the License, or 9 (at your option) 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, see <http://www.gnu.org/licenses/>. */ 18 19/* Written by Jim Meyering. */ 20 21#include <config.h> 22 23#include "save-cwd.h" 24 25#include <errno.h> 26#include <stdbool.h> 27#include <stdio.h> 28#include <stdlib.h> 29#include <unistd.h> 30 31#include "chdir-long.h" 32#include "fcntl--.h" 33#include "xgetcwd.h" 34 35/* On systems without the fchdir function (WOE), pretend that open 36 always returns -1 so that save_cwd resorts to using xgetcwd. 37 Since chdir_long requires fchdir, use chdir instead. */ 38#if !HAVE_FCHDIR 39# undef open 40# define open(File, Flags) (-1) 41# undef fchdir 42# define fchdir(Fd) (abort (), -1) 43# undef chdir_long 44# define chdir_long(Dir) chdir (Dir) 45#endif 46 47/* Record the location of the current working directory in CWD so that 48 the program may change to other directories and later use restore_cwd 49 to return to the recorded location. This function may allocate 50 space using malloc (via xgetcwd) or leave a file descriptor open; 51 use free_cwd to perform the necessary free or close. Upon failure, 52 no memory is allocated, any locally opened file descriptors are 53 closed; return non-zero -- in that case, free_cwd need not be 54 called, but doing so is ok. Otherwise, return zero. 55 56 The `raison d'etre' for this interface is that the working directory 57 is sometimes inaccessible, and getcwd is not robust or as efficient. 58 So, we prefer to use the open/fchdir approach, but fall back on 59 getcwd if necessary. 60 61 Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin, 62 SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it 63 doesn't work for partitions on which auditing is enabled. If 64 you're still using an obsolete system with these problems, please 65 send email to the maintainer of this code. */ 66 67int 68save_cwd (struct saved_cwd *cwd) 69{ 70 cwd->name = NULL; 71 72 cwd->desc = open (".", O_RDONLY); 73 if (cwd->desc < 0) 74 { 75 cwd->name = xgetcwd (); 76 return cwd->name ? 0 : -1; 77 } 78 79 return 0; 80} 81 82/* Change to recorded location, CWD, in directory hierarchy. 83 Upon failure, return -1 (errno is set by chdir or fchdir). 84 Upon success, return zero. */ 85 86int 87restore_cwd (const struct saved_cwd *cwd) 88{ 89 if (0 <= cwd->desc) 90 return fchdir (cwd->desc); 91 else 92 return chdir_long (cwd->name); 93} 94 95void 96free_cwd (struct saved_cwd *cwd) 97{ 98 if (cwd->desc >= 0) 99 close (cwd->desc); 100 if (cwd->name) 101 free (cwd->name); 102} 103