| 1 | /* save-cwd.c -- Save and restore current working directory. |
| 2 | |
| 3 | Copyright (C) 1995, 1997-1998, 2003-2006, 2009-2016 Free Software |
| 4 | 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 <fcntl.h> |
| 27 | #include <stdbool.h> |
| 28 | #include <stdio.h> |
| 29 | #include <stdlib.h> |
| 30 | |
| 31 | #include "chdir-long.h" |
| 32 | #include "unistd--.h" |
| 33 | #include "cloexec.h" |
| 34 | |
| 35 | #if GNULIB_FCNTL_SAFER |
| 36 | # include "fcntl--.h" |
| 37 | #else |
| 38 | # define GNULIB_FCNTL_SAFER 0 |
| 39 | #endif |
| 40 | |
| 41 | /* Record the location of the current working directory in CWD so that |
| 42 | the program may change to other directories and later use restore_cwd |
| 43 | to return to the recorded location. This function may allocate |
| 44 | space using malloc (via getcwd) or leave a file descriptor open; |
| 45 | use free_cwd to perform the necessary free or close. Upon failure, |
| 46 | no memory is allocated, any locally opened file descriptors are |
| 47 | closed; return non-zero -- in that case, free_cwd need not be |
| 48 | called, but doing so is ok. Otherwise, return zero. |
| 49 | |
| 50 | The _raison d'etre_ for this interface is that the working directory |
| 51 | is sometimes inaccessible, and getcwd is not robust or as efficient. |
| 52 | So, we prefer to use the open/fchdir approach, but fall back on |
| 53 | getcwd if necessary. This module works for most cases with just |
| 54 | the getcwd-lgpl module, but to be truly robust, use the getcwd module. |
| 55 | |
| 56 | Some systems lack fchdir altogether: e.g., OS/2, pre-2001 Cygwin, |
| 57 | SCO Xenix. Also, SunOS 4 and Irix 5.3 provide the function, yet it |
| 58 | doesn't work for partitions on which auditing is enabled. If |
| 59 | you're still using an obsolete system with these problems, please |
| 60 | send email to the maintainer of this code. */ |
| 61 | |
| 62 | int |
| 63 | save_cwd (struct saved_cwd *cwd) |
| 64 | { |
| 65 | cwd->name = NULL; |
| 66 | |
| 67 | cwd->desc = open (".", O_SEARCH); |
| 68 | if (!GNULIB_FCNTL_SAFER) |
| 69 | cwd->desc = fd_safer (cwd->desc); |
| 70 | if (cwd->desc < 0) |
| 71 | { |
| 72 | cwd->name = getcwd (NULL, 0); |
| 73 | return cwd->name ? 0 : -1; |
| 74 | } |
| 75 | |
| 76 | set_cloexec_flag (cwd->desc, true); |
| 77 | return 0; |
| 78 | } |
| 79 | |
| 80 | /* Change to recorded location, CWD, in directory hierarchy. |
| 81 | Upon failure, return -1 (errno is set by chdir or fchdir). |
| 82 | Upon success, return zero. */ |
| 83 | |
| 84 | int |
| 85 | restore_cwd (const struct saved_cwd *cwd) |
| 86 | { |
| 87 | if (0 <= cwd->desc) |
| 88 | return fchdir (cwd->desc); |
| 89 | else |
| 90 | return chdir_long (cwd->name); |
| 91 | } |
| 92 | |
| 93 | void |
| 94 | free_cwd (struct saved_cwd *cwd) |
| 95 | { |
| 96 | if (cwd->desc >= 0) |
| 97 | close (cwd->desc); |
| 98 | free (cwd->name); |
| 99 | } |