filelock.h revision 8b23a6c7e1aee255004dd19098d4c2462b61b849 
1/* Copyright (C) 2007-2008 The Android Open Source Project
2**
3** This software is licensed under the terms of the GNU General Public
4** License version 2, as published by the Free Software Foundation, and
5** may be copied, distributed, and modified under those terms.
6**
7** This program is distributed in the hope that it will be useful,
8** but WITHOUT ANY WARRANTY; without even the implied warranty of
9** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10** GNU General Public License for more details.
11*/
12
13#ifndef _ANDROID_UTILS_FILELOCK_H
14#define _ANDROID_UTILS_FILELOCK_H
15
16/** FILE LOCKS SUPPORT
17 **
18 ** a FileLock is useful to prevent several emulator instances from using the same
19 ** writable file (e.g. the userdata.img disk images).
20 **
21 ** create a FileLock object with filelock_create(), the function will return
22 ** NULL only if the corresponding path is already locked by another emulator
23 ** of if the path is read-only.
24 **
25 ** note that 'path' can designate a non-existing path and that the lock creation
26 ** function can detect stale file locks that can longer when the emulator
27 ** crashes unexpectedly, and will happily clean them for you.
28 **
29 ** you can call filelock_release() to release a file lock explicitely. otherwise
30 ** all file locks are automatically released when the program exits.
31 **/
32
33typedef struct FileLock  FileLock;
34
35extern FileLock*  filelock_create ( const char*  path );
36extern void       filelock_release( FileLock*  lock );
37
38#endif /* _ANDROID_UTILS_FILELOCK_H */
39