edb89af3 |
1 | /* -*-c-*- |
2 | * |
8656dc50 |
3 | * $Id: lock.h,v 1.3 2004/04/08 01:36:13 mdw Exp $ |
edb89af3 |
4 | * |
5 | * Simplified POSIX locking interface |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
c6e0eaf0 |
30 | #ifndef MLIB_LOCK_H |
31 | #define MLIB_LOCK_H |
edb89af3 |
32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Magic constants ---------------------------------------------------*/ |
38 | |
39 | enum { |
40 | LOCK_UNLOCK, /* Release a lock I obtained */ |
41 | LOCK_EXCL, /* Obtain an exclusive lock */ |
42 | LOCK_NONEXCL /* Obtain a nonexclusive lock */ |
43 | }; |
44 | |
45 | /*----- Functions provided ------------------------------------------------*/ |
46 | |
47 | /* --- @lock_file@ --- * |
48 | * |
49 | * Arguments: @int fd@ = file descriptor to lock |
50 | * @unsigned how@ = type of lock required |
51 | * |
52 | * Returns: 0 if OK, -1 if it failed. |
53 | * |
54 | * Use: Acquires a lock on the given file. The value @how@ |
55 | * specifies the type of lock to acquire: @LOCK_EXCL@ gets |
56 | * an exclusive (write) lock; @LOCK_NONEXCL@ gets a non- |
57 | * exclusive (read) lock and @LOCK_UNLOCK@ releases any locks. |
58 | * Acquiring a lock gets timed out after a while with an |
59 | * error. |
60 | */ |
61 | |
62 | extern int lock_file(int /*fd*/, unsigned /*how*/); |
63 | |
64 | /*----- That's all, folks -------------------------------------------------*/ |
65 | |
66 | #ifdef __cplusplus |
67 | } |
68 | #endif |
69 | |
70 | #endif |