edb89af3 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: lock.h,v 1.1 1999/05/15 10:33:53 mdw Exp $ |
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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: lock.h,v $ |
33 | * Revision 1.1 1999/05/15 10:33:53 mdw |
34 | * Add simplified locking code. |
35 | * |
36 | */ |
37 | |
38 | #ifndef LOCK_H |
39 | #define LOCK_H |
40 | |
41 | #ifdef __cplusplus |
42 | extern "C" { |
43 | #endif |
44 | |
45 | /*----- Magic constants ---------------------------------------------------*/ |
46 | |
47 | enum { |
48 | LOCK_UNLOCK, /* Release a lock I obtained */ |
49 | LOCK_EXCL, /* Obtain an exclusive lock */ |
50 | LOCK_NONEXCL /* Obtain a nonexclusive lock */ |
51 | }; |
52 | |
53 | /*----- Functions provided ------------------------------------------------*/ |
54 | |
55 | /* --- @lock_file@ --- * |
56 | * |
57 | * Arguments: @int fd@ = file descriptor to lock |
58 | * @unsigned how@ = type of lock required |
59 | * |
60 | * Returns: 0 if OK, -1 if it failed. |
61 | * |
62 | * Use: Acquires a lock on the given file. The value @how@ |
63 | * specifies the type of lock to acquire: @LOCK_EXCL@ gets |
64 | * an exclusive (write) lock; @LOCK_NONEXCL@ gets a non- |
65 | * exclusive (read) lock and @LOCK_UNLOCK@ releases any locks. |
66 | * Acquiring a lock gets timed out after a while with an |
67 | * error. |
68 | */ |
69 | |
70 | extern int lock_file(int /*fd*/, unsigned /*how*/); |
71 | |
72 | /*----- That's all, folks -------------------------------------------------*/ |
73 | |
74 | #ifdef __cplusplus |
75 | } |
76 | #endif |
77 | |
78 | #endif |