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