3 * $Id: lock.h,v 1.2 1999/12/10 23:42:04 mdw Exp $
5 * Simplified POSIX locking interface
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.2 1999/12/10 23:42:04 mdw
34 * Change header file guard names.
36 * Revision 1.1 1999/05/15 10:33:53 mdw
37 * Add simplified locking code.
48 /*----- Magic constants ---------------------------------------------------*/
51 LOCK_UNLOCK, /* Release a lock I obtained */
52 LOCK_EXCL, /* Obtain an exclusive lock */
53 LOCK_NONEXCL /* Obtain a nonexclusive lock */
56 /*----- Functions provided ------------------------------------------------*/
58 /* --- @lock_file@ --- *
60 * Arguments: @int fd@ = file descriptor to lock
61 * @unsigned how@ = type of lock required
63 * Returns: 0 if OK, -1 if it failed.
65 * Use: Acquires a lock on the given file. The value @how@
66 * specifies the type of lock to acquire: @LOCK_EXCL@ gets
67 * an exclusive (write) lock; @LOCK_NONEXCL@ gets a non-
68 * exclusive (read) lock and @LOCK_UNLOCK@ releases any locks.
69 * Acquiring a lock gets timed out after a while with an
73 extern int lock_file(int /*fd*/, unsigned /*how*/);
75 /*----- That's all, folks -------------------------------------------------*/