• Home
  • History
  • Annotate
  • Line#
  • Navigate
  • Raw
  • Download
  • only in /netgear-WNDR4500v2-V1.0.0.60_1.0.38/ap/gpl/timemachine/netatalk-2.2.5/libatalk/util/
1/*
2   $Id: locking.c,v 1.4 2010-01-05 19:05:52 franklahm Exp $
3   Copyright (c) 2009 Frank Lahm <franklahm@gmail.com>
4
5   This program is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by
7   the Free Software Foundation; either version 2 of the License, or
8   (at your option) any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13   GNU General Public License for more details.
14*/
15
16/*!
17 * @file
18 * Netatalk utility functions
19 */
20
21#ifdef HAVE_CONFIG_H
22#include "config.h"
23#endif /* HAVE_CONFIG_H */
24
25#include <unistd.h>
26#include <fcntl.h>
27#include <atalk/util.h>
28
29/*!
30 * @def read_lock(fd, offset, whence, len)
31 * @brief place read lock on file
32 *
33 * @param   fd         (r) File descriptor
34 * @param   offset     (r) byte offset relative to l_whence
35 * @param   whence     (r) SEEK_SET, SEEK_CUR, SEEK_END
36 * @param   len        (r) no. of bytes (0 means to EOF)
37 *
38 * @returns 0 on success, -1 on failure with
39 *          fcntl return value and errno
40 */
41
42/*!
43 * @def write_lock(fd, offset, whence, len)
44 * @brief place write lock on file
45 *
46 * @param   fd         (r) File descriptor
47 * @param   offset     (r) byte offset relative to l_whence
48 * @param   whence     (r) SEEK_SET, SEEK_CUR, SEEK_END
49 * @param   len        (r) no. of bytes (0 means to EOF)
50 *
51 * @returns 0 on success, -1 on failure with
52 *          fcntl return value and errno
53 */
54
55/*!
56 * @def unlock(fd, offset, whence, len)
57 * @brief unlock a file
58 *
59 * @param   fd         (r) File descriptor
60 * @param   offset     (r) byte offset relative to l_whence
61 * @param   whence     (r) SEEK_SET, SEEK_CUR, SEEK_END
62 * @param   len        (r) no. of bytes (0 means to EOF)
63 *
64 * @returns 0 on success, -1 on failure with
65 *          fcntl return value and errno
66 */
67
68/*!
69 * @brief lock a file with fctnl
70 *
71 * This function is called via the macros:
72 * read_lock, write_lock, un_lock
73 *
74 * @param   fd         (r) File descriptor
75 * @param   cmd        (r) cmd to fcntl, only F_SETLK is usable here
76 * @param   type       (r) F_RDLCK, F_WRLCK, F_UNLCK
77 * @param   offset     (r) byte offset relative to l_whence
78 * @param   whence     (r) SEEK_SET, SEEK_CUR, SEEK_END
79 * @param   len        (r) no. of bytes (0 means to EOF)
80 *
81 * @returns 0 on success, -1 on failure with
82 *          fcntl return value and errno
83 *
84 * @sa read_lock, write_lock, unlock
85 */
86int lock_reg(int fd, int cmd, int type, off_t offset, int whence, off_t len)
87{
88    struct flock lock;
89
90    lock.l_type = type;
91    lock.l_start = offset;
92    lock.l_whence = whence;
93    lock.l_len = len;
94
95    return (fcntl(fd, cmd, &lock));
96}
97