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/*
$Id: locking.c,v 1.4 2010-01-05 19:05:52 franklahm Exp $
Copyright (c) 2009 Frank Lahm <franklahm@gmail.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
*/
/*!
* @file
* Netatalk utility functions
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */
#include <unistd.h>
#include <fcntl.h>
#include <atalk/util.h>
/*!
* @def read_lock(fd, offset, whence, len)
* @brief place read lock on file
*
* @param fd (r) File descriptor
* @param offset (r) byte offset relative to l_whence
* @param whence (r) SEEK_SET, SEEK_CUR, SEEK_END
* @param len (r) no. of bytes (0 means to EOF)
*
* @returns 0 on success, -1 on failure with
* fcntl return value and errno
*/
/*!
* @def write_lock(fd, offset, whence, len)
* @brief place write lock on file
*
* @param fd (r) File descriptor
* @param offset (r) byte offset relative to l_whence
* @param whence (r) SEEK_SET, SEEK_CUR, SEEK_END
* @param len (r) no. of bytes (0 means to EOF)
*
* @returns 0 on success, -1 on failure with
* fcntl return value and errno
*/
/*!
* @def unlock(fd, offset, whence, len)
* @brief unlock a file
*
* @param fd (r) File descriptor
* @param offset (r) byte offset relative to l_whence
* @param whence (r) SEEK_SET, SEEK_CUR, SEEK_END
* @param len (r) no. of bytes (0 means to EOF)
*
* @returns 0 on success, -1 on failure with
* fcntl return value and errno
*/
/*!
* @brief lock a file with fctnl
*
* This function is called via the macros:
* read_lock, write_lock, un_lock
*
* @param fd (r) File descriptor
* @param cmd (r) cmd to fcntl, only F_SETLK is usable here
* @param type (r) F_RDLCK, F_WRLCK, F_UNLCK
* @param offset (r) byte offset relative to l_whence
* @param whence (r) SEEK_SET, SEEK_CUR, SEEK_END
* @param len (r) no. of bytes (0 means to EOF)
*
* @returns 0 on success, -1 on failure with
* fcntl return value and errno
*
* @sa read_lock, write_lock, unlock
*/
int lock_reg(int fd, int cmd, int type, off_t offset, int whence, off_t len)
{
struct flock lock;
lock.l_type = type;
lock.l_start = offset;
lock.l_whence = whence;
lock.l_len = len;
return (fcntl(fd, cmd, &lock));
}
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