Show misc_lock.c syntax highlighted
/*
*
* Copyright (c) 2003 The Regents of the University of California. All
* rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Neither the name of the University nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/*
* file locking related utilities
*
* part of libmisc
*
* $Id: misc_lock.c,v 1.3 2003/07/11 22:29:49 cerpa Exp $
*/
char misc_lock_c_cvsid[] = "$Id: misc_lock.c,v 1.3 2003/07/11 22:29:49 cerpa Exp $";
#include <misc.h>
int misc_lock_reg(int fd, int cmd, int type, off_t offset, int whence,
off_t len)
{
struct flock lock;
lock.l_type = type; /* F_RDLCK, F_WRLCK, F_UNLCK */
lock.l_start = offset; /* byte offset, relative to l_whence */
lock.l_whence = whence; /* SEEK_SET, SEEK_CUR, SEEK_END */
lock.l_len = len; /* #bytes (0 means to EOF) */
return( fcntl(fd, cmd, &lock) );
}
pid_t misc_lock_test(int fd, int type, off_t offset, int whence, off_t
len)
{
struct flock lock;
lock.l_type = type; /* F_RDLCK or F_WRLCK */
lock.l_start = offset; /* byte offset, relative to l_whence */
lock.l_whence = whence; /* SEEK_SET, SEEK_CUR, SEEK_END */
lock.l_len = len; /* #bytes (0 means to EOF) */
if (fcntl(fd, F_GETLK, &lock) < 0) {
fprintf(stderr, "misc_lock_test(): fcntl error: %s",
strerror(errno));
exit(1);
}
if (lock.l_type == F_UNLCK)
return(0); /* false, region is not locked by another proc */
return(lock.l_pid); /* true, return pid of lock owner */
}
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