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/*
* Copyright (c) 1998-2000 Sendmail, Inc. and its suppliers.
* All rights reserved.
* Copyright (c) 1983, 1995-1997 Eric P. Allman. All rights reserved.
* Copyright (c) 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* By using this file, you agree to the terms and conditions set
* forth in the LICENSE file which can be found at the top level of
* the sendmail distribution.
*
*/
#ifndef lint
static char id[] = "@(#)$Sendmail: lockfile.c,v 8.3.16.11 2000/11/16 02:54:28 geir Exp $";
#endif /* ! lint */
#include <sendmail.h>
/*
** LOCKFILE -- lock a file using flock or (shudder) fcntl locking
**
** Parameters:
** fd -- the file descriptor of the file.
** filename -- the file name (for error messages). [unused]
** ext -- the filename extension. [unused]
** type -- type of the lock. Bits can be:
** LOCK_EX -- exclusive lock.
** LOCK_NB -- non-blocking.
** LOCK_UN -- unlock.
**
** Returns:
** TRUE if the lock was acquired.
** FALSE otherwise.
*/
bool
lockfile(fd, filename, ext, type)
int fd;
char *filename;
char *ext;
int type;
{
#if !HASFLOCK
int action;
struct flock lfd;
extern int errno;
memset(&lfd, '\0', sizeof lfd);
if (bitset(LOCK_UN, type))
lfd.l_type = F_UNLCK;
else if (bitset(LOCK_EX, type))
lfd.l_type = F_WRLCK;
else
lfd.l_type = F_RDLCK;
if (bitset(LOCK_NB, type))
action = F_SETLK;
else
action = F_SETLKW;
if (fcntl(fd, action, &lfd) >= 0)
return TRUE;
/*
** On SunOS, if you are testing using -oQ/tmp/mqueue or
** -oA/tmp/aliases or anything like that, and /tmp is mounted
** as type "tmp" (that is, served from swap space), the
** previous fcntl will fail with "Invalid argument" errors.
** Since this is fairly common during testing, we will assume
** that this indicates that the lock is successfully grabbed.
*/
if (errno == EINVAL)
return TRUE;
#else /* !HASFLOCK */
if (flock(fd, type) >= 0)
return TRUE;
#endif /* !HASFLOCK */
return FALSE;
}
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