1*7c478bd9Sstevel@tonic-gate /*
2*7c478bd9Sstevel@tonic-gate  * Copyright (c) 1998-2001 Sendmail, Inc. and its suppliers.
3*7c478bd9Sstevel@tonic-gate  *	All rights reserved.
4*7c478bd9Sstevel@tonic-gate  * Copyright (c) 1983, 1995-1997 Eric P. Allman.  All rights reserved.
5*7c478bd9Sstevel@tonic-gate  * Copyright (c) 1988, 1993
6*7c478bd9Sstevel@tonic-gate  *	The Regents of the University of California.  All rights reserved.
7*7c478bd9Sstevel@tonic-gate  *
8*7c478bd9Sstevel@tonic-gate  * By using this file, you agree to the terms and conditions set
9*7c478bd9Sstevel@tonic-gate  * forth in the LICENSE file which can be found at the top level of
10*7c478bd9Sstevel@tonic-gate  * the sendmail distribution.
11*7c478bd9Sstevel@tonic-gate  *
12*7c478bd9Sstevel@tonic-gate  */
14*7c478bd9Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
16*7c478bd9Sstevel@tonic-gate #include <sendmail.h>
18*7c478bd9Sstevel@tonic-gate SM_RCSID("@(#)$Id: lockfile.c,v 8.21 2003/11/10 22:57:38 ca Exp $")
21*7c478bd9Sstevel@tonic-gate /*
22*7c478bd9Sstevel@tonic-gate **  LOCKFILE -- lock a file using flock or (shudder) fcntl locking
23*7c478bd9Sstevel@tonic-gate **
24*7c478bd9Sstevel@tonic-gate **	Parameters:
25*7c478bd9Sstevel@tonic-gate **		fd -- the file descriptor of the file.
26*7c478bd9Sstevel@tonic-gate **		filename -- the file name (for error messages). [unused]
27*7c478bd9Sstevel@tonic-gate **		ext -- the filename extension. [unused]
28*7c478bd9Sstevel@tonic-gate **		type -- type of the lock.  Bits can be:
29*7c478bd9Sstevel@tonic-gate **			LOCK_EX -- exclusive lock.
30*7c478bd9Sstevel@tonic-gate **			LOCK_NB -- non-blocking.
31*7c478bd9Sstevel@tonic-gate **			LOCK_UN -- unlock.
32*7c478bd9Sstevel@tonic-gate **
33*7c478bd9Sstevel@tonic-gate **	Returns:
34*7c478bd9Sstevel@tonic-gate **		true if the lock was acquired.
35*7c478bd9Sstevel@tonic-gate **		false otherwise.
36*7c478bd9Sstevel@tonic-gate */
38*7c478bd9Sstevel@tonic-gate bool
39*7c478bd9Sstevel@tonic-gate lockfile(fd, filename, ext, type)
40*7c478bd9Sstevel@tonic-gate 	int fd;
41*7c478bd9Sstevel@tonic-gate 	char *filename;
42*7c478bd9Sstevel@tonic-gate 	char *ext;
43*7c478bd9Sstevel@tonic-gate 	int type;
44*7c478bd9Sstevel@tonic-gate {
45*7c478bd9Sstevel@tonic-gate #if !HASFLOCK
46*7c478bd9Sstevel@tonic-gate 	int action;
47*7c478bd9Sstevel@tonic-gate 	struct flock lfd;
49*7c478bd9Sstevel@tonic-gate 	memset(&lfd, '\0', sizeof lfd);
50*7c478bd9Sstevel@tonic-gate 	if (bitset(LOCK_UN, type))
51*7c478bd9Sstevel@tonic-gate 		lfd.l_type = F_UNLCK;
52*7c478bd9Sstevel@tonic-gate 	else if (bitset(LOCK_EX, type))
53*7c478bd9Sstevel@tonic-gate 		lfd.l_type = F_WRLCK;
54*7c478bd9Sstevel@tonic-gate 	else
55*7c478bd9Sstevel@tonic-gate 		lfd.l_type = F_RDLCK;
56*7c478bd9Sstevel@tonic-gate 	if (bitset(LOCK_NB, type))
57*7c478bd9Sstevel@tonic-gate 		action = F_SETLK;
58*7c478bd9Sstevel@tonic-gate 	else
59*7c478bd9Sstevel@tonic-gate 		action = F_SETLKW;
61*7c478bd9Sstevel@tonic-gate 	if (fcntl(fd, action, &lfd) >= 0)
62*7c478bd9Sstevel@tonic-gate 		return true;
64*7c478bd9Sstevel@tonic-gate 	/*
65*7c478bd9Sstevel@tonic-gate 	**  On SunOS, if you are testing using -oQ/tmp/mqueue or
66*7c478bd9Sstevel@tonic-gate 	**  -oA/tmp/aliases or anything like that, and /tmp is mounted
67*7c478bd9Sstevel@tonic-gate 	**  as type "tmp" (that is, served from swap space), the
68*7c478bd9Sstevel@tonic-gate 	**  previous fcntl will fail with "Invalid argument" errors.
69*7c478bd9Sstevel@tonic-gate 	**  Since this is fairly common during testing, we will assume
70*7c478bd9Sstevel@tonic-gate 	**  that this indicates that the lock is successfully grabbed.
71*7c478bd9Sstevel@tonic-gate 	*/
73*7c478bd9Sstevel@tonic-gate 	if (errno == EINVAL)
74*7c478bd9Sstevel@tonic-gate 		return true;
76*7c478bd9Sstevel@tonic-gate #else /* !HASFLOCK */
78*7c478bd9Sstevel@tonic-gate 	if (flock(fd, type) >= 0)
79*7c478bd9Sstevel@tonic-gate 		return true;
81*7c478bd9Sstevel@tonic-gate #endif /* !HASFLOCK */
83*7c478bd9Sstevel@tonic-gate 	return false;
84*7c478bd9Sstevel@tonic-gate }