83 lines
1.9 KiB
C
83 lines
1.9 KiB
C
/*
|
|
* Copyright (c) 1998-2001 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.
|
|
*
|
|
*/
|
|
|
|
#include <sendmail.h>
|
|
|
|
SM_RCSID("@(#)$Id: lockfile.c,v 8.21 2003/11/10 22:57:38 ca Exp $")
|
|
|
|
|
|
/*
|
|
** 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;
|
|
|
|
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;
|
|
}
|