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83 lines
1.9 KiB
C
83 lines
1.9 KiB
C
/*
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* Copyright (c) 1998-2001 Sendmail, Inc. and its suppliers.
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* All rights reserved.
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* Copyright (c) 1983, 1995-1997 Eric P. Allman. All rights reserved.
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* Copyright (c) 1988, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* By using this file, you agree to the terms and conditions set
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* forth in the LICENSE file which can be found at the top level of
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* the sendmail distribution.
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*
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*/
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#include <sendmail.h>
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SM_RCSID("@(#)$Id: lockfile.c,v 8.21 2003/11/10 22:57:38 ca Exp $")
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/*
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** LOCKFILE -- lock a file using flock or (shudder) fcntl locking
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**
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** Parameters:
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** fd -- the file descriptor of the file.
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** filename -- the file name (for error messages). [unused]
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** ext -- the filename extension. [unused]
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** type -- type of the lock. Bits can be:
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** LOCK_EX -- exclusive lock.
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** LOCK_NB -- non-blocking.
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** LOCK_UN -- unlock.
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**
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** Returns:
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** true if the lock was acquired.
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** false otherwise.
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*/
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bool
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lockfile(fd, filename, ext, type)
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int fd;
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char *filename;
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char *ext;
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int type;
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{
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#if !HASFLOCK
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int action;
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struct flock lfd;
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memset(&lfd, '\0', sizeof lfd);
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if (bitset(LOCK_UN, type))
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lfd.l_type = F_UNLCK;
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else if (bitset(LOCK_EX, type))
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lfd.l_type = F_WRLCK;
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else
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lfd.l_type = F_RDLCK;
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if (bitset(LOCK_NB, type))
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action = F_SETLK;
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else
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action = F_SETLKW;
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if (fcntl(fd, action, &lfd) >= 0)
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return true;
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/*
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** On SunOS, if you are testing using -oQ/tmp/mqueue or
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** -oA/tmp/aliases or anything like that, and /tmp is mounted
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** as type "tmp" (that is, served from swap space), the
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** previous fcntl will fail with "Invalid argument" errors.
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** Since this is fairly common during testing, we will assume
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** that this indicates that the lock is successfully grabbed.
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*/
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if (errno == EINVAL)
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return true;
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#else /* !HASFLOCK */
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if (flock(fd, type) >= 0)
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return true;
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#endif /* !HASFLOCK */
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return false;
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}
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