1 files changed, 82 insertions, 0 deletions
diff --git a/sendmail/libsmutil/lockfile.c b/sendmail/libsmutil/lockfile.c
new file mode 100644
index 0000000..17d6237
--- /dev/null
+++ b/sendmail/libsmutil/lockfile.c
@@ -0,0 +1,82 @@
+/*
+ * 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;
+}