1 files changed, 118 insertions, 0 deletions
diff --git a/libraries/liblutil/lockf.c b/libraries/liblutil/lockf.c
new file mode 100644
index 0000000..e939909
--- /dev/null
+++ b/libraries/liblutil/lockf.c
@@ -0,0 +1,118 @@
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 1998-2022 The OpenLDAP Foundation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+
+/*
+ * File Locking Routines
+ *
+ * Implementations (in order of preference)
+ *	- lockf
+ *	- fcntl
+ *  - flock
+ *
+ * Other implementations will be added as needed.
+ *
+ * NOTE: lutil_lockf() MUST block until an exclusive lock is acquired.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/unistd.h>
+
+#undef LOCK_API
+
+#if defined(HAVE_LOCKF) && defined(F_LOCK)
+#	define USE_LOCKF 1
+#	define LOCK_API	"lockf"
+#endif
+
+#if !defined(LOCK_API) && defined(HAVE_FCNTL)
+#	ifdef HAVE_FCNTL_H
+#		include <fcntl.h>
+#	endif
+#	ifdef F_WRLCK
+#		define USE_FCNTL 1
+#		define LOCK_API	"fcntl"
+#	endif
+#endif
+
+#if !defined(LOCK_API) && defined(HAVE_FLOCK)
+#	ifdef HAVE_SYS_FILE_H
+#		include <sys/file.h>
+#	endif
+#	define USE_FLOCK 1
+#	define LOCK_API	"flock"
+#endif
+
+#if !defined(USE_LOCKF) && !defined(USE_FCNTL) && !defined(USE_FLOCK)
+int lutil_lockf ( int fd ) {
+    fd = fd;
+    return 0;
+}
+
+int lutil_unlockf ( int fd ) {
+    fd = fd;
+    return 0;
+}
+#endif
+
+#ifdef USE_LOCKF
+int lutil_lockf ( int fd ) {
+	/* use F_LOCK instead of F_TLOCK, ie: block */
+	return lockf( fd, F_LOCK, 0 );
+}
+
+int lutil_unlockf ( int fd ) {
+	return lockf( fd, F_ULOCK, 0 );
+}
+#endif
+
+#ifdef USE_FCNTL
+int lutil_lockf ( int fd ) {
+	struct flock file_lock;
+
+	memset( &file_lock, '\0', sizeof( file_lock ) );
+	file_lock.l_type = F_WRLCK;
+	file_lock.l_whence = SEEK_SET;
+	file_lock.l_start = 0;
+	file_lock.l_len = 0;
+
+	/* use F_SETLKW instead of F_SETLK, ie: block */
+	return( fcntl( fd, F_SETLKW, &file_lock ) );
+}
+
+int lutil_unlockf ( int fd ) {
+	struct flock file_lock;
+
+	memset( &file_lock, '\0', sizeof( file_lock ) );
+	file_lock.l_type = F_UNLCK;
+	file_lock.l_whence = SEEK_SET;
+	file_lock.l_start = 0;
+	file_lock.l_len = 0;
+
+	return( fcntl ( fd, F_SETLKW, &file_lock ) );
+}
+#endif
+
+#ifdef USE_FLOCK
+int lutil_lockf ( int fd ) {
+	/* use LOCK_EX instead of LOCK_EX|LOCK_NB, ie: block */
+	return flock( fd, LOCK_EX );
+}
+
+int lutil_unlockf ( int fd ) {
+	return flock( fd, LOCK_UN );
+}
+#endif