An implementation of lockf() function call.

Obtained from:	NetBSD (author: Klaus Klein)

1 files changed, 96 insertions, 0 deletions

diff --git a/lib/libc/gen/lockf.c b/lib/libc/gen/lockf.c
new file mode 100644
index 0000000..0419390
--- /dev/null
+++ b/lib/libc/gen/lockf.c
@@ -0,0 +1,96 @@
+/*	$NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $	*/
+
+/*-
+ * Copyright (c) 1997 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+#if defined(LIBC_SCCS) && !defined(lint)
+__RCSID("$NetBSD: lockf.c,v 1.1 1997/12/20 20:23:18 kleink Exp $");
+#endif
+
+#include "namespace.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#ifdef __weak_alias
+__weak_alias(lockf,_lockf);
+#endif
+
+
+int
+lockf(filedes, function, size)
+	int filedes;
+	int function;
+	off_t size;
+{
+	struct flock fl;
+	int cmd;
+
+	fl.l_start = 0;
+	fl.l_len = size;
+	fl.l_whence = SEEK_CUR;
+
+	switch (function) {
+	case F_ULOCK:
+		cmd = F_SETLK;
+		fl.l_type = F_UNLCK;
+		break;
+	case F_LOCK:
+		cmd = F_SETLKW;
+		fl.l_type = F_WRLCK;
+		break;
+	case F_TLOCK:
+		cmd = F_SETLK;
+		fl.l_type = F_WRLCK;
+		break;
+	case F_TEST:
+		fl.l_type = F_WRLCK;
+		if (fcntl(filedes, F_GETLK, &fl) == -1)
+			return (-1);
+		if (fl.l_type == F_UNLCK || fl.l_pid == getpid())
+			return (0);
+		errno = EAGAIN;
+		return (-1);
+		/* NOTREACHED */
+	default:
+		errno = EINVAL;
+		return (-1);
+		/* NOTREACHED */
+	}
+
+	return (fcntl(filedes, cmd, &fl));
+}