From 94e760567d654ada216cd794352e9deca31dff08 Mon Sep 17 00:00:00 2001
From: des <des@FreeBSD.org>
Date: Sat, 6 Jun 2009 18:47:03 +0000
Subject: [PATCH] Revert (once again, and hopefully for the last time) to
 flock(2) locks. The problem with fcntl(2) locks is that they are not
 inherited by child processes.  This breaks pidfile(3), where the common idiom
 is to open and lock the PID file before daemonizing.

---
 lib/libutil/flopen.3 | 24 +++++++++---------------
 lib/libutil/flopen.c | 13 +++++--------
 2 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/lib/libutil/flopen.3 b/lib/libutil/flopen.3
index fe54b765c525..26d1c044aefc 100644
--- a/lib/libutil/flopen.3
+++ b/lib/libutil/flopen.3
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 10, 2007
+.Dd June 6, 2009
 .Dt FLOPEN 3
 .Os
 .Sh NAME
@@ -46,13 +46,12 @@ The
 function opens or creates a file and acquires an exclusive lock on it.
 It is essentially equivalent with calling
 .Fn open
-with the same parameters followed by an
-.Fn fcntl
-.Dv F_SETLK
-or
-.Dv F_SETLKW
-operation with lock type
-.Dv F_WRLCK ,
+with the same parameters followed by
+.Fn flock
+with an
+.Va operation
+argument of
+.Dv LOCK_EX ,
 except that
 .Fn flopen
 will attempt to detect and handle races that may occur between opening
@@ -87,18 +86,13 @@ returns a valid file descriptor.
 Otherwise, it returns -1, and sets
 .Va errno
 as described in
-.Xr fcntl 2
+.Xr flock 2
 and
 .Xr open 2 .
 .Sh SEE ALSO
 .Xr errno 2 ,
-.Xr fcntl 2 ,
+.Xr flock 2 ,
 .Xr open 2
-.Sh HISTORY
-The
-.Fn flopen
-function first appeared in
-.Fx 6.3 .
 .Sh AUTHORS
 .An -nosplit
 The
diff --git a/lib/libutil/flopen.c b/lib/libutil/flopen.c
index ae98daf94202..754c9c037fa2 100644
--- a/lib/libutil/flopen.c
+++ b/lib/libutil/flopen.c
@@ -28,12 +28,11 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <sys/file.h>
 #include <sys/stat.h>
 
 #include <errno.h>
-#include <fcntl.h>
 #include <stdarg.h>
-#include <string.h>
 #include <unistd.h>
 
 #include <libutil.h>
@@ -42,7 +41,6 @@ int
 flopen(const char *path, int flags, ...)
 {
 	int fd, operation, serrno, trunc;
-	struct flock lock;
 	struct stat sb, fsb;
 	mode_t mode;
 
@@ -59,10 +57,9 @@ flopen(const char *path, int flags, ...)
 		va_end(ap);
 	}
 
-	memset(&lock, 0, sizeof lock);
-	lock.l_type = ((flags & O_ACCMODE) == O_RDONLY) ? F_RDLCK : F_WRLCK;
-	lock.l_whence = SEEK_SET;
-	operation = (flags & O_NONBLOCK) ? F_SETLK : F_SETLKW;
+        operation = LOCK_EX;
+        if (flags & O_NONBLOCK)
+                operation |= LOCK_NB;
 
 	trunc = (flags & O_TRUNC);
 	flags &= ~O_TRUNC;
@@ -71,7 +68,7 @@ flopen(const char *path, int flags, ...)
 		if ((fd = open(path, flags, mode)) == -1)
 			/* non-existent or no access */
 			return (-1);
-		if (fcntl(fd, operation, &lock) == -1) {
+		if (flock(fd, operation) == -1) {
 			/* unsupported or interrupted */
 			serrno = errno;
 			(void)close(fd);