From 80de06ed6b796541c956ea77e8c6354eca0e2141 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= <des@FreeBSD.org>
Date: Mon, 20 Oct 2008 18:02:16 +0000
Subject: [PATCH] Reimplement flopen(3) using fcntl(2) locks instead of
 flock(2) locks.

---
 lib/libutil/flopen.3 | 17 +++++++++--------
 lib/libutil/flopen.c | 12 +++++++-----
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/lib/libutil/flopen.3 b/lib/libutil/flopen.3
index 97a48f169cd6..fe54b765c525 100644
--- a/lib/libutil/flopen.3
+++ b/lib/libutil/flopen.3
@@ -46,12 +46,13 @@ 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
-.Fn flock
-with an
-.Va operation
-argument of
-.Dv LOCK_EX ,
+with the same parameters followed by an
+.Fn fcntl
+.Dv F_SETLK
+or
+.Dv F_SETLKW
+operation with lock type
+.Dv F_WRLCK ,
 except that
 .Fn flopen
 will attempt to detect and handle races that may occur between opening
@@ -86,12 +87,12 @@ returns a valid file descriptor.
 Otherwise, it returns -1, and sets
 .Va errno
 as described in
-.Xr flock 2
+.Xr fcntl 2
 and
 .Xr open 2 .
 .Sh SEE ALSO
 .Xr errno 2 ,
-.Xr flock 2 ,
+.Xr fcntl 2 ,
 .Xr open 2
 .Sh HISTORY
 The
diff --git a/lib/libutil/flopen.c b/lib/libutil/flopen.c
index 23742f7ceec7..a5bf8c6542c6 100644
--- a/lib/libutil/flopen.c
+++ b/lib/libutil/flopen.c
@@ -28,12 +28,12 @@
 #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>
@@ -42,6 +42,7 @@ int
 flopen(const char *path, int flags, ...)
 {
 	int fd, operation, serrno, trunc;
+	struct flock flock;
 	struct stat sb, fsb;
 	mode_t mode;
 
@@ -58,9 +59,10 @@ flopen(const char *path, int flags, ...)
 		va_end(ap);
 	}
 
-	operation = LOCK_EX;
-	if (flags & O_NONBLOCK)
-		operation |= LOCK_NB;
+	memset(&flock, 0, sizeof flock);
+	flock.l_type = F_WRLCK;
+	flock.l_whence = SEEK_SET;
+	operation = (flags & O_NONBLOCK) ? F_SETLK : F_SETLKW;
 
 	trunc = (flags & O_TRUNC);
 	flags &= ~O_TRUNC;
@@ -69,7 +71,7 @@ flopen(const char *path, int flags, ...)
 		if ((fd = open(path, flags, mode)) == -1)
 			/* non-existent or no access */
 			return (-1);
-		if (flock(fd, operation) == -1) {
+		if (fcntl(fd, operation, &flock) == -1) {
 			/* unsupported or interrupted */
 			serrno = errno;
 			close(fd);