From 4ffe7630675d3faf9068264f9a1e7b494a71477b Mon Sep 17 00:00:00 2001
From: Dag-Erling Smørgrav <des@FreeBSD.org>
Date: Wed, 23 May 2007 08:12:34 +0000
Subject: If (flags & O_TRUNC), don't truncate the file until we've
 successfully locked it.

MFC after:	3 weeks
---
 libutil/flopen.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

(limited to 'libutil')

diff --git a/libutil/flopen.c b/libutil/flopen.c
index 687ebac..92254cc 100644
--- a/libutil/flopen.c
+++ b/libutil/flopen.c
@@ -41,7 +41,7 @@ __FBSDID("$FreeBSD$");
 int
 flopen(const char *path, int flags, ...)
 {
-	int fd, operation, serrno;
+	int fd, operation, serrno, truncate;
 	struct stat sb, fsb;
 	mode_t mode;
 
@@ -62,6 +62,9 @@ flopen(const char *path, int flags, ...)
 	if (flags & O_NONBLOCK)
 		operation |= LOCK_NB;
 
+	truncate = (flags & O_TRUNC);
+	flags |= ~O_TRUNC;
+
 	for (;;) {
 		if ((fd = open(path, flags, mode)) == -1)
 			/* non-existent or no access */
@@ -91,6 +94,13 @@ flopen(const char *path, int flags, ...)
 			close(fd);
 			continue;
 		}
+		if (truncate && ftruncate(fd, 0) != 0) {
+			/* can't happen [tm] */
+			serrno = errno;
+			close(fd);
+			errno = serrno;
+			return (-1);
+		}
 		return (fd);
 	}
 }
-- 
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