From: Theodore Ts'o <tytso@mit.edu>
Date: Fri, 15 Feb 2008 22:41:38 +0000 (-0500)
Subject: libuuid: use fcntl locking instead of lockf
X-Git-Tag: v1.40.7~41
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=e70f32b79d29e287f8347c5d41c6716f094cc654;p=tools%2Fe2fsprogs.git

libuuid: use fcntl locking instead of lockf

Cygwin doesn't support lockf(), so move to fcntl() locking as more
portable.  Also fix a bug which could cause get_lock() to loop forever
if the attempt to lock the file fails for some reason.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/lib/uuid/gen_uuid.c b/lib/uuid/gen_uuid.c
index 9254eb6..d4befe4 100644
--- a/lib/uuid/gen_uuid.c
+++ b/lib/uuid/gen_uuid.c
@@ -266,6 +266,7 @@ static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
 	THREAD_LOCAL FILE		*state_f;
 	THREAD_LOCAL uint16_t		clock_seq;
 	struct timeval 			tv;
+	struct flock			fl;
 	unsigned long long		clock_reg;
 	mode_t				save_umask;
 
@@ -280,14 +281,20 @@ static int get_clock(uint32_t *clock_high, uint32_t *clock_low,
 			state_fd = -1;
 		}
 	}
+	fl.l_type = F_WRLCK;
+	fl.l_whence = SEEK_SET;
+	fl.l_start = 0;
+	fl.l_len = 0;
+	fl.l_pid = 0;
 	if (state_fd >= 0) {
 		rewind(state_f);
-		while (lockf(state_fd, F_LOCK, 0) < 0) {
+		while (fcntl(state_fd, F_SETLKW, &fl) < 0) {
 			if ((errno == EAGAIN) || (errno == EINTR))
 				continue;
 			fclose(state_f);
 			close(state_fd);
 			state_fd = -1;
+			break;
 		}
 	}
 	if (state_fd >= 0) {
@@ -348,7 +355,8 @@ try_again:
 			clock_seq, last.tv_sec, last.tv_usec, adjustment);
 		fflush(state_f);
 		rewind(state_f);
-		lockf(state_fd, F_ULOCK, 0);
+		fl.l_type = F_UNLCK;
+		fcntl(state_fd, F_SETLK, &fl);
 	}
 
 	*clock_high = clock_reg >> 32;