From: Petr Uzel <petr.uzel@suse.cz>
Date: Mon, 7 Feb 2011 13:18:28 +0000 (+0100)
Subject: libuuid: fix locking of clock state counter file
X-Git-Tag: v2.19~16
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c190c6c2e987816ca0f273e2de528701d10cbbc1;p=thirdparty%2Futil-linux.git

libuuid: fix locking of clock state counter file

fcntl(2) does not work for synchronization of threads belonging
to the same process. Use flock(2) instead.

http://marc.info/?l=util-linux-ng&m=129708412829971&w=2

Signed-off-by: Petr Uzel <petr.uzel@suse.cz>
---

diff --git a/shlibs/uuid/src/gen_uuid.c b/shlibs/uuid/src/gen_uuid.c
index a90bd8ee01..720fda4340 100644
--- a/shlibs/uuid/src/gen_uuid.c
+++ b/shlibs/uuid/src/gen_uuid.c
@@ -315,7 +315,6 @@ 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;
 	uint64_t			clock_reg;
 	mode_t				save_umask;
 	int				len;
@@ -331,14 +330,9 @@ 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 (fcntl(state_fd, F_SETLKW, &fl) < 0) {
+		while (flock(state_fd, LOCK_EX) < 0) {
 			if ((errno == EAGAIN) || (errno == EINTR))
 				continue;
 			fclose(state_f);
@@ -409,8 +403,7 @@ try_again:
 			fflush(state_f);
 		}
 		rewind(state_f);
-		fl.l_type = F_UNLCK;
-		fcntl(state_fd, F_SETLK, &fl);
+		flock(state_fd, LOCK_UN);
 	}
 
 	*clock_high = clock_reg >> 32;