In pidfile_open(), if the pidfile is locked, but empty (PID is not stored yet)

and the caller requested other process' PID by passing non-NULL pidptr
argument, we will wait at most 100ms for the PID to show up in the file and if
it won't, we will store -1 in *pidptr.

From now on, pidfile_open() function never sets errno to EAGAIN on failure.

In collaboration with:	des
MFC after:		1 week

1 files changed, 12 insertions, 12 deletions

diff --git a/lib/libutil/pidfile.c b/lib/libutil/pidfile.c
index 6b99936..953d1e0 100644
--- a/lib/libutil/pidfile.c
+++ b/lib/libutil/pidfile.c
@@ -119,20 +119,20 @@ pidfile_open(const char *path, mode_t mode, pid_t *pidptr)
 	fd = flopen(pfh->pf_path,
 	    O_WRONLY | O_CREAT | O_TRUNC | O_NONBLOCK, mode);
 	if (fd == -1) {
-		count = 0;
-		rqtp.tv_sec = 0;
-		rqtp.tv_nsec = 5000000;
 		if (errno == EWOULDBLOCK && pidptr != NULL) {
-		again:
-			errno = pidfile_read(pfh->pf_path, pidptr);
-			if (errno == 0)
-				errno = EEXIST;
-			else if (errno == EAGAIN) {
-				if (++count <= 3) {
-					nanosleep(&rqtp, 0);
-					goto again;
-				}
+			count = 20;
+			rqtp.tv_sec = 0;
+			rqtp.tv_nsec = 5000000;
+			for (;;) {
+				errno = pidfile_read(pfh->pf_path, pidptr);
+				if (errno != EAGAIN || --count == 0)
+					break;
+				nanosleep(&rqtp, 0);
 			}
+			if (errno == EAGAIN)
+				*pidptr = -1;
+			if (errno == 0 || errno == EAGAIN)
+				errno = EEXIST;
 		}
 		free(pfh);
 		return (NULL);