sem_open: Make sure to fail an O_CREAT|O_EXCL open, even if that semaphore

is already open in this process.

If the named semaphore is already open, sem_open() only increments a
reference count and did not take the flags into account (which otherwise
happens by passing them to open()). Add an extra check for O_CREAT|O_EXCL.

PR:		kern/166706
Reviewed by:	davidxu
MFC after:	10 days

1 files changed, 10 insertions, 4 deletions

diff --git a/lib/libc/gen/sem_new.c b/lib/libc/gen/sem_new.c
index 222a465..b748b49 100644
--- a/lib/libc/gen/sem_new.c
+++ b/lib/libc/gen/sem_new.c
@@ -162,10 +162,16 @@ _sem_open(const char *name, int flags, ...)
 	_pthread_mutex_lock(&sem_llock);
 	LIST_FOREACH(ni, &sem_list, next) {
 		if (strcmp(name, ni->name) == 0) {
-			ni->open_count++;
-			sem = ni->sem;
-			_pthread_mutex_unlock(&sem_llock);
-			return (sem);
+			if ((flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL)) {
+				_pthread_mutex_unlock(&sem_llock);
+				errno = EEXIST;
+				return (SEM_FAILED);
+			} else {
+				ni->open_count++;
+				sem = ni->sem;
+				_pthread_mutex_unlock(&sem_llock);
+				return (sem);
+			}
 		}
 	}