- pthread_t curthread = _pthread_self();
-
- /*
- * Check if this file is owned by the current thread:
- */
- if (fp->_fl_owner == curthread) {
- /*
- * Check if this thread has locked the FILE
- * more than once:
- */
- if (fp->_fl_count > 1)
- /*
- * Decrement the count of the number of
- * times the running thread has locked this
- * file:
- */
- fp->_fl_count--;
- else {
- /*
- * The running thread will release the
- * lock now:
- */
- fp->_fl_count = 0;
- fp->_fl_owner = NULL;
- _pthread_mutex_unlock(&fp->_fl_mutex);
- }
- }
+ // <rdar://problem/21533199> - preserve errno.
+ int save_errno = errno;
+ _pthread_mutex_unlock(&fp->_fl_mutex);
+ errno = save_errno;