stream: return -EIO when doing get_time in != STREAMING

The stream should be streaming before the get_time call is meaningful.

Various places in the code already check this an fall back to a default
value, we just need to return an error here.

src/pipewire/filter.c

@@ -1986,7 +1986,8 @@ int pw_filter_get_time(struct pw_filter *filter, struct pw_time *time)
 	pw_log_trace("%p: %"PRIi64" %"PRIi64" %"PRIu64" %d/%d ", filter,
 			time->now, time->delay, time->ticks,
 			time->rate.num, time->rate.denom);
-	return 0;
+
+	return filter->state == PW_FILTER_STATE_STREAMING ? 0 : -EIO;
 }
 
 SPA_EXPORT

src/pipewire/stream.c

@@ -2504,7 +2504,8 @@ int pw_stream_get_time_n(struct pw_stream *stream, struct pw_time *time, size_t
 			impl->dequeued.outcount, impl->dequeued.incount,
 			impl->queued.outcount, impl->queued.incount,
 			avail_buffers, impl->n_buffers);
-	return 0;
+
+	return stream->state == PW_STREAM_STATE_STREAMING ? 0 : -EIO;
 }
 
 SPA_EXPORT

src/pipewire/stream.h

@@ -293,7 +293,8 @@ struct pw_stream_control {
  * Use pw_stream_get_time_n() to get an updated time snapshot of the stream.
  * The time snapshot can give information about the time in the driver of the
  * graph, the delay to the edge of the graph and the internal queuing in the
- * stream.
+ * stream. This function should only be called in the STREAMING state and will
+ * return an error when called in any other state.
  *
  * pw_time.ticks gives a monotonic increasing counter of the time in the graph
  * driver. I can be used to generate a timeline to schedule samples as well
@@ -594,7 +595,7 @@ const struct pw_stream_control *pw_stream_get_control(struct pw_stream *stream,
 /** Set control values */
 int pw_stream_set_control(struct pw_stream *stream, uint32_t id, uint32_t n_values, float *values, ...);
 
-/** Query the time on the stream, RT safe */
+/** Query the time on the stream. Returns an error when the stream is not running. RT safe */
 int pw_stream_get_time_n(struct pw_stream *stream, struct pw_time *time, size_t size);
 
 /** Get the current time in nanoseconds. This value can be compared with

src/tests/test-stream.c

@@ -151,7 +151,7 @@ static void test_create(void)
 	/* check id, only when connected */
 	spa_assert_se(pw_stream_get_node_id(stream) == SPA_ID_INVALID);
 
-	spa_assert_se(pw_stream_get_time_n(stream, &tm, sizeof(tm)) == 0);
+	spa_assert_se(pw_stream_get_time_n(stream, &tm, sizeof(tm)) == -EIO);
 	spa_assert_se(tm.now == 0);
 	spa_assert_se(tm.rate.num == 0);
 	spa_assert_se(tm.rate.denom == 0);