output_api: play() returns a length

The old API required an output plugin to not return until all data
passed to the play() method is consumed.  Some output plugins have to
loop to fulfill that requirement, and may block during that.  Simplify
these, by letting them consume only part of the buffer: make play()
return the length of the consumed data.

1 files changed, 7 insertions, 10 deletions

diff --git a/src/output/fifo_plugin.c b/src/output/fifo_plugin.c
index b0c6d12f4..1be0f2a7d 100644
--- a/src/output/fifo_plugin.c
+++ b/src/output/fifo_plugin.c
@@ -237,11 +237,10 @@ static void fifo_dropBufferedAudio(void *data)
 	}
 }
 
-static bool
+static size_t
 fifo_playAudio(void *data, const char *playChunk, size_t size)
 {
 	FifoData *fd = (FifoData *)data;
-	size_t offset = 0;
 	ssize_t bytes;
 
 	if (!fd->timer->started)
@@ -251,8 +250,11 @@ fifo_playAudio(void *data, const char *playChunk, size_t size)
 
 	timer_add(fd->timer, size);
 
-	while (size) {
-		bytes = write(fd->output, playChunk + offset, size);
+	while (true) {
+		bytes = write(fd->output, playChunk, size);
+		if (bytes > 0)
+			return (size_t)bytes;
+
 		if (bytes < 0) {
 			switch (errno) {
 			case EAGAIN:
@@ -265,14 +267,9 @@ fifo_playAudio(void *data, const char *playChunk, size_t size)
 
 			g_warning("Closing FIFO output \"%s\" due to write error: %s",
 				  fd->path, strerror(errno));
-			return false;
+			return 0;
 		}
-
-		size -= bytes;
-		offset += bytes;
 	}
-
-	return true;
 }
 
 const struct audio_output_plugin fifoPlugin = {