libobs/util: Split buffered writer queue into chunks

libobs/util/buffered-file-serializer.c

@@ -179,11 +179,19 @@ static void *io_thread(void *opaque)
 					next_seek_position + chunk_used;
 
 				want_seek = false;
+
+				// If we did a seek but do not have any data left to write
+				// break out here.
+				if (!chunk_used) {
+					force_flush_chunk = false;
+					break;
+				}
 			}
 
 			if (!chunk_used) {
-				blog(LOG_WARNING,
-				     "Attempted flushing empty chunk");
+				blog(LOG_ERROR, "Tried to write 0-byte chunk!");
+				os_atomic_set_bool(&out->io.output_error, true);
+				goto error;
 			}
 
 			// Write the current chunk to the output file
@@ -248,10 +256,9 @@ static int64_t file_output_seek(void *opaque, int64_t offset,
 	return (int64_t)out->io.next_pos;
 }
 
-static size_t file_output_write(void *opaque, const void *buf, size_t buf_size)
+static inline size_t enqueue_chunk(struct file_output_data *out,
+				   const void *buf, size_t buf_size)
 {
-	struct file_output_data *out = opaque;
-
 	// If the output thread failed, signal that back up the stack
 	if (os_atomic_load_bool(&out->io.output_error))
 		return 0;
@@ -292,6 +299,36 @@ static size_t file_output_write(void *opaque, const void *buf, size_t buf_size)
 	return buf_size;
 }
 
+static size_t file_output_write(void *opaque, const void *buf, size_t buf_size)
+{
+	struct file_output_data *out = opaque;
+
+	if (!buf_size)
+		return 0;
+
+	if (buf_size <= out->io.chunk_size) {
+		enqueue_chunk(out, buf, buf_size);
+	} else {
+		// Split writes into at most chunk_size chunks
+		uintptr_t ptr = (uintptr_t)buf;
+		size_t remaining = buf_size;
+
+		while (remaining) {
+			size_t chunk_size = remaining > out->io.chunk_size
+						    ? out->io.chunk_size
+						    : remaining;
+
+			if (!enqueue_chunk(out, (const void *)ptr, buf_size))
+				return 0;
+
+			remaining -= chunk_size;
+			ptr += chunk_size;
+		}
+	}
+
+	return buf_size;
+}
+
 static int64_t file_output_get_pos(void *opaque)
 {
 	struct file_output_data *out = opaque;