encoder/null: use fifo_buffer instead of pcm_buffer

This fixes a buffer corruption bug; pcm_buffer is not designed to be a
persistent buffers, and will discard anything between two consecutive
calls.

NEWS

@@ -2,7 +2,7 @@ ver 0.16.6 (2010/??/??)
 * decoder:
   - fix assertion failure when resuming streams
 * encoder:
-  - flac, wave: fix buffer corruption bug
+  - flac, null, wave: fix buffer corruption bug
 * event_pipe: fix WIN32 regression
 * define WINVER in ./configure
 * WIN32: autodetect filesystem encoding

src/encoder/null_encoder.c

@@ -20,7 +20,8 @@
 #include "config.h"
 #include "encoder_api.h"
 #include "encoder_plugin.h"
-#include "pcm_buffer.h"
+#include "fifo_buffer.h"
+#include "growing_fifo.h"
 
 #include <assert.h>
 #include <string.h>
@@ -28,8 +29,7 @@
 struct null_encoder {
 	struct encoder encoder;
 
-	struct pcm_buffer buffer;
-	size_t buffer_length;
+	struct fifo_buffer *buffer;
 };
 
 extern const struct encoder_plugin null_encoder_plugin;
@@ -65,7 +65,7 @@ null_encoder_close(struct encoder *_encoder)
 {
 	struct null_encoder *encoder = (struct null_encoder *)_encoder;
 
-	pcm_buffer_deinit(&encoder->buffer);
+	fifo_buffer_free(encoder->buffer);
 }
 
 
@@ -76,9 +76,7 @@ null_encoder_open(struct encoder *_encoder,
 {
 	struct null_encoder *encoder = (struct null_encoder *)_encoder;
 
-	encoder->buffer_length = 0;
-	pcm_buffer_init(&encoder->buffer);
-
+	encoder->buffer = growing_fifo_new();
 	return true;
 }
 
@@ -88,28 +86,26 @@ null_encoder_write(struct encoder *_encoder,
 		   G_GNUC_UNUSED GError **error)
 {
 	struct null_encoder *encoder = (struct null_encoder *)_encoder;
-	char *buffer = pcm_buffer_get(&encoder->buffer, encoder->buffer_length + length);
 
-	memcpy(buffer+encoder->buffer_length, data, length);
-
-	encoder->buffer_length += length;
-	return true;
+	growing_fifo_append(&encoder->buffer, data, length);
+	return length;
 }
 
 static size_t
 null_encoder_read(struct encoder *_encoder, void *dest, size_t length)
 {
 	struct null_encoder *encoder = (struct null_encoder *)_encoder;
-	char *buffer = pcm_buffer_get(&encoder->buffer, encoder->buffer_length);
 
-	if (length > encoder->buffer_length)
-		length = encoder->buffer_length;
+	size_t max_length;
+	const void *src = fifo_buffer_read(encoder->buffer, &max_length);
+	if (src == NULL)
+		return 0;
 
-	memcpy(dest, buffer, length);
-
-	encoder->buffer_length -= length;
-	memmove(buffer, buffer + length, encoder->buffer_length);
+	if (length > max_length)
+		length = max_length;
 
+	memcpy(dest, src, length);
+	fifo_buffer_consume(encoder->buffer, length);
 	return length;
 }