decoder/Client: add virtual method Read()

test/FakeDecoderAPI.cxx

@@ -80,51 +80,15 @@ FakeDecoder::OpenUri(const char *uri)
 }
 
 size_t
-decoder_read(gcc_unused DecoderClient *client,
-	     InputStream &is,
-	     void *buffer, size_t length)
+FakeDecoder::Read(InputStream &is, void *buffer, size_t length)
 {
 	try {
 		return is.LockRead(buffer, length);
-	} catch (const std::runtime_error &) {
+	} catch (const std::runtime_error &e) {
 		return 0;
 	}
 }
 
-bool
-decoder_read_full(DecoderClient *client, InputStream &is,
-		  void *_buffer, size_t size)
-{
-	uint8_t *buffer = (uint8_t *)_buffer;
-
-	while (size > 0) {
-		size_t nbytes = decoder_read(client, is, buffer, size);
-		if (nbytes == 0)
-			return false;
-
-		buffer += nbytes;
-		size -= nbytes;
-	}
-
-	return true;
-}
-
-bool
-decoder_skip(DecoderClient *client, InputStream &is, size_t size)
-{
-	while (size > 0) {
-		char buffer[1024];
-		size_t nbytes = decoder_read(client, is, buffer,
-					     std::min(sizeof(buffer), size));
-		if (nbytes == 0)
-			return false;
-
-		size -= nbytes;
-	}
-
-	return true;
-}
-
 void
 FakeDecoder::SubmitTimestamp(gcc_unused double t)
 {