spa: add dynamic builder helper

Resizes the buffer dynamically. Be careful with getting the address
of a pod in the buffer, it might not be valid after building more stuff
with the builder.

spa/include/spa/pod/dynamic.h

@@ -0,0 +1,81 @@
+/* Simple Plugin API
+ *
+ * Copyright © 2018 Wim Taymans
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef SPA_POD_DYNAMIC_H
+#define SPA_POD_DYNAMIC_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <spa/pod/builder.h>
+
+struct spa_pod_dynamic_builder {
+	struct spa_pod_builder b;
+	void *data;
+	uint32_t extend;
+	uint32_t _padding;
+};
+
+static int spa_pod_dynamic_builder_overflow(void *data, uint32_t size)
+{
+	struct spa_pod_dynamic_builder *d = data;
+	int32_t old_size = d->b.size;
+	int32_t new_size = SPA_ROUND_UP_N(size, d->extend);
+	void *old_data = d->b.data;
+
+	if (old_data == d->data)
+		d->b.data = NULL;
+	if ((d->b.data = realloc(d->b.data, new_size)) == NULL)
+		return -errno;
+	if (old_data == d->data && d->b.data != old_data && old_size > 0)
+		memcpy(d->b.data, old_data, old_size);
+	d->b.size = new_size;
+        return 0;
+}
+
+static inline void spa_pod_dynamic_builder_init(struct spa_pod_dynamic_builder *builder,
+		void *data, uint32_t size, uint32_t extend)
+{
+	static const struct spa_pod_builder_callbacks spa_pod_dynamic_builder_callbacks = {
+		SPA_VERSION_POD_BUILDER_CALLBACKS,
+		.overflow = spa_pod_dynamic_builder_overflow
+	};
+	builder->b = SPA_POD_BUILDER_INIT(data, size);
+	spa_pod_builder_set_callbacks(&builder->b, &spa_pod_dynamic_builder_callbacks, builder);
+	builder->extend = extend;
+	builder->data = data;
+}
+
+static inline void spa_pod_dynamic_builder_clean(struct spa_pod_dynamic_builder *builder)
+{
+	if (builder->data != builder->b.data)
+		free(builder->b.data);
+}
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+
+#endif /* SPA_POD_DYNAMIC_H */

src/modules/module-filter-chain.c

@@ -39,6 +39,7 @@
 #include <spa/utils/string.h>
 #include <spa/utils/json.h>
 #include <spa/param/profiler.h>
+#include <spa/pod/dynamic.h>
 #include <spa/debug/pod.h>
 
 #include <pipewire/utils.h>
@@ -613,26 +614,12 @@ static const struct pw_stream_events out_stream_events = {
 	.param_changed = param_changed
 };
 
-static int builder_overflow(void *data, uint32_t size)
-{
-	struct spa_pod_builder *b = data;
-	b->size = SPA_ROUND_UP_N(size, 4096);
-	if ((b->data = realloc(b->data, b->size)) == NULL)
-		return -errno;
-        return 0;
-}
-
-static const struct spa_pod_builder_callbacks builder_callbacks = {
-	SPA_VERSION_POD_BUILDER_CALLBACKS,
-	.overflow = builder_overflow
-};
-
 static int setup_streams(struct impl *impl)
 {
 	int res;
 	uint32_t i, n_params;
 	const struct spa_pod *params[256];
-	struct spa_pod_builder b;
+	struct spa_pod_dynamic_builder b;
 	struct graph *graph = &impl->graph;
 
 	impl->capture = pw_stream_new(impl->core,
@@ -656,16 +643,15 @@ static int setup_streams(struct impl *impl)
 			&out_stream_events, impl);
 
 	n_params = 0;
-	spa_pod_builder_init(&b, NULL, 0);
+	spa_pod_dynamic_builder_init(&b, NULL, 0, 4096);
-	spa_pod_builder_set_callbacks(&b, &builder_callbacks, &b);
 
-	params[n_params++] = spa_format_audio_raw_build(&b,
+	params[n_params++] = spa_format_audio_raw_build(&b.b,
 			SPA_PARAM_EnumFormat, &impl->capture_info);
 
 	for (i = 0; i < graph->n_control; i++)
-		params[n_params++] = get_prop_info(graph, &b, i);
+		params[n_params++] = get_prop_info(graph, &b.b, i);
 
-	params[n_params++] = get_props_param(graph, &b);
+	params[n_params++] = get_props_param(graph, &b.b);
 
 	res = pw_stream_connect(impl->capture,
 			PW_DIRECTION_INPUT,
@@ -674,14 +660,14 @@ static int setup_streams(struct impl *impl)
 			PW_STREAM_FLAG_MAP_BUFFERS |
 			PW_STREAM_FLAG_RT_PROCESS,
 			params, n_params);
-	free(b.data);
+
+	spa_pod_dynamic_builder_clean(&b);
 	if (res < 0)
 		return res;
 
 	n_params = 0;
-	spa_pod_builder_init(&b, NULL, 0);
+	spa_pod_dynamic_builder_init(&b, NULL, 0, 4096);
-	spa_pod_builder_set_callbacks(&b, &builder_callbacks, &b);
+	params[n_params++] = spa_format_audio_raw_build(&b.b,
-	params[n_params++] = spa_format_audio_raw_build(&b,
 			SPA_PARAM_EnumFormat, &impl->playback_info);
 
 	res = pw_stream_connect(impl->playback,
@@ -692,7 +678,7 @@ static int setup_streams(struct impl *impl)
 			PW_STREAM_FLAG_RT_PROCESS  |
 			PW_STREAM_FLAG_TRIGGER,
 			params, n_params);
-	free(b.data);
+	spa_pod_dynamic_builder_clean(&b);
 
 	if (res < 0)
 		return res;