buffer: add wlr_dmabuf_buffer

include/types/wlr_buffer.h

@@ -53,6 +53,25 @@ struct wlr_readonly_data_buffer *readonly_data_buffer_create(uint32_t format,
  */
 bool readonly_data_buffer_drop(struct wlr_readonly_data_buffer *buffer);
 
+struct wlr_dmabuf_buffer {
+	struct wlr_buffer base;
+	struct wlr_dmabuf_attributes dmabuf;
+	bool saved;
+};
+
+/**
+ * Wraps a DMA-BUF into a wlr_buffer. The DMA-BUF may be accessed until
+ * dmabuf_buffer_drop() is called.
+ */
+struct wlr_dmabuf_buffer *dmabuf_buffer_create(
+	struct wlr_dmabuf_attributes *dmabuf);
+/**
+ * Drops ownership of the buffer (see wlr_buffer_drop() for more details) and
+ * takes a reference to the DMA-BUF (by dup'ing its file descriptors) if a
+ * consumer still has the buffer locked.
+ */
+bool dmabuf_buffer_drop(struct wlr_dmabuf_buffer *buffer);
+
 /**
  * Buffer capabilities.
  *

types/wlr_buffer.c

@@ -528,3 +528,67 @@ bool readonly_data_buffer_drop(struct wlr_readonly_data_buffer *buffer) {
 	wlr_buffer_drop(&buffer->base);
 	return ok;
 }
+
+static const struct wlr_buffer_impl dmabuf_buffer_impl;
+
+static struct wlr_dmabuf_buffer *dmabuf_buffer_from_buffer(
+		struct wlr_buffer *buffer) {
+	assert(buffer->impl == &dmabuf_buffer_impl);
+	return (struct wlr_dmabuf_buffer *)buffer;
+}
+
+static void dmabuf_buffer_destroy(struct wlr_buffer *wlr_buffer) {
+	struct wlr_dmabuf_buffer *buffer = dmabuf_buffer_from_buffer(wlr_buffer);
+	if (buffer->saved) {
+		wlr_dmabuf_attributes_finish(&buffer->dmabuf);
+	}
+	free(buffer);
+}
+
+static bool dmabuf_buffer_get_dmabuf(struct wlr_buffer *wlr_buffer,
+		struct wlr_dmabuf_attributes *dmabuf) {
+	struct wlr_dmabuf_buffer *buffer = dmabuf_buffer_from_buffer(wlr_buffer);
+	if (buffer->dmabuf.n_planes == 0) {
+		return false;
+	}
+	*dmabuf = buffer->dmabuf;
+	return true;
+}
+
+static const struct wlr_buffer_impl dmabuf_buffer_impl = {
+	.destroy = dmabuf_buffer_destroy,
+	.get_dmabuf = dmabuf_buffer_get_dmabuf,
+};
+
+struct wlr_dmabuf_buffer *dmabuf_buffer_create(
+		struct wlr_dmabuf_attributes *dmabuf) {
+	struct wlr_dmabuf_buffer *buffer = calloc(1, sizeof(*buffer));
+	if (buffer == NULL) {
+		return NULL;
+	}
+	wlr_buffer_init(&buffer->base, &dmabuf_buffer_impl,
+		dmabuf->width, dmabuf->height);
+
+	buffer->dmabuf = *dmabuf;
+
+	return buffer;
+}
+
+bool dmabuf_buffer_drop(struct wlr_dmabuf_buffer *buffer) {
+	bool ok = true;
+
+	if (buffer->base.n_locks > 0) {
+		struct wlr_dmabuf_attributes saved_dmabuf = {0};
+		if (!wlr_dmabuf_attributes_copy(&saved_dmabuf, &buffer->dmabuf)) {
+			wlr_log(WLR_ERROR, "Failed to save DMA-BUF");
+			ok = false;
+			memset(&buffer->dmabuf, 0, sizeof(buffer->dmabuf));
+		} else {
+			buffer->dmabuf = saved_dmabuf;
+			buffer->saved = true;
+		}
+	}
+
+	wlr_buffer_drop(&buffer->base);
+	return ok;
+}