buffer: add data_ptr access flags

This allows callers to specify the operations they'll perform on
the returned data pointer. The motivations for this are:

- The upcoming Linux MAP_NOSIGBUS flag may only be usable on
  read-only mappings.
- gbm_bo_map with GBM_BO_TRANSFER_READ hurts performance.

4 files changed, 14 insertions, 8 deletions

diff --git a/render/allocator/drm_dumb.c b/render/allocator/drm_dumb.c
index ea982a03..170d9c33 100644
--- a/render/allocator/drm_dumb.c
+++ b/render/allocator/drm_dumb.c
@@ -128,7 +128,7 @@ create_err:
 }
 
 static bool drm_dumb_buffer_begin_data_ptr_access(struct wlr_buffer *wlr_buffer,
-		void **data, uint32_t *format, size_t *stride) {
+		uint32_t flags, void **data, uint32_t *format, size_t *stride) {
 	struct wlr_drm_dumb_buffer *buf = drm_dumb_buffer_from_buffer(wlr_buffer);
 	*data = buf->data;
 	*stride = buf->stride;
diff --git a/render/allocator/shm.c b/render/allocator/shm.c
index 7b32cf8d..77054dbe 100644
--- a/render/allocator/shm.c
+++ b/render/allocator/shm.c
@@ -31,7 +31,7 @@ static bool buffer_get_shm(struct wlr_buffer *wlr_buffer,
 }
 
 static bool shm_buffer_begin_data_ptr_access(struct wlr_buffer *wlr_buffer,
-		void **data, uint32_t *format, size_t *stride) {
+		uint32_t flags, void **data, uint32_t *format, size_t *stride) {
 	struct wlr_shm_buffer *buffer = shm_buffer_from_buffer(wlr_buffer);
 	*data = buffer->data;
 	*format = buffer->shm.format;
diff --git a/render/gles2/texture.c b/render/gles2/texture.c
index 0368c1a1..64ac05ac 100644
--- a/render/gles2/texture.c
+++ b/render/gles2/texture.c
@@ -346,7 +346,8 @@ struct wlr_texture *gles2_texture_from_buffer(struct wlr_renderer *wlr_renderer,
 	struct wlr_dmabuf_attributes dmabuf;
 	if (wlr_buffer_get_dmabuf(buffer, &dmabuf)) {
 		return gles2_texture_from_dmabuf_buffer(renderer, buffer, &dmabuf);
-	} else if (buffer_begin_data_ptr_access(buffer, &data, &format, &stride)) {
+	} else if (buffer_begin_data_ptr_access(buffer,
+			WLR_BUFFER_DATA_PTR_ACCESS_READ, &data, &format, &stride)) {
 		struct wlr_texture *tex = gles2_texture_from_pixels(wlr_renderer,
 			format, stride, buffer->width, buffer->height, data);
 		buffer_end_data_ptr_access(buffer);
diff --git a/render/pixman/renderer.c b/render/pixman/renderer.c
index e153cf00..4eb1bd3f 100644
--- a/render/pixman/renderer.c
+++ b/render/pixman/renderer.c
@@ -96,7 +96,9 @@ static struct wlr_pixman_buffer *create_buffer(
 	void *data = NULL;
 	uint32_t drm_format;
 	size_t stride;
-	if (!buffer_begin_data_ptr_access(wlr_buffer, &data, &drm_format, &stride)) {
+	if (!buffer_begin_data_ptr_access(wlr_buffer,
+			WLR_BUFFER_DATA_PTR_ACCESS_READ | WLR_BUFFER_DATA_PTR_ACCESS_WRITE,
+			&data, &drm_format, &stride)) {
 		wlr_log(WLR_ERROR, "Failed to get buffer data");
 		goto error_buffer;
 	}
@@ -143,7 +145,9 @@ static void pixman_begin(struct wlr_renderer *wlr_renderer, uint32_t width,
 	void *data = NULL;
 	uint32_t drm_format;
 	size_t stride;
-	buffer_begin_data_ptr_access(buffer->buffer, &data, &drm_format, &stride);
+	buffer_begin_data_ptr_access(buffer->buffer,
+		WLR_BUFFER_DATA_PTR_ACCESS_READ | WLR_BUFFER_DATA_PTR_ACCESS_WRITE,
+		&data, &drm_format, &stride);
 
 	// If the data pointer has changed, re-create the Pixman image. This can
 	// happen if it's a client buffer and the wl_shm_pool has been resized.
@@ -229,8 +233,8 @@ static bool pixman_render_subtexture_with_matrix(
 		void *data;
 		uint32_t drm_format;
 		size_t stride;
-		if (!buffer_begin_data_ptr_access(texture->buffer, &data, &drm_format,
-				&stride)) {
+		if (!buffer_begin_data_ptr_access(texture->buffer,
+				WLR_BUFFER_DATA_PTR_ACCESS_READ, &data, &drm_format, &stride)) {
 			return false;
 		}
 
@@ -376,7 +380,8 @@ static struct wlr_texture *pixman_texture_from_buffer(
 	void *data = NULL;
 	uint32_t drm_format;
 	size_t stride;
-	if (!buffer_begin_data_ptr_access(buffer, &data, &drm_format, &stride)) {
+	if (!buffer_begin_data_ptr_access(buffer, WLR_BUFFER_DATA_PTR_ACCESS_READ,
+			&data, &drm_format, &stride)) {
 		return NULL;
 	}
 	buffer_end_data_ptr_access(buffer);