Add calls to wl_shm_buffer_begin/end_access

This wraps all accesses to an SHM buffer between wl_shm_buffer_begin
and end so that wayland-shm can install a handler for SIGBUS and catch
attempts to pass the compositor a buffer that is too small.

src/compositor-drm.c

@@ -974,6 +974,7 @@ static void
 drm_output_set_cursor(struct drm_output *output)
 {
 	struct weston_view *ev = output->cursor_view;
+	struct weston_buffer *buffer;
 	struct drm_compositor *c =
 		(struct drm_compositor *) output->base.compositor;
 	EGLint handle, stride;
@@ -988,18 +989,22 @@ drm_output_set_cursor(struct drm_output *output)
 		return;
 	}
 
-	if (ev->surface->buffer_ref.buffer &&
+	buffer = ev->surface->buffer_ref.buffer;
+
+	if (buffer &&
 	    pixman_region32_not_empty(&output->cursor_plane.damage)) {
 		pixman_region32_fini(&output->cursor_plane.damage);
 		pixman_region32_init(&output->cursor_plane.damage);
 		output->current_cursor ^= 1;
 		bo = output->cursor_bo[output->current_cursor];
 		memset(buf, 0, sizeof buf);
-		stride = wl_shm_buffer_get_stride(ev->surface->buffer_ref.buffer->shm_buffer);
-		s = wl_shm_buffer_get_data(ev->surface->buffer_ref.buffer->shm_buffer);
+		stride = wl_shm_buffer_get_stride(buffer->shm_buffer);
+		s = wl_shm_buffer_get_data(buffer->shm_buffer);
+		wl_shm_buffer_begin_access(buffer->shm_buffer);
 		for (i = 0; i < ev->geometry.height; i++)
 			memcpy(buf + i * 64, s + i * stride,
 			       ev->geometry.width * 4);
+		wl_shm_buffer_end_access(buffer->shm_buffer);
 
 		if (gbm_bo_write(bo, buf, sizeof buf) < 0)
 			weston_log("failed update cursor: %m\n");

src/gl-renderer.c

@@ -899,10 +899,12 @@ gl_renderer_flush_damage(struct weston_surface *surface)
 	glBindTexture(GL_TEXTURE_2D, gs->textures[0]);
 
 	if (!gr->has_unpack_subimage) {
+		wl_shm_buffer_begin_access(buffer->shm_buffer);
 		glTexImage2D(GL_TEXTURE_2D, 0, format,
 			     gs->pitch, buffer->height, 0,
 			     format, pixel_type,
 			     wl_shm_buffer_get_data(buffer->shm_buffer));
+		wl_shm_buffer_end_access(buffer->shm_buffer);
 
 		goto done;
 	}
@@ -914,13 +916,16 @@ gl_renderer_flush_damage(struct weston_surface *surface)
 	if (gs->needs_full_upload) {
 		glPixelStorei(GL_UNPACK_SKIP_PIXELS_EXT, 0);
 		glPixelStorei(GL_UNPACK_SKIP_ROWS_EXT, 0);
+		wl_shm_buffer_begin_access(buffer->shm_buffer);
 		glTexSubImage2D(GL_TEXTURE_2D, 0,
 				0, 0, gs->pitch, buffer->height,
 				format, pixel_type, data);
+		wl_shm_buffer_end_access(buffer->shm_buffer);
 		goto done;
 	}
 
 	rectangles = pixman_region32_rectangles(&gs->texture_damage, &n);
+	wl_shm_buffer_begin_access(buffer->shm_buffer);
 	for (i = 0; i < n; i++) {
 		pixman_box32_t r;
 
@@ -932,6 +937,7 @@ gl_renderer_flush_damage(struct weston_surface *surface)
 				r.x2 - r.x1, r.y2 - r.y1,
 				format, pixel_type, data);
 	}
+	wl_shm_buffer_end_access(buffer->shm_buffer);
 #endif
 
 done:

src/pixman-renderer.c

@@ -305,6 +305,9 @@ repaint_region(struct weston_view *ev, struct weston_output *output,
 	else
 		pixman_image_set_filter(ps->image, PIXMAN_FILTER_NEAREST, NULL, 0);
 
+	if (ps->buffer_ref.buffer)
+		wl_shm_buffer_begin_access(ps->buffer_ref.buffer->shm_buffer);
+
 	pixman_image_composite32(pixman_op,
 				 ps->image, /* src */
 				 NULL /* mask */,
@@ -315,6 +318,9 @@ repaint_region(struct weston_view *ev, struct weston_output *output,
 				 pixman_image_get_width (po->shadow_image), /* width */
 				 pixman_image_get_height (po->shadow_image) /* height */);
 
+	if (ps->buffer_ref.buffer)
+		wl_shm_buffer_end_access(ps->buffer_ref.buffer->shm_buffer);
+
 	if (pr->repaint_debug)
 		pixman_image_composite32(PIXMAN_OP_OVER,
 					 pr->debug_color, /* src */

src/rpi-renderer.c

@@ -342,6 +342,8 @@ rpi_resource_update(struct rpi_resource *resource, struct weston_buffer *buffer,
 		pixman_region32_intersect(&write_region,
 					  &write_region, region);
 
+	wl_shm_buffer_begin_access(buffer->shm_buffer);
+
 #ifdef HAVE_RESOURCE_WRITE_DATA_RECT
 	/* XXX: Can this do a format conversion, so that scanout does not have to? */
 	r = pixman_region32_rectangles(&write_region, &n);
@@ -376,6 +378,8 @@ rpi_resource_update(struct rpi_resource *resource, struct weston_buffer *buffer,
 	    width, r->y2 - r->y1, 0, r->y1, ret);
 #endif
 
+	wl_shm_buffer_end_access(buffer->shm_buffer);
+
 	pixman_region32_fini(&write_region);
 
 	return ret ? -1 : 0;

src/screenshooter.c

@@ -144,6 +144,8 @@ screenshooter_frame_notify(struct wl_listener *listener, void *data)
 	d = wl_shm_buffer_get_data(l->buffer->shm_buffer);
 	s = pixels + stride * (l->buffer->height - 1);
 
+	wl_shm_buffer_begin_access(l->buffer->shm_buffer);
+
 	switch (compositor->read_format) {
 	case PIXMAN_a8r8g8b8:
 	case PIXMAN_x8r8g8b8:
@@ -163,6 +165,8 @@ screenshooter_frame_notify(struct wl_listener *listener, void *data)
 		break;
 	}
 
+	wl_shm_buffer_end_access(l->buffer->shm_buffer);
+
 	screenshooter_send_done(l->resource);
 	free(pixels);
 	free(l);