[PATCH weston] Add calls to wl_shm_buffer_begin/end_access

[Neil Roberts]

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.

Note, this patch doesn't do anything to fix the pixman renderer.
---
 src/compositor-drm.c  | 3 +++
 src/gl-renderer.c     | 6 ++++++
 src/pixman-renderer.c | 2 ++
 src/rpi-renderer.c    | 4 ++++
 src/screenshooter.c   | 4 ++++
 5 files changed, 19 insertions(+)

diff --git a/src/compositor-drm.c b/src/compositor-drm.c
index 2770c85..180c3ee 100644
--- a/src/compositor-drm.c
+++ b/src/compositor-drm.c
@@ -964,9 +964,12 @@ drm_output_set_cursor(struct drm_output *output)
 		memset(buf, 0, sizeof buf);
 		stride = wl_shm_buffer_get_stride(es->buffer_ref.buffer->shm_buffer);
 		s = wl_shm_buffer_get_data(es->buffer_ref.buffer->shm_buffer);
+
+		wl_shm_buffer_begin_access(es->buffer_ref.buffer->shm_buffer);
 		for (i = 0; i < es->geometry.height; i++)
 			memcpy(buf + i * 64, s + i * stride,
 			       es->geometry.width * 4);
+		wl_shm_buffer_end_access(es->buffer_ref.buffer->shm_buffer);
 
 		if (gbm_bo_write(bo, buf, sizeof buf) < 0)
 			weston_log("failed update cursor: %m\n");
diff --git a/src/gl-renderer.c b/src/gl-renderer.c
index ae69f22..90e8148 100644
--- a/src/gl-renderer.c
+++ b/src/gl-renderer.c
@@ -875,10 +875,12 @@ 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;
 	}
@@ -890,13 +892,16 @@ 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;
 
@@ -908,6 +913,7 @@ 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:
diff --git a/src/pixman-renderer.c b/src/pixman-renderer.c
index 987c539..80d41a8 100644
--- a/src/pixman-renderer.c
+++ b/src/pixman-renderer.c
@@ -574,6 +574,8 @@ pixman_renderer_attach(struct weston_surface *es, struct weston_buffer *buffer)
 	buffer->width = wl_shm_buffer_get_width(shm_buffer);
 	buffer->height = wl_shm_buffer_get_height(shm_buffer);
 
+	/* XXX what about wl_shm_buffer_begin_access? */
+
 	ps->image = pixman_image_create_bits(pixman_format,
 		buffer->width, buffer->height,
 		wl_shm_buffer_get_data(shm_buffer),
diff --git a/src/rpi-renderer.c b/src/rpi-renderer.c
index 3ba5fc4..a964899 100644
--- a/src/rpi-renderer.c
+++ b/src/rpi-renderer.c
@@ -277,6 +277,8 @@ 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);
@@ -311,6 +313,8 @@ 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;
diff --git a/src/screenshooter.c b/src/screenshooter.c
index 645114d..0c657bc 100644
--- a/src/screenshooter.c
+++ b/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);
-- 
1.8.3.1