drm: Provide a failure path when getting the fb

This is helpful for debugging as you will bail early with an error
message instead of a random SIGSEGV (or something more obscure).

2 files changed, 17 insertions, 0 deletions

diff --git a/drm-atomic.c b/drm-atomic.c
index 27c6b1e..c06e52f 100644
--- a/drm-atomic.c
+++ b/drm-atomic.c
@@ -187,6 +187,11 @@ static int atomic_run(const struct gbm *gbm, const struct egl *egl)
 	eglSwapBuffers(egl->display, egl->surface);
 	bo = gbm_surface_lock_front_buffer(gbm->surface);
 	fb = drm_fb_get_from_bo(bo);
+	if (!fb) {
+		printf("Failed to get a new framebuffer BO\n");
+		return -1;
+	}
+
 
 	drm.kms_in_fence_fd = -1;
 
@@ -235,6 +240,10 @@ static int atomic_run(const struct gbm *gbm, const struct egl *egl)
 
 		next_bo = gbm_surface_lock_front_buffer(gbm->surface);
 		fb = drm_fb_get_from_bo(next_bo);
+		if (!fb) {
+			printf("Failed to get a new framebuffer BO\n");
+			return -1;
+		}
 
 		/*
 		 * Here you could also update drm plane layers if you want
diff --git a/drm-legacy.c b/drm-legacy.c
index 3b407f8..a0b419a 100644
--- a/drm-legacy.c
+++ b/drm-legacy.c
@@ -60,6 +60,10 @@ static int legacy_run(const struct gbm *gbm, const struct egl *egl)
 	eglSwapBuffers(egl->display, egl->surface);
 	bo = gbm_surface_lock_front_buffer(gbm->surface);
 	fb = drm_fb_get_from_bo(bo);
+	if (!fb) {
+		fprintf(stderr, "Failed to get a new framebuffer BO\n");
+		return -1;
+	}
 
 	/* set mode: */
 	ret = drmModeSetCrtc(drm.fd, drm.crtc_id, fb->fb_id, 0, 0,
@@ -78,6 +82,10 @@ static int legacy_run(const struct gbm *gbm, const struct egl *egl)
 		eglSwapBuffers(egl->display, egl->surface);
 		next_bo = gbm_surface_lock_front_buffer(gbm->surface);
 		fb = drm_fb_get_from_bo(next_bo);
+		if (!fb) {
+			fprintf(stderr, "Failed to get a new framebuffer BO\n");
+			return -1;
+		}
 
 		/*
 		 * Here you could also update drm plane layers if you want