1 files changed, 60 insertions, 12 deletions

diff --git a/src/common/backend.c b/src/common/backend.c
index ccb9c27..23275d6 100644
--- a/src/common/backend.c
+++ b/src/common/backend.c
@@ -81,10 +81,18 @@ uint32_t yasl_display_caps(const struct yasl_display *d)
 
 int yasl_display_dispatch(struct yasl_display *d, int timeout_ms)
 {
-    if (!d) return -1;
-    if (d->ops->display_dispatch_timeout)
-        return d->ops->display_dispatch_timeout(d, timeout_ms);
-    return -1;
+    if (!d) {
+        errno = EINVAL;
+        return -1;
+    }
+    if (!d->ops->display_dispatch_timeout) {
+        errno = ENOTSUP;
+        return -1;
+    }
+    errno = 0;
+    int result = d->ops->display_dispatch_timeout(d, timeout_ms);
+    if (result < 0 && !errno) errno = EIO;
+    return result;
 }
 
 void yasl_display_flush(struct yasl_display *d)
@@ -127,7 +135,12 @@ bool yasl_display_drag_start(struct yasl_display *d, struct yasl_surface *origin
         return 0;
     if (!origin || origin->display != d)
         return false;
-    return d->ops->display_drag_start(d, origin, image, l, ud);
+    if (image && (!image->pixels || image->size.x <= 0 || image->size.y <= 0 ||
+        image->size.x > 32767 || image->size.y > 32767 ||
+        (int64_t)image->size.x * image->size.y * 4 > INT32_MAX))
+        return false;
+    const struct yasl_drag_listener empty = {0};
+    return d->ops->display_drag_start(d, origin, image, l ? l : &empty, ud);
 }
 
 void yasl_display_drag_cancel(struct yasl_display *d)
@@ -151,7 +164,10 @@ struct yasl_surface *yasl_create_toplevel(struct yasl_display *d,
         errno = ENOTSUP;
         return NULL;
     }
-    return d->ops->surface_create_toplevel(d, spec, graphics_device);
+    errno = 0;
+    struct yasl_surface *s = d->ops->surface_create_toplevel(d, spec, graphics_device);
+    if (!s && !errno) errno = ENODEV;
+    return s;
 }
 
 struct yasl_surface *yasl_surface_create_toplevel(struct yasl_display *d,
@@ -160,18 +176,50 @@ struct yasl_surface *yasl_surface_create_toplevel(struct yasl_display *d,
     return yasl_create_toplevel(d, spec, NULL);
 }
 
+static bool popup_spec_valid(const struct yasl_popup_spec *spec)
+{
+    return spec && spec->size.x > 0 && spec->size.y > 0 &&
+        spec->size.x <= 32767 && spec->size.y <= 32767 &&
+        (int64_t)spec->size.x * spec->size.y * 4 <= INT32_MAX &&
+        spec->anchor.width >= 0 && spec->anchor.height >= 0 &&
+        spec->content_offset.x >= 0 && spec->content_offset.y >= 0 &&
+        spec->content_size.x >= 0 && spec->content_size.y >= 0 &&
+        (int64_t)spec->content_offset.x + spec->content_size.x <= spec->size.x &&
+        (int64_t)spec->content_offset.y + spec->content_size.y <= spec->size.y;
+}
+
 struct yasl_surface *yasl_surface_create_popup(struct yasl_surface *parent, const struct yasl_popup_spec *spec)
 {
-    if (!parent || !parent->display->ops->surface_create_popup)
-        return 0;
-    return parent->display->ops->surface_create_popup(parent, spec);
+    if (!parent || !popup_spec_valid(spec)) {
+        errno = EINVAL;
+        return NULL;
+    }
+    if (!(yasl_display_caps(parent->display) & YASL_CAP_POPUPS) ||
+        !parent->display->ops->surface_create_popup) {
+        errno = ENOTSUP;
+        return NULL;
+    }
+    errno = 0;
+    struct yasl_surface *s = parent->display->ops->surface_create_popup(parent, spec);
+    if (!s && !errno) errno = ENODEV;
+    return s;
 }
 
 bool yasl_surface_popup_reposition(struct yasl_surface *popup, const struct yasl_popup_spec *spec)
 {
-    if (!popup || !popup->display->ops->surface_popup_reposition)
-        return 0;
-    return popup->display->ops->surface_popup_reposition(popup, spec);
+    if (!popup || !popup_spec_valid(spec)) {
+        errno = EINVAL;
+        return false;
+    }
+    if (!(yasl_display_caps(popup->display) & YASL_CAP_POPUPS) ||
+        !popup->display->ops->surface_popup_reposition) {
+        errno = ENOTSUP;
+        return false;
+    }
+    errno = 0;
+    bool result = popup->display->ops->surface_popup_reposition(popup, spec);
+    if (!result && !errno) errno = ENODEV;
+    return result;
 }
 
 void yasl_surface_destroy(struct yasl_surface *s)