core: set focused surface pointer to null if matches on delete

We previously never set the focused pointer to null. I thought this
would be fine because a `hasSurface` check would say it doesn't exist.
But I didn't account for the fact that a deleted surface followed very
quickly by a new surface would free the pointer, then the allocation
would reuse the very same pointer, making `hasSurface` return a false
positive.

Well, technically, hasSurface is not wrong, the surface exists, but its
not really the same surface, its just a surface that happens to have the
same pointer as a previously freed surface.

Co-authored-by: Will Pragnell <wpragnell@gmail.com>
This commit is contained in:
Mitchell Hashimoto
2023-08-25 20:57:28 -07:00
parent 134568c395
commit 6a8d302fa0

View File

@ -139,6 +139,16 @@ pub fn addSurface(self: *App, rt_surface: *apprt.Surface) !void {
/// Delete the surface from the known surface list. This will NOT call the
/// destructor or free the memory.
pub fn deleteSurface(self: *App, rt_surface: *apprt.Surface) void {
// If this surface is the focused surface then we need to clear it.
// There was a bug where we relied on hasSurface to return false and
// just let focused surface be but the allocator was reusing addresses
// after free and giving false positives, so we must clear it.
if (self.focused_surface) |focused| {
if (focused == &rt_surface.core_surface) {
self.focused_surface = null;
}
}
var i: usize = 0;
while (i < self.surfaces.items.len) {
if (self.surfaces.items[i] == rt_surface) {