seat: fix NULL deref in handle_seat_node_destroy - #9246
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seat_get_focus_inactive(seat, &root->node) can return NULL when the seat's focus_stack is empty (e.g. a secondary seat that never received real focus, in a multi-seat setup, once the last tracked container/workspace in its focus_stack is destroyed). The focus_inactive branch of handle_seat_node_destroy dereferenced that return value unconditionally (focus->type), causing an immediate crash of the whole compositor in that state. This guards the dereference with a NULL check, matching the safe usage pattern already used elsewhere in the codebase (workspace_consider_destroy compares the return value with == instead of dereferencing it directly).
WhyNotHugo
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Aug 4, 2026
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LGTM, description and implementation are both sound.
Avoids the extra indentation level, as suggested by WhyNotHugo in review.
WhyNotHugo
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Aug 5, 2026
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seat_get_focus_inactive(seat, &root->node) can return NULL when the seat's focus_stack is empty (e.g. a secondary seat that never received real focus, in a multi-seat setup, once the last tracked container/workspace in its focus_stack is destroyed).
The focus_inactive branch of handle_seat_node_destroy dereferenced that return value unconditionally
(focus->type), causing an immediate crash of the whole compositor in that state.
This guards the dereference with a NULL check, matching the safe usage pattern already used elsewhere in the codebase (workspace_consider_destroy compares the return value with == instead of dereferencing it directly).