fix: fix ddm crash on treeland crash

[calsys456]

The problem is caused by reckless cleanup process. Check those pointers carefully to make reconnection works.

Summary by Sourcery

Guard Treeland connection teardown to prevent crashes during disconnect and allow safe reconnection.

Bug Fixes:

• Avoid dereferencing or deleting a null notifier when disconnecting from the Treeland display.
• Reset Treeland connector display and DDM pointers to null after disconnect to prevent use-after-free crashes.

[deepin-ci-robot]

Hi @calsys456. Thanks for your PR.

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[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Adds null checks around Treeland connector cleanup to prevent crashes when disconnecting, and ensures internal pointers are reset after teardown.

Updated class diagram for TreelandConnector disconnect lifecycle

classDiagram
    class TreelandConnector {
        - void* m_display
        - QSocketNotifier* m_notifier
        - DdmClient* m_ddm
        + void connect(QString socketPath)
        + void disconnect()
    }

    %% Key behavioral changes in disconnect()
    TreelandConnector : disconnect() checks m_display before teardown
    TreelandConnector : disconnect() checks m_notifier before setEnabled(false)
    TreelandConnector : disconnect() checks m_notifier before delete
    TreelandConnector : disconnect() sets m_display to nullptr after wl_display_disconnect
    TreelandConnector : disconnect() sets m_ddm to nullptr after teardown

Loading

File-Level Changes

Change	Details	Files
Harden Treeland disconnection logic to avoid dereferencing or reusing invalid pointers during cleanup.	Guard notifier usage in disconnect() with a null check before disabling it Guard notifier deletion with a null check to avoid deleting a null or already-reset pointer Reset m_display to nullptr after wl_display_disconnect to avoid stale pointer reuse Reset m_ddm to nullptr on disconnect to keep state consistent after teardown	src/daemon/TreelandConnector.cpp

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[sourcery-ai]

Hey - I've left some high level feedback:

• After deleting m_notifier, consider setting m_notifier to nullptr as well to avoid dangling pointers and make the cleanup pattern consistent with m_display and m_ddm.
• The repeated if (m_notifier) checks can be simplified by wrapping both setEnabled(false) and delete in a single block or helper, improving readability and reducing the chance of future divergence.
• The if (m_ddm) guard before m_ddm = nullptr; is unnecessary since assigning nullptr is safe even if it is already nullptr, so you can drop the condition to simplify the logic.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- After deleting `m_notifier`, consider setting `m_notifier` to `nullptr` as well to avoid dangling pointers and make the cleanup pattern consistent with `m_display` and `m_ddm`.
- The repeated `if (m_notifier)` checks can be simplified by wrapping both `setEnabled(false)` and `delete` in a single block or helper, improving readability and reducing the chance of future divergence.
- The `if (m_ddm)` guard before `m_ddm = nullptr;` is unnecessary since assigning `nullptr` is safe even if it is already `nullptr`, so you can drop the condition to simplify the logic.

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[Copilot]

Pull request overview

This PR fixes crashes that occur when Treeland (the Wayland compositor used as greeter) crashes by adding null pointer checks to the disconnect() method in TreelandConnector. The changes prevent dereferencing null pointers during cleanup and ensure proper state reset for reconnection.

Changes:

• Added null pointer checks before accessing m_notifier in the disconnect method
• Reset m_display and m_ddm pointers to nullptr after cleanup to support safe reconnection

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: calsys456, wineee, zccrs

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• debian/deepin/OWNERS

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