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fix: prevent X11 IO error crash on mode switch - #1755
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1. Root cause: dde-shell does not install a custom X11 IO error handler, libX11 default _XDefaultIOError calls exit(1) on X connection death, triggering C++ static destructors that access the dead X11 connection, causing SIGSEGV 2. Fix: install custom x11IOErrorHandler calling _exit(0) to bypass C++ destructor chain, add X11 link dependency in CMakeLists.txt 3. Impact: only affects process exit path when X11 connection is lost, no behavior change for normal operation Log: fix crash when switching from terminal mode to graphical mode Influence: 1. Test switching from init 3 to init 5, verify no coredump 2. Verify normal desktop panel display and interaction 3. Verify no regression on existing dde-shell functionality fix: 修复终端模式切换到图形化时的崩溃问题 1. 根因：dde-shell 未安装自定义 X11 IO 错误处理器，libX11 默认的 _XDefaultIOError 在 X 连接断开时调用 exit(1)，触发 C++ 静态 析构函数访问已断开的 X11 连接，导致 SIGSEGV 2. 方案：安装自定义 x11IOErrorHandler 调用 _exit(0) 绕过 C++ 析构 链，并在 CMakeLists.txt 中添加 X11 链接依赖 3. 影响：仅影响 X11 连接断开时的进程退出路径，正常运行无行为变化 Log: 修复终端模式切换到图形化时的崩溃问题 Influence: 1. 测试 init 3 切换到 init 5 后 dde-shell 无 coredump 2. 验证桌面面板正常显示和交互 3. 验证现有 dde-shell 功能无回归 PMS: BUG-378799
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[APPROVALNOTIFIER] This PR is NOT APPROVED This pull-request has been approved by: MyLeeJiEun The full list of commands accepted by this bot can be found here. DetailsNeeds approval from an approver in each of these files:Approvers can indicate their approval by writing |
Reviewer's guide (collapsed on small PRs)Reviewer's GuideThe PR prevents dde-shell from crashing when the X11 server disappears during terminal/graphical mode transitions by registering an Xlib I/O error handler that bypasses unsafe C++ destructors with immediate process termination, and adds the corresponding X11 build dependency. Review the handler’s registration timing and the intentional loss of graceful cleanup on X11 disconnect, then verify init 3/init 5 switching and normal desktop behavior. Sequence diagram for safe dde-shell termination on X11 disconnectsequenceDiagram
participant X11 as X11Server
participant Shell as dde_shell
participant Xlib as libX11
participant Handler as x11IOErrorHandler
participant OS as Process
Shell->>Xlib: XSetIOErrorHandler(x11IOErrorHandler)
Shell->>X11: Maintain display connection
X11-->>Xlib: Connection lost during mode switch
Xlib->>Handler: x11IOErrorHandler(Display *)
Handler->>OS: _exit(0)
OS-->>Shell: Terminate immediately without C++ destructors
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Hi @MyLeeJiEun. Thanks for your PR. I'm waiting for a linuxdeepin member to verify that this patch is reasonable to test. If it is, they should reply with Once the patch is verified, the new status will be reflected by the I understand the commands that are listed here. DetailsInstructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. |
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Hey - I've found 2 issues
Prompt for AI Agents
Please address the comments from this code review:
## Individual Comments
### Comment 1
<location path="shell/CMakeLists.txt" line_range="9" />
<code_context>
find_package(Qt${QT_VERSION_MAJOR} ${REQUIRED_QT_VERSION} REQUIRED COMPONENTS Widgets Gui WaylandClient)
find_package(TreelandProtocols REQUIRED)
pkg_check_modules(WaylandClient REQUIRED IMPORTED_TARGET wayland-client)
+pkg_check_modules(X11 REQUIRED IMPORTED_TARGET x11)
if (NOT DEFINED SYSTEMD_USER_UNIT_DIR)
</code_context>
<issue_to_address>
**Wayland-only builds still require X11**
When `BUILD_WITH_X11` is disabled and X11 development files are unavailable, the unconditional `pkg_check_modules(X11 REQUIRED ...)` lookup fails during CMake configuration, and the unconditional Xlib include in `main.cpp` also prevents a build without X11. The Wayland-only build cannot complete.
Gate the X11 pkg-config lookup and Xlib include on `BUILD_WITH_X11`.
Also at `shell/main.cpp:19-20`, `shell/main.cpp:265`, `shell/CMakeLists.txt:52`.
</issue_to_address>
### Comment 2
<location path="shell/main.cpp" line_range="265" />
<code_context>
manager.exec();
}, Qt::QueuedConnection);
+ XSetIOErrorHandler(x11IOErrorHandler);
+
QObject::connect(qApp, &QCoreApplication::aboutToQuit, qApp, [&manager]() {
</code_context>
<issue_to_address>
**Startup X11 errors still trigger destructor crashes**
When the X server connection fails during application or shell startup, before `XSetIOErrorHandler` is called, the default libX11 handler remains active while the application and applet setup run; it calls `exit()` on an I/O error, running destructors against the dead display and potentially crashing dde-shell.
Install the I/O error handler before any startup code can use the X11 connection.
</issue_to_address>| find_package(Qt${QT_VERSION_MAJOR} ${REQUIRED_QT_VERSION} REQUIRED COMPONENTS Widgets Gui WaylandClient) | ||
| find_package(TreelandProtocols REQUIRED) | ||
| pkg_check_modules(WaylandClient REQUIRED IMPORTED_TARGET wayland-client) | ||
| pkg_check_modules(X11 REQUIRED IMPORTED_TARGET x11) |
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🟡 Medium · Wayland-only builds still require X11
When BUILD_WITH_X11 is disabled and X11 development files are unavailable, the unconditional pkg_check_modules(X11 REQUIRED ...) lookup fails during CMake configuration, and the unconditional Xlib include in main.cpp also prevents a build without X11. The Wayland-only build cannot complete.
Gate the X11 pkg-config lookup and Xlib include on BUILD_WITH_X11.
Also at shell/main.cpp:19-20, shell/main.cpp:265, shell/CMakeLists.txt:52.
Prompt for AI agents
In `shell/CMakeLists.txt` at line 9:
**Wayland-only builds still require X11**
When `BUILD_WITH_X11` is disabled and X11 development files are unavailable, the unconditional `pkg_check_modules(X11 REQUIRED ...)` lookup fails during CMake configuration, and the unconditional Xlib include in `main.cpp` also prevents a build without X11. The Wayland-only build cannot complete.
Gate the X11 pkg-config lookup and Xlib include on `BUILD_WITH_X11`.
Also at `shell/main.cpp:19-20`, `shell/main.cpp:265`, `shell/CMakeLists.txt:52`.| manager.exec(); | ||
| }, Qt::QueuedConnection); | ||
|
|
||
| XSetIOErrorHandler(x11IOErrorHandler); |
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🟡 Medium · Startup X11 errors still trigger destructor crashes
When the X server connection fails during application or shell startup, before XSetIOErrorHandler is called, the default libX11 handler remains active while the application and applet setup run; it calls exit() on an I/O error, running destructors against the dead display and potentially crashing dde-shell.
Install the I/O error handler before any startup code can use the X11 connection.
Prompt for AI agents
In `shell/main.cpp` at line 265:
**Startup X11 errors still trigger destructor crashes**
When the X server connection fails during application or shell startup, before `XSetIOErrorHandler` is called, the default libX11 handler remains active while the application and applet setup run; it calls `exit()` on an I/O error, running destructors against the dead display and potentially crashing dde-shell.
Install the I/O error handler before any startup code can use the X11 connection.
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TAG Bot New tag: 2.0.57 |
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TAG Bot New tag: 2.0.58 |
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TAG Bot New tag: 2.0.59 |
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TAG Bot New tag: 2.0.60 |
Root Cause Analysis
When switching from terminal mode (
sudo init 3) back to graphical mode (sudo init 5), the X11 server shuts down duringinit 3. Processes still holding X11 display connections (dde-shell) encounter an X11 IO error. Since dde-shell does not install a custom X11 IO error handler, libX11's default_XDefaultIOErrorcallsexit(1), which triggers C++ static destructors (e.g.,QWindow::~QWindow()→QSurface::~QSurface()→QOpenGLContext::currentContext()) that access the dead X11 connection, causing SIGSEGV.Key evidence:
exit()called from_XDefaultIOError→_XIOErrordde-shell/shell/main.cppnever callsXSetIOErrorHandler()before entering the event loopFix
Install a custom X11 IO error handler
x11IOErrorHandlerthat calls_exit(0)to bypass the C++ destructor chain, and register it viaXSetIOErrorHandler()before the event loop starts. Also add X11 link dependency (pkg_check_modules(X11 REQUIRED IMPORTED_TARGET x11)) inCMakeLists.txt.Change Safety Assessment
Code Safety
Business Impact Scope
Affects the dde-shell desktop process exit path when the X11 connection is lost. Normal desktop panel display and interaction are unaffected. The fix ensures clean process termination without SIGSEGV during display server transitions.
Verification Suggestion
Test
sudo init 3→sudo init 5switching and verify no coredump for dde-shell. Verify normal desktop panel display and interaction work after mode switch.根因分析
从终端模式（
sudo init 3）切换回图形化模式（sudo init 5）时，init 3期间 X11 服务器关闭。仍持有 X11 显示连接的进程（dde-shell）遭遇 X11 IO 错误。由于 dde-shell 未安装自定义 X11 IO 错误处理器，libX11 默认处理器_XDefaultIOError调用exit(1)，触发 C++ 静态析构函数（如QWindow::~QWindow()→QSurface::~QSurface()→QOpenGLContext::currentContext()）访问已失效的 X11 连接，导致 SIGSEGV。关键证据：
exit()中，由_XDefaultIOError→_XIOError调用dde-shell/shell/main.cpp在进入事件循环前从未调用XSetIOErrorHandler()修复方案
安装自定义 X11 IO 错误处理器
x11IOErrorHandler，调用_exit(0)绕过 C++ 析构链，在事件循环开始前通过XSetIOErrorHandler()注册。同时在CMakeLists.txt中添加 X11 链接依赖（pkg_check_modules(X11 REQUIRED IMPORTED_TARGET x11)）。改动安全评估
代码安全
业务影响范围
影响 dde-shell 桌面进程在 X11 连接断开时的退出路径。正常桌面面板显示和交互不受影响。修复确保在显示服务器切换期间进程干净退出，不产生 SIGSEGV。
验证建议
测试
sudo init 3→sudo init 5切换，验证 dde-shell 无 coredump。验证模式切换后桌面面板正常显示和交互。PMS: BUG-378799
Summary by Sourcery
Handle X11 connection loss with immediate process termination to avoid destructor-related crashes during terminal-to-graphical mode switches.
Bug Fixes:
Build: