[re2zero]

Root Cause Analysis

When a UVC camera device control query times out (GET_MAX returns -110 ETIMEDOUT),
QCamera construction fails internally, leaving its private state invalid. In
startCamera() (src/src/camera.cpp:244), QCameraInfo cameraInfo(*m_camera)
is constructed immediately after new QCamera() without any error check, causing
a null pointer dereference at offset 8 (segfault at 8) inside libQt5Core.so.
The same QCameraInfo(*m_camera) pattern in restartCamera() (camera.cpp:136)
has an identical risk.

Fix Approach

Added QCamera::error() check after new QCamera() in startCamera() — on
error, clean up via stopCamera(), emit cameraCannotUsed(), and return early.
Connected QCamera::error signal to cameraCannotUsed() so runtime errors are
also handled. QCameraInfo is only constructed when QCamera is in a valid
state. Applied the same error() guard in restartCamera() before
QCameraInfo(*m_camera) construction.

Change Safety Assessment

Code Safety

• Risk Level: Low
• Only adds null check / early return and signal connection; no function
  signature changes, no public member modifications, no behavior change on
  the normal path
• Does not revert any historical fix; 4e4a444 (unplug crash fix) addressed a
  different code path and remains intact

Business Impact Scope

Affects camera initialization and device hot-plug/restart paths. When camera
hardware initialization fails (e.g., UVC timeout via USB passthrough), the app
emits cameraCannotUsed() and recovers gracefully instead of crashing. Valid
camera devices are unaffected.

Verification Suggestion

Test camera open with a working UVC camera (normal path should be unchanged).
Simulate camera initialization failure (e.g., faulty USB passthrough device)
and verify the app shows "camera unavailable" instead of crashing.

---

根因分析

当 UVC 相机设备控制查询超时（GET_MAX 返回 -110 ETIMEDOUT）时，QCamera 构造函数内部
初始化失败，私有状态无效。startCamera()（src/src/camera.cpp:244）在 new QCamera()
后未做任何错误检查即构造 QCameraInfo cameraInfo(*m_camera)，导致 libQt5Core.so 内部
空指针解引用（segfault at 8）。restartCamera()（camera.cpp:136）中的
QCameraInfo(*m_camera) 存在相同风险。

修复方案

在 startCamera() 的 new QCamera() 后增加 QCamera::error() 检查——错误时通过
stopCamera() 清理、发出 cameraCannotUsed() 信号并提前返回。连接 QCamera::error
信号到 cameraCannotUsed() 以处理运行时错误。仅在 QCamera 有效时才构造
QCameraInfo。在 restartCamera() 的 QCameraInfo(*m_camera) 构造前同步增加
error() 检查。

改动安全评估

代码安全评估

• 风险等级: 低风险
• 仅增加空指针检查 / 提前返回和信号连接，不改变函数签名、不修改公开成员、
  正常路径无行为变化
• 不撤销任何历史修复；4e4a444（拔摄像头崩溃修复）覆盖不同代码路径，不受影响

业务影响范围

影响相机初始化和设备热插拔/重启路径。当相机硬件初始化失败（如 USB 透传环境下 UVC
超时）时，应用发出 cameraCannotUsed() 信号并优雅恢复，而非崩溃。有效相机设备不受影响。

验证建议

使用正常 UVC 相机测试打开功能（验证正常路径无回归）。模拟相机初始化失败（如故障 USB
透传设备），验证应用提示"相机不可用"而非崩溃。

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[github-actions]

Warning

[Debian检查]

• 检测到敏感词dmidecode变动

详情

    {
    "dmidecode": {
        "src/main.cpp": [
            "        options << QString(QStringLiteral(\"dmidecode -t 11 | grep 'String 4' | awk '{print $NF}' && \"",
            "                                          \"dmidecode -s system-product-name|awk '{print $NF}'\"));"
        ]
    }
}

[github-actions]

TAG Bot

TAG: 6.0.13
EXISTED: no
DISTRIBUTION: unstable

[github-actions]

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I have read the CLA Document and I hereby sign the CLA.

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3 out of 4 committers have signed the CLA.
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