feat: avoid duplicate ll-package-manager startup by checking existing

[dengbo11]

connection

1. Add startProcess helper to launch detached processes with proper environment and cleanup on exit.
2. Replace unconditional startDetached and sleep with a D-Bus peer connection check to see if ll-package-manager is already running.
3. Only start a new process when no existing daemon is detected; otherwise log reuse of existing instance.
4. Include signal handling to terminate spawned processes when the application quits.

Log: Improved process management for ll-package-manager to prevent duplicate instances.

Influence:

1. Verify that ll-package-manager starts correctly when not already running.
2. Test that when ll-package-manager is already running, a new process is not spawned.
3. Confirm that spawned processes are terminated when the main application exits.
4. Check logging output for "reuse existing process" or "start" messages.
5. Verify D-Bus connection to the peer socket works as expected.
6. Test in scenarios where the socket file might be stale or missing.

[gemini-code-assist]

Code Review

This pull request introduces a check to see if ll-package-manager is already running via a peer DBus connection before attempting to start a new instance. If it is not running, a new helper function startProcess is used to start it detached and register a cleanup callback to terminate the process when the application quits. The review feedback highlights critical issues in startProcess: first, calling process.environment() on a new QProcess returns an empty list, which wipes out the system environment; second, if startDetached fails, the PID remains 0, leading to a dangerous kill(0, SIGTERM) call that terminates the entire process group. Additionally, the reviewer notes that using the connection name "ll-package-manager" for the temporary check can conflict with subsequent connections, and suggests using a distinct name and explicitly disconnecting.

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[gemini-code-assist]

There are two critical issues in the startProcess helper function:

1. Environment Wiping: Calling process.environment() on a newly constructed QProcess returns an empty list. Appending "QT_FORCE_STDERR_LOGGING=1" and calling process.setEnvironment(envs) replaces the entire environment of the child process with just this single variable. This discards all system environment variables (such as PATH, LD_LIBRARY_PATH, USER, etc.), which will cause sudo or ll-package-manager to fail to start or run incorrectly. Use QProcess::systemEnvironment() to preserve the parent process's environment.

2. Dangerous Signal Handling: If process.startDetached(&pid) fails, pid remains 0. Calling kill(0, SIGTERM) inside the aboutToQuit lambda will send SIGTERM to the entire process group of ll-cli, abruptly terminating the CLI itself and potentially other sibling/parent processes. You must check that startDetached succeeded and that pid > 0 before registering the cleanup connection.

void startProcess(const QString &program, const QStringList &args = {})
{
    QProcess process;
    auto envs = QProcess::systemEnvironment();
    envs.push_back("QT_FORCE_STDERR_LOGGING=1");
    process.setEnvironment(envs);
    process.setProgram(program);
    process.setArguments(args);

    qint64 pid = 0;
    if (process.startDetached(&pid) && pid > 0) {
        LogD("start {} {} as {}", program.toStdString(), args.join(" ").toStdString(), pid);

        QObject::connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit, [pid]() {
            LogD("kill {}", pid);
            kill(pid, SIGTERM);
        });
    } else {
        LogE("failed to start process: {}", program.toStdString());
    }
}

[gemini-code-assist]

Using the connection name "ll-package-manager" for the temporary startup check can conflict with the actual connection established later in cli.cpp (line 471).

If the connection is not fully unregistered or closed immediately upon the destruction of pkgManConn (due to Qt's internal DBus thread handling or event loop delays), the subsequent connectToPeer call in cli.cpp will fail with a "connection already exists" error, preventing ll-cli from working in --no-dbus mode.

To prevent this, use a distinct connection name (e.g., "ll-package-manager-check") and explicitly disconnect from it once the check is complete.

        const auto pkgManAddress = QString("unix:path=/tmp/linglong-package-manager.socket");

        // Check if ll-package-manager is already running
        bool alreadyRunning = false;
        {
            auto checkConn = QDBusConnection::connectToPeer(pkgManAddress, "ll-package-manager-check");
            if (checkConn.isConnected()) {
                alreadyRunning = true;
                QDBusConnection::disconnectFromPeer("ll-package-manager-check");
            }
        }

        if (!alreadyRunning) {
            // Only start a new process if no existing one is listening
            startProcess("sudo",
                         { "--user",
                           LINGLONG_USERNAME,
                           "--preserve-env=QT_FORCE_STDERR_LOGGING",
                           "--preserve-env=QDBUS_DEBUG",
                           LINGLONG_LIBEXEC_DIR "/ll-package-manager",
                           "--no-dbus" });
            using namespace std::chrono_literals;
            std::this_thread::sleep_for(1s);
        } else {
            LogD("ll-package-manager is already running, reuse existing process");
        }

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: dengbo11

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: dengbo11

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

❌ Patch coverage is 0% with 20 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
apps/ll-cli/src/main.cpp	0.00%	20 Missing ⚠️

Files with missing lines	Coverage Δ
apps/ll-cli/src/main.cpp	0.00% <0.00%> (ø)

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