feat: add plasma-face-unlock

src/daemon/main.cpp

@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+// plasma-face-unlockd: the part that runs as root.
+//
+// It owns the camera and the face data, and it is the only thing that does.
+// Everything else (the lock screen agent, sudo, the setup window, the menu)
+// asks it over one socket. systemd starts it on the first connection and it
+// exits again after a minute with nothing to do, so most of the time it is not
+// running at all.
+
+#include "server.h"
+
+#include "buildconfig.h"
+
+#include <QCommandLineParser>
+#include <QCoreApplication>
+#include <QSocketNotifier>
+
+#include <csignal>
+#include <sys/signalfd.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+namespace
+{
+// sd_listen_fds(), without linking libsystemd for one function.
+int systemdSocket()
+{
+    const QByteArray pid = qgetenv("LISTEN_PID");
+    const QByteArray fds = qgetenv("LISTEN_FDS");
+    if (pid.isEmpty() || fds.isEmpty() || pid.toLongLong() != getpid() || fds.toInt() < 1) {
+        return -1;
+    }
+    qunsetenv("LISTEN_PID");
+    qunsetenv("LISTEN_FDS");
+    qunsetenv("LISTEN_FDNAMES");
+    return 3;
+}
+
+// SIGTERM from systemd is the normal way this ends. The camera thread is
+// cancelled and joined on the way out rather than being cut off mid-frame.
+void quitOnSignals(QCoreApplication &app)
+{
+    sigset_t mask;
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGTERM);
+    sigaddset(&mask, SIGINT);
+    sigprocmask(SIG_BLOCK, &mask, nullptr);
+    const int fd = signalfd(-1, &mask, SFD_CLOEXEC | SFD_NONBLOCK);
+    if (fd < 0) {
+        return;
+    }
+    auto *notifier = new QSocketNotifier(fd, QSocketNotifier::Read, &app);
+    QObject::connect(notifier, &QSocketNotifier::activated, &app, [fd] {
+        signalfd_siginfo info;
+        while (read(fd, &info, sizeof(info)) > 0) {
+        }
+        QCoreApplication::quit();
+    });
+}
+} // namespace
+
+int main(int argc, char **argv)
+{
+    // Face data and state are for root's eyes only, whatever creates them.
+    umask(077);
+
+    QCoreApplication app(argc, argv);
+    app.setApplicationName(QStringLiteral("plasma-face-unlockd"));
+    app.setApplicationVersion(QStringLiteral(PFU_VERSION));
+    qSetMessagePattern(QStringLiteral("%{if-warning}warning: %{endif}%{if-critical}error: %{endif}%{message}"));
+
+    QCommandLineParser parser;
+    parser.setApplicationDescription(QStringLiteral("Face unlock daemon for KDE Plasma"));
+    parser.addHelpOption();
+    parser.addVersionOption();
+    const QCommandLineOption socketOpt(QStringLiteral("socket"), QStringLiteral("Listen here instead of the system socket."), QStringLiteral("path"),
+                                       QStringLiteral(PFU_SOCKET));
+    const QCommandLineOption stateOpt(QStringLiteral("state-dir"), QStringLiteral("Where face data is kept."), QStringLiteral("dir"),
+                                      QStringLiteral(PFU_STATEDIR));
+    const QCommandLineOption configOpt(QStringLiteral("config"), QStringLiteral("The settings file."), QStringLiteral("file"), QStringLiteral(PFU_CONFIG));
+    const QCommandLineOption modelOpt(QStringLiteral("models"), QStringLiteral("Where the networks are."), QStringLiteral("dir"),
+                                      QStringLiteral(PFU_MODELDIR));
+    const QCommandLineOption idleOpt(QStringLiteral("idle-exit"), QStringLiteral("Exit after this many idle seconds (0: never)."), QStringLiteral("seconds"));
+    parser.addOptions({socketOpt, stateOpt, configOpt, modelOpt, idleOpt});
+    parser.process(app);
+
+    ServerOptions options;
+    options.socketPath = parser.value(socketOpt);
+    options.stateDir = parser.value(stateOpt);
+    options.configPath = parser.value(configOpt);
+    options.modelDir = parser.value(modelOpt);
+    options.systemdFd = systemdSocket();
+    // Started by the socket: go away again when there is nothing to do.
+    // Started by hand (development): stay.
+    options.idleSeconds = parser.isSet(idleOpt) ? parser.value(idleOpt).toInt() : (options.systemdFd >= 0 ? 60 : 0);
+    options.askPolkit = geteuid() == 0;
+    if (!options.askPolkit) {
+        qInfo("not running as root: face changes are not checked with polkit (development only)");
+    }
+
+    quitOnSignals(app);
+
+    Server server(options);
+    QString error;
+    if (!server.start(&error)) {
+        qCritical("cannot listen: %s", qPrintable(error));
+        return 1;
+    }
+    return app.exec();
+}