Allow CK support to be disabled at runtime for systemd

Gentoo linux users may wish to run dual systems, where they may
boot systemd (needing no CK) or another init/rc system (needing CK)
at will.  In such cases, slim needs to have consolekit support
enabled at compile time but disabled at runtime from within the
systemd unit.  This commit adds such behaviour.

https://bugs.gentoo.org/show_bug.cgi?id=481016

app.cpp

@@ -135,13 +135,16 @@ App::App(int argc, char** argv)
     ServerPID(-1), testing(false),
     serverStarted(false), mcookie(string(App::mcookiesize, 'a')),
     daemonmode(false), force_nodaemon(false),
+#ifdef USE_CONSOLEKIT
+    consolekit_support_enabled = true;
+#endif
     firstlogin(true), Dpy(NULL)
 {
     int tmp;
 
     // Parse command line
     // Note: we force a option for nodaemon switch to handle "-nodaemon"
-    while((tmp = getopt(argc, argv, "vhp:n:d?")) != EOF) {
+    while((tmp = getopt(argc, argv, "vhsp:n:d?")) != EOF) {
         switch (tmp) {
         case 'p':    // Test theme
             testtheme = optarg;
@@ -162,6 +165,11 @@ App::App(int argc, char** argv)
             std::cout << APPNAME << " version " << VERSION << endl;
             exit(OK_EXIT);
             break;
+#ifdef USE_CONSOLEKIT
+        case 's':    // Disable consolekit support
+            consolekit_support_enabled = false;
+            break;
+#endif
         case '?':    // Illegal
             logStream << endl;
         case 'h':    // Help
@@ -170,6 +178,9 @@ App::App(int argc, char** argv)
             << "    -d: daemon mode" << endl
             << "    -nodaemon: no-daemon mode" << endl
             << "    -v: show version" << endl
+#ifdef USE_CONSOLEKIT
+            << "    -s: start for systemd, disable consolekit support" << endl
+#endif
             << "    -p /path/to/theme/dir: preview theme" << endl;
             exit(OK_EXIT);
             break;
@@ -565,13 +576,15 @@ void App::Login() {
 #endif
 
 #ifdef USE_CONSOLEKIT
-    // Setup the ConsoleKit session
-    try {
-        ck.open_session(DisplayName, pw->pw_uid);
-    }
-    catch(Ck::Exception &e) {
-        logStream << APPNAME << ": " << e << endl;
-        exit(ERR_EXIT);
+    if (consolekit_support_enabled) {
+        // Setup the ConsoleKit session
+        try {
+            ck.open_session(DisplayName, pw->pw_uid);
+        }
+        catch(Ck::Exception &e) {
+            logStream << APPNAME << ": " << e << endl;
+            exit(ERR_EXIT);
+        }
     }
 #endif
 
@@ -584,18 +597,20 @@ void App::Login() {
         char** child_env = pam.getenvlist();
 
 # ifdef USE_CONSOLEKIT
-        char** old_env = child_env;
+        if (consolekit_support_enabled) {
+            char** old_env = child_env;
 
-        // Grow the copy of the environment for the session cookie
-        int n;
-        for(n = 0; child_env[n] != NULL ; n++);
+            // Grow the copy of the environment for the session cookie
+            int n;
+            for(n = 0; child_env[n] != NULL ; n++);
 
-        n++;
+            n++;
 
-        child_env = static_cast<char**>(malloc(sizeof(char*)*(n+1)));
-        memcpy(child_env, old_env, sizeof(char*)*n);
-        child_env[n - 1] = StrConcat("XDG_SESSION_COOKIE=", ck.get_xdg_session_cookie());
-        child_env[n] = NULL;
+            child_env = static_cast<char**>(malloc(sizeof(char*)*(n+1)));
+            memcpy(child_env, old_env, sizeof(char*)*n);
+            child_env[n - 1] = StrConcat("XDG_SESSION_COOKIE=", ck.get_xdg_session_cookie());
+            child_env[n] = NULL;
+        }
 # endif /* USE_CONSOLEKIT */
 #else
 
@@ -617,7 +632,9 @@ void App::Login() {
         child_env[n++]=StrConcat("MAIL=", maildir.c_str());
         child_env[n++]=StrConcat("XAUTHORITY=", xauthority.c_str());
 # ifdef USE_CONSOLEKIT
-        child_env[n++]=StrConcat("XDG_SESSION_COOKIE=", ck.get_xdg_session_cookie());
+        if (consolekit_support_enabled) {
+            child_env[n++]=StrConcat("XDG_SESSION_COOKIE=", ck.get_xdg_session_cookie());
+        }
 # endif /* USE_CONSOLEKIT */
         child_env[n++]=0;
 
@@ -662,12 +679,14 @@ void App::Login() {
     }
 
 #ifdef USE_CONSOLEKIT
-    try {
-        ck.close_session();
+    if (consolekit_support_enabled) {
+        try {
+            ck.close_session();
+        }
+        catch(Ck::Exception &e) {
+            logStream << APPNAME << ": " << e << endl;
+        };
     }
-    catch(Ck::Exception &e) {
-        logStream << APPNAME << ": " << e << endl;
-    };
 #endif
 
 #ifdef USE_PAM

app.h

@@ -89,6 +89,7 @@ class App {
 #endif
 #ifdef USE_CONSOLEKIT
     Ck::Session ck;
+    bool consolekit_support_enabled;
 #endif
 
     // Options

build_files/slim.service

@@ -3,7 +3,7 @@ Description=SLiM Simple Login Manager
 After=systemd-user-sessions.service
 
 [Service]
-ExecStart=/usr/bin/slim -nodaemon
+ExecStart=/usr/bin/slim -nodaemon -s
 Restart=on-failure
 
 [Install]