Merge branch 'systemd' of https://github.com/CendioOssman/tigervnc

BUILDING.txt

    * All build requirements Xorg imposes (see its documentation)
    * patch
 
+-- If building x0vncserver with socket activation support:
+   * libsystemd
+
 -- Optional ffmpeg development kit support (libav)
    * You might have to enable additional repositories for this. E.g.,
      on RHEL, EPEL and RPMFusion (free + nonfree) need to be enabled.

CMakeLists.txt

   endif()
 endif()
 
+# check for systemd support (socket activation)
+if(UNIX AND NOT APPLE)
+  find_package(PkgConfig)
+  if (PKG_CONFIG_FOUND)
+    pkg_check_modules(LIBSYSTEMD libsystemd)
+  endif()
+endif()
+
 # Generate config.h and make sure the source finds it
 configure_file(config.h.in config.h)
 add_definitions(-DHAVE_CONFIG_H)

unix/x0vncserver/CMakeLists.txt

 target_include_directories(x0vncserver PUBLIC ${CMAKE_SOURCE_DIR}/common)
 target_link_libraries(x0vncserver tx rfb network rdr unixcommon)
 
+# systemd support (socket activation)
+if (LIBSYSTEMD_FOUND)
+  add_definitions(-DHAVE_SYSTEMD_H)
+  target_link_libraries(x0vncserver ${LIBSYSTEMD_LIBRARIES})
+endif()
+
 if(X11_FOUND AND X11_XTest_LIB)
   add_definitions(-DHAVE_XTEST)
   target_link_libraries(x0vncserver ${X11_XTest_LIB})

unix/x0vncserver/x0vncserver.cxx

 #include <rfb/Timer.h>
 #include <network/TcpSocket.h>
 #include <network/UnixSocket.h>
+#ifdef HAVE_SYSTEMD_H
+#  include <systemd/sd-daemon.h>
+#endif
 
 #include <signal.h>
 #include <X11/X.h>
   caughtSignal = true;
 }
 
+static bool hasSystemdListeners()
+{
+#ifdef HAVE_SYSTEMD_H
+  // This also returns true on errors, because we then assume we were
+  // meant to use systemd but failed somewhere
+  return sd_listen_fds(0) != 0;
+#else
+  return false;
+#endif
+}
+
+static int createSystemdListeners(std::list<SocketListener*> *listeners)
+{
+#ifdef HAVE_SYSTEMD_H
+  int count = sd_listen_fds(0);
+  if (count < 0) {
+    vlog.error("Error getting listening sockets from systemd: %s",
+               strerror(-count));
+    return count;
+  }
+
+  for (int i = 0; i < count; ++i)
+      listeners->push_back(new TcpListener(SD_LISTEN_FDS_START + i));
+
+  return count;
+#else
+  (void)listeners;
+  return 0;
+#endif
+}
+
 
 class FileTcpFilter : public TcpFilter
 {
   Configuration::removeParam("SendCutText");
   Configuration::removeParam("MaxCutText");
 
+  // Assume different defaults when socket activated
+  if (hasSystemdListeners())
+    rfbport.setParam(-1);
+
   for (int i = 1; i < argc; i++) {
     if (Configuration::setParam(argv[i]))
       continue;
 
     VNCServerST server(desktopName, &desktop);
 
+    if (createSystemdListeners(&listeners) > 0) {
+      // When systemd is in charge of listeners, do not listen to anything else
+      vlog.info("Listening on systemd sockets");
+    }
+
     if (rfbunixpath.getValueStr()[0] != '\0') {
       listeners.push_back(new network::UnixListener(rfbunixpath, rfbunixmode));
       vlog.info("Listening on %s (mode %04o)", (const char*)rfbunixpath, (int)rfbunixmode);

unix/x0vncserver/x0vncserver.man

 .B \-rfbport \fIport\fP
 Specifies the TCP port on which x0vncserver listens for connections from
 viewers (the protocol used in VNC is called RFB - "remote framebuffer").
-The default port is 5900. Specify \fB-1\fP to disable listening on a TCP
-port.
+Specify \fB-1\fP to disable listening on a TCP port. The default port is
+5900 when started directly, and -1 when activated by a systemd socket.
 .
 .TP
 .B \-UseIPv4
 .TP
 .B \-rfbunixpath \fIpath\fP
 Specifies the path of a Unix domain socket on which x0vncserver listens for
-connections from viewers.
+connections from viewers. Default is to not listen to any Unix domain
+socket.
 .
 .TP
 .B \-rfbunixmode \fImode\fP