Support daemon mode on MS-Windows (bug#19688)

 src/emacs.c <w32_daemon_event> [WINDOWSNT]: New global var.
 (main) [WINDOWSNT]: Initialize it to NULL.  Create the event to
 signal clients we are ready for connections.
 (Fdaemon_initialized): Use DAEMON_RUNNING.
 [WINDOWSNT]: MS-Windows specific code to signal clients we are
 ready for connections.
 src/lisp.h (DAEMON_RUNNING): New macro, encapsulates Posix and
 MS-Windows conditions for running in daemon mode.
 src/minibuf.c (read_minibuf): Use DAEMON_RUNNING.
 src/keyboard.c (kbd_buffer_get_event): Use DAEMON_RUNNING.
 src/dispnew.c (init_display) [WINDOWSNT]: Initialize frames/terminal
 even in daemon mode.

 nt/inc/ms-w32.h (W32_DAEMON_EVENT): New macro.

 lib-src/emacsclient.c (decode_options) [WINDOWSNT]: Don't reject empty
 arguments for --alternate-editor.
 (print_help_and_exit) [WINDOWSNT]: Don't refrain from advertising
 empty arguments for --alternate-editor.
 (start_daemon_and_retry_set_socket) [WINDOWSNT]: MS-Windows
 specific code to start Emacs in daemon mode and wait for it to be
 ready for client connections.

 lisp/server.el (server-process-filter): Force GUI frames on
 MS-Windows in daemon mode, even if a TTY frame was requested.
 lisp/frameset.el (frameset-keep-original-display-p): Don't assume
 windows-nt cannot be in daemon mode.
 lisp/frame.el (window-system-for-display): Don't assume windows-nt
 cannot be in daemon mode.

2 files changed, 82 insertions, 10 deletions

diff --git a/lib-src/ChangeLog b/lib-src/ChangeLog
index 5c55bcea506..83855afa675 100644
--- a/lib-src/ChangeLog
+++ b/lib-src/ChangeLog
@@ -1,3 +1,14 @@
+2015-02-27  Mark Laws  <mdl@60hz.org>
+
+        Support daemon mode on MS-Windows (bug#19688)
+        * emacsclient.c (decode_options) [WINDOWSNT]: Don't reject empty
+        arguments for --alternate-editor.
+        (print_help_and_exit) [WINDOWSNT]: Don't refrain from advertising
+        empty arguments for --alternate-editor.
+        (start_daemon_and_retry_set_socket) [WINDOWSNT]: MS-Windows
+        specific code to start Emacs in daemon mode and wait for it to be
+        ready for client connections.
+
 2015-02-23  Pete Williamson  <petewil0@googlemail.com>  (tiny change)
 
         Use ${EXEEXT} more uniformly in makefiles
diff --git a/lib-src/emacsclient.c b/lib-src/emacsclient.c
index a04dda6408f..806275f5b1d 100644
--- a/lib-src/emacsclient.c
+++ b/lib-src/emacsclient.c
@@ -595,13 +595,6 @@ decode_options (int argc, char **argv)
       display = NULL;
       tty = 1;
     }
-
-  if (alternate_editor && alternate_editor[0] == '\0')
-    {
-      message (true, "--alternate-editor argument or ALTERNATE_EDITOR variable cannot be\n\
-an empty string");
-      exit (EXIT_FAILURE);
-    }
 #endif /* WINDOWSNT */
 }
 
@@ -642,10 +635,8 @@ The following OPTIONS are accepted:\n\
                         Set filename of the TCP authentication file\n\
 -a EDITOR, --alternate-editor=EDITOR\n\
                         Editor to fallback to if the server is not running\n"
-#ifndef WINDOWSNT
 "                       If EDITOR is the empty string, start Emacs in daemon\n\
                         mode and try connecting again\n"
-#endif /* not WINDOWSNT */
 "\n\
 Report bugs with M-x report-emacs-bug.\n");
   exit (EXIT_SUCCESS);
@@ -1511,7 +1502,77 @@ start_daemon_and_retry_set_socket (void)
       execvp ("emacs", d_argv);
       message (true, "%s: error starting emacs daemon\n", progname);
     }
-#endif /* WINDOWSNT */
+#else  /* WINDOWSNT */
+  DWORD wait_result;
+  HANDLE w32_daemon_event;
+  STARTUPINFO si;
+  PROCESS_INFORMATION pi;
+
+  ZeroMemory (&si, sizeof si);
+  si.cb = sizeof si;
+  ZeroMemory (&pi, sizeof pi);
+
+  /* We start Emacs in daemon mode, and then wait for it to signal us
+     it is ready to accept client connections, by asserting an event
+     whose name is known to the daemon (defined by nt/inc/ms-w32.h).  */
+
+  if (!CreateProcess (NULL, "emacs --daemon", NULL, NULL, FALSE,
+                      CREATE_NO_WINDOW, NULL, NULL, &si, &pi))
+    {
+      char* msg = NULL;
+
+      FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM
+                     | FORMAT_MESSAGE_ALLOCATE_BUFFER
+                     | FORMAT_MESSAGE_ARGUMENT_ARRAY,
+                     NULL, GetLastError (), 0, (LPTSTR)&msg, 0, NULL);
+      message (true, "%s: error starting emacs daemon (%s)\n", progname, msg);
+      exit (EXIT_FAILURE);
+    }
+
+  w32_daemon_event = CreateEvent (NULL, TRUE, FALSE, W32_DAEMON_EVENT);
+  if (w32_daemon_event == NULL)
+    {
+      message (true, "Couldn't create Windows daemon event");
+      exit (EXIT_FAILURE);
+    }
+  if ((wait_result = WaitForSingleObject (w32_daemon_event, INFINITE))
+      != WAIT_OBJECT_0)
+    {
+      char *msg = NULL;
+
+      switch (wait_result)
+        {
+        case WAIT_ABANDONED:
+          msg = "The daemon exited unexpectedly";
+          break;
+        case WAIT_TIMEOUT:
+          /* Can't happen due to INFINITE.  */
+        default:
+        case WAIT_FAILED:
+          FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM
+                         | FORMAT_MESSAGE_ALLOCATE_BUFFER
+                         | FORMAT_MESSAGE_ARGUMENT_ARRAY,
+                         NULL, GetLastError (), 0, (LPTSTR)&msg, 0, NULL);
+          break;
+        }
+      message (true, "Error: Could not start the Emacs daemon: %s\n", msg);
+      exit (EXIT_FAILURE);
+    }
+  CloseHandle (w32_daemon_event);
+
+  /* Try connecting, the daemon should have started by now.  */
+  /* It's just a progress message, so don't pop a dialog if this is
+     emacsclientw.  */
+  if (!w32_window_app ())
+    message (true,
+             "Emacs daemon should have started, trying to connect again\n");
+  if ((emacs_socket = set_socket (1)) == INVALID_SOCKET)
+    {
+      message (true,
+               "Error: Cannot connect even after starting the Emacs daemon\n");
+      exit (EXIT_FAILURE);
+    }
+#endif  /* WINDOWSNT */
 }
 
 int