* startup.el (command-line): Call daemon-initialized after

starting the server.
* emacs.c (daemon_pipe): New variable
(main): Create a pipe before forking, make the parent exit only after
the child has closed its end of the pipe.  Move closing the
descriptors ...
(Fdaemon_initialized): ... here.  New function.

2 files changed, 83 insertions, 8 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 3dd47c8484b..f86b94ed7d8 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2008-10-26  Romain Francoise  <romain@orebokech.com>
+
+        * emacs.c (daemon_pipe): New variable
+        (main): Create a pipe before forking, make the parent exit only after
+        the child has closed its end of the pipe.  Move closing the
+        descriptors ...
+        (Fdaemon_initialized): ... here.  New function.
+
 2008-10-26  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         * chartab.c (Foptimize_char_table): Make sure `ascii' doesn't point to
diff --git a/src/emacs.c b/src/emacs.c
index 4712e9c1d0b..bcc7fb05792 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -238,6 +238,10 @@ int noninteractive1;
 /* Nonzero means Emacs was started as a daemon.  */
 int is_daemon = 0;
 
+/* Pipe used to send exit notification to the daemon parent at
+   startup.  */
+static int daemon_pipe[2];
+
 /* Save argv and argc.  */
 char **initial_argv;
 int initial_argc;
@@ -1073,21 +1077,54 @@ main (int argc, char **argv)
   if (argmatch (argv, argc, "-daemon", "--daemon", 5, NULL, &skip_args))
     {
 #ifndef DOS_NT
-      pid_t f = fork ();
-      int nfd;
+      pid_t f;
+
+      /* Start as a daemon: fork a new child process which will run the
+         rest of the initialization code, then exit.
+
+         We want to avoid exiting before the server socket is ready, so
+         use a pipe for synchronization.  The parent waits for the child
+         to close its end of the pipe (using `daemon-initialized')
+         before exiting.  */
+      if (pipe (daemon_pipe) == -1)
+        {
+          fprintf (stderr, "Cannot pipe!\n");
+          exit (1);
+        }
+
+      f = fork ();
       if (f > 0)
-        exit (0);
+        {
+          int retval;
+          char buf[1];
+
+          /* Close unused writing end of the pipe.  */
+          close (daemon_pipe[1]);
+
+          /* Just wait for the child to close its end of the pipe.  */
+          do
+            {
+              retval = read (daemon_pipe[0], &buf, 1);
+            }
+          while (retval == -1 && errno == EINTR);
+
+          if (retval < 0)
+            {
+              fprintf (stderr, "Error reading status from child\n");
+              exit (1);
+            }
+
+          close (daemon_pipe[0]);
+          exit (0);
+        }
       if (f < 0)
         {
           fprintf (stderr, "Cannot fork!\n");
           exit (1);
         }
 
-      nfd = open ("/dev/null", O_RDWR);
-      dup2 (nfd, 0);
-      dup2 (nfd, 1);
-      dup2 (nfd, 2);
-      close (nfd);
+      /* Close unused reading end of the pipe.  */
+      close (daemon_pipe[0]);
       is_daemon = 1;
 #ifdef HAVE_SETSID
       setsid();
@@ -2388,6 +2425,35 @@ DEFUN ("daemonp", Fdaemonp, Sdaemonp, 0, 0, 0,
   return is_daemon ? Qt : Qnil;
 }
 
+DEFUN ("daemon-initialized", Fdaemon_initialized, Sdaemon_initialized, 0, 0, 0,
+       doc: /* Mark the Emacs daemon as being initialized.  */)
+  ()
+{
+  int nfd;
+
+  if (!is_daemon)
+    error ("This function can only be called if emacs is run as a daemon");
+
+  if (daemon_pipe[1] < 0)
+    error ("The daemon has already been initialized");
+
+  if (NILP (Vafter_init_time))
+    error ("This function can only be called after loading the init files");
+
+  /* Get rid of stdin, stdout and stderr.  */
+  open ("/dev/null", O_RDWR);
+  dup2 (nfd, 0);
+  dup2 (nfd, 1);
+  dup2 (nfd, 2);
+  close (nfd);
+
+  /* Closing the pipe will notify the parent that it can exit.  */
+  close (daemon_pipe[1]);
+  /* Set it to an invalid value so we know we've already run this function.  */
+  daemon_pipe[1] = -1;
+  return Qt;
+}
+
 void
 syms_of_emacs ()
 {
@@ -2407,6 +2473,7 @@ syms_of_emacs ()
   defsubr (&Sinvocation_name);
   defsubr (&Sinvocation_directory);
   defsubr (&Sdaemonp);
+  defsubr (&Sdaemon_initialized);
 
   DEFVAR_LISP ("command-line-args", &Vcommand_line_args,
                doc: /* Args passed by shell to Emacs, as a list of strings.