..

src/Makefile.am

@@ -1,7 +1,25 @@
 
 SUBDIRS=uislave
 
-INCLUDES=@METACITY_CFLAGS@ -DMETACITY_LIBEXECDIR=\"$(libexecdir)\" -DHOST_ALIAS=\"@HOST_ALIAS@\"
+INCLUDES=@METACITY_CFLAGS@ -DMETACITY_LIBEXECDIR=\"$(libexecdir)\" -DHOST_ALIAS=\"@HOST_ALIAS@\" -DMETACITY_COMPILE=1
+
+## convenience libraries lead to annoying slow compiles, plus we want
+## to be extra-hacky by using #ifdef METACITY_COMPILE, ergo cheesy
+## hack that follows.
+copied_sources= \
+	messagequeue.h \
+	messagequeue.c
+copied_sources_deps= \
+	$(srcdir)/uislave/messagequeue.h \
+	$(srcdir)/uislave/messagequeue.c
+
+BUILT_SOURCES=$(copied_sources)
+
+$(copied_sources): $(copied_sources_deps)
+	for I in $(copied_sources); do				\
+		rm -f $$I ;					\
+		cp $(srcdir)/uislave/$$I . ;			\
+	done
 
 metacity_SOURCES= 				\
 	api.c					\
@@ -27,7 +45,8 @@ metacity_SOURCES= 				\
 	util.c					\
 	util.h					\
 	window.c				\
-	window.h
+	window.h				\
+	$(copied_sources)
 
 bin_PROGRAMS=metacity
 

src/run-metacity.sh

@@ -1,5 +1,7 @@
 #! /bin/bash
-
-Xnest :1 -scrns 2 -geometry 270x270 &
+if test -z "$SCREENS"; then
+  SCREENS=2
+fi
+Xnest :1 -scrns $SCREENS -geometry 270x270 &
 METACITY_UISLAVE_DIR=./uislave DISPLAY=:1 unst libtool --mode=execute gdb ./metacity
 killall Xnest

src/uislave.c

@@ -25,6 +25,7 @@
 #include <stdlib.h>
 #include <errno.h>
 #include <signal.h>
+#include <fcntl.h>
 
 typedef enum
 {
@@ -34,9 +35,6 @@ typedef enum
 } ReadResult;
 
 static void       respawn_child   (MetaUISlave   *uislave);
-static gboolean   output_callback (GIOChannel    *source,
-                                   GIOCondition   condition,
-                                   gpointer       data);
 static gboolean   error_callback  (GIOChannel    *source,
                                    GIOCondition   condition,
                                    gpointer       data);
@@ -149,8 +147,6 @@ respawn_child (MetaUISlave *uislave)
       uislave->child_pid = child_pid;
       uislave->in_pipe = inpipe;
       uislave->err_pipe = errpipe;
-      uislave->out_poll.fd = outpipe;
-      uislave->out_poll.events = G_IO_IN;
 
       uislave->err_channel = g_io_channel_unix_new (errpipe);
       
@@ -159,6 +155,11 @@ respawn_child (MetaUISlave *uislave)
                                           error_callback,
                                           uislave);
       
+      uislave->out_poll.fd = outpipe;
+      uislave->out_poll.events = G_IO_IN;
+
+      g_source_add_poll ((GSource*)uislave, &uislave->out_poll);
+      
       meta_verbose ("Spawned UI slave with PID %d\n", uislave->child_pid);
     }
   else
@@ -182,6 +183,10 @@ append_pending (MetaUISlave *uislave)
   needed = MIN (needed, uislave->buf->len);
   
   /* Move data from buf to current_message */
+  if (needed > 0)
+    {
+      meta_verbose ("Moving %d bytes from buffer to current incomplete message\n",
+                    needed);
       g_string_append_len (uislave->current_message,
                            uislave->buf->str,
                            needed);
@@ -189,35 +194,48 @@ append_pending (MetaUISlave *uislave)
                       0, needed);
     }
   
-static gboolean
-output_callback (GIOChannel   *source,
-                 GIOCondition  condition,
-                 gpointer      data)
+  g_assert (uislave->current_message->len <= uislave->current_required_len);
+
+  if (uislave->current_required_len > 0 &&
+      uislave->current_message->len == uislave->current_required_len)
     {
-  /* Read messages from slave */
-  MetaUISlave *uislave;
-  ReadResult res;
+      MetaMessage *message;
+      MetaMessageFooter *footer;
   
-  uislave = data;
+      message = g_new (MetaMessage, 1);
       
-  res = read_data (uislave->buf, uislave->out_pipe);
+      memcpy (message,
+              uislave->current_message->str, uislave->current_message->len);
 
-  switch (res)
+      if (message->header.length != uislave->current_required_len)
+        meta_bug ("Message length changed?\n");
+
+      if (message->header.serial != uislave->last_serial)
+        meta_bug ("Message serial changed?\n");
+      
+      footer = META_MESSAGE_FOOTER (message);
+      
+      if (footer->checksum == META_MESSAGE_CHECKSUM (message))
         {
-    case READ_OK:
-      meta_verbose ("Read data from slave, %d bytes in buffer\n",
-                    uislave->buf->len);
-      break;
-    case READ_EOF:
-      meta_verbose ("EOF reading stdout from slave process\n");
-      break;
+          g_queue_push_tail (uislave->queue, message);
 
-    case READ_FAILED:
-      /* read_data printed the error */
-      break;
+          meta_verbose ("Added %d-byte message serial %d to queue\n",
+                        uislave->current_message->len, message->header.serial);
+        }
+      else
+        {
+          meta_bug ("Bad checksum %d on %d-byte message from UI slave\n",
+                    footer->checksum, uislave->current_message->len);
         }
       
-  return TRUE;
+      uislave->current_required_len = 0;
+      g_string_truncate (uislave->current_message, 0);
+    }
+  else if (uislave->current_required_len > 0)
+    {
+      meta_verbose ("Storing %d bytes of incomplete message\n",
+                    uislave->current_message->len);
+    }
 }
 
 static gboolean
@@ -251,10 +269,31 @@ error_callback  (GIOChannel   *source,
 static void
 mq_queue_messages (MetaUISlave *uislave)
 {  
-  if (uislave->buf->len == 0)
-    return;
+  if (uislave->out_poll.revents & G_IO_IN)
+    {
+      ReadResult res;
 
-  if (uislave->current_message->len > 0)
+      res = read_data (uislave->buf, uislave->out_poll.fd);
+      
+      switch (res)
+        {
+        case READ_OK:
+          meta_verbose ("Read data from slave, %d bytes in buffer\n",
+                        uislave->buf->len);
+          break;
+        case READ_EOF:
+          meta_verbose ("EOF reading stdout from slave process\n");
+          break;
+          
+        case READ_FAILED:
+          /* read_data printed the error */
+          break;
+        }
+    }
+  
+  while (uislave->buf->len > 0)
+    {  
+      if (uislave->current_required_len > 0)
         {
           /* We had a pending message. */
           append_pending (uislave);
@@ -267,18 +306,23 @@ mq_queue_messages (MetaUISlave *uislave)
           const char *esc;
           MetaMessageHeader header;
 
-      /* note that the string from the UI slave includes the nul byte */
+          g_assert (uislave->current_required_len == 0);
+          g_assert (uislave->current_message->len == 0);
+          
+          meta_verbose ("Scanning for escape sequence in %d bytes\n",
+                        uislave->buf->len);
+          
+          /* note that the data from the UI slave includes the nul byte */
           esc = META_MESSAGE_ESCAPE;
       
-      esc_pos = 0;
+          esc_pos = -1;
           p = uislave->buf->str;
           while (p != (uislave->buf->str + uislave->buf->len) &&
                  esc_pos < META_MESSAGE_ESCAPE_LEN)
             {
-          if (*p != esc[esc_pos])
-            esc_pos = 0;
-          else
               ++esc_pos;
+              if (*p != esc[esc_pos])
+                esc_pos = -1;
 
               ++p;
             }
@@ -297,63 +341,74 @@ mq_queue_messages (MetaUISlave *uislave)
               
               if (ignored > 0)
                 {
-              meta_verbose ("Ignoring %d bytes from UI slave\n",
-                            ignored);
-
                   g_string_erase (uislave->buf, 0, ignored);
+                  meta_verbose ("Ignoring %d bytes before escape, new buffer len %d\n",
+                                ignored, uislave->buf->len);
+                }
+              else
+                {
+                  g_assert (p == (uislave->buf->str + META_MESSAGE_ESCAPE_LEN));
                 }
             }
-      else if (esc_pos == 0)
+          else if (esc_pos < 0)
             {
               /* End of buffer doesn't begin an escape sequence;
                * toss out entire buffer.
                */
-          meta_verbose ("Ignoring %d bytes from UI slave\n",
+              meta_verbose ("Emptying %d-byte buffer not containing escape sequence\n",
                             uislave->buf->len);
               g_string_truncate (uislave->buf, 0);
+              goto need_more_data;
+            }
+          else
+            {
+              meta_verbose ("Buffer ends with partial escape sequence: '%s'\n",
+                            uislave->buf->str + (uislave->buf->len - esc_pos));
+              goto need_more_data;
             }
 
-      if (uislave->buf->len < (META_MESSAGE_ESCAPE_LEN + sizeof (MetaMessageHeader)))
-        return; /* Not enough data yet. */
+          g_assert (strcmp (uislave->buf->str, META_MESSAGE_ESCAPE) == 0);
           
-      memcpy (&header, uislave->buf->str + META_MESSAGE_ESCAPE_LEN, sizeof (MetaMessageHeader));
+          if (uislave->buf->len < (META_MESSAGE_ESCAPE_LEN + sizeof (MetaMessageHeader)))
+            {
+              meta_verbose ("Buffer has full escape sequence but lacks header\n");
+              goto need_more_data;
+            }
+
+          g_string_erase (uislave->buf, 0, META_MESSAGE_ESCAPE_LEN);
+          meta_verbose ("Stripped escape off front of buffer, new buffer len %d\n",
+                        uislave->buf->len);
+
+          g_assert (uislave->buf->len >= sizeof (MetaMessageHeader));
+          
+          memcpy (&header, uislave->buf->str, sizeof (MetaMessageHeader));
 
           /* Length includes the header even though it's in the header. */
-      meta_verbose ("Read header code: %d length: %d from UI slave\n",
-                    header.message_code, header.length);
+          meta_verbose ("Read header, code: %d length: %d serial: %d\n",
+                        header.message_code, header.length, header.serial);
 
+          if (header.serial != uislave->last_serial + 1)
+            meta_bug ("Wrong message serial number %d from UI slave!\n", header.serial);
+
+          uislave->last_serial = header.serial;
           uislave->current_required_len = header.length;
-      g_string_erase (uislave->buf, 0, META_MESSAGE_ESCAPE_LEN);
           
           append_pending (uislave);
         }
-
-  g_assert (uislave->current_message->len <= uislave->current_required_len);
-
-  if (uislave->current_required_len > 0 &&
-      uislave->current_message->len == uislave->current_required_len)
-    {
-      MetaMessage *message;
-
-      message = g_new (MetaMessage, 1);
-      
-      memcpy (message,
-              uislave->current_message->str, uislave->current_message->len);
-
-      g_queue_push_tail (uislave->queue, message);
-
-      meta_verbose ("Added %d-byte message to queue\n",
-                    uislave->current_message->len);
-      
-      uislave->current_required_len = 0;
-      g_string_truncate (uislave->current_message, 0);
+      else
+        goto need_more_data;
     }
+
+ need_more_data:
+  return;
 }
 
 static gboolean
 mq_messages_pending (MetaUISlave *uislave)
 {
-  return uislave->queue->length > 0 || uislave->buf->len > 0;
+  return uislave->queue->length > 0 ||
+    uislave->buf->len > 0 ||
+    uislave->current_message->len > 0;
 }
 
 static gboolean
@@ -365,6 +420,8 @@ mq_prepare (GSource *source, gint *timeout)
   
   *timeout = -1;
 
+  mq_queue_messages (uislave);
+  
   return mq_messages_pending (uislave);
 }
 
@@ -375,6 +432,9 @@ mq_check (GSource  *source)
   
   uislave = (MetaUISlave*) source;
 
+  mq_queue_messages (uislave);
+  uislave->out_poll.revents = 0;
+  
   return mq_messages_pending (uislave);
 }
 
@@ -385,8 +445,6 @@ mq_dispatch (GSource *source, GSourceFunc callback, gpointer user_data)
 
   uislave = (MetaUISlave*) source;
   
-  mq_queue_messages (uislave);
-  
   if (uislave->queue->length > 0)
     {
       MetaUISlaveFunc func;
@@ -411,20 +469,17 @@ mq_dispatch (GSource *source, GSourceFunc callback, gpointer user_data)
 static void
 kill_child (MetaUISlave *uislave)
 {
-  if (uislave->outwatch != 0)
-    g_source_remove (uislave->outwatch);
-
   if (uislave->errwatch != 0)
     g_source_remove (uislave->errwatch);  
 
-  if (uislave->out_channel)
-    g_io_channel_unref (uislave->out_channel);
-
   if (uislave->err_channel)
     g_io_channel_unref (uislave->err_channel);
 
-  if (uislave->out_pipe >= 0)
-    close (uislave->out_pipe);
+  if (uislave->out_poll.fd >= 0)
+    {
+      g_source_remove_poll ((GSource*)uislave, &uislave->out_poll);
+      close (uislave->out_poll.fd);
+    }
 
   if (uislave->in_pipe >= 0)
     close (uislave->in_pipe);
@@ -467,14 +522,13 @@ reset_vals (MetaUISlave *uislave)
 {
   uislave->child_pid = 0;
   uislave->in_pipe = -1;
-  uislave->out_pipe = -1;
   uislave->err_pipe = -1;
+  uislave->out_poll.fd = -1;
   uislave->no_respawn = FALSE;
-  uislave->out_channel = NULL;
   uislave->err_channel = NULL;
-  uislave->outwatch = 0;
   uislave->errwatch = 0;
   uislave->current_required_len = 0;
+  uislave->last_serial = -1;
 }
 
 static void
@@ -503,7 +557,7 @@ static ReadResult
 read_data (GString *str,
            gint     fd)
 {
-#define BUFSIZE 16
+#define BUFSIZE 4000
   gint bytes;
   gchar buf[BUFSIZE];
 

src/uislave.h

@@ -45,6 +45,7 @@ struct _MetaUISlave
   GString *buf;
   GString *current_message;
   int current_required_len;
+  int last_serial;
   /* if we determine that our available slave is hosed,
    * set this bit.
    */

src/uislave/Makefile.am

@@ -4,7 +4,9 @@ INCLUDES=@UISLAVE_CFLAGS@ -DHOST_ALIAS=\"@HOST_ALIAS@\"
 metacity_uislave_SOURCES = 	\
 	main.c			\
 	messages.c		\
-	messages.h
+	messages.h		\
+	messagequeue.c		\
+	messagequeue.h
 
 libexec_PROGRAMS=metacity-uislave
 

src/uislave/main.c

@@ -23,6 +23,7 @@
 
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
 #include <gtk/gtk.h>
 
@@ -50,13 +51,15 @@ main (int argc, char **argv)
 
   /* report our nature to the window manager */
   meta_message_send_check ();
+  write (1, "abcdefghijklmnopqrstuvwxyz", 27);
   
 #if 1
   /* Try breaking message queue system. */
   i = 0;
-  while (i < 100)
+  while (i < 1500)
     {
       meta_message_send_check ();
+      write (1, "abcdefghijklmnopqrstuvwxyz", 27);
       if (g_random_boolean ())
         {
           int j;

src/uislave/main.h

@@ -0,0 +1,31 @@
+/* Metacity UI slave main() */
+
+/* 
+ * Copyright (C) 2001 Havoc Pennington
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#ifndef META_UI_MAIN_H
+#define META_UI_MAIN_H
+
+void meta_ui_warning (const char *format, ...);
+
+/* FIXME */
+#define _(x) x
+
+
+#endif

src/uislave/messagequeue.c

@@ -0,0 +1,38 @@
+/* Metacity IPC message source for main loop */
+
+/* 
+ * Copyright (C) 2001 Havoc Pennington
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include "messagequeue.h"
+
+MetaMessageQueue*
+meta_message_queue_new  (int                  fd,
+                         MetaMessageQueueFunc func,
+                         gpointer             data)
+{
+
+
+}
+
+void
+meta_message_queue_free (MetaMessageQueue *mq)
+{
+  
+
+}

src/uislave/messagequeue.h

@@ -0,0 +1,56 @@
+/* Metacity IPC message source for main loop */
+
+/* 
+ * Copyright (C) 2001 Havoc Pennington
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#ifndef META_MESSAGE_QUEUE_H
+#define META_MESSAGE_QUEUE_H
+
+#include <glib.h>
+
+#ifdef METACITY_COMPILE
+#include "uislave/messages.h"
+#else
+#include "messages.h"
+#endif
+
+typedef struct _MetaMessageQueue MetaMessageQueue;
+
+typedef void (* MetaMessageQueueFunc) (MetaMessageQueue *mq,
+                                       MetaMessage      *message,
+                                       gpointer          data);
+
+struct _MetaMessageQueue
+{
+  GSource source;
+
+  GPollFD out_poll;
+  GQueue *queue;
+  GString *buf;
+  GString *current_message;
+  int current_required_len;
+  int last_serial;
+};
+
+MetaMessageQueue* meta_message_queue_new  (int                   fd,
+                                           MetaMessageQueueFunc  func,
+                                           gpointer              data);
+void              meta_message_queue_free (MetaMessageQueue     *mq);
+
+#endif

src/uislave/messages.c

@@ -27,6 +27,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <string.h>
+#include <ctype.h>
 #include <config.h>
 
 typedef enum
@@ -41,14 +42,17 @@ static ReadResult read_data       (GString       *str,
 
 static void send_message (MetaMessage *message);
 
+#define META_MESSAGE_LENGTH(real_type) \
+   (G_STRUCT_OFFSET (real_type, footer) + sizeof (MetaMessageFooter))
+
 void
 meta_message_send_check (void)
 {
   MetaMessageCheck check;
 
-  memset (&check, 0, sizeof (check));
+  memset (&check, 0, META_MESSAGE_LENGTH (MetaMessageCheck));
   check.header.message_code = MetaMessageCheckCode;
-  check.header.length = sizeof (check);
+  check.header.length = META_MESSAGE_LENGTH (MetaMessageCheck);
   strcpy (check.metacity_version, VERSION);
   strcpy (check.host_alias, HOST_ALIAS);
   check.metacity_version[META_MESSAGE_MAX_VERSION_LEN] = '\0';
@@ -62,33 +66,76 @@ static int
 write_bytes (void *buf, int bytes)
 {
   const char *p;
+  int left;
 
+  left = bytes;
   p = (char*) buf;
-  while (bytes > 0)
+  while (left > 0)
     {
       int written;
 
-      written = write (1, p, bytes);
+      written = write (1, p, left);
 
       if (written < 0)
         return -1;
 
-      bytes -= written;
+      left -= written;
       p += written;
     }
 
+  g_assert (p == ((char*)buf) + bytes); 
+  
   return 0;
 }
 
+#if 0
+static void
+print_mem (int fd, void *mem, int len)
+{
+  char *p = (char*) mem;
+  int i;
+  char unknown = 'Z';
+  char null = 'n';
+  
+  i = 0;
+  while (i < len)
+    {
+      if (p[i] == '\0')
+        write (fd, &null, 1);
+      else if (isascii (p[i]))
+        write (fd, p + i, 1);
+      else
+        write (fd, &unknown, 1);
+      
+      ++i;
+    }
+}
+#endif
+
 static void
 send_message (MetaMessage *message)
 {
-  /* Not much point checking for errors here. We can't
-   * really report them anyway.
-   */
+  static int serial = 0;
+  MetaMessageFooter *footer;
   
-  write_bytes (META_MESSAGE_ESCAPE, META_MESSAGE_ESCAPE_LEN);
-  write_bytes (message, message->header.length);
+  message->header.serial = serial;
+  footer = META_MESSAGE_FOOTER (message);
+  
+  footer->checksum = META_MESSAGE_CHECKSUM (message);
+  ++serial;
+
+#if 0
+  meta_ui_warning ("'");
+  print_mem (2, message, message->header.length);
+  meta_ui_warning ("'\n");
+#endif
+  
+  if (write_bytes (META_MESSAGE_ESCAPE, META_MESSAGE_ESCAPE_LEN) < 0)
+    meta_ui_warning ("Failed to write escape sequence: %s\n",
+                     g_strerror (errno));
+  if (write_bytes (message, message->header.length) < 0)
+    meta_ui_warning ("Failed to write message: %s\n",
+                     g_strerror (errno));
 }
 
 static ReadResult

src/uislave/messages.h

@@ -24,11 +24,14 @@
 
 #include <glib.h>
 
+/* This thing badly violates the KISS principle. */
+
 /* This header is shared between the WM and the UI slave */
 /* Note that our IPC can be kind of lame; we trust both sides
  * of the connection, and assume that they were compiled at the
  * same time vs. the same libs on the same arch
  */
+/* (and lo and behold, our IPC is kind of lame) */
 
 /* We increment this when we change this header, so we can
  * check for mismatched UI slave and WM
@@ -45,11 +48,19 @@
 /* len includes nul byte which is a required part of the escape */
 #define META_MESSAGE_ESCAPE_LEN 15
 
+/* This is totally useless of course. Playing around. */
+#define META_MESSAGE_CHECKSUM(msg) ((msg)->header.length | (msg)->header.serial << 16) 
+#define META_MESSAGE_FOOTER(msg) ((MetaMessageFooter*) (((char*)(msg)) + ((msg)->header.length - sizeof (MetaMessageFooter))));
+
+#define META_MESSAGE_MAX_SIZE (sizeof(MetaMessage));
+
 #define META_MESSAGE_MAX_VERSION_LEN 15
 #define META_MESSAGE_MAX_HOST_ALIAS_LEN 50
+#define META_MESSAGE_MAX_TIP_TEXT 128
 
 typedef union  _MetaMessage         MetaMessage;
 typedef struct _MetaMessageHeader   MetaMessageHeader;
+typedef struct _MetaMessageFooter   MetaMessageFooter;
 typedef struct _MetaMessageCheck    MetaMessageCheck;
 typedef struct _MetaMessageShowTip  MetaMessageShowTip;
 typedef struct _MetaMessageHideTip  MetaMessageHideTip;
@@ -69,6 +80,13 @@ struct _MetaMessageHeader
 {
   MetaMessageCode message_code;
   int length;
+  int serial;
+};
+
+/* The footer thing was pretty much just a debug hack and could die. */
+struct _MetaMessageFooter
+{
+  int checksum;
 };
 
 /* just a ping to see if we have the right
@@ -84,6 +102,8 @@ struct _MetaMessageCheck
   char metacity_version[META_MESSAGE_MAX_VERSION_LEN + 1];
   char host_alias[META_MESSAGE_MAX_HOST_ALIAS_LEN + 1];
   int messages_version;
+
+  MetaMessageFooter footer;
 };
 
 struct _MetaMessageShowTip
@@ -91,13 +111,15 @@ struct _MetaMessageShowTip
   MetaMessageHeader header;
   int root_x;
   int root_y;
-  /* Then a nul-terminated string follows */
+  char markup[META_MESSAGE_MAX_TIP_TEXT];
+  MetaMessageFooter footer;
 };
 
 struct _MetaMessageHideTip
 {
   MetaMessageHeader header;
   /* just hides the current tip */
+  MetaMessageFooter footer;
 };
 
 union _MetaMessage