--- a/src/emacs.c	Mon Aug 13 10:13:49 2007 +0200
+++ b/src/emacs.c	Mon Aug 13 10:14:14 2007 +0200
@@ -460,7 +460,7 @@
 #define main_1 STACK_TRACE_EYE_CATCHER
 
 static DOESNT_RETURN
-main_1 (int argc, char **argv, char **envp)
+main_1 (int argc, char **argv, char **envp, int restart)
 {
   char stack_bottom_variable;
   int skip_args = 0;
@@ -1438,8 +1438,14 @@
   init_console_stream (); /* Create the first console */
 
   /* try to get the actual pathname of the exec file we are running */
+  if (!restart)
   {
     Vinvocation_name = Fcar (Vcommand_line_args);
+    if (XSTRING_DATA(Vinvocation_name)[0] == '-')
+      {
+	/* XEmacs as a login shell, oh goody! */
+	Vinvocation_name = build_string(getenv("SHELL"));
+      }
     Vinvocation_directory = Vinvocation_name;
 
     if (!NILP (Ffile_name_directory (Vinvocation_name)))
@@ -1796,6 +1802,29 @@
   int     volatile vol_argc = argc;
   char ** volatile vol_argv = argv;
   char ** volatile vol_envp = envp;
+  /* This is hairy.  We need to compute where the XEmacs binary was invoked */
+  /* from because temacs initialization requires it to find the lisp */
+  /* directories.  The code that recomputes the path is guarded by the */
+  /* restarted flag.  There are three possible paths I've found so far */
+  /* through this: */
+  /* temacs -- When running temacs for basic build stuff, the first main_1 */
+  /*  will be the only one invoked.  It must compute the path else there */
+  /*  will be a very ugly bomb in startup.el (can't find obvious location */
+  /*  for doc-directory data-directory, etc.).  */
+  /* temacs w/ run-temacs on the command line -- This is run to bytecompile */
+  /*  all the out of date dumped lisp.  It will execute both of the main_1 */
+  /*  calls and the second one must not touch the first computation because */
+  /*  argc/argv are hosed the second time through. */
+  /* xemacs -- Only the second main_1 is executed.  The invocation path must */
+  /*  computed but this only matters when running in place or when running */
+  /*  as a login shell. */
+  /* As a bonus for straightening this out, XEmacs can now be run in place */
+  /*  as a login shell.  This never used to work. */
+  /* As another bonus, we can now guarantee that */
+  /* (concat invocation-directory invocation-name) contains the filename */
+  /* of the XEmacs binary we are running.  This can now be used in a */
+  /* definite test for out of date dumped files.  -slb */
+  int restarted = 0;
 #ifdef QUANTIFY
   quantify_stop_recording_data ();
   quantify_clear_data ();
@@ -1811,8 +1840,11 @@
     {
       run_temacs_argc = 0;
       if (! SETJMP (run_temacs_catch))
-	main_1 (vol_argc, vol_argv, vol_envp);
+	{
+	  main_1 (vol_argc, vol_argv, vol_envp, 0);
+	}
       /* run-emacs-from-temacs called */
+      restarted = 1;
       vol_argc = run_temacs_argc;
       vol_argv = run_temacs_argv;
 #ifdef _SCO_DS
@@ -1839,7 +1871,7 @@
     }
   run_temacs_argc = -1;
 
-  main_1 (vol_argc, vol_argv, vol_envp);
+  main_1 (vol_argc, vol_argv, vol_envp, restarted);
   return 0; /* unreached */
 }