Prevent crashes using $arg0

[Daniel Jacobowitz <drow@false.org>]

This patch fixes a crash Andrew Stubbs reported:

if 1 == 1
  print $arg0
end

The new response is:
$arg0 used outside of any user function

Comments?  Not thrilled with the wording of the error, but it'll do.

-- 
Daniel Jacobowitz
CodeSourcery

2006-02-07  Daniel Jacobowitz  <dan@codesourcery.com>

	* cli/cli-script.c (insert_args): Handle NULL user_args.

2006-02-07  Daniel Jacobowitz  <dan@codesourcery.com>


	* gdb.base/commands.exp (stray_arg0_test): New test.

Index: cli/cli-script.c
===================================================================
RCS file: /cvs/src/src/gdb/cli/cli-script.c,v
retrieving revision 1.32
diff -u -p -r1.32 cli-script.c
--- cli/cli-script.c	17 Dec 2005 22:40:17 -0000	1.32
+++ cli/cli-script.c	7 Feb 2006 19:37:18 -0000
@@ -1,8 +1,8 @@
 /* GDB CLI command scripting.
 
    Copyright (c) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
-   1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2005 Free
-   Software Foundation, Inc.
+   1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2005, 2006
+   Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -598,7 +598,9 @@ insert_args (char *line)
       len += p - line;
       i = p[4] - '0';
 
-      if (p[4] == 'c')
+      if (user_args == NULL)
+	error (_("%.5s used outside of any user function"), p);
+      else if (p[4] == 'c')
 	{
 	  /* $argc.  Number will be <=10.  */
 	  len += user_args->count == 10 ? 2 : 1;
Index: testsuite/gdb.base/commands.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/commands.exp,v
retrieving revision 1.14
diff -u -p -r1.14 commands.exp
--- testsuite/gdb.base/commands.exp	7 Mar 2005 21:36:16 -0000	1.14
+++ testsuite/gdb.base/commands.exp	7 Feb 2006 19:37:19 -0000
@@ -1,5 +1,5 @@
 #   Copyright 1988, 1990, 1991, 1992, 1994, 1995, 1997, 1998, 1999, 2000,
-#   2001, 2002, 2003 Free Software Foundation, Inc.
+#   2001, 2002, 2003, 2005, 2006 Free Software Foundation, Inc.
 
 # 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
@@ -563,6 +563,12 @@ proc temporary_breakpoint_commands {} {
 	timeout { fail "(timeout) run factorial until temporary breakpoint" }
     }
 }
+
+proc stray_arg0_test { } {
+    gdb_test "if 1 == 1\nprint \$arg0\nend" \
+	"\\\$arg0 used outside of any user function" \
+	"stray_arg0_test #1"
+}
   
 gdbvar_simple_if_test
 gdbvar_simple_while_test
@@ -579,3 +585,4 @@ test_command_prompt_position
 deprecated_command_test
 bp_deleted_in_command_test
 temporary_breakpoint_commands
+stray_arg0_test