Constify main.c:get_init_files.

A following patch will want to make the "gdbinit" global array const.
As usual, that forces in a cascading series of const additions.  This
patch preemptively does those.  I went all the way up to constifying
catch_command_errors, but then that would require constifying
execute_command as well (which is a much more significant effort).  So
as stop point, I found the cleanest would be to add a variant of
catch_command_errors that takes const args, and use that in the few
spots that needed it due to the the get_init_files constification.

gdb/
2013-07-01  Pedro Alves  <palves@redhat.com>

	* cli/cli-cmds.c (source_script): Make 'file' parameter const.
	* cli/cli-cmds.h (source_script): Likewise.
	* exceptions.c (catch_command_errors_const): New function.
	* exceptions.h (catch_command_errors_const): Declare.
	* main.c (get_init_files): Make parameters const, and adjust.
	(captured_main): Make 'system_gdbinit', 'home_gdbinit' and
	'local_gdbinit' locals const.  Adjust to use
	catch_command_errors_const.
	(print_gdb_help): Make 'system_gdbinit', 'home_gdbinit' and
	'local_gdbinit' locals const.

gdb/ChangeLog

@@ -1,3 +1,16 @@
+2013-07-01  Pedro Alves  <palves@redhat.com>
+
+	* cli/cli-cmds.c (source_script): Make 'file' parameter const.
+	* cli/cli-cmds.h (source_script): Likewise.
+	* exceptions.c (catch_command_errors_const): New function.
+	* exceptions.h (catch_command_errors_const): Declare.
+	* main.c (get_init_files): Make parameters const, and adjust.
+	(captured_main): Make 'system_gdbinit', 'home_gdbinit' and
+	'local_gdbinit' locals const.  Adjust to use
+	catch_command_errors_const.
+	(print_gdb_help): Make 'system_gdbinit', 'home_gdbinit' and
+	'local_gdbinit' locals const.
+
 2013-07-01  Pedro Alves  <palves@redhat.com>
 
 	* defs.h: Don't check HAVE_UNISTD_H before including <unistd.h>.

gdb/cli/cli-cmds.c

@@ -597,7 +597,7 @@ source_script_with_search (const char *file, int from_tty, int search_path)
    for use in loading .gdbinit scripts.  */
 
 void
-source_script (char *file, int from_tty)
+source_script (const char *file, int from_tty)
 {
   source_script_with_search (file, from_tty, 0);
 }

gdb/cli/cli-cmds.h

@@ -117,7 +117,7 @@ extern void cd_command (char *, int);
 
 extern void quit_command (char *, int);
 
-extern void source_script (char *, int);
+extern void source_script (const char *, int);
 
 /* Exported to objfiles.c.  */
 

gdb/exceptions.c

@@ -577,3 +577,19 @@ catch_command_errors (catch_command_errors_ftype *command,
     return 0;
   return 1;
 }
+
+int
+catch_command_errors_const (catch_command_errors_const_ftype *command,
+			    const char *arg, int from_tty, return_mask mask)
+{
+  volatile struct gdb_exception e;
+
+  TRY_CATCH (e, mask)
+    {
+      command (arg, from_tty);
+    }
+  print_any_exception (gdb_stderr, NULL, e);
+  if (e.reason < 0)
+    return 0;
+  return 1;
+}

gdb/exceptions.h

@@ -257,4 +257,10 @@ typedef void (catch_command_errors_ftype) (char *, int);
 extern int catch_command_errors (catch_command_errors_ftype *func,
 				 char *arg, int from_tty, return_mask);
 
+/* Like catch_command_errors, but works with const command and args.  */
+
+typedef void (catch_command_errors_const_ftype) (const char *, int);
+extern int catch_command_errors_const (catch_command_errors_const_ftype *func,
+				       const char *arg, int from_tty, return_mask);
+
 #endif

gdb/main.c

@@ -160,13 +160,13 @@ relocate_gdb_directory (const char *initial, int flag)
    to be loaded, then SYSTEM_GDBINIT (resp. HOME_GDBINIT and
    LOCAL_GDBINIT) is set to NULL.  */
 static void
-get_init_files (char **system_gdbinit,
+get_init_files (const char **system_gdbinit,
-		char **home_gdbinit,
+		const char **home_gdbinit,
-		char **local_gdbinit)
+		const char **local_gdbinit)
 {
-  static char *sysgdbinit = NULL;
+  static const char *sysgdbinit = NULL;
   static char *homeinit = NULL;
-  static char *localinit = NULL;
+  static const char *localinit = NULL;
   static int initialized = 0;
 
   if (!initialized)
@@ -336,9 +336,9 @@ captured_main (void *data)
   int ndir;
 
   /* gdb init files.  */
-  char *system_gdbinit;
+  const char *system_gdbinit;
-  char *home_gdbinit;
+  const char *home_gdbinit;
-  char *local_gdbinit;
+  const char *local_gdbinit;
 
   int i;
   int save_auto_load;
@@ -894,7 +894,8 @@ captured_main (void *data)
      processed; it sets global parameters, which are independent of
      what file you are debugging or what directory you are in.  */
   if (system_gdbinit && !inhibit_gdbinit)
-    catch_command_errors (source_script, system_gdbinit, 0, RETURN_MASK_ALL);
+    catch_command_errors_const (source_script, system_gdbinit,
+				0, RETURN_MASK_ALL);
 
   /* Read and execute $HOME/.gdbinit file, if it exists.  This is done
      *before* all the command line arguments are processed; it sets
@@ -902,15 +903,16 @@ captured_main (void *data)
      debugging or what directory you are in.  */
 
   if (home_gdbinit && !inhibit_gdbinit && !inhibit_home_gdbinit)
-    catch_command_errors (source_script, home_gdbinit, 0, RETURN_MASK_ALL);
+    catch_command_errors_const (source_script,
+				home_gdbinit, 0, RETURN_MASK_ALL);
 
   /* Process '-ix' and '-iex' options early.  */
   for (i = 0; VEC_iterate (cmdarg_s, cmdarg_vec, i, cmdarg_p); i++)
     switch (cmdarg_p->type)
     {
       case CMDARG_INIT_FILE:
-        catch_command_errors (source_script, cmdarg_p->string,
+        catch_command_errors_const (source_script, cmdarg_p->string,
-			      !batch_flag, RETURN_MASK_ALL);
+				    !batch_flag, RETURN_MASK_ALL);
 	break;
       case CMDARG_INIT_COMMAND:
         catch_command_errors (execute_command, cmdarg_p->string,
@@ -1006,8 +1008,8 @@ captured_main (void *data)
 	{
 	  auto_load_local_gdbinit_loaded = 1;
 
-	  catch_command_errors (source_script, local_gdbinit, 0,
+	  catch_command_errors_const (source_script, local_gdbinit, 0,
-				RETURN_MASK_ALL);
+				      RETURN_MASK_ALL);
 	}
     }
 
@@ -1024,8 +1026,8 @@ captured_main (void *data)
     switch (cmdarg_p->type)
     {
       case CMDARG_FILE:
-        catch_command_errors (source_script, cmdarg_p->string,
+        catch_command_errors_const (source_script, cmdarg_p->string,
-			      !batch_flag, RETURN_MASK_ALL);
+				    !batch_flag, RETURN_MASK_ALL);
 	break;
       case CMDARG_COMMAND:
         catch_command_errors (execute_command, cmdarg_p->string,
@@ -1075,9 +1077,9 @@ gdb_main (struct captured_main_args *args)
 static void
 print_gdb_help (struct ui_file *stream)
 {
-  char *system_gdbinit;
+  const char *system_gdbinit;
-  char *home_gdbinit;
+  const char *home_gdbinit;
-  char *local_gdbinit;
+  const char *local_gdbinit;
 
   get_init_files (&system_gdbinit, &home_gdbinit, &local_gdbinit);