readline fix for rl_undo_list pointer aliasing; arith command sets word_top

lib/readline/histlib.h

@@ -1,6 +1,6 @@
 /* histlib.h -- internal definitions for the history library. */
 
-/* Copyright (C) 1989-2009,2021-2022 Free Software Foundation, Inc.
+/* Copyright (C) 1989-2009,2021-2023 Free Software Foundation, Inc.
 
    This file contains the GNU History Library (History), a set of
    routines for managing the text of previously typed lines.
@@ -91,6 +91,7 @@ extern int _hs_history_search (const char *, int, int);
 
 /* history.c */
 extern void _hs_replace_history_data (int, histdata_t *, histdata_t *);
+extern int _hs_search_history_data (histdata_t *);
 extern int _hs_at_end_of_history (void);
 
 /* histfile.c */

lib/readline/history.c

@@ -1,6 +1,6 @@
 /* history.c -- standalone history library */
 
-/* Copyright (C) 1989-2021 Free Software Foundation, Inc.
+/* Copyright (C) 1989-2023 Free Software Foundation, Inc.
 
    This file contains the GNU History Library (History), a set of
    routines for managing the text of previously typed lines.
@@ -458,7 +458,7 @@ _hs_replace_history_data (int which, histdata_t *old, histdata_t *new)
     }
 
   last = -1;
-  for (i = 0; i < history_length; i++)
+  for (i = history_length - 1; i >= 0; i--)
     {
       entry = the_history[i];
       if (entry == 0)
@@ -475,7 +475,27 @@ _hs_replace_history_data (int which, histdata_t *old, histdata_t *new)
       entry = the_history[last];
       entry->data = new;	/* XXX - we don't check entry->old */
     }
-}      
+}
+
+int
+_hs_search_history_data (histdata_t *needle)
+{
+  register int i;
+  HIST_ENTRY *entry;
+
+  if (history_length == 0 || the_history == 0)
+    return -1;
+
+  for (i = history_length - 1; i >= 0; i--)
+    {
+      entry = the_history[i];
+      if (entry == 0)
+	continue;
+      if (entry->data == needle)
+	return i;
+    }
+  return -1;
+}
   
 /* Remove history element WHICH from the history.  The removed
    element is returned to you so you can free the line, data,

lib/readline/misc.c

@@ -340,6 +340,9 @@ rl_maybe_replace_line (void)
       xfree (temp->line);
       FREE (temp->timestamp);
       xfree (temp);
+      /* XXX - what about _rl_saved_line_for_history? if the saved undo list
+	 is rl_undo_list, and we just put that into a history entry, should
+	 we set the saved undo list to NULL? */
     }
   return 0;
 }
@@ -385,14 +388,16 @@ _rl_free_saved_history_line (void)
 {
   if (_rl_saved_line_for_history)
     {
-      if (rl_undo_list && rl_undo_list == (UNDO_LIST *)_rl_saved_line_for_history->data)
-	rl_undo_list = 0;
-      /* Have to free this separately because _rl_free_history entry can't:
-	 it doesn't know whether or not this has application data. Only the
-	 callers that know this is _rl_saved_line_for_history can know that
-	 it's an undo list. */
-      if (_rl_saved_line_for_history->data)
-	_rl_free_undo_list ((UNDO_LIST *)_rl_saved_line_for_history->data);
+      UNDO_LIST *sentinel;
+
+      sentinel = (UNDO_LIST *)_rl_saved_line_for_history->data;
+
+      /* We should only free `data' if it's not the current rl_undo_list and
+	 it's not the `data' member in a history entry somewhere. We have to
+	 free it separately because only the callers know it's an undo list. */
+      if (sentinel && sentinel != rl_undo_list && _hs_search_history_data ((histdata_t *)sentinel) < 0)
+	_rl_free_undo_list (sentinel);
+
       _rl_free_history_entry (_rl_saved_line_for_history);
       _rl_saved_line_for_history = (HIST_ENTRY *)NULL;
     }

lib/readline/search.c

@@ -88,8 +88,10 @@ make_history_line_current (HIST_ENTRY *entry)
 
   xlist = _rl_saved_line_for_history ? (UNDO_LIST *)_rl_saved_line_for_history->data : 0;
   /* At this point, rl_undo_list points to a private search string list. */
-  if (rl_undo_list && rl_undo_list != (UNDO_LIST *)entry->data && rl_undo_list != xlist)
+  if (rl_undo_list && rl_undo_list != (UNDO_LIST *)entry->data && rl_undo_list != xlist &&
+	_hs_search_history_data ((histdata_t *)rl_undo_list) < 0)
     rl_free_undo_list ();
+  rl_undo_list = 0;	/* XXX */
 
   /* Now we create a new undo list with a single insert for this text.
      WE DON'T CHANGE THE ORIGINAL HISTORY ENTRY UNDO LIST */