Discarding the entire undo stack, to prevent nano from dying (or

making mistakes) when trying to undo edits after a justification.
This works around Savannah bug #45531.


git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@5473 35c25a1d-7b9e-4130-9fde-d3aeb78583b8

ChangeLog

 2015-12-03  Benno Schulenberg  <bensberg@justemail.net>
 	* src/text.c (discard_until): Move the trimming of the undo stack
 	into a separate function, so it can be used elsewhere.
+	* src/text.c (do_justify): Discard the entire undo stack, to prevent
+	nano from dying (or making mistakes) when trying to undo edits after
+	a justification.  This works around Savannah bug #45531.
 
 2015-12-02  Benno Schulenberg  <bensberg@justemail.net>
 	* doc/syntax/python.nanorc: Don't colour triple quotes by themselves.

src/text.c

@@ -912,7 +912,7 @@ void discard_until(undo *thisone)
     while (dropit != NULL && dropit != thisone) {
 	openfile->undotop = dropit->next;
 	free(dropit->strdata);
-	if (dropit->cutbuffer)
+	if (dropit->cutbuffer != NULL)
 	    free_filestruct(dropit->cutbuffer);
 	free(dropit);
 	dropit = openfile->undotop;
@@ -2315,8 +2315,14 @@ void do_justify(bool full_justify)
 	    edit_refresh_needed = TRUE;
 	}
     } else {
+	/* Put the keystroke back into the queue. */
 	unget_kbinput(kbinput, meta_key, func_key);
 
+	/* Throw away the entire undo stack, to prevent a crash when
+	 * the user tries to undo something in the justified text. */
+	discard_until(NULL);
+	openfile->current_undo = NULL;
+
 	/* Blow away the text in the justify buffer. */
 	free_filestruct(jusbuffer);
 	jusbuffer = NULL;