Re: 21.2.24 Crashes!
Shenghuo ZHU <zsh(a)cs.rochester.edu> writes:
When I run this code (a simplified version), XEmacs crashes. The
problem is the text property.
(defun test-decode (word)
(let ((i -1) (s (substring word 0)) v)
(while (< (incf i) (length s))
(if (eq (setq v (aref s i)) ? ) nil
(aset s i (+ 128 v))))
s))
(let ((s "~{<:Ky2;S{#,NpJ)l6HK!#~}"))
(put-text-property 0 (length s) 'face 'bold s)
(setq s (test-decode s))
(decode-coding-string s 'cn-gb-2312))
A simple test case for this is:
(let ((s "ab"))
(put-text-property 0 (length s) 'face 'bold s)
(aset s 0 128)
s)
what happens is this:
- set_string_char() is called to set the first character.
- The new char needs two bytes, therefore resize_string ( pos=0,
delta=1) is called.
- in resize_string() space is made and the string length is set to 3
- adjust_extents(from=-1, to=3, amount=1) is called
- since extents use memind's the starting point of the extent is
adjusted from 0 to 1. Now it points into the middle of the
character, resulting in the crash later on.
I think the semantics of resize_string are slightly under-specified:
/* Resize the string S so that DELTA bytes can be inserted starting
at POS. [...] */
It is not clear whether we insert new characters or just need more
space for the existing character. In the former case we need to adjust
extents with start=pos in the latter we mustn't.
resize_string also has problems if the string is shrunk as extents
might have endpoints to the right of the new string end and therefore
won't get adjusted.
Any suggestions?
Gunnar