Bug #4366: UTF-8文字列に対しての部分文字列取得操作で結果にゴミがつくことがある

• Status: Closed
• Assignee: -
• Target version: 1.9.2
• ruby -v: ruby 1.9.3dev (2011-02-04 trunk 30761) [x86_64-linux]

[kosaki (Motohiro KOSAKI)]

=begin
test.rb

coding: utf-8

str="あいうえお"

p str[2,17]

結果

% ./ruby -v test.rb
ruby 1.9.3dev (2011-02-04 trunk 30761) [x86_64-linux]
"うえお\u0000"

で、考察なんですが、

static char *
str_utf8_nth(const char *p, const char *e, long *nthp)
{
long nth = *nthp;

 if ((int)SIZEOF_VALUE < e - p && (int)SIZEOF_VALUE * 2 < nth) {

             ↑ e-pつまり文字列長の判定がsizeof(VALUE)*2ではなくsizeof(VALUE) (1)

     do {
         nth -= count_utf8_lead_bytes_with_word(s);
         s++;
     } while (s < t && (int)sizeof(VALUE) <= nth);

              ↑ここがwhileではなくdoループ (2)

なので(1)によりs==tがありえて、その場合(2)により文字列外にたいして
count_utf8_lead_bytes_with_word()呼んじゃってるようです。
=end

[kosaki (Motohiro KOSAKI)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

=begin
This issue was solved with changeset r30779.
Motohiro, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• string.c (str_utf8_nth): fixed a conditon of optimized lead
  byte counting. [Bug #4366][ruby-dev:43170]
  =end