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Date: Tue, 28 Jul 2009 06:22:56 +0100
Message-ID: <416096c60907272222m6cfdd29dk8e2b2cc4b0a04281@mail.gmail.com>
Subject: Re: bug in mbrtowc?
From: Andy Koppe <andy DOT koppe AT gmail DOT com>
To: cygwin AT cygwin DOT com
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2009/7/28 Pedro Izecksohn:
>> #include <stdio.h>
>> #include <locale.h>
>> #include <stdlib.h>
>> #include <wchar.h>
>>
>> int main(void) {
>>  wchar_t wc;
>>  size_t ret;
>>  mbstate_t s =3D { 0 };
>>  puts(setlocale(LC_CTYPE, "en_GB.UTF-8"));
>>  printf("%i\n", mbrtowc(&wc, "\xe2", 1, 0));
>>  printf("%i\n", mbrtowc(&wc, "\x94", 1, 0));
>>  printf("%i\n", mbrtowc(&wc, "\x84", 1, 0));
>>  printf("%x\n", wc);
>>  return 0;
>> }
>>
>> The sequence E2 94 84 should translate to U+2514. Instead, the second
>> and third calls to mbrtowc report encoding errors. It does work
>> correctly if the three bytes are passed to mbrtowc() in one go:
> =C2=A0From the "Linux Programmer=E2=80=99s Manual" (release 3.15 of the L=
inux man-pages):
> "If the n bytes starting at s do not contain a complete multibyte
> character, =C2=A0mbrtowc() =C2=A0returns =C2=A0(size_t) -2."

Correct. And the first call to mbrtowc() does just that. The problem
is that the second call returns -1, which signals an encoding error,
even though E2 94 is a valid yet incomplete sequence, i.e. it should
also return -2 and remember what it's seen so far in its internal
state. The third call should return 1 and write 0x2504 to wc.

Andy

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