On Tue, Nov 06, 2007 at 11:32:15PM +0900, Tetsuo Handa wrote:
> Hello.
>
> Adrian Bunk wrote:
> > And \* is not a replacement for \?. It's quite common to have both ways
> > to express "one character" and to express "at least one character", and
> > both have their use cases and will get used if available.
> You can use \? to represent "one character" and
> \?\* to represent "at least one character".
Not "one character", it's "one byte".
> > But the problem is that in your code you only match one byte for \?,
> > and this might or might not be equal to one character.
> "one byte" is almost equal to "one character".
> "\?" matches to one of the following types.
>
> * 1 ASCII printable character (for 0x21-0x2E or 0x30-0x5B or 0x5D-0x7E)
> * 2 ASCII printable characters \\ (for 0x5C, which means single "\")
> * 4 ASCII printable characters \ooo (for 0x01-0x20 or 0x7F-0xFF, where "ooo" is octal value)
>
> These 3 types represents one *byte*.
> I want to say "\? matches to one character",
> but since expression of a character depends on the value of that byte,
> I'm saying "\? matches to one *byte* character" instead.
> Well, this sentence might be confusing, but how can I express more accurately?
The problem is that your code matches one byte, not one character.
More or less all userspace programs handle multi-byte UTF-8 characters
just fine without bothering the user with the fact whether a character
consists of one or more bytes.
And users will try to use this \? for matching one character when
writing a pattern that denies access.
That's not just a documentation problem.
> Thanks.
cu
Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
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