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Date: Wed, 22 Apr 2009 10:31:45 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: [1.7] Updated: cygwin-1.7.0-45
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On Apr 21 22:18, Eric Blake wrote:
> The bug was that isblank(-1) was blindly treated as if were equivalent
> with isblank(0xff), which, in some locales, is flat out wrong
> (isblank(EOF) should always be 0, even when isblank(0xff) is well-defined
> as 1).  Broken apps can't tell the difference between isblank((char)0xff)
> and isblank(EOF), but correct apps, like sed, CAN tell the difference
> between 0xff and EOF in "int ch = getchar(); isblank(ch)" since getchar()
> returns an int containing an unsigned char value (and not a char).
> 
> Sed's infinite loop, then, was because of newlib/cygwin's bug - sed
> reached the end of the file while trying to skip blanks, but because
> isblank() was returning the wrong value for -1, sed thought that EOF was a
> blank and kept trying to read the file instead of breaking out of the loop.

Thanks for the explanation.  Apparently I'm unable to explain this
clearly enough.


Corinna

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Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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