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Date: Thu, 28 Aug 2008 15:22:09 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH] [RESEND] wrap up use of dangerous ctype.h
	macros
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To: qemu-devel@nongnu.org

Ian Jackson wrote:
> The macros isupper, isspace, tolower, and so forth (from <ctype.h>)
> are defined to take an int containing the value of an unsigned char,
> or EOF.
>
> This means that you mustn't write:
>    char *p;
>    ...
>    if (isspace(*p)) { ...
>
> If *p is a top-bit-set character, and your host architecture has
> signed chars by default (most do), then the result is passing a
> negative number to isspace, which is not allowed.  glibc permits this
> but not all libcs do, and it is wrong according to C89 and C99.
>
> The correct use is:
>    if (isspace((unsigned char)*p)) { ...
>
> This is rather unweildy and error-prone so I in the attached patch
> have invented a CTYPE macro which takes some but not all of the pain
> out of it.
>   

Can't we just have qemu_isspace() macros?  I find the CTYPE macro quite 
awkward.  I don't think most people are comfortable with that kind of 
syntax.

Regards,

Anthony Liguori