Re: [PATCH] isalpha.3: behavior is undefined if c is out-of-range

[Alejandro Colomar <alx.manpages@gmail.com>]

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Hi Yedidyah,

On 6/5/23 13:17, Yedidyah Bar David wrote:
> Clarify that the behavior of these functions is undefined if c is
> neither in the unsigned char range nor EOF.
> 
> I copied the added text from toupper.3.
> 
> In practice, calling them on out-of-range values - tested with recent
> glibc/gcc - is simply reading from random process memory - meaning, you
> either get some garbage, if the memory was readable, or a segmentation
> fault. See also:
> 
> https://stackoverflow.com/questions/65514890/glibcs-isalpha-function-and-the-en-us-utf-8-locale
> 
> Signed-off-by: Yedidyah Bar David <didi@redhat.com>

This is already covered by the NOTES section, isn't it?  BTW, I'll
rename that section to CAVEATS.

Thanks,
Alex

> ---
>  man3/isalpha.3 | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/man3/isalpha.3 b/man3/isalpha.3
> index 443c2aa09..8ad997c29 100644
> --- a/man3/isalpha.3
> +++ b/man3/isalpha.3
> @@ -145,6 +145,15 @@ is the special locale object
>  .BR duplocale (3))
>  or is not a valid locale object handle.
>  .PP
> +If
> +.I c
> +is neither an
> +.I "unsigned char"
> +value nor
> +.BR EOF ,
> +the behavior of these functions
> +is undefined.
> +.PP
>  The list below explains the operation of the functions without
>  the "_l" suffix;
>  the functions with the "_l" suffix differ only in using the locale object
> --
> 2.31.1
> 
> Best regards,
> --
> Didi
> 

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