Re: [PATCH v2] error.3: ATTRIBUTES: Note functions that are/aren't thread-safe

["Michael Kerrisk (man-pages)" <mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hello Zeng Linggang,

On 07/17/2015 05:15 AM, Zeng Linggang wrote:
> The markings match glibc markings.
> markings of functions in glibc are:
> - error:         MT-Safe locale
> - error_at_line: MT-Unsafe race:error_at_line/error_one_per_line locale

Thanks for fixing the patch. Applied.

Cheers,

Michael

> 
> Signed-off-by: Zeng Linggang <zenglg.jy-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
> ---
>  man3/error.3 | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/man3/error.3 b/man3/error.3
> index 7e1d47c..7a92a76 100644
> --- a/man3/error.3
> +++ b/man3/error.3
> @@ -118,6 +118,37 @@ is assigned the address of a function
>  instead of prefixing the message with the program name and colon.
>  The function should print a suitable string to
>  .IR stderr .
> +.SH ATTRIBUTES
> +For an explanation of the terms used in this section, see
> +.BR attributes (7).
> +.TS
> +allbox;
> +lb lb lbw37
> +l l l.
> +Interface	Attribute	Value
> +T{
> +.BR error ()
> +T}	Thread safety	MT-Safe locale
> +T{
> +.BR error_at_line ()
> +T}	Thread safety	T{
> +MT-Unsafe race:error_at_line/error_one_per_line locale
> +T}
> +.TE
> +
> +The internal
> +.I error_one_per_line
> +variable is accessed (without any form of synchronization, but since
> +it's an int used once, it should be safe enough) and, if
> +.I error_one_per_line
> +is set nonzero, the internal static variables(not exposed to users)
> +used to hold the last printed file name and line number are accessed
> +and modified without synchronization; the update is not atomic and it
> +occurs before disabling cancellation, so it can be interrupted after
> +only one of the two variables is modified. After that,
> +.BR error_at_line (3)
> +is very much like
> +.BR error (3).
>  .SH CONFORMING TO
>  These functions and variables are GNU extensions, and should not be
>  used in programs intended to be portable.
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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