Re: segfault in strftime

Re: segfault in strftime

[Bart Schaefer]

[>workers]

On Feb 26,  4:45pm, Peter Stephenson wrote:
} Subject: Re: segfault in strftime
}
} Vincent Lefevre wrote:
} > Wouldn't it be better to test only errno != 0 ?
} 
} Well, given we're setting it to 0 beforehand that seems reasonable.

That's *probably* safe in this case ... but in general I don't think
so.  The standards make no guarantee about the value of errno in the
case where the library call returns "successfully" (however that may
be defined) -- that is, the implementation is allowed to set errno
to what the next upcoming error *might* be, and is not required to
then clear errno before returning success.

Re: segfault in strftime

[Vincent Lefevre]

On 2010-02-26 09:47:31 -0800, Bart Schaefer wrote:
> That's *probably* safe in this case ... but in general I don't think
> so.  The standards make no guarantee about the value of errno in the
> case where the library call returns "successfully" (however that may
> be defined) -- that is, the implementation is allowed to set errno
> to what the next upcoming error *might* be, and is not required to
> then clear errno before returning success.

It is safe for functions that use errno: "The value of errno may
be set to nonzero by a library function call whether or not there
is an error, provided the use of errno is not documented in the
description of the function in this International Standard."

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Vincent Lefèvre <vincent@vinc17.net> - Web: <http://www.vinc17.net/>
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