printf field width argument handling

[Jeff Johnston]

On 25/11/09 08:09 AM, Eric Blake wrote:
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> According to Corinna Vinschen on 11/25/2009 1:50 AM:
>> I don't think we have to return with errno set, either.  I'm not even
>> sure if we should change the behaviour at all, given that practically
>> all BSD-based systems behave that way.
>
> POSIX is explicit that use of an improperly formed specifier (such as
> %**s) gives unspecified results; it permits but does not require failure
> with EINVAL, and returning successfully after printing an extremely huge
> field width still qualifies as a valid action for unspecified results.
> Besides, an invalid string is something you can audit for (after all, gcc
> - -Wall catches this particular one if you did it via a compile-time string,
> and if you are using arbitrary user input as a runtime-provided format
> string, you are already vulnerable to %n exploits), so why bloat the code
> to stop the user from doing something they should have already prevented
> at compile time?
>

Agreed.

-- Jeff J.

> - --
> Don't work too hard, make some time for fun as well!
>
> Eric Blake             ebb9@byu.net
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