Big documentation shortcoming: QString::arg()

[qt-bugs at trolltech.com]

On Mittwoch, 10 Jul 2002 19:56, Marc Mutz wrote:
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> 
> Hi!
> 
> Code using multiple QString::arg()'s on a string sequentially can be 
> tricked into replacing the wrong parts of texts. If :arg() is used to 
> insert (multiple) "user-supplied" strings, then the resulting program 
> may be vulnerable to quite a few attacks. A simple test program is 
> attached. Try e.g.
> $ testqstring '%1 first text' 'second text'
> 1: s == 1: %1 first text; 2: %2
> 2: s == 1: second text first text; 2:
> 
> This is particularly dangerous if this mechnism is used to construct 
> command lines to be executed.
> Of course, a careful programmer will never use arg() for this and always 
> check the to-be-inserted strings for "%n" and warn if one is found, but 
> nonetheless a big fat warning in the documentation of QString::arg() 
> should be in order.
> 
> Thanks,
> Marc
> 

Hi Marc,

I'm afraid this is a bit beyond the scope of the Qt documentation, which is
supposed to explain the purpose of a function and how to use it rather than
the dangers of a function in certain circumstances. We would have to add
big fat warnings in the documentation for every destructor (a'la warning:
calling the destructor deletes the object and may crash your application),
which would definitely not look very nice.

Best regards,
Volker

-- 
Volker Hilsheimer, Support Manager
Trolltech AS, Waldemar Thranes gt. 98, N-0175 Oslo, Norway