[pypy-dev] [pypy-svn] r45269 - in pypy/dist/pypy/rpython/module: . tes

[Christian Tismer]

On 24.07.2007, at 18:08, Armin Rigo wrote:

> Hi Fijal,
>
> On Mon, Jul 23, 2007 at 02:38:32PM +0200, Maciek Fijalkowski wrote:
>>        The length of the arrays in a struct utsname is  
>> unspecified; the
>> fields
>>        are terminated by a null byte (?????? ???).
>>
>> I'm completely confused.
>
> It means that the structure looks like this in lltype notation:
>
>       Struct('utsname', ('text1', FixedSizeArray(Char, 10)),
>                         ('text2', FixedSizeArray(Char, 20)),
>                         ...)
>
> where, annoyingly, the numbers '10' and '20' are platform-dependent  
> and
> must be obtained by trying to compile snippets of C code using  
> sizeof()
> and offsetof().
>
> Or are you confused about the bit saying that the fields are
> zero-terminated?  It just means that in the array, characters 0 to N-1
> are non-null, charater N is null, and the rest of the characters are
> undefined.

Which reminds us to implement this carefully and not to rely on the
terminating byte, or we will open the door to buffer overflow  
exploits :-)

ciao - chris

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