Christian Tismer wrote:
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
I personally don't think that implementation of uname() might be a security hazard - if kernel really wants to hack us it can for sure :] Cheers, fijal :.