Michael Richardson <[EMAIL PROTECTED]>:
>> My suggestion:
>>
>> change the typedef, (or probably, add a new one):
>>
>> struct des_ks_struct
>> {
>> union {
>> des_cblock _;
>> /* make sure things are correct size on machines with
>> * 8 byte longs */
>> DES_LONG pad[2];
>> } ks[16];
>> };
>>
>> typedef struct des_ks_struct * des_key_schedule;
> I see the error of my ways.
>
> des_key_schedule gets to be a nice chameleon.
> If declared as an auto/static, its gets storage like a structure.
> If declared in a parameter list, it gets treated like a pointer. This is
> the nature of arrays in C. (And before structure passing, this was the case
> for structures as well)
>
> The above breaks lots of programs.
> The problem is that one can't cast a pointer to a "des_key_schedule"
> (as it was defined before) because that is an array type, not a pointer to an
> array. So, one needs at a minimum:
>
> struct des_eks {
> des_key_schedule ks;
> };
>
> so that one can do ((struct des_eks *)foo)->ks to get the right type to
> satisfy the prototype.
Actually a change similar to what you proposed above was done in the
development version of OpenSSL (0.9.7-dev, snapshots available at
<URL: ftp://ftp.openssl.org/snapshot;type=d>), except that
des_key_schedule is now the actual struct and not a pointer to the
struct.
OpenSSL 0.9.6 definition:
typedef struct des_ks_struct
{
union {
des_cblock cblock;
/* make sure things are correct size on machines with
* 8 byte longs */
DES_LONG deslong[2];
} ks;
int weak_key;
} des_key_schedule[16];
(des_key_schedule is an array of structs containing just a union.)
Current definition (0.9.7-dev):
typedef struct des_ks
{
union
{
des_cblock cblock;
/* make sure things are correct size on machines with
* 8 byte longs */
DES_LONG deslong[2];
} ks[16];
} des_key_schedule;
No doubt this will break many programs (binary compatibility will be
maintained at least) because if you have
des_key_schedule ks;
(which is still valid for variable definitions) then 'ks' will not
automatically replaced by an appropriate pointer and you have to use
'&ks' in function calls. If I remember correctly, I was the only one
worried about this though. (Apart from transition difficulties, the
new scheme surely is less confusing.)
--
Bodo M�ller <[EMAIL PROTECTED]>
PGP http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/moeller/0x36d2c658.html
* TU Darmstadt, Theoretische Informatik, Alexanderstr. 10, D-64283 Darmstadt
* Tel. +49-6151-16-6628, Fax +49-6151-16-6036
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