Improvements of SM implementation

[frankmorgner]

Needs to be tested with real cards.

[viktorTarasov]

Cherry-picked into 'staging' your commit 'use error code if no SM ...', thank you.
31bdbd6

As for the commit 'avoid manual memory ...':

• static buffers of 0xFFFF length makes me scare -- 'MEM05-C: Avoid large stack allocations' .
• your thesis that 'manual', as you call it, memory allocation breaks the OpenSC habits is not relevant:
  Look onto sc_connect_card(), sc_select_file(), pkcs15 bind and get-object functions.
• anyway, for the sm-apdu the card specific 'get-apdu' and 'free-apdu' handlers are called,
  and I prefer to let these handlers to (de)allocate the memory -- they know better how much they need and how to deal with it.

Let me know if 'manual' allocation makes impossible the implementation of the support for your card -- we will try to find solution .

[frankmorgner]

Hi!

As for the commit 'avoid manual memory ...':

• static buffers of 0xFFFF length makes me scare -- 'MEM05-C: Avoid large stack allocations' .

Memory is cheap. 0xffff+0xffff is 128 kB.

MEM05-C doesn't apply here:
The growth of the stack can not be controlled or influenced by an
attacker. 128 kB are always allocated.

Even if MEM05-C would apply, OpenSC is not a secure software by any
means. Not having to handle malloc, calloc, free and their errors
reduces complexity and potential errors of the programmer.

• your thesis that 'manual', as you call it, memory allocation breaks the OpenSC habits is not relevant:
  Look onto sc_connect_card(), sc_select_file(), pkcs15 bind and get-object functions.

I didn't say that OpenSC consistently follows its own design goals.

• anyway, for the sm-apdu the card specific 'get-apdu' and 'free-apdu' handlers are called,
  and I prefer to let these handlers to (de)allocate the memory -- they know better how much they need and how to deal with it.

Let me know if 'manual' allocation makes impossible the implementation of the support for your card -- we will try to find solution .

Cheers, Frank.