Re: [PATCH/RFC 2/8] crypto: compress - Add pcomp interface

[Herbert Xu]

On Thu, Dec 18, 2008 at 06:28:09PM +0100, Geert Uytterhoeven wrote:
>
> Can you please elaborate a bit more?

In the old scheme, each type required you to change crypto_tfm
and crypto_alg since they had the type-specific information
embedded in it.  Starting with crypto_shash, we are now totally
decentralised.  All type-specific information is now added to
the base structures.  Let's take shash_alg as an example, in
the old days we'd put the algorithms into a structure and embed
the structure in crypto_alg, now we instead put crypto_alg in
shash_alg, like this:

struct shash_alg {
	int (*init)(struct shash_desc *desc);
	int (*reinit)(struct shash_desc *desc);
	int (*update)(struct shash_desc *desc, const u8 *data,
		      unsigned int len);
	int (*final)(struct shash_desc *desc, u8 *out);
	int (*finup)(struct shash_desc *desc, const u8 *data,
		     unsigned int len, u8 *out);
	int (*digest)(struct shash_desc *desc, const u8 *data,
		      unsigned int len, u8 *out);
	int (*setkey)(struct crypto_shash *tfm, const u8 *key,
		      unsigned int keylen);

	unsigned int descsize;
	unsigned int digestsize;

	struct crypto_alg base;
};

> You mean pcomp should provide a struct crypto_type?

Yes, it should.  Although starting wish shash crypto_type no
longer needs to be directly visible to the algorithms as each
new type should now provide its own registration function which
can fill in the type object.

> And the underlying algorithms shouldn't use crypto_alg directly anymore?

Right.  Please take a look at include/crypto/hash.h, crypto/shash.c,
and crypto/sha1_generic.c from the cryptodev tree.  This should
provide everything you need to write a new type.

Thanks,
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