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git/block-sha1/sha1.h
Atousa Pahlevan Duprat 3bc72fde3f sha1: provide another level of indirection for the SHA-1 functions
The git source uses git_SHA1_Update() and friends to call into the
code that computes the hashes.  Traditionally, we used to map these
directly to underlying implementation of the SHA-1 hash (e.g.
SHA1_Update() from OpenSSL or blk_SHA1_Update() from block-sha1/).

This arrangement however makes it hard to tweak behaviour of the
underlying implementation without fully replacing.  If we want to
introduce a tweaked_SHA1_Update() wrapper to implement the "Update"
in a slightly different way, for example, the implementation of the
wrapper still would want to call into the underlying implementation,
but tweaked_SHA1_Update() cannot call git_SHA1_Update() to get to
the underlying implementation (often but not always SHA1_Update()).

Add another level of indirection that maps platform_SHA1_Update()
and friends to their underlying implementations, and by default make
git_SHA1_Update() and friends map to platform_SHA1_* functions.

Doing it this way will later allow us to map git_SHA1_Update() to
tweaked_SHA1_Update(), and the latter can use platform_SHA1_Update()
in its implementation.

Signed-off-by: Atousa Pahlevan Duprat <apahlevan@ieee.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-11-05 10:35:11 -08:00

22 lines
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C

/*
* SHA1 routine optimized to do word accesses rather than byte accesses,
* and to avoid unnecessary copies into the context array.
*
* This was initially based on the Mozilla SHA1 implementation, although
* none of the original Mozilla code remains.
*/
typedef struct {
unsigned long long size;
unsigned int H[5];
unsigned int W[16];
} blk_SHA_CTX;
void blk_SHA1_Init(blk_SHA_CTX *ctx);
void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *dataIn, unsigned long len);
void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx);
#define platform_SHA_CTX blk_SHA_CTX
#define platform_SHA1_Init blk_SHA1_Init
#define platform_SHA1_Update blk_SHA1_Update
#define platform_SHA1_Final blk_SHA1_Final