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git/block-sha1/sha1.h
Jeff King 9bb4542b8c block-sha1: take a size_t length parameter
The block-sha1 implementation takes an "unsigned long" for the length of
a buffer to hash, but our hash algorithm wrappers take a size_t, as do
other implementations we support like openssl or sha1dc. On many
systems, including Linux, these two are equivalent, but they are not on
Windows (where only a "long long" is 64 bits). As a result, passing
large chunks to a single the_hash_algo->update_fn() would produce wrong
answers there.

Note that we don't need to update any other sizes outside of the
function interface. We store the cumulative size in a "long long" (which
we must do since we hash things bigger than 4GB, like packfiles, even on
32-bit platforms). And internally, we break that size_t len down into
64-byte blocks to feed into the guts of the algorithm.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-11-16 13:41:35 -08:00

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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, size_t 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