diff options
author | brian m. carlson <sandals@crustytoothpaste.net> | 2021-04-26 04:02:52 +0300 |
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committer | Junio C Hamano <gitster@pobox.com> | 2021-04-27 10:31:38 +0300 |
commit | ab795f0d77aec52496557eb69a5fc9e4f60ea1fd (patch) | |
tree | 78a5e3451fac3e53b12364f4f8c5c854da318e84 /hash.h | |
parent | c3b4e4ee366b8de9802fa752d0a81be92e690e17 (diff) |
hash: add a function to finalize object IDs
To avoid the penalty of having to branch in hash comparison functions,
we'll want to always compare the full hash member in a struct object_id,
which will require that SHA-1 object IDs be zero-padded. To do so, add
a function which finalizes a hash context and writes it into an object
ID that performs this padding.
Move the definition of struct object_id and the constant definitions
higher up so we they are available for us to use.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'hash.h')
-rw-r--r-- | hash.h | 50 |
1 files changed, 27 insertions, 23 deletions
@@ -95,6 +95,29 @@ static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *s /* Number of algorithms supported (including unknown). */ #define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1) +/* The length in bytes and in hex digits of an object name (SHA-1 value). */ +#define GIT_SHA1_RAWSZ 20 +#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ) +/* The block size of SHA-1. */ +#define GIT_SHA1_BLKSZ 64 + +/* The length in bytes and in hex digits of an object name (SHA-256 value). */ +#define GIT_SHA256_RAWSZ 32 +#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ) +/* The block size of SHA-256. */ +#define GIT_SHA256_BLKSZ 64 + +/* The length in byte and in hex digits of the largest possible hash value. */ +#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ +#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ +/* The largest possible block size for any supported hash. */ +#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ + +struct object_id { + unsigned char hash[GIT_MAX_RAWSZ]; + int algo; +}; + /* A suitably aligned type for stack allocations of hash contexts. */ union git_hash_ctx { git_SHA_CTX sha1; @@ -106,6 +129,7 @@ typedef void (*git_hash_init_fn)(git_hash_ctx *ctx); typedef void (*git_hash_clone_fn)(git_hash_ctx *dst, const git_hash_ctx *src); typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len); typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx); +typedef void (*git_hash_final_oid_fn)(struct object_id *oid, git_hash_ctx *ctx); struct git_hash_algo { /* @@ -138,6 +162,9 @@ struct git_hash_algo { /* The hash finalization function. */ git_hash_final_fn final_fn; + /* The hash finalization function for object IDs. */ + git_hash_final_oid_fn final_oid_fn; + /* The OID of the empty tree. */ const struct object_id *empty_tree; @@ -161,29 +188,6 @@ static inline int hash_algo_by_ptr(const struct git_hash_algo *p) return p - hash_algos; } -/* The length in bytes and in hex digits of an object name (SHA-1 value). */ -#define GIT_SHA1_RAWSZ 20 -#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ) -/* The block size of SHA-1. */ -#define GIT_SHA1_BLKSZ 64 - -/* The length in bytes and in hex digits of an object name (SHA-256 value). */ -#define GIT_SHA256_RAWSZ 32 -#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ) -/* The block size of SHA-256. */ -#define GIT_SHA256_BLKSZ 64 - -/* The length in byte and in hex digits of the largest possible hash value. */ -#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ -#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ -/* The largest possible block size for any supported hash. */ -#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ - -struct object_id { - unsigned char hash[GIT_MAX_RAWSZ]; - int algo; -}; - #define the_hash_algo the_repository->hash_algo extern const struct object_id null_oid; |