diff options
Diffstat (limited to 'hash.h')
| -rw-r--r-- | hash.h | 206 |
1 files changed, 187 insertions, 19 deletions
@@ -2,6 +2,7 @@ #define HASH_H #include "git-compat-util.h" +#include "repository.h" #if defined(SHA1_PPC) #include "ppc/sha1.h" @@ -16,6 +17,7 @@ #endif #if defined(SHA256_GCRYPT) +#define SHA256_NEEDS_CLONE_HELPER #include "sha256/gcrypt.h" #elif defined(SHA256_OPENSSL) #include <openssl/sha.h> @@ -54,12 +56,28 @@ #define git_SHA256_Update platform_SHA256_Update #define git_SHA256_Final platform_SHA256_Final +#ifdef platform_SHA256_Clone +#define git_SHA256_Clone platform_SHA256_Clone +#endif + #ifdef SHA1_MAX_BLOCK_SIZE #include "compat/sha1-chunked.h" #undef git_SHA1_Update #define git_SHA1_Update git_SHA1_Update_Chunked #endif +static inline void git_SHA1_Clone(git_SHA_CTX *dst, const git_SHA_CTX *src) +{ + memcpy(dst, src, sizeof(*dst)); +} + +#ifndef SHA256_NEEDS_CLONE_HELPER +static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *src) +{ + memcpy(dst, src, sizeof(*dst)); +} +#endif + /* * Note that these constants are suitable for indexing the hash_algos array and * comparing against each other, but are otherwise arbitrary, so they should not @@ -77,6 +95,29 @@ /* 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; /* XXX requires 4-byte alignment */ +}; + /* A suitably aligned type for stack allocations of hash contexts. */ union git_hash_ctx { git_SHA_CTX sha1; @@ -85,8 +126,10 @@ union git_hash_ctx { typedef union git_hash_ctx git_hash_ctx; 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 { /* @@ -110,17 +153,26 @@ struct git_hash_algo { /* The hash initialization function. */ git_hash_init_fn init_fn; + /* The hash context cloning function. */ + git_hash_clone_fn clone_fn; + /* The hash update function. */ git_hash_update_fn update_fn; /* 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; /* The OID of the empty blob. */ const struct object_id *empty_blob; + + /* The all-zeros OID. */ + const struct object_id *null_oid; }; extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS]; @@ -139,28 +191,144 @@ 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 +#define the_hash_algo the_repository->hash_algo -/* 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 +const struct object_id *null_oid(void); -/* 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 +static inline int hashcmp_algop(const unsigned char *sha1, const unsigned char *sha2, const struct git_hash_algo *algop) +{ + /* + * Teach the compiler that there are only two possibilities of hash size + * here, so that it can optimize for this case as much as possible. + */ + if (algop->rawsz == GIT_MAX_RAWSZ) + return memcmp(sha1, sha2, GIT_MAX_RAWSZ); + return memcmp(sha1, sha2, GIT_SHA1_RAWSZ); +} -struct object_id { - unsigned char hash[GIT_MAX_RAWSZ]; -}; +static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2) +{ + return hashcmp_algop(sha1, sha2, the_hash_algo); +} -#define the_hash_algo the_repository->hash_algo +static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2) +{ + const struct git_hash_algo *algop; + if (!oid1->algo) + algop = the_hash_algo; + else + algop = &hash_algos[oid1->algo]; + return hashcmp_algop(oid1->hash, oid2->hash, algop); +} + +static inline int hasheq_algop(const unsigned char *sha1, const unsigned char *sha2, const struct git_hash_algo *algop) +{ + /* + * We write this here instead of deferring to hashcmp so that the + * compiler can properly inline it and avoid calling memcmp. + */ + if (algop->rawsz == GIT_MAX_RAWSZ) + return !memcmp(sha1, sha2, GIT_MAX_RAWSZ); + return !memcmp(sha1, sha2, GIT_SHA1_RAWSZ); +} + +static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2) +{ + return hasheq_algop(sha1, sha2, the_hash_algo); +} + +static inline int oideq(const struct object_id *oid1, const struct object_id *oid2) +{ + const struct git_hash_algo *algop; + if (!oid1->algo) + algop = the_hash_algo; + else + algop = &hash_algos[oid1->algo]; + return hasheq_algop(oid1->hash, oid2->hash, algop); +} + +static inline int is_null_oid(const struct object_id *oid) +{ + return oideq(oid, null_oid()); +} + +static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src) +{ + memcpy(sha_dst, sha_src, the_hash_algo->rawsz); +} + +static inline void oidcpy(struct object_id *dst, const struct object_id *src) +{ + memcpy(dst->hash, src->hash, GIT_MAX_RAWSZ); + dst->algo = src->algo; +} + +/* Like oidcpy() but zero-pads the unused bytes in dst's hash array. */ +static inline void oidcpy_with_padding(struct object_id *dst, + const struct object_id *src) +{ + size_t hashsz; + + if (!src->algo) + hashsz = the_hash_algo->rawsz; + else + hashsz = hash_algos[src->algo].rawsz; + + memcpy(dst->hash, src->hash, hashsz); + memset(dst->hash + hashsz, 0, GIT_MAX_RAWSZ - hashsz); + dst->algo = src->algo; +} + +static inline struct object_id *oiddup(const struct object_id *src) +{ + struct object_id *dst = xmalloc(sizeof(struct object_id)); + oidcpy(dst, src); + return dst; +} + +static inline void hashclr(unsigned char *hash) +{ + memset(hash, 0, the_hash_algo->rawsz); +} + +static inline void oidclr(struct object_id *oid) +{ + memset(oid->hash, 0, GIT_MAX_RAWSZ); + oid->algo = hash_algo_by_ptr(the_hash_algo); +} + +static inline void oidread(struct object_id *oid, const unsigned char *hash) +{ + memcpy(oid->hash, hash, the_hash_algo->rawsz); + oid->algo = hash_algo_by_ptr(the_hash_algo); +} + +static inline int is_empty_blob_sha1(const unsigned char *sha1) +{ + return hasheq(sha1, the_hash_algo->empty_blob->hash); +} + +static inline int is_empty_blob_oid(const struct object_id *oid) +{ + return oideq(oid, the_hash_algo->empty_blob); +} + +static inline int is_empty_tree_sha1(const unsigned char *sha1) +{ + return hasheq(sha1, the_hash_algo->empty_tree->hash); +} + +static inline int is_empty_tree_oid(const struct object_id *oid) +{ + return oideq(oid, the_hash_algo->empty_tree); +} + +static inline void oid_set_algo(struct object_id *oid, const struct git_hash_algo *algop) +{ + oid->algo = hash_algo_by_ptr(algop); +} + +const char *empty_tree_oid_hex(void); +const char *empty_blob_oid_hex(void); #endif |