diff options
Diffstat (limited to 'hash.h')
| -rw-r--r-- | hash.h | 340 |
1 files changed, 340 insertions, 0 deletions
@@ -0,0 +1,340 @@ +#ifndef HASH_H +#define HASH_H + +#include "git-compat-util.h" +#include "repository.h" + +#if defined(SHA1_APPLE) +#include <CommonCrypto/CommonDigest.h> +#elif defined(SHA1_OPENSSL) +#include <openssl/sha.h> +#elif defined(SHA1_DC) +#include "sha1dc_git.h" +#else /* SHA1_BLK */ +#include "block-sha1/sha1.h" +#endif + +#if defined(SHA256_NETTLE) +#include "sha256/nettle.h" +#elif defined(SHA256_GCRYPT) +#define SHA256_NEEDS_CLONE_HELPER +#include "sha256/gcrypt.h" +#elif defined(SHA256_OPENSSL) +#include <openssl/sha.h> +#else +#include "sha256/block/sha256.h" +#endif + +#ifndef platform_SHA_CTX +/* + * platform's underlying implementation of SHA-1; could be OpenSSL, + * blk_SHA, Apple CommonCrypto, etc... Note that the relevant + * SHA-1 header may have already defined platform_SHA_CTX for our + * own implementations like block-sha1, so we list + * the default for OpenSSL compatible SHA-1 implementations here. + */ +#define platform_SHA_CTX SHA_CTX +#define platform_SHA1_Init SHA1_Init +#define platform_SHA1_Update SHA1_Update +#define platform_SHA1_Final SHA1_Final +#endif + +#define git_SHA_CTX platform_SHA_CTX +#define git_SHA1_Init platform_SHA1_Init +#define git_SHA1_Update platform_SHA1_Update +#define git_SHA1_Final platform_SHA1_Final + +#ifndef platform_SHA256_CTX +#define platform_SHA256_CTX SHA256_CTX +#define platform_SHA256_Init SHA256_Init +#define platform_SHA256_Update SHA256_Update +#define platform_SHA256_Final SHA256_Final +#endif + +#define git_SHA256_CTX platform_SHA256_CTX +#define git_SHA256_Init platform_SHA256_Init +#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 + * be exposed to the user or serialized to disk. To know whether a + * git_hash_algo struct points to some usable hash function, test the format_id + * field for being non-zero. Use the name field for user-visible situations and + * the format_id field for fixed-length fields on disk. + */ +/* An unknown hash function. */ +#define GIT_HASH_UNKNOWN 0 +/* SHA-1 */ +#define GIT_HASH_SHA1 1 +/* SHA-256 */ +#define GIT_HASH_SHA256 2 +/* Number of algorithms supported (including unknown). */ +#define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1) + +/* "sha1", big-endian */ +#define GIT_SHA1_FORMAT_ID 0x73686131 + +/* 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 + +/* "s256", big-endian */ +#define GIT_SHA256_FORMAT_ID 0x73323536 + +/* 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; + git_SHA256_CTX sha256; +}; +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 { + /* + * The name of the algorithm, as appears in the config file and in + * messages. + */ + const char *name; + + /* A four-byte version identifier, used in pack indices. */ + uint32_t format_id; + + /* The length of the hash in binary. */ + size_t rawsz; + + /* The length of the hash in hex characters. */ + size_t hexsz; + + /* The block size of the hash. */ + size_t blksz; + + /* 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]; + +/* + * Return a GIT_HASH_* constant based on the name. Returns GIT_HASH_UNKNOWN if + * the name doesn't match a known algorithm. + */ +int hash_algo_by_name(const char *name); +/* Identical, except based on the format ID. */ +int hash_algo_by_id(uint32_t format_id); +/* Identical, except based on the length. */ +int hash_algo_by_length(int len); +/* Identical, except for a pointer to struct git_hash_algo. */ +static inline int hash_algo_by_ptr(const struct git_hash_algo *p) +{ + return p - hash_algos; +} + +#define the_hash_algo the_repository->hash_algo + +const struct object_id *null_oid(void); + +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); +} + +static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2) +{ + return hashcmp_algop(sha1, sha2, the_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 |