Andrew's git - gitweb.git/blob

   1#ifndef HASH_H
   2#define HASH_H
   3
   4#include "git-compat-util.h"
   5
   6#if defined(SHA1_PPC)
   7#include "ppc/sha1.h"
   8#elif defined(SHA1_APPLE)
   9#include <CommonCrypto/CommonDigest.h>
  10#elif defined(SHA1_OPENSSL)
  11#include <openssl/sha.h>
  12#elif defined(SHA1_DC)
  13#include "sha1dc_git.h"
  14#else /* SHA1_BLK */
  15#include "block-sha1/sha1.h"
  16#endif
  17
  18#if defined(SHA256_GCRYPT)
  19#include "sha256/gcrypt.h"
  20#elif defined(SHA256_OPENSSL)
  21#include <openssl/sha.h>
  22#else
  23#include "sha256/block/sha256.h"
  24#endif
  25
  26#ifndef platform_SHA_CTX
  27/*
  28 * platform's underlying implementation of SHA-1; could be OpenSSL,
  29 * blk_SHA, Apple CommonCrypto, etc...  Note that the relevant
  30 * SHA-1 header may have already defined platform_SHA_CTX for our
  31 * own implementations like block-sha1 and ppc-sha1, so we list
  32 * the default for OpenSSL compatible SHA-1 implementations here.
  33 */
  34#define platform_SHA_CTX        SHA_CTX
  35#define platform_SHA1_Init      SHA1_Init
  36#define platform_SHA1_Update    SHA1_Update
  37#define platform_SHA1_Final     SHA1_Final
  38#endif
  39
  40#define git_SHA_CTX             platform_SHA_CTX
  41#define git_SHA1_Init           platform_SHA1_Init
  42#define git_SHA1_Update         platform_SHA1_Update
  43#define git_SHA1_Final          platform_SHA1_Final
  44
  45#ifndef platform_SHA256_CTX
  46#define platform_SHA256_CTX     SHA256_CTX
  47#define platform_SHA256_Init    SHA256_Init
  48#define platform_SHA256_Update  SHA256_Update
  49#define platform_SHA256_Final   SHA256_Final
  50#endif
  51
  52#define git_SHA256_CTX          platform_SHA256_CTX
  53#define git_SHA256_Init         platform_SHA256_Init
  54#define git_SHA256_Update       platform_SHA256_Update
  55#define git_SHA256_Final        platform_SHA256_Final
  56
  57#ifdef SHA1_MAX_BLOCK_SIZE
  58#include "compat/sha1-chunked.h"
  59#undef git_SHA1_Update
  60#define git_SHA1_Update         git_SHA1_Update_Chunked
  61#endif
  62
  63/*
  64 * Note that these constants are suitable for indexing the hash_algos array and
  65 * comparing against each other, but are otherwise arbitrary, so they should not
  66 * be exposed to the user or serialized to disk.  To know whether a
  67 * git_hash_algo struct points to some usable hash function, test the format_id
  68 * field for being non-zero.  Use the name field for user-visible situations and
  69 * the format_id field for fixed-length fields on disk.
  70 */
  71/* An unknown hash function. */
  72#define GIT_HASH_UNKNOWN 0
  73/* SHA-1 */
  74#define GIT_HASH_SHA1 1
  75/* SHA-256  */
  76#define GIT_HASH_SHA256 2
  77/* Number of algorithms supported (including unknown). */
  78#define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
  79
  80/* A suitably aligned type for stack allocations of hash contexts. */
  81union git_hash_ctx {
  82        git_SHA_CTX sha1;
  83        git_SHA256_CTX sha256;
  84};
  85typedef union git_hash_ctx git_hash_ctx;
  86
  87typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
  88typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
  89typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
  90
  91struct git_hash_algo {
  92        /*
  93         * The name of the algorithm, as appears in the config file and in
  94         * messages.
  95         */
  96        const char *name;
  97
  98        /* A four-byte version identifier, used in pack indices. */
  99        uint32_t format_id;
 100
 101        /* The length of the hash in binary. */
 102        size_t rawsz;
 103
 104        /* The length of the hash in hex characters. */
 105        size_t hexsz;
 106
 107        /* The block size of the hash. */
 108        size_t blksz;
 109
 110        /* The hash initialization function. */
 111        git_hash_init_fn init_fn;
 112
 113        /* The hash update function. */
 114        git_hash_update_fn update_fn;
 115
 116        /* The hash finalization function. */
 117        git_hash_final_fn final_fn;
 118
 119        /* The OID of the empty tree. */
 120        const struct object_id *empty_tree;
 121
 122        /* The OID of the empty blob. */
 123        const struct object_id *empty_blob;
 124};
 125extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
 126
 127/*
 128 * Return a GIT_HASH_* constant based on the name.  Returns GIT_HASH_UNKNOWN if
 129 * the name doesn't match a known algorithm.
 130 */
 131int hash_algo_by_name(const char *name);
 132/* Identical, except based on the format ID. */
 133int hash_algo_by_id(uint32_t format_id);
 134/* Identical, except based on the length. */
 135int hash_algo_by_length(int len);
 136/* Identical, except for a pointer to struct git_hash_algo. */
 137static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
 138{
 139        return p - hash_algos;
 140}
 141
 142#endif