hash.h

   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 #define SHA256_NEEDS_CLONE_HELPER
  20 #include "sha256/gcrypt.h"
  21 #elif defined(SHA256_OPENSSL)
  22 #include <openssl/sha.h>
  23 #else
  24 #include "sha256/block/sha256.h"
  25 #endif
  26
  27 #ifndef platform_SHA_CTX
  28 /*
  29  * platform's underlying implementation of SHA-1; could be OpenSSL,
  30  * blk_SHA, Apple CommonCrypto, etc...  Note that the relevant
  31  * SHA-1 header may have already defined platform_SHA_CTX for our
  32  * own implementations like block-sha1 and ppc-sha1, so we list
  33  * the default for OpenSSL compatible SHA-1 implementations here.
  34  */
  35 #define platform_SHA_CTX        SHA_CTX
  36 #define platform_SHA1_Init      SHA1_Init
  37 #define platform_SHA1_Update    SHA1_Update
  38 #define platform_SHA1_Final     SHA1_Final
  39 #endif
  40
  41 #define git_SHA_CTX             platform_SHA_CTX
  42 #define git_SHA1_Init           platform_SHA1_Init
  43 #define git_SHA1_Update         platform_SHA1_Update
  44 #define git_SHA1_Final          platform_SHA1_Final
  45
  46 #ifndef platform_SHA256_CTX
  47 #define platform_SHA256_CTX     SHA256_CTX
  48 #define platform_SHA256_Init    SHA256_Init
  49 #define platform_SHA256_Update  SHA256_Update
  50 #define platform_SHA256_Final   SHA256_Final
  51 #endif
  52
  53 #define git_SHA256_CTX          platform_SHA256_CTX
  54 #define git_SHA256_Init         platform_SHA256_Init
  55 #define git_SHA256_Update       platform_SHA256_Update
  56 #define git_SHA256_Final        platform_SHA256_Final
  57
  58 #ifdef platform_SHA256_Clone
  59 #define git_SHA256_Clone        platform_SHA256_Clone
  60 #endif
  61
  62 #ifdef SHA1_MAX_BLOCK_SIZE
  63 #include "compat/sha1-chunked.h"
  64 #undef git_SHA1_Update
  65 #define git_SHA1_Update         git_SHA1_Update_Chunked
  66 #endif
  67
  68 static inline void git_SHA1_Clone(git_SHA_CTX *dst, const git_SHA_CTX *src)
  69 {
  70         memcpy(dst, src, sizeof(*dst));
  71 }
  72
  73 #ifndef SHA256_NEEDS_CLONE_HELPER
  74 static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *src)
  75 {
  76         memcpy(dst, src, sizeof(*dst));
  77 }
  78 #endif
  79
  80 /*
  81  * Note that these constants are suitable for indexing the hash_algos array and
  82  * comparing against each other, but are otherwise arbitrary, so they should not
  83  * be exposed to the user or serialized to disk.  To know whether a
  84  * git_hash_algo struct points to some usable hash function, test the format_id
  85  * field for being non-zero.  Use the name field for user-visible situations and
  86  * the format_id field for fixed-length fields on disk.
  87  */
  88 /* An unknown hash function. */
  89 #define GIT_HASH_UNKNOWN 0
  90 /* SHA-1 */
  91 #define GIT_HASH_SHA1 1
  92 /* SHA-256  */
  93 #define GIT_HASH_SHA256 2
  94 /* Number of algorithms supported (including unknown). */
  95 #define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
  96
  97 /* A suitably aligned type for stack allocations of hash contexts. */
  98 union git_hash_ctx {
  99         git_SHA_CTX sha1;
 100         git_SHA256_CTX sha256;
 101 };
 102 typedef union git_hash_ctx git_hash_ctx;
 103
 104 typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
 105 typedef void (*git_hash_clone_fn)(git_hash_ctx *dst, const git_hash_ctx *src);
 106 typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
 107 typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
 108
 109 struct git_hash_algo {
 110         /*
 111          * The name of the algorithm, as appears in the config file and in
 112          * messages.
 113          */
 114         const char *name;
 115
 116         /* A four-byte version identifier, used in pack indices. */
 117         uint32_t format_id;
 118
 119         /* The length of the hash in binary. */
 120         size_t rawsz;
 121
 122         /* The length of the hash in hex characters. */
 123         size_t hexsz;
 124
 125         /* The block size of the hash. */
 126         size_t blksz;
 127
 128         /* The hash initialization function. */
 129         git_hash_init_fn init_fn;
 130
 131         /* The hash context cloning function. */
 132         git_hash_clone_fn clone_fn;
 133
 134         /* The hash update function. */
 135         git_hash_update_fn update_fn;
 136
 137         /* The hash finalization function. */
 138         git_hash_final_fn final_fn;
 139
 140         /* The OID of the empty tree. */
 141         const struct object_id *empty_tree;
 142
 143         /* The OID of the empty blob. */
 144         const struct object_id *empty_blob;
 145 };
 146 extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
 147
 148 /*
 149  * Return a GIT_HASH_* constant based on the name.  Returns GIT_HASH_UNKNOWN if
 150  * the name doesn't match a known algorithm.
 151  */
 152 int hash_algo_by_name(const char *name);
 153 /* Identical, except based on the format ID. */
 154 int hash_algo_by_id(uint32_t format_id);
 155 /* Identical, except based on the length. */
 156 int hash_algo_by_length(int len);
 157 /* Identical, except for a pointer to struct git_hash_algo. */
 158 static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
 159 {
 160         return p - hash_algos;
 161 }
 162
 163 /* The length in bytes and in hex digits of an object name (SHA-1 value). */
 164 #define GIT_SHA1_RAWSZ 20
 165 #define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
 166 /* The block size of SHA-1. */
 167 #define GIT_SHA1_BLKSZ 64
 168
 169 /* The length in bytes and in hex digits of an object name (SHA-256 value). */
 170 #define GIT_SHA256_RAWSZ 32
 171 #define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
 172 /* The block size of SHA-256. */
 173 #define GIT_SHA256_BLKSZ 64
 174
 175 /* The length in byte and in hex digits of the largest possible hash value. */
 176 #define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ
 177 #define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ
 178 /* The largest possible block size for any supported hash. */
 179 #define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ
 180
 181 struct object_id {
 182         unsigned char hash[GIT_MAX_RAWSZ];
 183 };
 184
 185 #define the_hash_algo the_repository->hash_algo
 186
 187 #endif