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 #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. */
  81 union git_hash_ctx {
  82         git_SHA_CTX sha1;
  83         git_SHA256_CTX sha256;
  84 };
  85 typedef union git_hash_ctx git_hash_ctx;
  86
  87 typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
  88 typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
  89 typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
  90
  91 struct 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 };
 125 extern 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  */
 131 int hash_algo_by_name(const char *name);
 132 /* Identical, except based on the format ID. */
 133 int hash_algo_by_id(uint32_t format_id);
 134 /* Identical, except based on the length. */
 135 int hash_algo_by_length(int len);
 136 /* Identical, except for a pointer to struct git_hash_algo. */
 137 static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
 138 {
 139         return p - hash_algos;
 140 }
 141
 142 /* The length in bytes and in hex digits of an object name (SHA-1 value). */
 143 #define GIT_SHA1_RAWSZ 20
 144 #define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
 145 /* The block size of SHA-1. */
 146 #define GIT_SHA1_BLKSZ 64
 147
 148 /* The length in bytes and in hex digits of an object name (SHA-256 value). */
 149 #define GIT_SHA256_RAWSZ 32
 150 #define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
 151 /* The block size of SHA-256. */
 152 #define GIT_SHA256_BLKSZ 64
 153
 154 /* The length in byte and in hex digits of the largest possible hash value. */
 155 #define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ
 156 #define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ
 157 /* The largest possible block size for any supported hash. */
 158 #define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ
 159
 160 struct object_id {
 161         unsigned char hash[GIT_MAX_RAWSZ];
 162 };
 163
 164 #define the_hash_algo the_repository->hash_algo
 165
 166 #endif