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 /*
  19  * Note that these constants are suitable for indexing the hash_algos array and
  20  * comparing against each other, but are otherwise arbitrary, so they should not
  21  * be exposed to the user or serialized to disk.  To know whether a
  22  * git_hash_algo struct points to some usable hash function, test the format_id
  23  * field for being non-zero.  Use the name field for user-visible situations and
  24  * the format_id field for fixed-length fields on disk.
  25  */
  26 /* An unknown hash function. */
  27 #define GIT_HASH_UNKNOWN 0
  28 /* SHA-1 */
  29 #define GIT_HASH_SHA1 1
  30 /* Number of algorithms supported (including unknown). */
  31 #define GIT_HASH_NALGOS (GIT_HASH_SHA1 + 1)
  32
  33 typedef void (*git_hash_init_fn)(void *ctx);
  34 typedef void (*git_hash_update_fn)(void *ctx, const void *in, size_t len);
  35 typedef void (*git_hash_final_fn)(unsigned char *hash, void *ctx);
  36
  37 struct git_hash_algo {
  38         /*
  39          * The name of the algorithm, as appears in the config file and in
  40          * messages.
  41          */
  42         const char *name;
  43
  44         /* A four-byte version identifier, used in pack indices. */
  45         uint32_t format_id;
  46
  47         /* The size of a hash context (e.g. git_SHA_CTX). */
  48         size_t ctxsz;
  49
  50         /* The length of the hash in binary. */
  51         size_t rawsz;
  52
  53         /* The length of the hash in hex characters. */
  54         size_t hexsz;
  55
  56         /* The hash initialization function. */
  57         git_hash_init_fn init_fn;
  58
  59         /* The hash update function. */
  60         git_hash_update_fn update_fn;
  61
  62         /* The hash finalization function. */
  63         git_hash_final_fn final_fn;
  64
  65         /* The OID of the empty tree. */
  66         const struct object_id *empty_tree;
  67
  68         /* The OID of the empty blob. */
  69         const struct object_id *empty_blob;
  70 };
  71 extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
  72
  73 #endif