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 #ifndef platform_SHA_CTX
  19 /*
  20  * platform's underlying implementation of SHA-1; could be OpenSSL,
  21  * blk_SHA, Apple CommonCrypto, etc...  Note that the relevant
  22  * SHA-1 header may have already defined platform_SHA_CTX for our
  23  * own implementations like block-sha1 and ppc-sha1, so we list
  24  * the default for OpenSSL compatible SHA-1 implementations here.
  25  */
  26 #define platform_SHA_CTX        SHA_CTX
  27 #define platform_SHA1_Init      SHA1_Init
  28 #define platform_SHA1_Update    SHA1_Update
  29 #define platform_SHA1_Final     SHA1_Final
  30 #endif
  31
  32 #define git_SHA_CTX             platform_SHA_CTX
  33 #define git_SHA1_Init           platform_SHA1_Init
  34 #define git_SHA1_Update         platform_SHA1_Update
  35 #define git_SHA1_Final          platform_SHA1_Final
  36
  37 #ifdef SHA1_MAX_BLOCK_SIZE
  38 #include "compat/sha1-chunked.h"
  39 #undef git_SHA1_Update
  40 #define git_SHA1_Update         git_SHA1_Update_Chunked
  41 #endif
  42
  43 /*
  44  * Note that these constants are suitable for indexing the hash_algos array and
  45  * comparing against each other, but are otherwise arbitrary, so they should not
  46  * be exposed to the user or serialized to disk.  To know whether a
  47  * git_hash_algo struct points to some usable hash function, test the format_id
  48  * field for being non-zero.  Use the name field for user-visible situations and
  49  * the format_id field for fixed-length fields on disk.
  50  */
  51 /* An unknown hash function. */
  52 #define GIT_HASH_UNKNOWN 0
  53 /* SHA-1 */
  54 #define GIT_HASH_SHA1 1
  55 /* Number of algorithms supported (including unknown). */
  56 #define GIT_HASH_NALGOS (GIT_HASH_SHA1 + 1)
  57
  58 /* A suitably aligned type for stack allocations of hash contexts. */
  59 union git_hash_ctx {
  60         git_SHA_CTX sha1;
  61 };
  62 typedef union git_hash_ctx git_hash_ctx;
  63
  64 typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
  65 typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
  66 typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
  67
  68 struct git_hash_algo {
  69         /*
  70          * The name of the algorithm, as appears in the config file and in
  71          * messages.
  72          */
  73         const char *name;
  74
  75         /* A four-byte version identifier, used in pack indices. */
  76         uint32_t format_id;
  77
  78         /* The length of the hash in binary. */
  79         size_t rawsz;
  80
  81         /* The length of the hash in hex characters. */
  82         size_t hexsz;
  83
  84         /* The hash initialization function. */
  85         git_hash_init_fn init_fn;
  86
  87         /* The hash update function. */
  88         git_hash_update_fn update_fn;
  89
  90         /* The hash finalization function. */
  91         git_hash_final_fn final_fn;
  92
  93         /* The OID of the empty tree. */
  94         const struct object_id *empty_tree;
  95
  96         /* The OID of the empty blob. */
  97         const struct object_id *empty_blob;
  98 };
  99 extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
 100
 101 #endif