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Merge branch 'bc/sha-256'

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Add sha-256 hash and plug it through the code to allow building Git
with the "NewHash".

* bc/sha-256:
  hash: add an SHA-256 implementation using OpenSSL
  sha256: add an SHA-256 implementation using libgcrypt
  Add a base implementation of SHA-256 support
  commit-graph: convert to using the_hash_algo
  t/helper: add a test helper to compute hash speed
  sha1-file: add a constant for hash block size
  t: make the sha1 test-tool helper generic
  t: add basic tests for our SHA-1 implementation
  cache: make hashcmp and hasheq work with larger hashes
  hex: introduce functions to print arbitrary hashes
  sha1-file: provide functions to look up hash algorithms
  sha1-file: rename algorithm to "sha1"
This commit is contained in:
Junio C Hamano
2019-01-29 12:47:55 -08:00
parent 5d3635db19 4b4e291809
commit 33e4ae9c50
16 changed files with 643 additions and 95 deletions
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51
cache.h
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@ -45,10 +45,20 @@ unsigned long git_deflate_bound(git_zstream *, unsigned long);
/* The length in bytes and in hex digits of an object name (SHA-1 value). */
#define GIT_SHA1_RAWSZ 20
#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
/* The block size of SHA-1. */
#define GIT_SHA1_BLKSZ 64
/* The length in bytes and in hex digits of an object name (SHA-256 value). */
#define GIT_SHA256_RAWSZ 32
#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
/* The block size of SHA-256. */
#define GIT_SHA256_BLKSZ 64
/* The length in byte and in hex digits of the largest possible hash value. */
#define GIT_MAX_RAWSZ GIT_SHA1_RAWSZ
#define GIT_MAX_HEXSZ GIT_SHA1_HEXSZ
#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ
#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ
/* The largest possible block size for any supported hash. */
#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ
struct object_id {
unsigned char hash[GIT_MAX_RAWSZ];
@ -1028,16 +1038,12 @@ extern const struct object_id null_oid;
static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
{
/*
* This is a temporary optimization hack. By asserting the size here,
* we let the compiler know that it's always going to be 20, which lets
* it turn this fixed-size memcmp into a few inline instructions.
*
* This will need to be extended or ripped out when we learn about
* hashes of different sizes.
* Teach the compiler that there are only two possibilities of hash size
* here, so that it can optimize for this case as much as possible.
*/
if (the_hash_algo->rawsz != 20)
BUG("hash size not yet supported by hashcmp");
return memcmp(sha1, sha2, the_hash_algo->rawsz);
if (the_hash_algo->rawsz == GIT_MAX_RAWSZ)
return memcmp(sha1, sha2, GIT_MAX_RAWSZ);
return memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
}
static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
@ -1047,7 +1053,13 @@ static inline int oidcmp(const struct object_id *oid1, const struct object_id *o
static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)
{
return !hashcmp(sha1, sha2);
/*
* We write this here instead of deferring to hashcmp so that the
* compiler can properly inline it and avoid calling memcmp.
*/
if (the_hash_algo->rawsz == GIT_MAX_RAWSZ)
return !memcmp(sha1, sha2, GIT_MAX_RAWSZ);
return !memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
}
static inline int oideq(const struct object_id *oid1, const struct object_id *oid2)
@ -1365,9 +1377,9 @@ extern int get_oid_hex(const char *hex, struct object_id *sha1);
extern int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
/*
* Convert a binary sha1 to its hex equivalent. The `_r` variant is reentrant,
* Convert a binary hash to its hex equivalent. The `_r` variant is reentrant,
* and writes the NUL-terminated output to the buffer `out`, which must be at
* least `GIT_SHA1_HEXSZ + 1` bytes, and returns a pointer to out for
* least `GIT_MAX_HEXSZ + 1` bytes, and returns a pointer to out for
* convenience.
*
* The non-`_r` variant returns a static buffer, but uses a ring of 4
@ -1375,10 +1387,13 @@ extern int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
*
* printf("%s -> %s", sha1_to_hex(one), sha1_to_hex(two));
*/
extern char *sha1_to_hex_r(char *out, const unsigned char *sha1);
extern char *oid_to_hex_r(char *out, const struct object_id *oid);
extern char *sha1_to_hex(const unsigned char *sha1); /* static buffer result! */
extern char *oid_to_hex(const struct object_id *oid); /* same static buffer as sha1_to_hex */
char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash, const struct git_hash_algo *);
char *sha1_to_hex_r(char *out, const unsigned char *sha1);
char *oid_to_hex_r(char *out, const struct object_id *oid);
char *hash_to_hex_algop(const unsigned char *hash, const struct git_hash_algo *); /* static buffer result! */
char *sha1_to_hex(const unsigned char *sha1); /* same static buffer */
char *hash_to_hex(const unsigned char *hash); /* same static buffer */
char *oid_to_hex(const struct object_id *oid); /* same static buffer */
/*
* Parse a 40-character hexadecimal object ID starting from hex, updating the