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git/hash-ll.h

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#ifndef HASH_LL_H
#define HASH_LL_H
#if defined(SHA1_APPLE)
#include <CommonCrypto/CommonDigest.h>
#elif defined(SHA1_OPENSSL)
# include <openssl/sha.h>
# if defined(OPENSSL_API_LEVEL) && OPENSSL_API_LEVEL >= 3
# define SHA1_NEEDS_CLONE_HELPER
# include "sha1/openssl.h"
# endif
#elif defined(SHA1_DC)
#include "sha1dc_git.h"
#else /* SHA1_BLK */
#include "block-sha1/sha1.h"
#endif
#if defined(SHA256_NETTLE)
#include "sha256/nettle.h"
#elif defined(SHA256_GCRYPT)
#define SHA256_NEEDS_CLONE_HELPER
#include "sha256/gcrypt.h"
#elif defined(SHA256_OPENSSL)
# include <openssl/sha.h>
# if defined(OPENSSL_API_LEVEL) && OPENSSL_API_LEVEL >= 3
# define SHA256_NEEDS_CLONE_HELPER
# include "sha256/openssl.h"
# endif
#else
#include "sha256/block/sha256.h"
#endif
#ifndef platform_SHA_CTX
/*
* platform's underlying implementation of SHA-1; could be OpenSSL,
* blk_SHA, Apple CommonCrypto, etc... Note that the relevant
* SHA-1 header may have already defined platform_SHA_CTX for our
* own implementations like block-sha1, so we list
* the default for OpenSSL compatible SHA-1 implementations here.
*/
#define platform_SHA_CTX SHA_CTX
#define platform_SHA1_Init SHA1_Init
#define platform_SHA1_Update SHA1_Update
#define platform_SHA1_Final SHA1_Final
#endif
#define git_SHA_CTX platform_SHA_CTX
#define git_SHA1_Init platform_SHA1_Init
#define git_SHA1_Update platform_SHA1_Update
#define git_SHA1_Final platform_SHA1_Final
#ifdef platform_SHA1_Clone
#define git_SHA1_Clone platform_SHA1_Clone
#endif
#ifndef platform_SHA256_CTX
#define platform_SHA256_CTX SHA256_CTX
#define platform_SHA256_Init SHA256_Init
#define platform_SHA256_Update SHA256_Update
#define platform_SHA256_Final SHA256_Final
#endif
#define git_SHA256_CTX platform_SHA256_CTX
#define git_SHA256_Init platform_SHA256_Init
#define git_SHA256_Update platform_SHA256_Update
#define git_SHA256_Final platform_SHA256_Final
#ifdef platform_SHA256_Clone
#define git_SHA256_Clone platform_SHA256_Clone
#endif
#ifdef SHA1_MAX_BLOCK_SIZE
#include "compat/sha1-chunked.h"
#undef git_SHA1_Update
#define git_SHA1_Update git_SHA1_Update_Chunked
#endif
#ifndef SHA1_NEEDS_CLONE_HELPER
static inline void git_SHA1_Clone(git_SHA_CTX *dst, const git_SHA_CTX *src)
{
memcpy(dst, src, sizeof(*dst));
}
#endif
#ifndef SHA256_NEEDS_CLONE_HELPER
static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *src)
{
memcpy(dst, src, sizeof(*dst));
}
#endif
/*
* Note that these constants are suitable for indexing the hash_algos array and
* comparing against each other, but are otherwise arbitrary, so they should not
* be exposed to the user or serialized to disk. To know whether a
* git_hash_algo struct points to some usable hash function, test the format_id
* field for being non-zero. Use the name field for user-visible situations and
* the format_id field for fixed-length fields on disk.
*/
/* An unknown hash function. */
#define GIT_HASH_UNKNOWN 0
/* SHA-1 */
#define GIT_HASH_SHA1 1
/* SHA-256 */
#define GIT_HASH_SHA256 2
/* Number of algorithms supported (including unknown). */
#define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
/* "sha1", big-endian */
#define GIT_SHA1_FORMAT_ID 0x73686131
/* 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
/* "s256", big-endian */
#define GIT_SHA256_FORMAT_ID 0x73323536
/* 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_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];
int algo; /* XXX requires 4-byte alignment */
};
#define GET_OID_QUIETLY 01
#define GET_OID_COMMIT 02
#define GET_OID_COMMITTISH 04
#define GET_OID_TREE 010
#define GET_OID_TREEISH 020
#define GET_OID_BLOB 040
#define GET_OID_FOLLOW_SYMLINKS 0100
#define GET_OID_RECORD_PATH 0200
#define GET_OID_ONLY_TO_DIE 04000
#define GET_OID_REQUIRE_PATH 010000
#define GET_OID_DISAMBIGUATORS \
(GET_OID_COMMIT | GET_OID_COMMITTISH | \
GET_OID_TREE | GET_OID_TREEISH | \
GET_OID_BLOB)
enum get_oid_result {
FOUND = 0,
MISSING_OBJECT = -1, /* The requested object is missing */
SHORT_NAME_AMBIGUOUS = -2,
/* The following only apply when symlinks are followed */
DANGLING_SYMLINK = -4, /*
* The initial symlink is there, but
* (transitively) points to a missing
* in-tree file
*/
SYMLINK_LOOP = -5,
NOT_DIR = -6, /*
* Somewhere along the symlink chain, a path is
* requested which contains a file as a
* non-final element.
*/
};
/* A suitably aligned type for stack allocations of hash contexts. */
union git_hash_ctx {
git_SHA_CTX sha1;
git_SHA256_CTX sha256;
};
typedef union git_hash_ctx git_hash_ctx;
typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
typedef void (*git_hash_clone_fn)(git_hash_ctx *dst, const git_hash_ctx *src);
typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
typedef void (*git_hash_final_oid_fn)(struct object_id *oid, git_hash_ctx *ctx);
struct git_hash_algo {
/*
* The name of the algorithm, as appears in the config file and in
* messages.
*/
const char *name;
/* A four-byte version identifier, used in pack indices. */
uint32_t format_id;
/* The length of the hash in binary. */
size_t rawsz;
/* The length of the hash in hex characters. */
size_t hexsz;
/* The block size of the hash. */
size_t blksz;
/* The hash initialization function. */
git_hash_init_fn init_fn;
/* The hash context cloning function. */
git_hash_clone_fn clone_fn;
/* The hash update function. */
git_hash_update_fn update_fn;
/* The hash finalization function. */
git_hash_final_fn final_fn;
/* The hash finalization function for object IDs. */
git_hash_final_oid_fn final_oid_fn;
/* The OID of the empty tree. */
const struct object_id *empty_tree;
/* The OID of the empty blob. */
const struct object_id *empty_blob;
/* The all-zeros OID. */
const struct object_id *null_oid;
};
extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
/*
* Return a GIT_HASH_* constant based on the name. Returns GIT_HASH_UNKNOWN if
* the name doesn't match a known algorithm.
*/
int hash_algo_by_name(const char *name);
/* Identical, except based on the format ID. */
int hash_algo_by_id(uint32_t format_id);
/* Identical, except based on the length. */
int hash_algo_by_length(int len);
/* Identical, except for a pointer to struct git_hash_algo. */
static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
{
return p - hash_algos;
}
const struct object_id *null_oid(void);
static inline int hashcmp_algop(const unsigned char *sha1, const unsigned char *sha2, const struct git_hash_algo *algop)
{
/*
* 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 (algop->rawsz == GIT_MAX_RAWSZ)
return memcmp(sha1, sha2, GIT_MAX_RAWSZ);
return memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
}
static inline int hasheq_algop(const unsigned char *sha1, const unsigned char *sha2, const struct git_hash_algo *algop)
{
/*
* We write this here instead of deferring to hashcmp so that the
* compiler can properly inline it and avoid calling memcmp.
*/
if (algop->rawsz == GIT_MAX_RAWSZ)
return !memcmp(sha1, sha2, GIT_MAX_RAWSZ);
return !memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
}
static inline void oidcpy(struct object_id *dst, const struct object_id *src)
{
memcpy(dst->hash, src->hash, GIT_MAX_RAWSZ);
dst->algo = src->algo;
}
static inline struct object_id *oiddup(const struct object_id *src)
{
struct object_id *dst = xmalloc(sizeof(struct object_id));
oidcpy(dst, src);
return dst;
}
static inline void oid_set_algo(struct object_id *oid, const struct git_hash_algo *algop)
{
oid->algo = hash_algo_by_ptr(algop);
}
/*
* Converts a cryptographic hash (e.g. SHA-1) into an int-sized hash code
* for use in hash tables. Cryptographic hashes are supposed to have
* uniform distribution, so in contrast to `memhash()`, this just copies
* the first `sizeof(int)` bytes without shuffling any bits. Note that
* the results will be different on big-endian and little-endian
* platforms, so they should not be stored or transferred over the net.
*/
static inline unsigned int oidhash(const struct object_id *oid)
{
/*
* Equivalent to 'return *(unsigned int *)oid->hash;', but safe on
* platforms that don't support unaligned reads.
*/
unsigned int hash;
memcpy(&hash, oid->hash, sizeof(hash));
return hash;
}
const char *empty_tree_oid_hex(void);
const char *empty_blob_oid_hex(void);
#endif
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