[thirdparty/git.git] / hash.h

#ifndef HASH_H
#define HASH_H

#if defined(SHA1_APPLE)
#define SHA1_BACKEND "SHA1_APPLE (No collision detection)"
#include <CommonCrypto/CommonDigest.h>
#elif defined(SHA1_OPENSSL)
#  define SHA1_BACKEND "SHA1_OPENSSL (No collision detection)"
#  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)
#define SHA1_BACKEND "SHA1_DC"
#include "sha1dc_git.h"
#else /* SHA1_BLK */
#define SHA1_BACKEND "SHA1_BLK (No collision detection)"
#include "block-sha1/sha1.h"
#endif

#if defined(SHA1_APPLE_UNSAFE)
#  define SHA1_UNSAFE_BACKEND "SHA1_APPLE_UNSAFE"
#  include <CommonCrypto/CommonDigest.h>
#  define platform_SHA_CTX_unsafe CC_SHA1_CTX
#  define platform_SHA1_Init_unsafe CC_SHA1_Init
#  define platform_SHA1_Update_unsafe CC_SHA1_Update
#  define platform_SHA1_Final_unsafe CC_SHA1_Final
#elif defined(SHA1_OPENSSL_UNSAFE)
#  define SHA1_UNSAFE_BACKEND "SHA1_OPENSSL_UNSAFE"
#  include <openssl/sha.h>
#  if defined(OPENSSL_API_LEVEL) && OPENSSL_API_LEVEL >= 3
#    define SHA1_NEEDS_CLONE_HELPER_UNSAFE
#    include "sha1/openssl.h"
#    define platform_SHA_CTX_unsafe openssl_SHA1_CTX
#    define platform_SHA1_Init_unsafe openssl_SHA1_Init
#    define platform_SHA1_Clone_unsafe openssl_SHA1_Clone
#    define platform_SHA1_Update_unsafe openssl_SHA1_Update
#    define platform_SHA1_Final_unsafe openssl_SHA1_Final
#  else
#    define platform_SHA_CTX_unsafe SHA_CTX
#    define platform_SHA1_Init_unsafe SHA1_Init
#    define platform_SHA1_Update_unsafe SHA1_Update
#    define platform_SHA1_Final_unsafe SHA1_Final
#  endif
#elif defined(SHA1_BLK_UNSAFE)
#  define SHA1_UNSAFE_BACKEND "SHA1_BLK_UNSAFE"
#  include "block-sha1/sha1.h"
#  define platform_SHA_CTX_unsafe blk_SHA_CTX
#  define platform_SHA1_Init_unsafe blk_SHA1_Init
#  define platform_SHA1_Update_unsafe blk_SHA1_Update
#  define platform_SHA1_Final_unsafe blk_SHA1_Final
#endif

#if defined(SHA256_NETTLE)
#define SHA256_BACKEND "SHA256_NETTLE"
#include "sha256/nettle.h"
#elif defined(SHA256_GCRYPT)
#define SHA256_BACKEND "SHA256_GCRYPT"
#define SHA256_NEEDS_CLONE_HELPER
#include "sha256/gcrypt.h"
#elif defined(SHA256_OPENSSL)
#  define SHA256_BACKEND "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
#define SHA256_BACKEND "SHA256_BLK"
#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

#ifndef platform_SHA_CTX_unsafe
#  define platform_SHA_CTX_unsafe      platform_SHA_CTX
#  define platform_SHA1_Init_unsafe    platform_SHA1_Init
#  define platform_SHA1_Update_unsafe  platform_SHA1_Update
#  define platform_SHA1_Final_unsafe   platform_SHA1_Final
#  ifdef platform_SHA1_Clone
#    define platform_SHA1_Clone_unsafe platform_SHA1_Clone
#  endif
#  ifdef SHA1_NEEDS_CLONE_HELPER
#    define SHA1_NEEDS_CLONE_HELPER_UNSAFE
#  endif
#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

#define git_SHA_CTX_unsafe	platform_SHA_CTX_unsafe
#define git_SHA1_Init_unsafe	platform_SHA1_Init_unsafe
#define git_SHA1_Update_unsafe	platform_SHA1_Update_unsafe
#define git_SHA1_Final_unsafe	platform_SHA1_Final_unsafe

#ifdef platform_SHA1_Clone
#define git_SHA1_Clone	platform_SHA1_Clone
#endif
#ifdef platform_SHA1_Clone_unsafe
#  define git_SHA1_Clone_unsafe platform_SHA1_Clone_unsafe
#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 SHA1_NEEDS_CLONE_HELPER_UNSAFE
static inline void git_SHA1_Clone_unsafe(git_SHA_CTX_unsafe *dst,
				       const git_SHA_CTX_unsafe *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_HASH_ANY             020000
#define GET_OID_SKIP_AMBIGUITY_CHECK 040000
#define GET_OID_GENTLY              0100000

#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.
		       */
};

#ifdef USE_THE_REPOSITORY_VARIABLE
# include "repository.h"
# define the_hash_algo the_repository->hash_algo
#endif

/* A suitably aligned type for stack allocations of hash contexts. */
struct git_hash_ctx {
	const struct git_hash_algo *algop;
	union {
		git_SHA_CTX sha1;
		git_SHA_CTX_unsafe sha1_unsafe;
		git_SHA256_CTX sha256;
	} state;
};

typedef void (*git_hash_init_fn)(struct git_hash_ctx *ctx);
typedef void (*git_hash_clone_fn)(struct git_hash_ctx *dst, const struct git_hash_ctx *src);
typedef void (*git_hash_update_fn)(struct git_hash_ctx *ctx, const void *in, size_t len);
typedef void (*git_hash_final_fn)(unsigned char *hash, struct git_hash_ctx *ctx);
typedef void (*git_hash_final_oid_fn)(struct object_id *oid, struct 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;

	/* The unsafe variant of this hash function, if one exists. */
	const struct git_hash_algo *unsafe;
};
extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];

static inline void git_hash_clone(struct git_hash_ctx *dst, const struct git_hash_ctx *src)
{
	src->algop->clone_fn(dst, src);
}

static inline void git_hash_update(struct git_hash_ctx *ctx, const void *in, size_t len)
{
	ctx->algop->update_fn(ctx, in, len);
}

static inline void git_hash_final(unsigned char *hash, struct git_hash_ctx *ctx)
{
	ctx->algop->final_fn(hash, ctx);
}

static inline void git_hash_final_oid(struct object_id *oid, struct git_hash_ctx *ctx)
{
	ctx->algop->final_oid_fn(oid, ctx);
}

/*
 * 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(size_t len);
/* Identical, except for a pointer to struct git_hash_algo. */
static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
{
	size_t i;
	for (i = 0; i < GIT_HASH_NALGOS; i++) {
		const struct git_hash_algo *algop = &hash_algos[i];
		if (p == algop)
			return i;
	}
	return GIT_HASH_UNKNOWN;
}

const struct git_hash_algo *unsafe_hash_algo(const struct git_hash_algo *algop);

const struct object_id *null_oid(const struct git_hash_algo *algop);

static inline int hashcmp(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(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 hashcpy(unsigned char *sha_dst, const unsigned char *sha_src,
			   const struct git_hash_algo *algop)
{
	memcpy(sha_dst, sha_src, algop->rawsz);
}

static inline void hashclr(unsigned char *hash, const struct git_hash_algo *algop)
{
	memset(hash, 0, algop->rawsz);
}

static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
{
	return memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);
}

static inline int oideq(const struct object_id *oid1, const struct object_id *oid2)
{
	return !memcmp(oid1->hash, oid2->hash, GIT_MAX_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 void oidread(struct object_id *oid, const unsigned char *hash,
			   const struct git_hash_algo *algop)
{
	memcpy(oid->hash, hash, algop->rawsz);
	if (algop->rawsz < GIT_MAX_RAWSZ)
		memset(oid->hash + algop->rawsz, 0, GIT_MAX_RAWSZ - algop->rawsz);
	oid->algo = hash_algo_by_ptr(algop);
}

static inline void oidclr(struct object_id *oid,
			  const struct git_hash_algo *algop)
{
	memset(oid->hash, 0, GIT_MAX_RAWSZ);
	oid->algo = hash_algo_by_ptr(algop);
}

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;
}

static inline int is_null_oid(const struct object_id *oid)
{
	static const unsigned char null_hash[GIT_MAX_RAWSZ];
	return !memcmp(oid->hash, null_hash, GIT_MAX_RAWSZ);
}

const char *empty_tree_oid_hex(const struct git_hash_algo *algop);

static inline int is_empty_blob_oid(const struct object_id *oid,
				    const struct git_hash_algo *algop)
{
	return oideq(oid, algop->empty_blob);
}

static inline int is_empty_tree_oid(const struct object_id *oid,
				    const struct git_hash_algo *algop)
{
	return oideq(oid, algop->empty_tree);
}

#endif
Commit	Line	Data
	1	#ifndef HASH_H
	2	#define HASH_H
	3
	4	#if defined(SHA1_APPLE)
	5	#define SHA1_BACKEND "SHA1_APPLE (No collision detection)"
	6	#include <CommonCrypto/CommonDigest.h>
	7	#elif defined(SHA1_OPENSSL)
	8	# define SHA1_BACKEND "SHA1_OPENSSL (No collision detection)"
	9	# include <openssl/sha.h>
	10	# if defined(OPENSSL_API_LEVEL) && OPENSSL_API_LEVEL >= 3
	11	# define SHA1_NEEDS_CLONE_HELPER
	12	# include "sha1/openssl.h"
	13	# endif
	14	#elif defined(SHA1_DC)
	15	#define SHA1_BACKEND "SHA1_DC"
	16	#include "sha1dc_git.h"
	17	#else /* SHA1_BLK */
	18	#define SHA1_BACKEND "SHA1_BLK (No collision detection)"
	19	#include "block-sha1/sha1.h"
	20	#endif
	21
	22	#if defined(SHA1_APPLE_UNSAFE)
	23	# define SHA1_UNSAFE_BACKEND "SHA1_APPLE_UNSAFE"
	24	# include <CommonCrypto/CommonDigest.h>
	25	# define platform_SHA_CTX_unsafe CC_SHA1_CTX
	26	# define platform_SHA1_Init_unsafe CC_SHA1_Init
	27	# define platform_SHA1_Update_unsafe CC_SHA1_Update
	28	# define platform_SHA1_Final_unsafe CC_SHA1_Final
	29	#elif defined(SHA1_OPENSSL_UNSAFE)
	30	# define SHA1_UNSAFE_BACKEND "SHA1_OPENSSL_UNSAFE"
	31	# include <openssl/sha.h>
	32	# if defined(OPENSSL_API_LEVEL) && OPENSSL_API_LEVEL >= 3
	33	# define SHA1_NEEDS_CLONE_HELPER_UNSAFE
	34	# include "sha1/openssl.h"
	35	# define platform_SHA_CTX_unsafe openssl_SHA1_CTX
	36	# define platform_SHA1_Init_unsafe openssl_SHA1_Init
	37	# define platform_SHA1_Clone_unsafe openssl_SHA1_Clone
	38	# define platform_SHA1_Update_unsafe openssl_SHA1_Update
	39	# define platform_SHA1_Final_unsafe openssl_SHA1_Final
	40	# else
	41	# define platform_SHA_CTX_unsafe SHA_CTX
	42	# define platform_SHA1_Init_unsafe SHA1_Init
	43	# define platform_SHA1_Update_unsafe SHA1_Update
	44	# define platform_SHA1_Final_unsafe SHA1_Final
	45	# endif
	46	#elif defined(SHA1_BLK_UNSAFE)
	47	# define SHA1_UNSAFE_BACKEND "SHA1_BLK_UNSAFE"
	48	# include "block-sha1/sha1.h"
	49	# define platform_SHA_CTX_unsafe blk_SHA_CTX
	50	# define platform_SHA1_Init_unsafe blk_SHA1_Init
	51	# define platform_SHA1_Update_unsafe blk_SHA1_Update
	52	# define platform_SHA1_Final_unsafe blk_SHA1_Final
	53	#endif
	54
	55	#if defined(SHA256_NETTLE)
	56	#define SHA256_BACKEND "SHA256_NETTLE"
	57	#include "sha256/nettle.h"
	58	#elif defined(SHA256_GCRYPT)
	59	#define SHA256_BACKEND "SHA256_GCRYPT"
	60	#define SHA256_NEEDS_CLONE_HELPER
	61	#include "sha256/gcrypt.h"
	62	#elif defined(SHA256_OPENSSL)
	63	# define SHA256_BACKEND "SHA256_OPENSSL"
	64	# include <openssl/sha.h>
	65	# if defined(OPENSSL_API_LEVEL) && OPENSSL_API_LEVEL >= 3
	66	# define SHA256_NEEDS_CLONE_HELPER
	67	# include "sha256/openssl.h"
	68	# endif
	69	#else
	70	#define SHA256_BACKEND "SHA256_BLK"
	71	#include "sha256/block/sha256.h"
	72	#endif
	73
	74	#ifndef platform_SHA_CTX
	75	/*
	76	* platform's underlying implementation of SHA-1; could be OpenSSL,
	77	* blk_SHA, Apple CommonCrypto, etc... Note that the relevant
	78	* SHA-1 header may have already defined platform_SHA_CTX for our
	79	* own implementations like block-sha1, so we list
	80	* the default for OpenSSL compatible SHA-1 implementations here.
	81	*/
	82	#define platform_SHA_CTX SHA_CTX
	83	#define platform_SHA1_Init SHA1_Init
	84	#define platform_SHA1_Update SHA1_Update
	85	#define platform_SHA1_Final SHA1_Final
	86	#endif
	87
	88	#ifndef platform_SHA_CTX_unsafe
	89	# define platform_SHA_CTX_unsafe platform_SHA_CTX
	90	# define platform_SHA1_Init_unsafe platform_SHA1_Init
	91	# define platform_SHA1_Update_unsafe platform_SHA1_Update
	92	# define platform_SHA1_Final_unsafe platform_SHA1_Final
	93	# ifdef platform_SHA1_Clone
	94	# define platform_SHA1_Clone_unsafe platform_SHA1_Clone
	95	# endif
	96	# ifdef SHA1_NEEDS_CLONE_HELPER
	97	# define SHA1_NEEDS_CLONE_HELPER_UNSAFE
	98	# endif
	99	#endif
	100
	101	#define git_SHA_CTX platform_SHA_CTX
	102	#define git_SHA1_Init platform_SHA1_Init
	103	#define git_SHA1_Update platform_SHA1_Update
	104	#define git_SHA1_Final platform_SHA1_Final
	105
	106	#define git_SHA_CTX_unsafe platform_SHA_CTX_unsafe
	107	#define git_SHA1_Init_unsafe platform_SHA1_Init_unsafe
	108	#define git_SHA1_Update_unsafe platform_SHA1_Update_unsafe
	109	#define git_SHA1_Final_unsafe platform_SHA1_Final_unsafe
	110
	111	#ifdef platform_SHA1_Clone
	112	#define git_SHA1_Clone platform_SHA1_Clone
	113	#endif
	114	#ifdef platform_SHA1_Clone_unsafe
	115	# define git_SHA1_Clone_unsafe platform_SHA1_Clone_unsafe
	116	#endif
	117
	118	#ifndef platform_SHA256_CTX
	119	#define platform_SHA256_CTX SHA256_CTX
	120	#define platform_SHA256_Init SHA256_Init
	121	#define platform_SHA256_Update SHA256_Update
	122	#define platform_SHA256_Final SHA256_Final
	123	#endif
	124
	125	#define git_SHA256_CTX platform_SHA256_CTX
	126	#define git_SHA256_Init platform_SHA256_Init
	127	#define git_SHA256_Update platform_SHA256_Update
	128	#define git_SHA256_Final platform_SHA256_Final
	129
	130	#ifdef platform_SHA256_Clone
	131	#define git_SHA256_Clone platform_SHA256_Clone
	132	#endif
	133
	134	#ifdef SHA1_MAX_BLOCK_SIZE
	135	#include "compat/sha1-chunked.h"
	136	#undef git_SHA1_Update
	137	#define git_SHA1_Update git_SHA1_Update_Chunked
	138	#endif
	139
	140	#ifndef SHA1_NEEDS_CLONE_HELPER
	141	static inline void git_SHA1_Clone(git_SHA_CTX dst, const git_SHA_CTX src)
	142	{
	143	memcpy(dst, src, sizeof(*dst));
	144	}
	145	#endif
	146	#ifndef SHA1_NEEDS_CLONE_HELPER_UNSAFE
	147	static inline void git_SHA1_Clone_unsafe(git_SHA_CTX_unsafe *dst,
	148	const git_SHA_CTX_unsafe *src)
	149	{
	150	memcpy(dst, src, sizeof(*dst));
	151	}
	152	#endif
	153
	154	#ifndef SHA256_NEEDS_CLONE_HELPER
	155	static inline void git_SHA256_Clone(git_SHA256_CTX dst, const git_SHA256_CTX src)
	156	{
	157	memcpy(dst, src, sizeof(*dst));
	158	}
	159	#endif
	160
	161	/*
	162	* Note that these constants are suitable for indexing the hash_algos array and
	163	* comparing against each other, but are otherwise arbitrary, so they should not
	164	* be exposed to the user or serialized to disk. To know whether a
	165	* git_hash_algo struct points to some usable hash function, test the format_id
	166	* field for being non-zero. Use the name field for user-visible situations and
	167	* the format_id field for fixed-length fields on disk.
	168	*/
	169	/* An unknown hash function. */
	170	#define GIT_HASH_UNKNOWN 0
	171	/* SHA-1 */
	172	#define GIT_HASH_SHA1 1
	173	/* SHA-256 */
	174	#define GIT_HASH_SHA256 2
	175	/* Number of algorithms supported (including unknown). */
	176	#define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
	177
	178	/* "sha1", big-endian */
	179	#define GIT_SHA1_FORMAT_ID 0x73686131
	180
	181	/* The length in bytes and in hex digits of an object name (SHA-1 value). */
	182	#define GIT_SHA1_RAWSZ 20
	183	#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
	184	/* The block size of SHA-1. */
	185	#define GIT_SHA1_BLKSZ 64
	186
	187	/* "s256", big-endian */
	188	#define GIT_SHA256_FORMAT_ID 0x73323536
	189
	190	/* The length in bytes and in hex digits of an object name (SHA-256 value). */
	191	#define GIT_SHA256_RAWSZ 32
	192	#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
	193	/* The block size of SHA-256. */
	194	#define GIT_SHA256_BLKSZ 64
	195
	196	/* The length in byte and in hex digits of the largest possible hash value. */
	197	#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ
	198	#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ
	199	/* The largest possible block size for any supported hash. */
	200	#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ
	201
	202	struct object_id {
	203	unsigned char hash[GIT_MAX_RAWSZ];
	204	int algo; /* XXX requires 4-byte alignment */
	205	};
	206
	207	#define GET_OID_QUIETLY 01
	208	#define GET_OID_COMMIT 02
	209	#define GET_OID_COMMITTISH 04
	210	#define GET_OID_TREE 010
	211	#define GET_OID_TREEISH 020
	212	#define GET_OID_BLOB 040
	213	#define GET_OID_FOLLOW_SYMLINKS 0100
	214	#define GET_OID_RECORD_PATH 0200
	215	#define GET_OID_ONLY_TO_DIE 04000
	216	#define GET_OID_REQUIRE_PATH 010000
	217	#define GET_OID_HASH_ANY 020000
	218	#define GET_OID_SKIP_AMBIGUITY_CHECK 040000
	219	#define GET_OID_GENTLY 0100000
	220
	221	#define GET_OID_DISAMBIGUATORS \
	222	(GET_OID_COMMIT \| GET_OID_COMMITTISH \| \
	223	GET_OID_TREE \| GET_OID_TREEISH \| \
	224	GET_OID_BLOB)
	225
	226	enum get_oid_result {
	227	FOUND = 0,
	228	MISSING_OBJECT = -1, /* The requested object is missing */
	229	SHORT_NAME_AMBIGUOUS = -2,
	230	/* The following only apply when symlinks are followed */
	231	DANGLING_SYMLINK = -4, /*
	232	* The initial symlink is there, but
	233	* (transitively) points to a missing
	234	* in-tree file
	235	*/
	236	SYMLINK_LOOP = -5,
	237	NOT_DIR = -6, /*
	238	* Somewhere along the symlink chain, a path is
	239	* requested which contains a file as a
	240	* non-final element.
	241	*/
	242	};
	243
	244	#ifdef USE_THE_REPOSITORY_VARIABLE
	245	# include "repository.h"
	246	# define the_hash_algo the_repository->hash_algo
	247	#endif
	248
	249	/* A suitably aligned type for stack allocations of hash contexts. */
	250	struct git_hash_ctx {
	251	const struct git_hash_algo *algop;
	252	union {
	253	git_SHA_CTX sha1;
	254	git_SHA_CTX_unsafe sha1_unsafe;
	255	git_SHA256_CTX sha256;
	256	} state;
	257	};
	258
	259	typedef void (git_hash_init_fn)(struct git_hash_ctx ctx);
	260	typedef void (git_hash_clone_fn)(struct git_hash_ctx dst, const struct git_hash_ctx *src);
	261	typedef void (git_hash_update_fn)(struct git_hash_ctx ctx, const void *in, size_t len);
	262	typedef void (git_hash_final_fn)(unsigned char hash, struct git_hash_ctx *ctx);
	263	typedef void (git_hash_final_oid_fn)(struct object_id oid, struct git_hash_ctx *ctx);
	264
	265	struct git_hash_algo {
	266	/*
	267	* The name of the algorithm, as appears in the config file and in
	268	* messages.
	269	*/
	270	const char *name;
	271
	272	/* A four-byte version identifier, used in pack indices. */
	273	uint32_t format_id;
	274
	275	/* The length of the hash in binary. */
	276	size_t rawsz;
	277
	278	/* The length of the hash in hex characters. */
	279	size_t hexsz;
	280
	281	/* The block size of the hash. */
	282	size_t blksz;
	283
	284	/* The hash initialization function. */
	285	git_hash_init_fn init_fn;
	286
	287	/* The hash context cloning function. */
	288	git_hash_clone_fn clone_fn;
	289
	290	/* The hash update function. */
	291	git_hash_update_fn update_fn;
	292
	293	/* The hash finalization function. */
	294	git_hash_final_fn final_fn;
	295
	296	/* The hash finalization function for object IDs. */
	297	git_hash_final_oid_fn final_oid_fn;
	298
	299	/* The OID of the empty tree. */
	300	const struct object_id *empty_tree;
	301
	302	/* The OID of the empty blob. */
	303	const struct object_id *empty_blob;
	304
	305	/* The all-zeros OID. */
	306	const struct object_id *null_oid;
	307
	308	/* The unsafe variant of this hash function, if one exists. */
	309	const struct git_hash_algo *unsafe;
	310	};
	311	extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
	312
	313	static inline void git_hash_clone(struct git_hash_ctx dst, const struct git_hash_ctx src)
	314	{
	315	src->algop->clone_fn(dst, src);
	316	}
	317
	318	static inline void git_hash_update(struct git_hash_ctx ctx, const void in, size_t len)
	319	{
	320	ctx->algop->update_fn(ctx, in, len);
	321	}
	322
	323	static inline void git_hash_final(unsigned char hash, struct git_hash_ctx ctx)
	324	{
	325	ctx->algop->final_fn(hash, ctx);
	326	}
	327
	328	static inline void git_hash_final_oid(struct object_id oid, struct git_hash_ctx ctx)
	329	{
	330	ctx->algop->final_oid_fn(oid, ctx);
	331	}
	332
	333	/*
	334	* Return a GIT_HASH_* constant based on the name. Returns GIT_HASH_UNKNOWN if
	335	* the name doesn't match a known algorithm.
	336	*/
	337	int hash_algo_by_name(const char *name);
	338	/* Identical, except based on the format ID. */
	339	int hash_algo_by_id(uint32_t format_id);
	340	/* Identical, except based on the length. */
	341	int hash_algo_by_length(size_t len);
	342	/* Identical, except for a pointer to struct git_hash_algo. */
	343	static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
	344	{
	345	size_t i;
	346	for (i = 0; i < GIT_HASH_NALGOS; i++) {
	347	const struct git_hash_algo *algop = &hash_algos[i];
	348	if (p == algop)
	349	return i;
	350	}
	351	return GIT_HASH_UNKNOWN;
	352	}
	353
	354	const struct git_hash_algo unsafe_hash_algo(const struct git_hash_algo algop);
	355
	356	const struct object_id null_oid(const struct git_hash_algo algop);
	357
	358	static inline int hashcmp(const unsigned char sha1, const unsigned char sha2, const struct git_hash_algo *algop)
	359	{
	360	/*
	361	* Teach the compiler that there are only two possibilities of hash size
	362	* here, so that it can optimize for this case as much as possible.
	363	*/
	364	if (algop->rawsz == GIT_MAX_RAWSZ)
	365	return memcmp(sha1, sha2, GIT_MAX_RAWSZ);
	366	return memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
	367	}
	368
	369	static inline int hasheq(const unsigned char sha1, const unsigned char sha2, const struct git_hash_algo *algop)
	370	{
	371	/*
	372	* We write this here instead of deferring to hashcmp so that the
	373	* compiler can properly inline it and avoid calling memcmp.
	374	*/
	375	if (algop->rawsz == GIT_MAX_RAWSZ)
	376	return !memcmp(sha1, sha2, GIT_MAX_RAWSZ);
	377	return !memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
	378	}
	379
	380	static inline void hashcpy(unsigned char sha_dst, const unsigned char sha_src,
	381	const struct git_hash_algo *algop)
	382	{
	383	memcpy(sha_dst, sha_src, algop->rawsz);
	384	}
	385
	386	static inline void hashclr(unsigned char hash, const struct git_hash_algo algop)
	387	{
	388	memset(hash, 0, algop->rawsz);
	389	}
	390
	391	static inline int oidcmp(const struct object_id oid1, const struct object_id oid2)
	392	{
	393	return memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);
	394	}
	395
	396	static inline int oideq(const struct object_id oid1, const struct object_id oid2)
	397	{
	398	return !memcmp(oid1->hash, oid2->hash, GIT_MAX_RAWSZ);
	399	}
	400
	401	static inline void oidcpy(struct object_id dst, const struct object_id src)
	402	{
	403	memcpy(dst->hash, src->hash, GIT_MAX_RAWSZ);
	404	dst->algo = src->algo;
	405	}
	406
	407	static inline void oidread(struct object_id oid, const unsigned char hash,
	408	const struct git_hash_algo *algop)
	409	{
	410	memcpy(oid->hash, hash, algop->rawsz);
	411	if (algop->rawsz < GIT_MAX_RAWSZ)
	412	memset(oid->hash + algop->rawsz, 0, GIT_MAX_RAWSZ - algop->rawsz);
	413	oid->algo = hash_algo_by_ptr(algop);
	414	}
	415
	416	static inline void oidclr(struct object_id *oid,
	417	const struct git_hash_algo *algop)
	418	{
	419	memset(oid->hash, 0, GIT_MAX_RAWSZ);
	420	oid->algo = hash_algo_by_ptr(algop);
	421	}
	422
	423	static inline struct object_id oiddup(const struct object_id src)
	424	{
	425	struct object_id *dst = xmalloc(sizeof(struct object_id));
	426	oidcpy(dst, src);
	427	return dst;
	428	}
	429
	430	static inline void oid_set_algo(struct object_id oid, const struct git_hash_algo algop)
	431	{
	432	oid->algo = hash_algo_by_ptr(algop);
	433	}
	434
	435	/*
	436	* Converts a cryptographic hash (e.g. SHA-1) into an int-sized hash code
	437	* for use in hash tables. Cryptographic hashes are supposed to have
	438	* uniform distribution, so in contrast to `memhash()`, this just copies
	439	* the first `sizeof(int)` bytes without shuffling any bits. Note that
	440	* the results will be different on big-endian and little-endian
	441	* platforms, so they should not be stored or transferred over the net.
	442	*/
	443	static inline unsigned int oidhash(const struct object_id *oid)
	444	{
	445	/*
	446	* Equivalent to 'return (unsigned int )oid->hash;', but safe on
	447	* platforms that don't support unaligned reads.
	448	*/
	449	unsigned int hash;
	450	memcpy(&hash, oid->hash, sizeof(hash));
	451	return hash;
	452	}
	453
	454	static inline int is_null_oid(const struct object_id *oid)
	455	{
	456	static const unsigned char null_hash[GIT_MAX_RAWSZ];
	457	return !memcmp(oid->hash, null_hash, GIT_MAX_RAWSZ);
	458	}
	459
	460	const char empty_tree_oid_hex(const struct git_hash_algo algop);
	461
	462	static inline int is_empty_blob_oid(const struct object_id *oid,
	463	const struct git_hash_algo *algop)
	464	{
	465	return oideq(oid, algop->empty_blob);
	466	}
	467
	468	static inline int is_empty_tree_oid(const struct object_id *oid,
	469	const struct git_hash_algo *algop)
	470	{
	471	return oideq(oid, algop->empty_tree);
	472	}
	473
	474	#endif