The fifteenth batch
[git.git] / hash.h
blob9e25c40e9accf514ea42a1b445f86551f7a46aa3
1 #ifndef HASH_H
2 #define HASH_H
4 #include "git-compat-util.h"
5 #include "repository.h"
7 #if defined(SHA1_PPC)
8 #include "ppc/sha1.h"
9 #elif defined(SHA1_APPLE)
10 #include <CommonCrypto/CommonDigest.h>
11 #elif defined(SHA1_OPENSSL)
12 #include <openssl/sha.h>
13 #elif defined(SHA1_DC)
14 #include "sha1dc_git.h"
15 #else /* SHA1_BLK */
16 #include "block-sha1/sha1.h"
17 #endif
19 #if defined(SHA256_GCRYPT)
20 #define SHA256_NEEDS_CLONE_HELPER
21 #include "sha256/gcrypt.h"
22 #elif defined(SHA256_OPENSSL)
23 #include <openssl/sha.h>
24 #else
25 #include "sha256/block/sha256.h"
26 #endif
28 #ifndef platform_SHA_CTX
30 * platform's underlying implementation of SHA-1; could be OpenSSL,
31 * blk_SHA, Apple CommonCrypto, etc... Note that the relevant
32 * SHA-1 header may have already defined platform_SHA_CTX for our
33 * own implementations like block-sha1 and ppc-sha1, so we list
34 * the default for OpenSSL compatible SHA-1 implementations here.
36 #define platform_SHA_CTX SHA_CTX
37 #define platform_SHA1_Init SHA1_Init
38 #define platform_SHA1_Update SHA1_Update
39 #define platform_SHA1_Final SHA1_Final
40 #endif
42 #define git_SHA_CTX platform_SHA_CTX
43 #define git_SHA1_Init platform_SHA1_Init
44 #define git_SHA1_Update platform_SHA1_Update
45 #define git_SHA1_Final platform_SHA1_Final
47 #ifndef platform_SHA256_CTX
48 #define platform_SHA256_CTX SHA256_CTX
49 #define platform_SHA256_Init SHA256_Init
50 #define platform_SHA256_Update SHA256_Update
51 #define platform_SHA256_Final SHA256_Final
52 #endif
54 #define git_SHA256_CTX platform_SHA256_CTX
55 #define git_SHA256_Init platform_SHA256_Init
56 #define git_SHA256_Update platform_SHA256_Update
57 #define git_SHA256_Final platform_SHA256_Final
59 #ifdef platform_SHA256_Clone
60 #define git_SHA256_Clone platform_SHA256_Clone
61 #endif
63 #ifdef SHA1_MAX_BLOCK_SIZE
64 #include "compat/sha1-chunked.h"
65 #undef git_SHA1_Update
66 #define git_SHA1_Update git_SHA1_Update_Chunked
67 #endif
69 static inline void git_SHA1_Clone(git_SHA_CTX *dst, const git_SHA_CTX *src)
71 memcpy(dst, src, sizeof(*dst));
74 #ifndef SHA256_NEEDS_CLONE_HELPER
75 static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *src)
77 memcpy(dst, src, sizeof(*dst));
79 #endif
82 * Note that these constants are suitable for indexing the hash_algos array and
83 * comparing against each other, but are otherwise arbitrary, so they should not
84 * be exposed to the user or serialized to disk. To know whether a
85 * git_hash_algo struct points to some usable hash function, test the format_id
86 * field for being non-zero. Use the name field for user-visible situations and
87 * the format_id field for fixed-length fields on disk.
89 /* An unknown hash function. */
90 #define GIT_HASH_UNKNOWN 0
91 /* SHA-1 */
92 #define GIT_HASH_SHA1 1
93 /* SHA-256 */
94 #define GIT_HASH_SHA256 2
95 /* Number of algorithms supported (including unknown). */
96 #define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
98 /* The length in bytes and in hex digits of an object name (SHA-1 value). */
99 #define GIT_SHA1_RAWSZ 20
100 #define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
101 /* The block size of SHA-1. */
102 #define GIT_SHA1_BLKSZ 64
104 /* The length in bytes and in hex digits of an object name (SHA-256 value). */
105 #define GIT_SHA256_RAWSZ 32
106 #define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
107 /* The block size of SHA-256. */
108 #define GIT_SHA256_BLKSZ 64
110 /* The length in byte and in hex digits of the largest possible hash value. */
111 #define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ
112 #define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ
113 /* The largest possible block size for any supported hash. */
114 #define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ
116 struct object_id {
117 unsigned char hash[GIT_MAX_RAWSZ];
118 int algo; /* XXX requires 4-byte alignment */
121 /* A suitably aligned type for stack allocations of hash contexts. */
122 union git_hash_ctx {
123 git_SHA_CTX sha1;
124 git_SHA256_CTX sha256;
126 typedef union git_hash_ctx git_hash_ctx;
128 typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
129 typedef void (*git_hash_clone_fn)(git_hash_ctx *dst, const git_hash_ctx *src);
130 typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
131 typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
132 typedef void (*git_hash_final_oid_fn)(struct object_id *oid, git_hash_ctx *ctx);
134 struct git_hash_algo {
136 * The name of the algorithm, as appears in the config file and in
137 * messages.
139 const char *name;
141 /* A four-byte version identifier, used in pack indices. */
142 uint32_t format_id;
144 /* The length of the hash in binary. */
145 size_t rawsz;
147 /* The length of the hash in hex characters. */
148 size_t hexsz;
150 /* The block size of the hash. */
151 size_t blksz;
153 /* The hash initialization function. */
154 git_hash_init_fn init_fn;
156 /* The hash context cloning function. */
157 git_hash_clone_fn clone_fn;
159 /* The hash update function. */
160 git_hash_update_fn update_fn;
162 /* The hash finalization function. */
163 git_hash_final_fn final_fn;
165 /* The hash finalization function for object IDs. */
166 git_hash_final_oid_fn final_oid_fn;
168 /* The OID of the empty tree. */
169 const struct object_id *empty_tree;
171 /* The OID of the empty blob. */
172 const struct object_id *empty_blob;
174 /* The all-zeros OID. */
175 const struct object_id *null_oid;
177 extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
180 * Return a GIT_HASH_* constant based on the name. Returns GIT_HASH_UNKNOWN if
181 * the name doesn't match a known algorithm.
183 int hash_algo_by_name(const char *name);
184 /* Identical, except based on the format ID. */
185 int hash_algo_by_id(uint32_t format_id);
186 /* Identical, except based on the length. */
187 int hash_algo_by_length(int len);
188 /* Identical, except for a pointer to struct git_hash_algo. */
189 static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
191 return p - hash_algos;
194 #define the_hash_algo the_repository->hash_algo
196 const struct object_id *null_oid(void);
198 static inline int hashcmp_algop(const unsigned char *sha1, const unsigned char *sha2, const struct git_hash_algo *algop)
201 * Teach the compiler that there are only two possibilities of hash size
202 * here, so that it can optimize for this case as much as possible.
204 if (algop->rawsz == GIT_MAX_RAWSZ)
205 return memcmp(sha1, sha2, GIT_MAX_RAWSZ);
206 return memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
209 static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
211 return hashcmp_algop(sha1, sha2, the_hash_algo);
214 static inline int oidcmp(const struct object_id *oid1, const struct object_id *oid2)
216 const struct git_hash_algo *algop;
217 if (!oid1->algo)
218 algop = the_hash_algo;
219 else
220 algop = &hash_algos[oid1->algo];
221 return hashcmp_algop(oid1->hash, oid2->hash, algop);
224 static inline int hasheq_algop(const unsigned char *sha1, const unsigned char *sha2, const struct git_hash_algo *algop)
227 * We write this here instead of deferring to hashcmp so that the
228 * compiler can properly inline it and avoid calling memcmp.
230 if (algop->rawsz == GIT_MAX_RAWSZ)
231 return !memcmp(sha1, sha2, GIT_MAX_RAWSZ);
232 return !memcmp(sha1, sha2, GIT_SHA1_RAWSZ);
235 static inline int hasheq(const unsigned char *sha1, const unsigned char *sha2)
237 return hasheq_algop(sha1, sha2, the_hash_algo);
240 static inline int oideq(const struct object_id *oid1, const struct object_id *oid2)
242 const struct git_hash_algo *algop;
243 if (!oid1->algo)
244 algop = the_hash_algo;
245 else
246 algop = &hash_algos[oid1->algo];
247 return hasheq_algop(oid1->hash, oid2->hash, algop);
250 static inline int is_null_oid(const struct object_id *oid)
252 return oideq(oid, null_oid());
255 static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src)
257 memcpy(sha_dst, sha_src, the_hash_algo->rawsz);
260 static inline void oidcpy(struct object_id *dst, const struct object_id *src)
262 memcpy(dst->hash, src->hash, GIT_MAX_RAWSZ);
263 dst->algo = src->algo;
266 /* Like oidcpy() but zero-pads the unused bytes in dst's hash array. */
267 static inline void oidcpy_with_padding(struct object_id *dst,
268 const struct object_id *src)
270 size_t hashsz;
272 if (!src->algo)
273 hashsz = the_hash_algo->rawsz;
274 else
275 hashsz = hash_algos[src->algo].rawsz;
277 memcpy(dst->hash, src->hash, hashsz);
278 memset(dst->hash + hashsz, 0, GIT_MAX_RAWSZ - hashsz);
279 dst->algo = src->algo;
282 static inline struct object_id *oiddup(const struct object_id *src)
284 struct object_id *dst = xmalloc(sizeof(struct object_id));
285 oidcpy(dst, src);
286 return dst;
289 static inline void hashclr(unsigned char *hash)
291 memset(hash, 0, the_hash_algo->rawsz);
294 static inline void oidclr(struct object_id *oid)
296 memset(oid->hash, 0, GIT_MAX_RAWSZ);
297 oid->algo = hash_algo_by_ptr(the_hash_algo);
300 static inline void oidread(struct object_id *oid, const unsigned char *hash)
302 memcpy(oid->hash, hash, the_hash_algo->rawsz);
303 oid->algo = hash_algo_by_ptr(the_hash_algo);
306 static inline int is_empty_blob_sha1(const unsigned char *sha1)
308 return hasheq(sha1, the_hash_algo->empty_blob->hash);
311 static inline int is_empty_blob_oid(const struct object_id *oid)
313 return oideq(oid, the_hash_algo->empty_blob);
316 static inline int is_empty_tree_sha1(const unsigned char *sha1)
318 return hasheq(sha1, the_hash_algo->empty_tree->hash);
321 static inline int is_empty_tree_oid(const struct object_id *oid)
323 return oideq(oid, the_hash_algo->empty_tree);
326 static inline void oid_set_algo(struct object_id *oid, const struct git_hash_algo *algop)
328 oid->algo = hash_algo_by_ptr(algop);
331 const char *empty_tree_oid_hex(void);
332 const char *empty_blob_oid_hex(void);
334 #endif