Imported Upstream version 2.17.1

[platform/upstream/git.git] / hash.h

diff --git a/hash.h b/hash.h
index b875ce6..7c8238b 100644 (file)
--- a/hash.h
+++ b/hash.h
@@ -1,43 +1,101 @@
 #ifndef HASH_H
 #define HASH_H
 
+#include "git-compat-util.h"
+
+#if defined(SHA1_PPC)
+#include "ppc/sha1.h"
+#elif defined(SHA1_APPLE)
+#include <CommonCrypto/CommonDigest.h>
+#elif defined(SHA1_OPENSSL)
+#include <openssl/sha.h>
+#elif defined(SHA1_DC)
+#include "sha1dc_git.h"
+#else /* SHA1_BLK */
+#include "block-sha1/sha1.h"
+#endif
+
+#ifndef platform_SHA_CTX
 /*
- * These are some simple generic hash table helper functions.
- * Not necessarily suitable for all users, but good for things
- * where you want to just keep track of a list of things, and
- * have a good hash to use on them.
- *
- * It keeps the hash table at roughly 50-75% free, so the memory
- * cost of the hash table itself is roughly
- *
- *     3 * 2*sizeof(void *) * nr_of_objects
- *
- * bytes.
- *
- * FIXME: on 64-bit architectures, we waste memory. It would be
- * good to have just 32-bit pointers, requiring a special allocator
- * for hashed entries or something.
+ * 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 and ppc-sha1, so we list
+ * the default for OpenSSL compatible SHA-1 implementations here.
  */
-struct hash_table_entry {
-       unsigned int hash;
-       void *ptr;
-};
+#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 SHA1_MAX_BLOCK_SIZE
+#include "compat/sha1-chunked.h"
+#undef git_SHA1_Update
+#define git_SHA1_Update                git_SHA1_Update_Chunked
+#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
+/* Number of algorithms supported (including unknown). */
+#define GIT_HASH_NALGOS (GIT_HASH_SHA1 + 1)
 
-struct hash_table {
-       unsigned int size, nr;
-       struct hash_table_entry *array;
+/* A suitably aligned type for stack allocations of hash contexts. */
+union git_hash_ctx {
+       git_SHA_CTX sha1;
 };
+typedef union git_hash_ctx git_hash_ctx;
 
-extern void *lookup_hash(unsigned int hash, const struct hash_table *table);
-extern void **insert_hash(unsigned int hash, void *ptr, struct hash_table *table);
-extern int for_each_hash(const struct hash_table *table, int (*fn)(void *, void *), void *data);
-extern void free_hash(struct hash_table *table);
-
-static inline void init_hash(struct hash_table *table)
-{
-       table->size = 0;
-       table->nr = 0;
-       table->array = NULL;
-}
+typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
+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);
+
+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 hash initialization function. */
+       git_hash_init_fn init_fn;
+
+       /* The hash update function. */
+       git_hash_update_fn update_fn;
+
+       /* The hash finalization function. */
+       git_hash_final_fn final_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;
+};
+extern const struct git_hash_algo hash_algos[GIT_HASH_NALGOS];
 
 #endif