Merge branch '2.16' of https://github.com/ChrisADR/git-po

[thirdparty/git.git] / hash.h

diff --git a/hash.h b/hash.h
index 024d0d3d50b174aac1d948e9ecfa7ae92020355a..7d7a864f5dd43bb53ee6b31d391df3e15cbdbb08 100644 (file)
--- a/hash.h
+++ b/hash.h
@@ -1,6 +1,8 @@
 #ifndef HASH_H
 #define HASH_H
 
+#include "git-compat-util.h"
+
 #if defined(SHA1_PPC)
 #include "ppc/sha1.h"
 #elif defined(SHA1_APPLE)
@@ -13,4 +15,59 @@
 #include "block-sha1/sha1.h"
 #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)
+
+typedef void (*git_hash_init_fn)(void *ctx);
+typedef void (*git_hash_update_fn)(void *ctx, const void *in, size_t len);
+typedef void (*git_hash_final_fn)(unsigned char *hash, void *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 size of a hash context (e.g. git_SHA_CTX). */
+       size_t ctxsz;
+
+       /* 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