hash: implement and use a context cloning function
For all of our SHA-1 implementations and most of our SHA-256 implementations, the hash context we use is a real struct. For these implementations, it's possible to copy a hash context by making a copy of the struct. However, for our libgcrypt implementation, our hash context is a pointer. Consequently, copying it does not lead to an independent hash context like we intended. Fortunately, however, libgcrypt provides us with a handy function to copy hash contexts. Let's add a cloning function to the hash algorithm API, and use it in the one place we need to make a hash context copy. With this change, our libgcrypt SHA-256 implementation is fully functional with all of our other hash implementations. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
brian m. carlson committed
Feb 22, 2020 at 20:17 UTC
768e30ea27c58aa69893e10b96ba5ba5680dc3cf
4 files changed
+46
-1
csum-file.c
+1
-1
@@ -157,7 +157,7 @@ void hashfile_checkpoint(struct hashfile *f, struct hashfile_checkpoint *checkpo
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{
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hashflush(f);
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checkpoint->offset = f->total;
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- checkpoint->ctx = f->ctx;
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+ the_hash_algo->clone_fn(&checkpoint->ctx, &f->ctx);
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}
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int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint)
hash.h
+21
@@ -16,6 +16,7 @@
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#endif
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#if defined(SHA256_GCRYPT)
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+#define SHA256_NEEDS_CLONE_HELPER
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#include "sha256/gcrypt.h"
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#elif defined(SHA256_OPENSSL)
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#include <openssl/sha.h>
@@ -54,12 +55,28 @@
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#define git_SHA256_Update platform_SHA256_Update
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#define git_SHA256_Final platform_SHA256_Final
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+#ifdef platform_SHA256_Clone
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+#define git_SHA256_Clone platform_SHA256_Clone
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+#endif
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+
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#ifdef SHA1_MAX_BLOCK_SIZE
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#include "compat/sha1-chunked.h"
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#undef git_SHA1_Update
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#define git_SHA1_Update git_SHA1_Update_Chunked
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#endif
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+static inline void git_SHA1_Clone(git_SHA_CTX *dst, const git_SHA_CTX *src)
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+{
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+ memcpy(dst, src, sizeof(*dst));
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+}
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+
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+#ifndef SHA256_NEEDS_CLONE_HELPER
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+static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *src)
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+{
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+ memcpy(dst, src, sizeof(*dst));
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+}
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+#endif
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+
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/*
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* Note that these constants are suitable for indexing the hash_algos array and
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* comparing against each other, but are otherwise arbitrary, so they should not
@@ -85,6 +102,7 @@ union git_hash_ctx {
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typedef union git_hash_ctx git_hash_ctx;
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typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
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+typedef void (*git_hash_clone_fn)(git_hash_ctx *dst, const git_hash_ctx *src);
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typedef void (*git_hash_update_fn)(git_hash_ctx *ctx, const void *in, size_t len);
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typedef void (*git_hash_final_fn)(unsigned char *hash, git_hash_ctx *ctx);
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@@ -110,6 +128,9 @@ struct git_hash_algo {
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/* The hash initialization function. */
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git_hash_init_fn init_fn;
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+ /* The hash context cloning function. */
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+ git_hash_clone_fn clone_fn;
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+
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/* The hash update function. */
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git_hash_update_fn update_fn;
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sha1-file.c
+18
@@ -74,6 +74,11 @@ static void git_hash_sha1_init(git_hash_ctx *ctx)
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git_SHA1_Init(&ctx->sha1);
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}
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+static void git_hash_sha1_clone(git_hash_ctx *dst, const git_hash_ctx *src)
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+{
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+ git_SHA1_Clone(&dst->sha1, &src->sha1);
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+}
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+
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static void git_hash_sha1_update(git_hash_ctx *ctx, const void *data, size_t len)
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{
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git_SHA1_Update(&ctx->sha1, data, len);
@@ -90,6 +95,11 @@ static void git_hash_sha256_init(git_hash_ctx *ctx)
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git_SHA256_Init(&ctx->sha256);
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}
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+static void git_hash_sha256_clone(git_hash_ctx *dst, const git_hash_ctx *src)
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+{
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+ git_SHA256_Clone(&dst->sha256, &src->sha256);
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+}
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+
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static void git_hash_sha256_update(git_hash_ctx *ctx, const void *data, size_t len)
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{
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git_SHA256_Update(&ctx->sha256, data, len);
@@ -105,6 +115,11 @@ static void git_hash_unknown_init(git_hash_ctx *ctx)
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BUG("trying to init unknown hash");
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}
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+static void git_hash_unknown_clone(git_hash_ctx *dst, const git_hash_ctx *src)
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+{
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+ BUG("trying to clone unknown hash");
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+}
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+
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static void git_hash_unknown_update(git_hash_ctx *ctx, const void *data, size_t len)
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{
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BUG("trying to update unknown hash");
@@ -123,6 +138,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
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0,
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0,
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git_hash_unknown_init,
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+ git_hash_unknown_clone,
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git_hash_unknown_update,
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git_hash_unknown_final,
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NULL,
@@ -136,6 +152,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
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GIT_SHA1_HEXSZ,
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GIT_SHA1_BLKSZ,
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git_hash_sha1_init,
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+ git_hash_sha1_clone,
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git_hash_sha1_update,
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git_hash_sha1_final,
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&empty_tree_oid,
@@ -149,6 +166,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
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GIT_SHA256_HEXSZ,
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GIT_SHA256_BLKSZ,
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git_hash_sha256_init,
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+ git_hash_sha256_clone,
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git_hash_sha256_update,
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git_hash_sha256_final,
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&empty_tree_oid_sha256,
sha256/gcrypt.h
+6
@@ -22,8 +22,14 @@ inline void gcrypt_SHA256_Final(unsigned char *digest, gcrypt_SHA256_CTX *ctx)
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memcpy(digest, gcry_md_read(*ctx, GCRY_MD_SHA256), SHA256_DIGEST_SIZE);
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}
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+inline void gcrypt_SHA256_Clone(gcrypt_SHA256_CTX *dst, const gcrypt_SHA256_CTX *src)
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+{
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+ gcry_md_copy(dst, *src);
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+}
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+
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#define platform_SHA256_CTX gcrypt_SHA256_CTX
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#define platform_SHA256_Init gcrypt_SHA256_Init
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+#define platform_SHA256_Clone gcrypt_SHA256_Clone
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#define platform_SHA256_Update gcrypt_SHA256_Update
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#define platform_SHA256_Final gcrypt_SHA256_Final
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