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>
diff --git a/csum-file.c b/csum-file.c
index 53ce37f..0f35fa5 100644
--- a/csum-file.c
+++ b/csum-file.c
@@ -157,7 +157,7 @@
{
hashflush(f);
checkpoint->offset = f->total;
- checkpoint->ctx = f->ctx;
+ the_hash_algo->clone_fn(&checkpoint->ctx, &f->ctx);
}
int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint)
diff --git a/hash.h b/hash.h
index 52a4f1a..e0f3f16 100644
--- a/hash.h
+++ b/hash.h
@@ -16,6 +16,7 @@
#endif
#if defined(SHA256_GCRYPT)
+#define SHA256_NEEDS_CLONE_HELPER
#include "sha256/gcrypt.h"
#elif defined(SHA256_OPENSSL)
#include <openssl/sha.h>
@@ -54,12 +55,28 @@
#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
+static inline void git_SHA1_Clone(git_SHA_CTX *dst, const git_SHA_CTX *src)
+{
+ memcpy(dst, src, sizeof(*dst));
+}
+
+#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
@@ -85,6 +102,7 @@
typedef union git_hash_ctx git_hash_ctx;
typedef void (*git_hash_init_fn)(git_hash_ctx *ctx);
+typedef void (*git_hash_clone_fn)(git_hash_ctx *dst, const git_hash_ctx *src);
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);
@@ -110,6 +128,9 @@
/* 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;
diff --git a/sha1-file.c b/sha1-file.c
index d785de8..c36ca5a 100644
--- a/sha1-file.c
+++ b/sha1-file.c
@@ -74,6 +74,11 @@
git_SHA1_Init(&ctx->sha1);
}
+static void git_hash_sha1_clone(git_hash_ctx *dst, const git_hash_ctx *src)
+{
+ git_SHA1_Clone(&dst->sha1, &src->sha1);
+}
+
static void git_hash_sha1_update(git_hash_ctx *ctx, const void *data, size_t len)
{
git_SHA1_Update(&ctx->sha1, data, len);
@@ -90,6 +95,11 @@
git_SHA256_Init(&ctx->sha256);
}
+static void git_hash_sha256_clone(git_hash_ctx *dst, const git_hash_ctx *src)
+{
+ git_SHA256_Clone(&dst->sha256, &src->sha256);
+}
+
static void git_hash_sha256_update(git_hash_ctx *ctx, const void *data, size_t len)
{
git_SHA256_Update(&ctx->sha256, data, len);
@@ -105,6 +115,11 @@
BUG("trying to init unknown hash");
}
+static void git_hash_unknown_clone(git_hash_ctx *dst, const git_hash_ctx *src)
+{
+ BUG("trying to clone unknown hash");
+}
+
static void git_hash_unknown_update(git_hash_ctx *ctx, const void *data, size_t len)
{
BUG("trying to update unknown hash");
@@ -123,6 +138,7 @@
0,
0,
git_hash_unknown_init,
+ git_hash_unknown_clone,
git_hash_unknown_update,
git_hash_unknown_final,
NULL,
@@ -136,6 +152,7 @@
GIT_SHA1_HEXSZ,
GIT_SHA1_BLKSZ,
git_hash_sha1_init,
+ git_hash_sha1_clone,
git_hash_sha1_update,
git_hash_sha1_final,
&empty_tree_oid,
@@ -149,6 +166,7 @@
GIT_SHA256_HEXSZ,
GIT_SHA256_BLKSZ,
git_hash_sha256_init,
+ git_hash_sha256_clone,
git_hash_sha256_update,
git_hash_sha256_final,
&empty_tree_oid_sha256,
diff --git a/sha256/gcrypt.h b/sha256/gcrypt.h
index 09bd8bb..501da5e 100644
--- a/sha256/gcrypt.h
+++ b/sha256/gcrypt.h
@@ -22,8 +22,14 @@
memcpy(digest, gcry_md_read(*ctx, GCRY_MD_SHA256), SHA256_DIGEST_SIZE);
}
+inline void gcrypt_SHA256_Clone(gcrypt_SHA256_CTX *dst, const gcrypt_SHA256_CTX *src)
+{
+ gcry_md_copy(dst, *src);
+}
+
#define platform_SHA256_CTX gcrypt_SHA256_CTX
#define platform_SHA256_Init gcrypt_SHA256_Init
+#define platform_SHA256_Clone gcrypt_SHA256_Clone
#define platform_SHA256_Update gcrypt_SHA256_Update
#define platform_SHA256_Final gcrypt_SHA256_Final
