Add some routines for SHA1 hash computation

[sp: Changed signature for output to use git_oid, and added
     a test case to verify an allocated git_hash_ctx can be
     reinitialized and reused.]

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 87 insertions, 0 deletions

diff --git a/src/hash.c b/src/hash.c
new file mode 100644
index 000000000..4ff1dd099
--- /dev/null
+++ b/src/hash.c
@@ -0,0 +1,87 @@
+/*
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2,
+ * as published by the Free Software Foundation.
+ *
+ * In addition to the permissions in the GNU General Public License,
+ * the authors give you unlimited permission to link the compiled
+ * version of this file into combinations with other programs,
+ * and to distribute those combinations without any restriction
+ * coming from the use of this file.  (The General Public License
+ * restrictions do apply in other respects; for example, they cover
+ * modification of the file, and distribution when not linked into
+ * a combined executable.)
+ *
+ * This file is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "common.h"
+#include "hash.h"
+#include <openssl/sha.h>
+
+struct git_hash_ctx {
+	SHA_CTX c;
+};
+
+git_hash_ctx *git_hash_new_ctx(void)
+{
+	git_hash_ctx *ctx = malloc(sizeof(*ctx));
+
+	if (!ctx)
+		return NULL;
+
+	SHA1_Init(&ctx->c);
+
+	return ctx;
+}
+
+void git_hash_free_ctx(git_hash_ctx *ctx)
+{
+	free(ctx);
+}
+
+void git_hash_init(git_hash_ctx *ctx)
+{
+	assert(ctx);
+	SHA1_Init(&ctx->c);
+}
+
+void git_hash_update(git_hash_ctx *ctx, const void *data, size_t len)
+{
+	assert(ctx);
+	SHA1_Update(&ctx->c, data, len);
+}
+
+void git_hash_final(git_oid *out, git_hash_ctx *ctx)
+{
+	assert(ctx);
+	SHA1_Final(out->id, &ctx->c);
+}
+
+void git_hash_buf(git_oid *out, const void *data, size_t len)
+{
+	SHA_CTX c;
+
+	SHA1_Init(&c);
+	SHA1_Update(&c, data, len);
+	SHA1_Final(out->id, &c);
+}
+
+void git_hash_vec(git_oid *out, git_buf_vec *vec, size_t n)
+{
+	SHA_CTX c;
+	size_t i;
+
+	SHA1_Init(&c);
+	for (i = 0; i < n; i++)
+		SHA1_Update(&c, vec[i].data, vec[i].len);
+	SHA1_Final(out->id, &c);
+}