index-pack: use hash_sha1_file()

Use hash_sha1_file() instead of duplicating code to compute object SHA1.
While at it make it accept a const pointer.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

cache.h

@@ -283,7 +283,7 @@ char *enter_repo(char *path, int strict);
 /* Read and unpack a sha1 file into memory, write memory to a sha1 file */
 extern int sha1_object_info(const unsigned char *, unsigned long *);
 extern void * read_sha1_file(const unsigned char *sha1, enum object_type *type, unsigned long *size);
-extern int hash_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *sha1);
+extern int hash_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1);
 extern int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *return_sha1);
 extern int pretend_sha1_file(void *, unsigned long, enum object_type, unsigned char *);
 

index-pack.c

@@ -348,26 +348,7 @@ static void sha1_object(const void *data, unsigned long size,
 			enum object_type type, unsigned char *sha1,
 			int test_for_collision)
 {
-	SHA_CTX ctx;
-	char header[50];
-	int header_size;
-	const char *type_str;
-
-	switch (type) {
-	case OBJ_COMMIT: type_str = commit_type; break;
-	case OBJ_TREE:   type_str = tree_type; break;
-	case OBJ_BLOB:   type_str = blob_type; break;
-	case OBJ_TAG:    type_str = tag_type; break;
-	default:
-		die("bad type %d", type);
-	}
-
-	header_size = sprintf(header, "%s %lu", type_str, size) + 1;
-
-	SHA1_Init(&ctx);
-	SHA1_Update(&ctx, header, header_size);
-	SHA1_Update(&ctx, data, size);
-	SHA1_Final(sha1, &ctx);
+	hash_sha1_file(data, size, typename(type), sha1);
 
 	if (test_for_collision && has_sha1_file(sha1)) {
 		void *has_data;

sha1_file.c

@@ -1808,7 +1808,7 @@ void *read_object_with_reference(const unsigned char *sha1,
 	}
 }
 
-static void write_sha1_file_prepare(void *buf, unsigned long len,
+static void write_sha1_file_prepare(const void *buf, unsigned long len,
                                     const char *type, unsigned char *sha1,
                                     char *hdr, int *hdrlen)
 {
@@ -1936,7 +1936,7 @@ static void setup_object_header(z_stream *stream, const char *type, unsigned lon
 	stream->avail_out -= hdrlen;
 }
 
-int hash_sha1_file(void *buf, unsigned long len, const char *type,
+int hash_sha1_file(const void *buf, unsigned long len, const char *type,
                    unsigned char *sha1)
 {
 	char hdr[32];