Use legacy hash for legacy formats

We have a large variety of data formats and protocols where no hash
algorithm was defined and the default was assumed to always be SHA-1.
Instead of explicitly stating SHA-1, let's use the constant to represent
the legacy hash algorithm (which is still SHA-1) so that it's clear
for documentary purposes that it's a legacy fallback option and not an
intentional choice to use SHA-1.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: bk2204

builtin/receive-pack.c

@@ -2136,7 +2136,7 @@ static struct command *read_head_info(struct packet_reader *reader,
 				use_push_options = 1;
 			hash = parse_feature_value(feature_list, "object-format", &len, NULL);
 			if (!hash) {
-				hash = hash_algos[GIT_HASH_SHA1].name;
+				hash = hash_algos[GIT_HASH_SHA1_LEGACY].name;
 				len = strlen(hash);
 			}
 			if (xstrncmpz(the_hash_algo->name, hash, len))

bundle.c

@@ -95,7 +95,7 @@ int read_bundle_header_fd(int fd, struct bundle_header *header,
 	 * by an "object-format=" capability, which is being handled in
 	 * `parse_capability()`.
 	 */
-	header->hash_algo = &hash_algos[GIT_HASH_SHA1];
+	header->hash_algo = &hash_algos[GIT_HASH_SHA1_LEGACY];
 
 	/* The bundle header ends with an empty line */
 	while (!strbuf_getwholeline_fd(&buf, fd, '\n') &&
@@ -507,7 +507,7 @@ int create_bundle(struct repository *r, const char *path,
 	 *    SHA1.
 	 * 2. @filter is required because we parsed an object filter.
 	 */
-	if (the_hash_algo != &hash_algos[GIT_HASH_SHA1] || revs.filter.choice)
+	if (the_hash_algo != &hash_algos[GIT_HASH_SHA1_LEGACY] || revs.filter.choice)
 		min_version = 3;
 
 	if (argc > 1) {

connect.c

@@ -251,7 +251,7 @@ static void process_capabilities(struct packet_reader *reader, size_t *linelen)
 			reader->hash_algo = &hash_algos[hash_algo];
 		free(hash_name);
 	} else {
-		reader->hash_algo = &hash_algos[GIT_HASH_SHA1];
+		reader->hash_algo = &hash_algos[GIT_HASH_SHA1_LEGACY];
 	}
 }
 
@@ -500,7 +500,7 @@ static void send_capabilities(int fd_out, struct packet_reader *reader)
 		reader->hash_algo = &hash_algos[hash_algo];
 		packet_write_fmt(fd_out, "object-format=%s", reader->hash_algo->name);
 	} else {
-		reader->hash_algo = &hash_algos[GIT_HASH_SHA1];
+		reader->hash_algo = &hash_algos[GIT_HASH_SHA1_LEGACY];
 	}
 	if (server_feature_v2("promisor-remote", &promisor_remote_info)) {
 		char *reply = promisor_remote_reply(promisor_remote_info);
@@ -665,7 +665,7 @@ int server_supports_hash(const char *desired, int *feature_supported)
 	if (feature_supported)
 		*feature_supported = !!hash;
 	if (!hash) {
-		hash = hash_algos[GIT_HASH_SHA1].name;
+		hash = hash_algos[GIT_HASH_SHA1_LEGACY].name;
 		len = strlen(hash);
 	}
 	while (hash) {

fetch-pack.c

@@ -1342,7 +1342,7 @@ static void write_fetch_command_and_capabilities(struct strbuf *req_buf,
 			die(_("mismatched algorithms: client %s; server %s"),
 			    the_hash_algo->name, hash_name);
 		packet_buf_write(req_buf, "object-format=%s", the_hash_algo->name);
-	} else if (hash_algo_by_ptr(the_hash_algo) != GIT_HASH_SHA1) {
+	} else if (hash_algo_by_ptr(the_hash_algo) != GIT_HASH_SHA1_LEGACY) {
 		die(_("the server does not support algorithm '%s'"),
 		    the_hash_algo->name);
 	}

pkt-line.c

@@ -617,7 +617,7 @@ void packet_reader_init(struct packet_reader *reader, int fd,
 	reader->buffer_size = sizeof(packet_buffer);
 	reader->options = options;
 	reader->me = "git";
-	reader->hash_algo = &hash_algos[GIT_HASH_SHA1];
+	reader->hash_algo = &hash_algos[GIT_HASH_SHA1_LEGACY];
 	strbuf_init(&reader->scratch, 0);
 }
 

remote-curl.c

@@ -285,7 +285,7 @@ static const struct git_hash_algo *detect_hash_algo(struct discovery *heads)
 	 * back to SHA1, which may or may not be correct.
 	 */
 	if (!p)
-		return &hash_algos[GIT_HASH_SHA1];
+		return &hash_algos[GIT_HASH_SHA1_LEGACY];
 
 	algo = hash_algo_by_length((p - heads->buf) / 2);
 	if (algo == GIT_HASH_UNKNOWN)

serve.c

@@ -14,7 +14,7 @@
 
 static int advertise_sid = -1;
 static int advertise_object_info = -1;
-static int client_hash_algo = GIT_HASH_SHA1;
+static int client_hash_algo = GIT_HASH_SHA1_LEGACY;
 
 static int always_advertise(struct repository *r UNUSED,
 			    struct strbuf *value UNUSED)

setup.c

@@ -2222,11 +2222,11 @@ void initialize_repository_version(int hash_algo,
 	 * version will get adjusted by git-clone(1) once it has learned about
 	 * the remote repository's format.
 	 */
-	if (hash_algo != GIT_HASH_SHA1 ||
+	if (hash_algo != GIT_HASH_SHA1_LEGACY ||
 	    ref_storage_format != REF_STORAGE_FORMAT_FILES)
 		target_version = GIT_REPO_VERSION_READ;
 
-	if (hash_algo != GIT_HASH_SHA1 && hash_algo != GIT_HASH_UNKNOWN)
+	if (hash_algo != GIT_HASH_SHA1_LEGACY && hash_algo != GIT_HASH_UNKNOWN)
 		git_config_set("extensions.objectformat",
 			       hash_algos[hash_algo].name);
 	else if (reinit)

transport.c

@@ -1243,7 +1243,7 @@ struct transport *transport_get(struct remote *remote, const char *url)
 			ret->smart_options->receivepack = remote->receivepack;
 	}
 
-	ret->hash_algo = &hash_algos[GIT_HASH_SHA1];
+	ret->hash_algo = &hash_algos[GIT_HASH_SHA1_LEGACY];
 
 	return ret;
 }