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builtin/clone: avoid failure with GIT_DEFAULT_HASH

If a user is cloning a SHA-1 repository with GIT_DEFAULT_HASH set to "sha256", then we can end up with a repository where the repository format version is 0 but the extensions.objectformat key is set to "sha256". This is both wrong (the user has a SHA-1 repository) and nonfunctional (because the extension cannot be used in a v0 repository). This happens because in a clone, we initially set up the repository, and then change its algorithm based on what the remote side tells us it's using. We've initially set up the repository as SHA-256 in this case, and then later on reset the repository version without clearing the extension. We could just always set the extension in this case, but that would mean that our SHA-1 repositories weren't compatible with older Git versions, even though there's no reason why they shouldn't be. And we also don't want to initialize the repository as SHA-1 initially, since that means if we're cloning an empty repository, we'll have failed to honor the GIT_DEFAULT_HASH variable and will end up with a SHA-1 repository, not a SHA-256 repository. Neither of those are appealing, so let's tell the repository initialization code if we're doing a reinit like this, and if so, to clear the extension if we're using SHA-1. This makes sure we produce a valid and functional repository and doesn't break any of our other use cases. Reported-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

brian m. carlson committed Sep 20, 2020 at 22:35 UTC 47ac970309dc26c95c4de4991b2e6aa7c7b7f615

4 files changed +20 -4

builtin/clone.c

+1 -1

@@ -1233,7 +1233,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)

1233 * Now that we know what algorithm the remote side is using,

1234 * let's set ours to the same thing.

1235 */

1236 - initialize_repository_version(hash_algo);

1236 + initialize_repository_version(hash_algo, 1);

1237 repo_set_hash_algo(the_repository, hash_algo);

1238

1239 mapped_refs = wanted_peer_refs(refs, &remote->fetch);

builtin/init-db.c

+4 -2

@@ -179,7 +179,7 @@ static int needs_work_tree_config(const char *git_dir, const char *work_tree)

179 return 1;

180 }

181

182 -void initialize_repository_version(int hash_algo)

182 +void initialize_repository_version(int hash_algo, int reinit)

183 {

184 char repo_version_string[10];

185 int repo_version = GIT_REPO_VERSION;

@@ -195,6 +195,8 @@ void initialize_repository_version(int hash_algo)

195 if (hash_algo != GIT_HASH_SHA1)

196 git_config_set("extensions.objectformat",

197 hash_algos[hash_algo].name);

198 + else if (reinit)

199 + git_config_set_gently("extensions.objectformat", NULL);

200 }

201

202 static int create_default_files(const char *template_path,

@@ -277,7 +279,7 @@ static int create_default_files(const char *template_path,

279 free(ref);

280 }

281

280 - initialize_repository_version(fmt->hash_algo);

282 + initialize_repository_version(fmt->hash_algo, 0);

283

284 /* Check filemode trustability */

285 path = git_path_buf(&buf, "config");

cache.h

+1 -1

@@ -629,7 +629,7 @@ int path_inside_repo(const char *prefix, const char *path);

629 int init_db(const char *git_dir, const char *real_git_dir,

630 const char *template_dir, int hash_algo,

631 const char *initial_branch, unsigned int flags);

632 -void initialize_repository_version(int hash_algo);

632 +void initialize_repository_version(int hash_algo, int reinit);

633

634 void sanitize_stdfds(void);

635 int daemonize(void);

t/t5601-clone.sh

+14

@@ -631,6 +631,20 @@ test_expect_success CASE_INSENSITIVE_FS 'colliding file detection' '

631 test_i18ngrep "the following paths have collided" icasefs/warning

632 '

633

634 +test_expect_success 'clone with GIT_DEFAULT_HASH' '

635 + (

636 + sane_unset GIT_DEFAULT_HASH &&

637 + git init --object-format=sha1 test-sha1 &&

638 + git init --object-format=sha256 test-sha256

639 + ) &&

640 + test_commit -C test-sha1 foo &&

641 + test_commit -C test-sha256 foo &&

642 + GIT_DEFAULT_HASH=sha1 git clone test-sha256 test-clone-sha256 &&

643 + GIT_DEFAULT_HASH=sha256 git clone test-sha1 test-clone-sha1 &&

644 + git -C test-clone-sha1 status &&

645 + git -C test-clone-sha256 status

646 +'

647 +

648 partial_clone_server () {

649 SERVER="$1" &&

650