@matheusbsbs / matheus-bagliano / commits / 7e88640cd1

setup: fix reinit of repos with incompatible GIT_DEFAULT_HASH

The exact same issue as described in the preceding commit also exists for GIT_DEFAULT_HASH. Thus, reinitializing a repository that e.g. uses SHA1 with `GIT_DEFAULT_HASH=sha256 git init` will cause the object format of that repository to change to SHA256. This is of course bogus as any existing objects and refs will not be converted, thus causing repository corruption: $ git init repo Initialized empty Git repository in /tmp/repo/.git/ $ cd repo/ $ git commit --allow-empty -m message [main (root-commit) 35a7344] message $ GIT_DEFAULT_HASH=sha256 git init Reinitialized existing Git repository in /tmp/repo/.git/ $ git show fatal: your current branch appears to be broken Fix the issue by ignoring the environment variable in case the repo has already been initialized with an object hash. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Patrick Steinhardt committed Jan 30, 2025 at 17:24 UTC 7e88640cd1801b6fe0288f744da7310b4749c0c8

2 files changed +15 -1

setup.c

+3 -1

@@ -2517,7 +2517,9 @@ static void repository_format_configure(struct repository_format *repo_fmt,

2517 int env_algo = hash_algo_by_name(env);

2518 if (env_algo == GIT_HASH_UNKNOWN)

2519 die(_("unknown hash algorithm '%s'"), env);

2520 - repo_fmt->hash_algo = env_algo;

2520 + if (repo_fmt->version < 0 ||

2521 + repo_fmt->hash_algo == GIT_HASH_UNKNOWN)

2522 + repo_fmt->hash_algo = env_algo;

2523 } else if (cfg.hash != GIT_HASH_UNKNOWN) {

2524 repo_fmt->hash_algo = cfg.hash;

2525 }

t/t0001-init.sh

+12

@@ -586,6 +586,18 @@ test_expect_success 'GIT_DEFAULT_HASH overrides init.defaultObjectFormat' '

586 echo sha256 >expected

587 '

588

589 +for hash in sha1 sha256

590 +do

591 + test_expect_success "reinit repository with GIT_DEFAULT_HASH=$hash does not change format" '

592 + test_when_finished "rm -rf repo" &&

593 + git init repo &&

594 + git -C repo rev-parse --show-object-format >expect &&

595 + GIT_DEFAULT_HASH=$hash git init repo &&

596 + git -C repo rev-parse --show-object-format >actual &&

597 + test_cmp expect actual

598 + '

599 +done

600 +

601 test_expect_success 'extensions.objectFormat is not allowed with repo version 0' '

602 test_when_finished "rm -rf explicit-v0" &&

603 git init --object-format=sha256 explicit-v0 &&