| Message ID | 20250130-b4-pks-reinit-default-ref-format-v1-3-d2769ca01207@pks.im (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 7e88640cd1801b6fe0288f744da7310b4749c0c8 |
| Headers | show |
| Series | setup: fix reinit of repos with different formats | expand |
Patrick Steinhardt <ps@pks.im> writes: > 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: The exact same comment on silently ignoring applies, but unlike the previous one, converting the entire history is far more expensive, so it may be much less likely to be worth going the automatic conversion route than the previous one. Thanks.
diff --git a/setup.c b/setup.c index 53ffeabc5b..7da7aa8984 100644 --- a/setup.c +++ b/setup.c @@ -2517,7 +2517,9 @@ static void repository_format_configure(struct repository_format *repo_fmt, int env_algo = hash_algo_by_name(env); if (env_algo == GIT_HASH_UNKNOWN) die(_("unknown hash algorithm '%s'"), env); - repo_fmt->hash_algo = env_algo; + if (repo_fmt->version < 0 || + repo_fmt->hash_algo == GIT_HASH_UNKNOWN) + repo_fmt->hash_algo = env_algo; } else if (cfg.hash != GIT_HASH_UNKNOWN) { repo_fmt->hash_algo = cfg.hash; } diff --git a/t/t0001-init.sh b/t/t0001-init.sh index 6dff8b75f1..c49d9e0d38 100755 --- a/t/t0001-init.sh +++ b/t/t0001-init.sh @@ -586,6 +586,18 @@ test_expect_success 'GIT_DEFAULT_HASH overrides init.defaultObjectFormat' ' echo sha256 >expected ' +for hash in sha1 sha256 +do + test_expect_success "reinit repository with GIT_DEFAULT_HASH=$hash does not change format" ' + test_when_finished "rm -rf repo" && + git init repo && + git -C repo rev-parse --show-object-format >expect && + GIT_DEFAULT_HASH=$hash git init repo && + git -C repo rev-parse --show-object-format >actual && + test_cmp expect actual + ' +done + test_expect_success 'extensions.objectFormat is not allowed with repo version 0' ' test_when_finished "rm -rf explicit-v0" && git init --object-format=sha256 explicit-v0 &&
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> --- setup.c | 4 +++- t/t0001-init.sh | 12 ++++++++++++ 2 files changed, 15 insertions(+), 1 deletion(-)