Derrick Stolee via GitGitGadgetFrom: Derrick Stolee <derrickstolee@github.com>
When cloning directly from a local repository, we load a list of refs based on scanning the $GIT_DIR/refs/ directory of the "server" repository. If files exist in that directory that do not parse as hexadecimal hashes, then the ref array used by write_remote_refs() ends up with some entries with null OIDs. This causes us to hit a BUG() statement in ref_transaction_create():
BUG: create called without valid new_oid
This BUG() call used to be a die() until 033abf97f (Replace all die("BUG: ...") calls by BUG() ones, 2018-05-02). Before that, the die() was added by f04c5b552 (ref_transaction_create(): check that new_sha1 is valid, 2015-02-17).
The original report for this bug [1] mentioned that this problem did not exist in Git 2.27.0. The failure bisects unsurprisingly to 968f12fda (refs: turn on GIT_REF_PARANOIA by default, 2021-09-24). When GIT_REF_PARANOIA is enabled, this case always fails as far back as I am able to successfully compile and test the Git codebase.
[1] https://github.com/git-for-windows/git/issues/3781
There are two approaches to consider here. One would be to remove this BUG() statement in favor of returning with an error. There are only two callers to ref_transaction_create(), so this would have a limited impact.
The other approach would be to add special casing in 'git clone' to avoid this faulty input to the method.
While I originally started with changing 'git clone', I decided that modifying ref_transaction_create() was a more complete solution. This prevents failing with a BUG() statement when we already have a good way to report an error (including a reason for that error) within the method. Both callers properly check the return value and die() with the error message, so this is an appropriate direction.
The added test helps check against a regression, but does check that our intended error message is handled correctly.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
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clone: ignore invalid local refs in remotePublished-As: https://github.com/gitgitgadget/git/releases/tag/pr-1214%2Fderrickstolee%2Frefs-bug-v1 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1214/derrickstolee/refs-bug-v1 Pull-Request: https://github.com/gitgitgadget/git/pull/1214
refs.c | 6 ++++-- t/t5605-clone-local.sh | 9 +++++++++ 2 files changed, 13 insertions(+), 2 deletions(-)
Show changes to 2 files +13 −2
refs.c, t/t5605-clone-local.sh
diff --git a/refs.c b/refs.c index 1a964505f92..f300f83e4d4 100644 --- a/refs.c +++ b/refs.c @@ -1111,8 +1111,10 @@ int ref_transaction_create(struct ref_transaction *transaction, unsigned int flags, const char *msg, struct strbuf *err) { - if (!new_oid || is_null_oid(new_oid)) - BUG("create called without valid new_oid"); + if (!new_oid || is_null_oid(new_oid)) { + strbuf_addf(err, "'%s' has a null OID", refname); + return 1; + } return ref_transaction_update(transaction, refname, new_oid, null_oid(), flags, msg, err); } diff --git a/t/t5605-clone-local.sh b/t/t5605-clone-local.sh index 7d63365f93a..21ab6192839 100755 --- a/t/t5605-clone-local.sh +++ b/t/t5605-clone-local.sh @@ -141,4 +141,13 @@ test_expect_success 'cloning locally respects "-u" for fetching refs' ' test_must_fail git clone --bare -u false a should_not_work.git ' +test_expect_success 'local clone from repo with corrupt refs fails gracefully' ' + git init corrupt && + test_commit -C corrupt one && + echo a >corrupt/.git/refs/heads/topic && + + test_must_fail git clone corrupt working 2>err && + grep "has a null OID" err +' + test_done base-commit: 11cfe552610386954886543f5de87dcc49ad5735
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