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refs: atomically record overwritten ref in update_symref

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When updating a symref with update_symref it's currently not possible to
know for sure what was the previous value that was overwritten. Extend
refs_update_symref under a new function name, to record the value after
the ref has been locked if the caller of refs_update_symref_extended
requests it via a new variable in the function call. Make the return
value of the function notify the caller, if the previous value was
actually not a symbolic reference. Keep the original refs_update_symref
function with the same signature, but now as a wrapper around
refs_update_symref_extended.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Bence Ferdinandy
2024-11-22 13:28:45 +01:00
committed by Junio C Hamano
parent 8102d10ff8
commit d842cd1301
2 changed files with 24 additions and 2 deletions
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22
refs.c
View File

@ -2115,6 +2115,13 @@ int peel_iterated_oid(struct repository *r, const struct object_id *base, struct
int refs_update_symref(struct ref_store *refs, const char *ref,
const char *target, const char *logmsg)
{
return refs_update_symref_extended(refs, ref, target, logmsg, NULL);
}
int refs_update_symref_extended(struct ref_store *refs, const char *ref,
const char *target, const char *logmsg,
struct strbuf *referent)
{
struct ref_transaction *transaction;
struct strbuf err = STRBUF_INIT;
@ -2125,10 +2132,22 @@ int refs_update_symref(struct ref_store *refs, const char *ref,
ref_transaction_update(transaction, ref, NULL, NULL,
target, NULL, REF_NO_DEREF,
logmsg, &err) ||
ref_transaction_commit(transaction, &err)) {
ref_transaction_prepare(transaction, &err)) {
ret = error("%s", err.buf);
goto cleanup;
}
if (referent && refs_read_symbolic_ref(refs, ref, referent) == NOT_A_SYMREF) {
struct object_id oid;
if (!refs_read_ref(refs, ref, &oid)) {
strbuf_addstr(referent, oid_to_hex(&oid));
ret = NOT_A_SYMREF;
}
}
if (ref_transaction_commit(transaction, &err))
ret = error("%s", err.buf);
cleanup:
strbuf_release(&err);
if (transaction)
ref_transaction_free(transaction);
@ -2948,4 +2967,3 @@ int ref_update_expects_existing_old_ref(struct ref_update *update)
return (update->flags & REF_HAVE_OLD) &&
(!is_null_oid(&update->old_oid) || update->old_target);
}

4
refs.h
View File

@ -584,6 +584,10 @@ int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
int refs_update_symref(struct ref_store *refs, const char *refname,
const char *target, const char *logmsg);
int refs_update_symref_extended(struct ref_store *refs, const char *refname,
const char *target, const char *logmsg,
struct strbuf *referent);
enum action_on_err {
UPDATE_REFS_MSG_ON_ERR,
UPDATE_REFS_DIE_ON_ERR,