refs.c: allow deleting refs with a broken sha1rs/ref-transaction-reflog

Add back support to make it possible to delete refs that have a broken
sha1.

Add new internal flags REF_ALLOW_BROKEN and RESOLVE_REF_ALLOW_BAD_SHA1
to pass intent from branch.c that we are willing to allow
resolve_ref_unsafe and lock_ref_sha1_basic to allow broken refs.
Since these refs can not actually be resolved to a sha1, they instead resolve
to null_sha1 when these flags are used.

For example, the ref:

   echo "Broken ref" > .git/refs/heads/foo-broken-1

can now be deleted using git branch -d foo-broken-1

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/refs.c b/refs.c
index 6d50a32b4b..f1ca9e4afc 100644
--- a/refs.c
+++ b/refs.c
@@ -1584,6 +1584,10 @@ const char *resolve_ref_unsafe(const char *refname, int resolve_flags, unsigned
 			    (buffer[40] != '\0' && !isspace(buffer[40]))) {
 				if (flags)
 					*flags |= REF_ISBROKEN;
+				if (resolve_flags & RESOLVE_REF_ALLOW_BAD_SHA1) {
+					hashclr(sha1);
+					return refname;
+				}
 				errno = EINVAL;
 				return NULL;
 			}
@@ -2265,6 +2269,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
 		if (flags & REF_NODEREF)
 			resolve_flags |= RESOLVE_REF_NO_RECURSE;
 	}
+	if (flags & REF_ALLOW_BROKEN)
+		resolve_flags |= RESOLVE_REF_ALLOW_BAD_SHA1;
 
 	refname = resolve_ref_unsafe(refname, resolve_flags,
 				     lock->old_sha1, &type);