From 8169d0d06ad721aa54d95f044f4b097d79151ea2 Mon Sep 17 00:00:00 2001 From: Michael Haggerty Date: Mon, 25 Apr 2016 17:38:35 +0200 Subject: lock_ref_for_update(): don't re-read non-symbolic references Before the previous patch, our first read of the reference happened before the reference was locked, so we couldn't trust its value and had to read it again. But now that our first read of the reference happens after acquiring the lock, there is no need to read it a second time. So move the read_ref_full() call into the (update->type & REF_ISSYMREF) block. Signed-off-by: Michael Haggerty --- refs/files-backend.c | 48 ++++++++++++++++++++++++++++++------------------ 1 file changed, 30 insertions(+), 18 deletions(-) diff --git a/refs/files-backend.c b/refs/files-backend.c index ffc30fd23..7bc18322a 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -3436,33 +3436,45 @@ static int lock_ref_for_update(struct ref_update *update, lock = update->lock; - if (read_ref_full(update->refname, - mustexist ? RESOLVE_REF_READING : 0, - lock->old_oid.hash, NULL)) { - if (update->flags & REF_HAVE_OLD) { - strbuf_addf(err, "cannot lock ref '%s': can't resolve old value", - update->refname); + if (update->type & REF_ISSYMREF) { + if (read_ref_full(update->refname, + mustexist ? RESOLVE_REF_READING : 0, + lock->old_oid.hash, NULL)) { + if (update->flags & REF_HAVE_OLD) { + strbuf_addf(err, "cannot lock ref '%s': can't resolve old value", + update->refname); + return TRANSACTION_GENERIC_ERROR; + } else { + hashclr(lock->old_oid.hash); + } + } + if ((update->flags & REF_HAVE_OLD) && + hashcmp(lock->old_oid.hash, update->old_sha1)) { + strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s", + update->refname, + sha1_to_hex(lock->old_oid.hash), + sha1_to_hex(update->old_sha1)); return TRANSACTION_GENERIC_ERROR; - } else { - hashclr(lock->old_oid.hash); } - } - if ((update->flags & REF_HAVE_OLD) && - hashcmp(lock->old_oid.hash, update->old_sha1)) { - strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s", - update->refname, - sha1_to_hex(lock->old_oid.hash), - sha1_to_hex(update->old_sha1)); - return TRANSACTION_GENERIC_ERROR; - } - if (update->type & REF_ISSYMREF) { if (!(update->flags & REF_NODEREF)) { ret = split_symref_update(update, referent.buf, transaction, affected_refnames, err); if (ret) return ret; } + } else if ((update->flags & REF_HAVE_OLD) && + hashcmp(lock->old_oid.hash, update->old_sha1)) { + if (is_null_sha1(update->old_sha1)) + strbuf_addf(err, "cannot lock ref '%s': reference already exists", + update->refname); + else + strbuf_addf(err, "cannot lock ref '%s': is at %s but expected %s", + update->refname, + sha1_to_hex(lock->old_oid.hash), + sha1_to_hex(update->old_sha1)); + + return TRANSACTION_GENERIC_ERROR; } if ((update->flags & REF_HAVE_NEW) && -- cgit v1.2.1