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authorJeff King <peff@peff.net>2016-01-12 16:45:09 -0500
committerJunio C Hamano <gitster@pobox.com>2016-01-13 09:05:42 -0800
commit2859dcd4c8605a5b9cf35efb815418ea8892658b (patch)
tree7e0f66dea2d55dd67b9fb6617c83d0f06d0cedc9 /refs
parent6294dcb49fb2654993fbc132f1b49443adfe4c87 (diff)
downloadgit-2859dcd4c8605a5b9cf35efb815418ea8892658b.tar.gz
lock_ref_sha1_basic: handle REF_NODEREF with invalid refsjk/symbolic-ref
We sometimes call lock_ref_sha1_basic with REF_NODEREF to operate directly on a symbolic ref. This is used, for example, to move to a detached HEAD, or when updating the contents of HEAD via checkout or symbolic-ref. However, the first step of the function is to resolve the refname to get the "old" sha1, and we do so without telling resolve_ref_unsafe() that we are only interested in the symref. As a result, we may detect a problem there not with the symref itself, but with something it points to. The real-world example I found (and what is used in the test suite) is a HEAD pointing to a ref that cannot exist, because it would cause a directory/file conflict with other existing refs. This situation is somewhat broken, of course, as trying to _commit_ on that HEAD would fail. But it's not explicitly forbidden, and we should be able to move away from it. However, neither "git checkout" nor "git symbolic-ref" can do so. We try to take the lock on HEAD, which is pointing to a non-existent ref. We bail from resolve_ref_unsafe() with errno set to EISDIR, and the lock code thinks we are attempting to create a d/f conflict. Of course we're not. The problem is that the lock code has no idea what level we were at when we got EISDIR, so trying to diagnose or remove empty directories for HEAD is not useful. To make things even more complicated, we only get EISDIR in the loose-ref case. If the refs are packed, the resolution may "succeed", giving us the pointed-to ref in "refname", but a null oid. Later, we say "ah, the null oid means we are creating; let's make sure there is room for it", but mistakenly check against the _resolved_ refname, not the original. We can fix this by making two tweaks: 1. Call resolve_ref_unsafe() with RESOLVE_REF_NO_RECURSE when REF_NODEREF is set. This means any errors we get will be from the orig_refname, and we can act accordingly. We already do this in the REF_DELETING case, but we should do it for update, too. 2. If we do get a "refname" return from resolve_ref_unsafe(), even with RESOLVE_REF_NO_RECURSE it may be the name of the ref pointed-to by a symref. We already normalize this back to orig_refname before taking the lockfile, but we need to do so before the null_oid check. While we're rearranging the REF_NODEREF handling, we can also bump the initialization of lflags to the top of the function, where we are setting up other flags. This saves us from having yet another conditional block on REF_NODEREF just to set it later. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'refs')
-rw-r--r--refs/files-backend.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 69c3ecfe1b..81c92b410e 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1887,7 +1887,8 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
const char *orig_refname = refname;
struct ref_lock *lock;
int last_errno = 0;
- int type, lflags;
+ int type;
+ int lflags = 0;
int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
int resolve_flags = 0;
int attempts_remaining = 3;
@@ -1898,10 +1899,11 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
if (mustexist)
resolve_flags |= RESOLVE_REF_READING;
- if (flags & REF_DELETING) {
+ if (flags & REF_DELETING)
resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
- if (flags & REF_NODEREF)
- resolve_flags |= RESOLVE_REF_NO_RECURSE;
+ if (flags & REF_NODEREF) {
+ resolve_flags |= RESOLVE_REF_NO_RECURSE;
+ lflags |= LOCK_NO_DEREF;
}
refname = resolve_ref_unsafe(refname, resolve_flags,
@@ -1937,6 +1939,10 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
goto error_return;
}
+
+ if (flags & REF_NODEREF)
+ refname = orig_refname;
+
/*
* If the ref did not exist and we are creating it, make sure
* there is no existing packed ref whose name begins with our
@@ -1952,11 +1958,6 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
lock->lk = xcalloc(1, sizeof(struct lock_file));
- lflags = 0;
- if (flags & REF_NODEREF) {
- refname = orig_refname;
- lflags |= LOCK_NO_DEREF;
- }
lock->ref_name = xstrdup(refname);
lock->orig_ref_name = xstrdup(orig_refname);
strbuf_git_path(&ref_file, "%s", refname);