fsck: check HAS_OBJ more consistently

There are two spots that call lookup_object() and assume
that a non-NULL result means we have the object:

1. When we're checking the objects given to us by the user
on the command line.

2. When we're checking if a reflog entry is valid.

This generally follows fsck's mental model that we will have
looked at and loaded a "struct object" for each object in
the repository. But it misses one case: if another object
_mentioned_ an object, but we didn't actually parse it or
verify that it exists, it will still have a struct.

It's not clear if this is a triggerable bug or not.
Certainly the later parts of the reachability check need to
be careful of this, and do so by checking the HAS_OBJ flag.
But both of these steps happen before we start traversing,
so probably we won't have followed any links yet. Still,
it's easy enough to be defensive here.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/fsck.c b/builtin/fsck.c
index 3d9ee310d2d16a17b278f315f3571bbb9165941f..57f529b41bf03e52901b55093746eaff6ea8dc95 100644 (file)
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -398,7 +398,7 @@ static void fsck_handle_reflog_sha1(const char *refname, unsigned char *sha1,
 
        if (!is_null_sha1(sha1)) {
                obj = lookup_object(sha1);
-               if (obj) {
+               if (obj && (obj->flags & HAS_OBJ)) {
                        if (timestamp && name_objects)
                                add_decoration(fsck_walk_options.object_names,
                                        obj,
@@ -755,7 +755,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
                if (!get_sha1(arg, sha1)) {
                        struct object *obj = lookup_object(sha1);
 
-                       if (!obj) {
+                       if (!obj || !(obj->flags & HAS_OBJ)) {
                                error("%s: object missing", sha1_to_hex(sha1));
                                errors_found |= ERROR_OBJECT;
                                continue;