From: Linus Torvalds Date: Mon, 4 Sep 2006 15:34:12 +0000 (-0700) Subject: Fix git-fsck-objects SIGSEGV/divide-by-zero X-Git-Tag: v1.4.3-rc1~142 X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=5d44cd1c8b27fb677fedc886303d38b19fbb07f7;p=git.git Fix git-fsck-objects SIGSEGV/divide-by-zero If you try to fsck a repository that isn't entirely empty, but that has no inter-object references (ie all the objects are blobs, and don't refer to anything else), git-fsck-objects currently fails. This probably cannot happen in practice, but can be tested with something like git init-db touch dummy git add dummy git fsck-objects where the fsck will die by a divide-by-zero when it tries to look up the references from the one object it found (hash_obj() will do a modulus by refs_hash_size). On some other archiectures (ppc, sparc) the divide-by-zero will go unnoticed, and we'll instead SIGSEGV when we hit the "refs_hash[j]" access. So move the test that should protect against this from mark_reachable() into lookup_object_refs(), which incidentally in the process also fixes mark_reachable() itself (it used to not mark the one object that _was_ reachable, because it decided that it had no refs too early). Signed-off-by: Linus Torvalds Signed-off-by: Junio C Hamano --- diff --git a/object-refs.c b/object-refs.c index b0034e4b2..98ea10005 100644 --- a/object-refs.c +++ b/object-refs.c @@ -55,9 +55,13 @@ static void add_object_refs(struct object *obj, struct object_refs *ref) struct object_refs *lookup_object_refs(struct object *obj) { - int j = hash_obj(obj, refs_hash_size); struct object_refs *ref; + int j; + /* nothing to lookup */ + if (!refs_hash_size) + return NULL; + j = hash_obj(obj, refs_hash_size); while ((ref = refs_hash[j]) != NULL) { if (ref->base == obj) break; @@ -125,9 +129,6 @@ void mark_reachable(struct object *obj, unsigned int mask) if (!track_object_refs) die("cannot do reachability with object refs turned off"); - /* nothing to lookup */ - if (!refs_hash_size) - return; /* If we've been here already, don't bother */ if (obj->flags & mask) return;