fsck: drop unused parameter from traverse_one_object()

Also add comments to seemingly unsafe pointer dereferences, that
are all safe.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/fsck.c b/builtin/fsck.c
index 6d5ebca7a9bc9333ea8e493057ecce1b4814c252..91409a0069ece772070a9778190456a1c62a9d60 100644 (file)
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -74,7 +74,13 @@ static int mark_object(struct object *obj, int type, void *data)
 {
        struct object *parent = data;
 
+       /*
+        * The only case data is NULL or type is OBJ_ANY is when
+        * mark_object_reachable() calls us.  All the callers of
+        * that function has non-NULL obj hence ...
+        */
        if (!obj) {
+               /* ... these references to parent->fld are safe here */
                printf("broken link from %7s %s\n",
                           typename(parent->type), sha1_to_hex(parent->sha1));
                printf("broken link from %7s %s\n",
@@ -84,6 +90,7 @@ static int mark_object(struct object *obj, int type, void *data)
        }
 
        if (type != OBJ_ANY && obj->type != type)
+               /* ... and the reference to parent is safe here */
                objerror(parent, "wrong object type in link");
 
        if (obj->flags & REACHABLE)
@@ -109,7 +116,7 @@ static void mark_object_reachable(struct object *obj)
        mark_object(obj, OBJ_ANY, NULL);
 }
 
-static int traverse_one_object(struct object *obj, struct object *parent)
+static int traverse_one_object(struct object *obj)
 {
        int result;
        struct tree *tree = NULL;
@@ -138,7 +145,7 @@ static int traverse_reachable(void)
                entry = pending.objects + --pending.nr;
                obj = entry->item;
                parent = (struct object *) entry->name;
-               result |= traverse_one_object(obj, parent);
+               result |= traverse_one_object(obj);
        }
        return !!result;
 }
@@ -556,8 +563,8 @@ static int fsck_cache_tree(struct cache_tree *it)
                              sha1_to_hex(it->sha1));
                        return 1;
                }
-               mark_object_reachable(obj);
                obj->used = 1;
+               mark_object_reachable(obj);
                if (obj->type != OBJ_TREE)
                        err |= objerror(obj, "non-tree in cache-tree");
        }