vfs2._resolve_path: require parent to be a path sequence

Require an actual path sequence for the parent since it provides the
context for the resolution of the path (with respect to relative
paths, symlinks containing .., etc.).

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Tested-by: Rob Browning <rlb@defaultvalue.org>

diff --git a/lib/bup/vfs2.py b/lib/bup/vfs2.py
index 7cfa928c54c49428379d97ad92ba252b3be1aa58..4408885d294f9dfed9e07e254777bd3eaffc88e0 100644 (file)
--- a/lib/bup/vfs2.py
+++ b/lib/bup/vfs2.py
@@ -211,6 +211,7 @@ Chunky = namedtuple('Chunky', ('meta', 'oid'))
 Root = namedtuple('Root', ('meta'))
 Tags = namedtuple('Tags', ('meta'))
 RevList = namedtuple('RevList', ('meta', 'oid'))
+item_types = (Item, Chunky, Root, Tags, RevList)
 
 _root = Root(meta=default_dir_mode)
 _tags = Tags(meta=default_dir_mode)
@@ -664,20 +665,27 @@ def contents(repo, item, names=None, want_meta=True):
         yield x
 
 def _resolve_path(repo, path, parent=None, want_meta=True, deref=False):
+    global _root
     assert repo
     assert len(path)
-    global _root
+    if parent:
+        for x in parent:
+            assert len(x) == 2
+            assert type(x[0]) in (bytes, str)
+            assert type(x[1]) in item_types
+        assert parent[0][1] == _root
     future = _decompose_path(path)
-    past = []
     if path.startswith('/'):
-        assert(not parent)
-        past = [('', _root)]
         if future == ['']: # path was effectively '/'
-            return tuple(past)
-    if not past and not parent:
+            return (('', _root),)
         past = [('', _root)]
-    if parent:
-        past = [parent]
+    else:
+        if parent:
+            past = list(parent)
+        else:
+            past = [('', _root)]
+    if not future:  # e.g. if path was effectively '.'
+        return tuple(past)
     hops = 0
     result = None
     while True:
@@ -762,11 +770,11 @@ def resolve(repo, path, parent=None, want_meta=True):
 
     Currently, a path ending in '/' will still resolve if it exists,
     even if not a directory.  The parent, if specified, must be a
-    (name, item) tuple, and will provide the starting point for the
-    resolution of the path.  Currently, the path must be relative when
-    a parent is provided.  The result may include parent directly, so
-    it must not be modified later.  If this is a concern, pass in
-    copy_item(parent) instead.
+    sequence of (name, item) tuples, and will provide the starting
+    point for the resolution of the path.  The result may include
+    elements of parent directly, so they must not be modified later.
+    If this is a concern, pass in "name, copy_item(item) for
+    name, item in parent" instead.
 
     When want_meta is true, detailed metadata will be included in each
     result item if it's avaiable, otherwise item.meta will be an