Conflicting logical paths

[pwinckles]

It's possible to create an object that is impossible to recreate on disk due to logical path parts being used both as directories and files. Here's an example:

{
    "id": "o1",
    "type": "https://ocfl.io/1.0/spec/#inventory",
    "digestAlgorithm": "sha512",
    "head": "v2",
    "contentDirectory": "content",
    "fixity": {},
    "manifest": {
        "40b244112641dd78dd4f93b6c9190dd46e0099194d5a44257b7efad6ef9ff4683da1eda0244448cb343aa688f5d3efd7314dafe580ac0bcbf115aeca9e8dc114": [
            "v2/content/sub/path"
        ],
        "4dff4ea340f0a823f15d3f4f01ab62eae0e5da579ccb851f8db9dfe84c58b2b37b89903a740e1ee172da793a6e79d560e5f7f9bd058a12a280433ed6fa46510a": [
            "v1/content/sub"
        ]
    },
    "versions": {
        "v1": {
            "created": "2020-04-29T13:04:34Z",
            "state": {
                "4dff4ea340f0a823f15d3f4f01ab62eae0e5da579ccb851f8db9dfe84c58b2b37b89903a740e1ee172da793a6e79d560e5f7f9bd058a12a280433ed6fa46510a": [
                    "sub"
                ]
            }
        },
        "v2": {
            "created": "2020-04-29T13:04:35Z",
            "state": {
                "40b244112641dd78dd4f93b6c9190dd46e0099194d5a44257b7efad6ef9ff4683da1eda0244448cb343aa688f5d3efd7314dafe580ac0bcbf115aeca9e8dc114": [
                    "sub/path"
                ],
                "4dff4ea340f0a823f15d3f4f01ab62eae0e5da579ccb851f8db9dfe84c58b2b37b89903a740e1ee172da793a6e79d560e5f7f9bd058a12a280433ed6fa46510a": [
                    "sub"
                ]
            }
        }
    }
}

In this example, logical path sub is used both as a file in the object and as a directory that contains sub/path.

There are two ways to create objects like this:

1. Logical paths are mapped directly to content paths and the conflicting logical paths are added in separate versions.
2. Logical paths are not mapped directly to content paths and the conflicting logical paths are added in the same or in separate versions.

In either case, it is not possible to recreate the HEAD version of the object on disk.

I don't know if the spec or implementation notes want to address this or not. It feels like clients should not allow conflicting logical paths to be created within a version state, though it may be a pain to enforce.

[zimeon]

Good point @pwinckles! In the current definition of state and logical paths within that (https://ocfl.io/draft/spec/#version) we make restrictions so that a the state for a particular version can be unpacked onto a filesystem. I think it would be consistent to say that the state for a particular version MUST NOT have entries that conflict in this way.

(I do think it is OK to have sub in v1, sub/file in v2, and sub again in v3 -- provided that in each version there isn't the conflicting entry)

[rosy1280]

discussed at 2020-05-05 editor's meeting

[zimeon]

Closed by #465