easy way to add a prefix to a loopback path?

[jmhodges]

I've got a directory /path/to/foobar on disk that I'd like to alias to /another/weirdpath/to/foobar. I have a solution to that problem but I suspect there's an easier way to do it.

Currently, I'm using lots of mounts of nodefs.NewMemNodeFSRoot on to one another. Like, so:

func aliasDirTo(newPath, origPath string, root nodefs.Node, conn *nodefs.FileSystemConnector) error {
    parts := strings.Split(newPath, "/")
    for i, p := range parts[:len(parts)-1] {
        lastRoot := root
        child := lastRoot.Inode().GetChild(p)
        if child == nil {
            root = nodefs.NewMemNodeFSRoot("")
            st := conn.Mount(lastRoot.Inode(), p, root, nil)
            if !st.Ok() {
                return fmt.Errorf("unable to mount %s while making it as part of the new alias %s for %s: %s", strings.Join(parts[:i+1], "/"), newPath, origPath, st)
            }

        } else {
            root = child.Node()
        }
    }
    lastMountDir := parts[len(parts)-1]
    fs := pathfs.NewLoopbackFileSystem(origPath)
    nodeFS := pathfs.NewPathNodeFs(pathfs.NewReadonlyFileSystem(fs), &pathfs.PathNodeFsOptions{ClientInodes: true})
    st := conn.Mount(root.Inode(), lastMountDir, nodeFS.Root(), nil)
    if !st.Ok() {
        return fmt.Errorf("unable to mount last dir in %s as an alias of %s: %s", newPath, origPath, st)
    }
    return nil
}

That seems a little complicated and the large amount of mounts is funny (and makes the dirs show up in funny colors, of course).

Is there an easier way to make this happen?

[hanwen]

the obvious solution would be a symlink, but I suppose that doesn't work for some reason.

what does 'alias' mean? Do you want regular files in both directories to share inodes, for example?

[jmhodges]

Yeah, this is for supporting some Go tooling so symlinks don't work.

There's a build process I can't change easily whose artifacts are Go libraries that I need to have under a different name (and directory structure) in order to work with things like mockgen etc

[jmhodges]

(This is for bazel stuff that has a different idea from Go of how things should be laid out)

[hanwen]

is this bazel stuff public, or can you talk about it? I designed the original Go rules for Bazel, and am in contact with Bazel team still, so maybe there is a better way.

[jmhodges]

My GOPATH-creation code is not public, yet.

For context: that code makes the assumption that you'll get a go_default_library.a because you used gazelle to generate your BUILD files and turns that into the right file name dogs.a or whatever. This is with bazel 0.4.5 and 7cce22ee036166177d803efed6eea608a1ba37d9 in https://github.com/bazelbuild/rules_go

[hanwen]

closing due to inactivity.