*
* Algorithmically this operates on two path buffers: "done" are the components of the path we already
* processed and resolved symlinks, "." and ".." of. "todo" are the components of the path we still need to
* process. On each iteration, we move one component from "todo" to "done", processing it's special meaning
* each time. The "todo" path always starts with at least one slash, the "done" path always ends in no
* slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races
*
* Algorithmically this operates on two path buffers: "done" are the components of the path we already
* processed and resolved symlinks, "." and ".." of. "todo" are the components of the path we still need to
* process. On each iteration, we move one component from "todo" to "done", processing it's special meaning
* each time. The "todo" path always starts with at least one slash, the "done" path always ends in no
* slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races