pathless.md

PathlessDirFs

A modern filesystem, built for humans.

What's a DirFs?

A DirFs is a filesystem where everything is both a file and a dir. So, for example, I can have file src/lib.rs with the following contents:

pub mod hello;

And file src/lib.rs/hello.rs with the following contents:

pub fn hello() {
    println!("hello world!");
}

At the same time.

What's a pathless FS?

A pathless FS is an FS where there are no path separators, but there are still paths, built on arrays and array elements rather than path separators.

["a", "b", "c"] in a pathless FS is equivalent to "a/b/c" in a pathful FS.

APIs

This is how PathlessDirFs uses POSIX APIs.

FILE *fopen(const char *pathname, const char *mode); (and friends)

The pathname may only refer to files in the current directory.

int open(const char *path, int oflag, ...);

As above.

int openat(int fd, const char *path, int oflag, ...);

The pathname may only refer to files relative to fd. It may be ...

These give the basis for a functioning PathlessDirFs.

// path is NULL-terminated
FILE *fopenatpath(int fd, const char *path[], const char *mode) {
    int i;
    for (i = 0; fd >= 0 && path[i+1]; i++) {
        fd = openat(fd, path[i], O_SEARCH | O_DIRECTORY); // O_DIRECTORY is a no-op.
    }
    if (fd < 0) {
        errno = -fd;
        return NULL;
    }
    return fopen(path[i], mode);
}

[TODO finish this at some point]