dirDeleteFile

fn dirDeleteFile(userdata: ?*anyopaque, dir: Dir, sub_path: []const u8) Dir.DeleteFileError!void {
    const ev: *Evented = @ptrCast(@alignCast(userdata));
    _ = ev;

    var path_buffer: [c.PATH_MAX]u8 = undefined;
    const sub_path_posix = try pathToPosix(sub_path, &path_buffer);

    while (true) switch (c.errno(c.unlinkat(dir.handle, sub_path_posix, 0))) {
        .SUCCESS => return,
        .INTR => {},
        // Some systems return permission errors when trying to delete a
        // directory, so we need to handle that case specifically and
        // translate the error.
        .PERM => {
            // Don't follow symlinks to match unlinkat (which acts on symlinks rather than follows them).
            var st = std.mem.zeroes(c.Stat);
            while (true) switch (c.errno(c.fstatat(
                dir.handle,
                sub_path_posix,
                &st,
                c.AT.SYMLINK_NOFOLLOW,
            ))) {
                .SUCCESS => break,
                .INTR => {},
                else => return error.PermissionDenied,
            };
            if (st.mode & c.S.IFMT == c.S.IFDIR) return error.IsDir else return error.PermissionDenied;
        },
        .ACCES => return error.AccessDenied,
        .BUSY => return error.FileBusy,
        .FAULT => |err| return errnoBug(err),
        .IO => return error.FileSystem,
        .ISDIR => return error.IsDir,
        .LOOP => return error.SymLinkLoop,
        .NAMETOOLONG => return error.NameTooLong,
        .NOENT => return error.FileNotFound,
        .NOTDIR => return error.NotDir,
        .NOMEM => return error.SystemResources,
        .ROFS => return error.ReadOnlyFileSystem,
        .EXIST => |err| return errnoBug(err),
        .NOTEMPTY => |err| return errnoBug(err), // Not passing AT.REMOVEDIR
        .ILSEQ => return error.BadPathName,
        .INVAL => |err| return errnoBug(err), // invalid flags, or pathname has . as last component
        .BADF => |err| return errnoBug(err), // File descriptor used after closed.
        else => |err| return unexpectedErrno(err),
    };
}