handle_registration_result

fn handle_registration_result(res: usize) !void {
    switch (linux.errno(res)) {
        .SUCCESS => {},
        // One or more fds in the array are invalid, or the kernel does not support sparse sets:
        .BADF => return error.FileDescriptorInvalid,
        .BUSY => return error.FilesAlreadyRegistered,
        .INVAL => return error.FilesEmpty,
        // Adding `nr_args` file references would exceed the maximum allowed number of files the
        // user is allowed to have according to the per-user RLIMIT_NOFILE resource limit and
        // the CAP_SYS_RESOURCE capability is not set, or `nr_args` exceeds the maximum allowed
        // for a fixed file set (older kernels have a limit of 1024 files vs 64K files):
        .MFILE => return error.UserFdQuotaExceeded,
        // Insufficient kernel resources, or the caller had a non-zero RLIMIT_MEMLOCK soft
        // resource limit but tried to lock more memory than the limit permitted (not enforced
        // when the process is privileged with CAP_IPC_LOCK):
        .NOMEM => return error.SystemResources,
        // Attempt to register files on a ring already registering files or being torn down:
        .NXIO => return error.RingShuttingDownOrAlreadyRegisteringFiles,
        else => |errno| return posix.unexpectedErrno(errno),
    }
}