//! SOLID-specific extensions to general I/O primitives

#![deny(unsafe_op_in_unsafe_fn)]

use crate::std::net;
use crate::std::sys;
use crate::std::sys_common::{self, AsInner, FromInner, IntoInner};

/// Raw file descriptors.
pub type RawFd = i32;

/// A trait to extract the raw SOLID Sockets file descriptor from an underlying
/// object.
pub trait AsRawFd {
    /// Extracts the raw file descriptor.
    ///
    /// This method does **not** pass ownership of the raw file descriptor
    /// to the caller. The descriptor is only guaranteed to be valid while
    /// the original object has not yet been destroyed.
    fn as_raw_fd(&self) -> RawFd;
}

/// A trait to express the ability to construct an object from a raw file
/// descriptor.
pub trait FromRawFd {
    /// Constructs a new instance of `Self` from the given raw file
    /// descriptor.
    ///
    /// This function **consumes ownership** of the specified file
    /// descriptor. The returned object will take responsibility for closing
    /// it when the object goes out of scope.
    ///
    /// This function is also unsafe as the primitives currently returned
    /// have the contract that they are the sole owner of the file
    /// descriptor they are wrapping. Usage of this function could
    /// accidentally allow violating this contract which can cause memory
    /// unsafety in code that relies on it being true.
    unsafe fn from_raw_fd(fd: RawFd) -> Self;
}

/// A trait to express the ability to consume an object and acquire ownership of
/// its raw file descriptor.
pub trait IntoRawFd {
    /// Consumes this object, returning the raw underlying file descriptor.
    ///
    /// This function **transfers ownership** of the underlying file descriptor
    /// to the caller. Callers are then the unique owners of the file descriptor
    /// and must close the descriptor once it's no longer needed.
    fn into_raw_fd(self) -> RawFd;
}

impl AsRawFd for RawFd {
    #[inline]
    fn as_raw_fd(&self) -> RawFd {
        *self
    }
}
impl IntoRawFd for RawFd {
    #[inline]
    fn into_raw_fd(self) -> RawFd {
        self
    }
}
impl FromRawFd for RawFd {
    #[inline]
    unsafe fn from_raw_fd(fd: RawFd) -> RawFd {
        fd
    }
}

macro_rules! impl_as_raw_fd {
    ($($t:ident)*) => {$(
                impl AsRawFd for net::$t {
            #[inline]
            fn as_raw_fd(&self) -> RawFd {
                *self.as_inner().socket().as_inner()
            }
        }
    )*};
}
impl_as_raw_fd! { TcpStream TcpListener UdpSocket }

macro_rules! impl_from_raw_fd {
    ($($t:ident)*) => {$(
                impl FromRawFd for net::$t {
            #[inline]
            unsafe fn from_raw_fd(fd: RawFd) -> net::$t {
                let socket = sys::net::Socket::from_inner(fd);
                net::$t::from_inner(sys_common::net::$t::from_inner(socket))
            }
        }
    )*};
}
impl_from_raw_fd! { TcpStream TcpListener UdpSocket }

macro_rules! impl_into_raw_fd {
    ($($t:ident)*) => {$(
                impl IntoRawFd for net::$t {
            #[inline]
            fn into_raw_fd(self) -> RawFd {
                self.into_inner().into_socket().into_inner()
            }
        }
    )*};
}
impl_into_raw_fd! { TcpStream TcpListener UdpSocket }
