std: Add IntoRaw{Fd,Handle,Socket} traits

This commit is an implementation of [RFC 1174][rfc] which adds three new traits
to the standard library:

* `IntoRawFd` - implemented on Unix for all I/O types (files, sockets, etc)
* `IntoRawHandle` - implemented on Windows for files, processes, etc
* `IntoRawSocket` - implemented on Windows for networking types

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/1174-into-raw-fd-socket-handle-traits.md

Closes #27062

Author: alexcrichton

src/libstd/fs.rs

@@ -24,8 +24,8 @@ use ffi::OsString;
 use io::{self, SeekFrom, Seek, Read, Write};
 use path::{Path, PathBuf};
 use sys::fs as fs_imp;
-use sys_common::{AsInnerMut, FromInner, AsInner};
 use sys_common::io::read_to_end_uninitialized;
+use sys_common::{AsInnerMut, FromInner, AsInner, IntoInner};
 use vec::Vec;
 
 /// A reference to an open file on the filesystem.
@@ -317,6 +317,11 @@ impl FromInner<fs_imp::File> for File {
         File { inner: f }
     }
 }
+impl IntoInner<fs_imp::File> for File {
+    fn into_inner(self) -> fs_imp::File {
+        self.inner
+    }
+}
 
 impl fmt::Debug for File {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

src/libstd/net/tcp.rs

@@ -17,9 +17,9 @@ use io::prelude::*;
 use fmt;
 use io;
 use net::{ToSocketAddrs, SocketAddr, Shutdown};
-use sys_common::net as net_imp;
-use sys_common::{AsInner, FromInner};
 use sys_common::io::read_to_end_uninitialized;
+use sys_common::net as net_imp;
+use sys_common::{AsInner, FromInner, IntoInner};
 use time::Duration;
 
 /// A structure which represents a TCP stream between a local socket and a
@@ -220,6 +220,10 @@ impl FromInner<net_imp::TcpStream> for TcpStream {
     fn from_inner(inner: net_imp::TcpStream) -> TcpStream { TcpStream(inner) }
 }
 
+impl IntoInner<net_imp::TcpStream> for TcpStream {
+    fn into_inner(self) -> net_imp::TcpStream { self.0 }
+}
+
 impl fmt::Debug for TcpStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.0.fmt(f)
@@ -298,6 +302,10 @@ impl FromInner<net_imp::TcpListener> for TcpListener {
     }
 }
 
+impl IntoInner<net_imp::TcpListener> for TcpListener {
+    fn into_inner(self) -> net_imp::TcpListener { self.0 }
+}
+
 impl fmt::Debug for TcpListener {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.0.fmt(f)

src/libstd/net/udp.rs

@@ -17,7 +17,7 @@ use fmt;
 use io::{self, Error, ErrorKind};
 use net::{ToSocketAddrs, SocketAddr, IpAddr};
 use sys_common::net as net_imp;
-use sys_common::{AsInner, FromInner};
+use sys_common::{AsInner, FromInner, IntoInner};
 use time::Duration;
 
 /// A User Datagram Protocol socket.
@@ -174,6 +174,10 @@ impl FromInner<net_imp::UdpSocket> for UdpSocket {
     fn from_inner(inner: net_imp::UdpSocket) -> UdpSocket { UdpSocket(inner) }
 }
 
+impl IntoInner<net_imp::UdpSocket> for UdpSocket {
+    fn into_inner(self) -> net_imp::UdpSocket { self.0 }
+}
+
 impl fmt::Debug for UdpSocket {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.0.fmt(f)

src/libstd/process.rs

@@ -23,7 +23,7 @@ use path;
 use sync::mpsc::{channel, Receiver};
 use sys::pipe::{self, AnonPipe};
 use sys::process as imp;
-use sys_common::{AsInner, AsInnerMut, FromInner};
+use sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
 use thread;
 
 /// Representation of a running or exited child process.
@@ -71,6 +71,10 @@ impl AsInner<imp::Process> for Child {
     fn as_inner(&self) -> &imp::Process { &self.handle }
 }
 
+impl IntoInner<imp::Process> for Child {
+    fn into_inner(self) -> imp::Process { self.handle }
+}
+
 /// A handle to a child procesess's stdin
 #[stable(feature = "process", since = "1.0.0")]
 pub struct ChildStdin {
@@ -92,6 +96,10 @@ impl AsInner<AnonPipe> for ChildStdin {
     fn as_inner(&self) -> &AnonPipe { &self.inner }
 }
 
+impl IntoInner<AnonPipe> for ChildStdin {
+    fn into_inner(self) -> AnonPipe { self.inner }
+}
+
 /// A handle to a child procesess's stdout
 #[stable(feature = "process", since = "1.0.0")]
 pub struct ChildStdout {
@@ -109,6 +117,10 @@ impl AsInner<AnonPipe> for ChildStdout {
     fn as_inner(&self) -> &AnonPipe { &self.inner }
 }
 
+impl IntoInner<AnonPipe> for ChildStdout {
+    fn into_inner(self) -> AnonPipe { self.inner }
+}
+
 /// A handle to a child procesess's stderr
 #[stable(feature = "process", since = "1.0.0")]
 pub struct ChildStderr {
@@ -126,6 +138,10 @@ impl AsInner<AnonPipe> for ChildStderr {
     fn as_inner(&self) -> &AnonPipe { &self.inner }
 }
 
+impl IntoInner<AnonPipe> for ChildStderr {
+    fn into_inner(self) -> AnonPipe { self.inner }
+}
+
 /// The `Command` type acts as a process builder, providing fine-grained control
 /// over how a new process should be spawned. A default configuration can be
 /// generated using `Command::new(program)`, where `program` gives a path to the

src/libstd/sys/common/net.rs

@@ -184,6 +184,8 @@ impl TcpStream {
 
     pub fn socket(&self) -> &Socket { &self.inner }
 
+    pub fn into_socket(self) -> Socket { self.inner }
+
     pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
         setsockopt(&self.inner, libc::IPPROTO_TCP, libc::TCP_NODELAY,
                    nodelay as c_int)
@@ -336,6 +338,8 @@ impl TcpListener {
 
     pub fn socket(&self) -> &Socket { &self.inner }
 
+    pub fn into_socket(self) -> Socket { self.inner }
+
     pub fn socket_addr(&self) -> io::Result<SocketAddr> {
         sockname(|buf, len| unsafe {
             libc::getsockname(*self.inner.as_inner(), buf, len)
@@ -396,6 +400,8 @@ impl UdpSocket {
 
     pub fn socket(&self) -> &Socket { &self.inner }
 
+    pub fn into_socket(self) -> Socket { self.inner }
+
     pub fn socket_addr(&self) -> io::Result<SocketAddr> {
         sockname(|buf, len| unsafe {
             libc::getsockname(*self.inner.as_inner(), buf, len)

src/libstd/sys/unix/ext/io.rs

@@ -16,7 +16,7 @@ use fs;
 use net;
 use os::raw;
 use sys;
-use sys_common::{self, AsInner, FromInner};
+use sys_common::{self, AsInner, FromInner, IntoInner};
 
 /// Raw file descriptors.
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -59,6 +59,18 @@ pub trait FromRawFd {
     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.
+#[unstable(feature = "into_raw_os", reason = "recently added API")]
+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;
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl AsRawFd for fs::File {
     fn as_raw_fd(&self) -> RawFd {
@@ -71,6 +83,11 @@ impl FromRawFd for fs::File {
         fs::File::from_inner(sys::fs::File::from_inner(fd))
     }
 }
+impl IntoRawFd for fs::File {
+    fn into_raw_fd(self) -> RawFd {
+        self.into_inner().into_fd().into_raw()
+    }
+}
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl AsRawFd for net::TcpStream {
@@ -106,3 +123,19 @@ impl FromRawFd for net::UdpSocket {
         net::UdpSocket::from_inner(sys_common::net::UdpSocket::from_inner(socket))
     }
 }
+
+impl IntoRawFd for net::TcpStream {
+    fn into_raw_fd(self) -> RawFd {
+        self.into_inner().into_socket().into_inner()
+    }
+}
+impl IntoRawFd for net::TcpListener {
+    fn into_raw_fd(self) -> RawFd {
+        self.into_inner().into_socket().into_inner()
+    }
+}
+impl IntoRawFd for net::UdpSocket {
+    fn into_raw_fd(self) -> RawFd {
+        self.into_inner().into_socket().into_inner()
+    }
+}

src/libstd/sys/unix/ext/process.rs

@@ -13,11 +13,11 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use os::unix::raw::{uid_t, gid_t};
-use os::unix::io::{FromRawFd, RawFd, AsRawFd};
+use os::unix::io::{FromRawFd, RawFd, AsRawFd, IntoRawFd};
 use prelude::v1::*;
 use process;
 use sys;
-use sys_common::{AsInnerMut, AsInner, FromInner};
+use sys_common::{AsInnerMut, AsInner, FromInner, IntoInner};
 
 /// Unix-specific extensions to the `std::process::Command` builder
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -92,3 +92,21 @@ impl AsRawFd for process::ChildStderr {
         self.as_inner().fd().raw()
     }
 }
+
+impl IntoRawFd for process::ChildStdin {
+    fn into_raw_fd(self) -> RawFd {
+        self.into_inner().into_fd().into_raw()
+    }
+}
+
+impl IntoRawFd for process::ChildStdout {
+    fn into_raw_fd(self) -> RawFd {
+        self.into_inner().into_fd().into_raw()
+    }
+}
+
+impl IntoRawFd for process::ChildStderr {
+    fn into_raw_fd(self) -> RawFd {
+        self.into_inner().into_fd().into_raw()
+    }
+}

src/libstd/sys/unix/fs.rs

@@ -331,6 +331,8 @@ impl File {
     }
 
     pub fn fd(&self) -> &FileDesc { &self.0 }
+
+    pub fn into_fd(self) -> FileDesc { self.0 }
 }
 
 impl DirBuilder {

src/libstd/sys/unix/net.rs

@@ -17,7 +17,7 @@ use str;
 use sys::c;
 use net::SocketAddr;
 use sys::fd::FileDesc;
-use sys_common::{AsInner, FromInner};
+use sys_common::{AsInner, FromInner, IntoInner};
 use sys_common::net::{getsockopt, setsockopt};
 use time::Duration;
 
@@ -127,3 +127,7 @@ impl AsInner<c_int> for Socket {
 impl FromInner<c_int> for Socket {
     fn from_inner(fd: c_int) -> Socket { Socket(FileDesc::new(fd)) }
 }
+
+impl IntoInner<c_int> for Socket {
+    fn into_inner(self) -> c_int { self.0.into_raw() }
+}

src/libstd/sys/unix/pipe.rs

@@ -46,4 +46,5 @@ impl AnonPipe {
 
     pub fn raw(&self) -> libc::c_int { self.0.raw() }
     pub fn fd(&self) -> &FileDesc { &self.0 }
+    pub fn into_fd(self) -> FileDesc { self.0 }
 }