resolved upstream merge conflicts

36 files changed, 1649 insertions, 355 deletions

diff --git a/src/libstd/sys/cloudabi/thread.rs b/src/libstd/sys/cloudabi/thread.rs
index 5d66936b2a4..8cca47efd22 100644
--- a/src/libstd/sys/cloudabi/thread.rs
+++ b/src/libstd/sys/cloudabi/thread.rs
@@ -32,7 +32,7 @@ unsafe impl Send for Thread {}
 unsafe impl Sync for Thread {}
 
 impl Thread {
-    pub unsafe fn new<'a>(stack: usize, p: Box<FnBox() + 'a>) -> io::Result<Thread> {
+    pub unsafe fn new<'a>(stack: usize, p: Box<dyn FnBox() + 'a>) -> io::Result<Thread> {
         let p = box p;
         let mut native: libc::pthread_t = mem::zeroed();
         let mut attr: libc::pthread_attr_t = mem::zeroed();
diff --git a/src/libstd/sys/mod.rs b/src/libstd/sys/mod.rs
index 1231898ed7e..c44db3b1072 100644
--- a/src/libstd/sys/mod.rs
+++ b/src/libstd/sys/mod.rs
@@ -67,6 +67,7 @@ cfg_if! {
         // (missing things in `libc` which is empty) so just omit everything
         // with an empty module
         #[unstable(issue = "0", feature = "std_internals")]
+        #[allow(missing_docs)]
         pub mod unix_ext {}
     } else {
         // On other platforms like Windows document the bare bones of unix
@@ -80,11 +81,13 @@ cfg_if! {
 cfg_if! {
     if #[cfg(windows)] {
         // On windows we'll just be documenting what's already available
+        #[allow(missing_docs)]
         pub use self::ext as windows_ext;
     } else if #[cfg(any(target_os = "cloudabi", target_arch = "wasm32"))] {
         // On CloudABI and wasm right now the shim below doesn't compile, so
         // just omit it
         #[unstable(issue = "0", feature = "std_internals")]
+        #[allow(missing_docs)]
         pub mod windows_ext {}
     } else {
         // On all other platforms (aka linux/osx/etc) then pull in a "minimal"
diff --git a/src/libstd/sys/redox/args.rs b/src/libstd/sys/redox/args.rs
index 59ae2a74a6d..556ed77372e 100644
--- a/src/libstd/sys/redox/args.rs
+++ b/src/libstd/sys/redox/args.rs
@@ -73,17 +73,15 @@ mod imp {
             CStr::from_ptr(*argv.offset(i) as *const libc::c_char).to_bytes().to_vec()
         }).collect();
 
-        LOCK.lock();
+        let _guard = LOCK.lock();
         let ptr = get_global_ptr();
         assert!((*ptr).is_none());
         (*ptr) = Some(box args);
-        LOCK.unlock();
     }
 
     pub unsafe fn cleanup() {
-        LOCK.lock();
+        let _guard = LOCK.lock();
         *get_global_ptr() = None;
-        LOCK.unlock();
     }
 
     pub fn args() -> Args {
@@ -96,16 +94,14 @@ mod imp {
 
     fn clone() -> Option<Vec<Vec<u8>>> {
         unsafe {
-            LOCK.lock();
+            let _guard = LOCK.lock();
             let ptr = get_global_ptr();
-            let ret = (*ptr).as_ref().map(|s| (**s).clone());
-            LOCK.unlock();
-            return ret
+            (*ptr).as_ref().map(|s| (**s).clone())
         }
     }
 
-    fn get_global_ptr() -> *mut Option<Box<Vec<Vec<u8>>>> {
-        unsafe { mem::transmute(&GLOBAL_ARGS_PTR) }
+    unsafe fn get_global_ptr() -> *mut Option<Box<Vec<Vec<u8>>>> {
+        mem::transmute(&GLOBAL_ARGS_PTR)
     }
 
 }
diff --git a/src/libstd/sys/redox/ext/mod.rs b/src/libstd/sys/redox/ext/mod.rs
index 9fd8d6c9186..cb2c75ae0bf 100644
--- a/src/libstd/sys/redox/ext/mod.rs
+++ b/src/libstd/sys/redox/ext/mod.rs
@@ -33,6 +33,7 @@
 pub mod ffi;
 pub mod fs;
 pub mod io;
+pub mod net;
 pub mod process;
 pub mod thread;
 
diff --git a/src/libstd/sys/redox/ext/net.rs b/src/libstd/sys/redox/ext/net.rs
new file mode 100644
index 00000000000..2ab77703242
--- /dev/null
+++ b/src/libstd/sys/redox/ext/net.rs
@@ -0,0 +1,769 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![stable(feature = "unix_socket_redox", since = "1.29")]
+
+//! Unix-specific networking functionality
+
+use fmt;
+use io::{self, Error, ErrorKind, Initializer};
+use net::Shutdown;
+use os::unix::io::{RawFd, AsRawFd, FromRawFd, IntoRawFd};
+use path::Path;
+use time::Duration;
+use sys::{cvt, fd::FileDesc, syscall};
+
+/// An address associated with a Unix socket.
+///
+/// # Examples
+///
+/// ```
+/// use std::os::unix::net::UnixListener;
+///
+/// let socket = match UnixListener::bind("/tmp/sock") {
+///     Ok(sock) => sock,
+///     Err(e) => {
+///         println!("Couldn't bind: {:?}", e);
+///         return
+///     }
+/// };
+/// let addr = socket.local_addr().expect("Couldn't get local address");
+/// ```
+#[derive(Clone)]
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+pub struct SocketAddr(());
+
+impl SocketAddr {
+    /// Returns the contents of this address if it is a `pathname` address.
+    ///
+    /// # Examples
+    ///
+    /// With a pathname:
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    /// use std::path::Path;
+    ///
+    /// let socket = UnixListener::bind("/tmp/sock").unwrap();
+    /// let addr = socket.local_addr().expect("Couldn't get local address");
+    /// assert_eq!(addr.as_pathname(), Some(Path::new("/tmp/sock")));
+    /// ```
+    ///
+    /// Without a pathname:
+    ///
+    /// ```
+    /// use std::os::unix::net::UnixDatagram;
+    ///
+    /// let socket = UnixDatagram::unbound().unwrap();
+    /// let addr = socket.local_addr().expect("Couldn't get local address");
+    /// assert_eq!(addr.as_pathname(), None);
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn as_pathname(&self) -> Option<&Path> {
+        None
+    }
+
+    /// Returns true if and only if the address is unnamed.
+    ///
+    /// # Examples
+    ///
+    /// A named address:
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    ///
+    /// let socket = UnixListener::bind("/tmp/sock").unwrap();
+    /// let addr = socket.local_addr().expect("Couldn't get local address");
+    /// assert_eq!(addr.is_unnamed(), false);
+    /// ```
+    ///
+    /// An unnamed address:
+    ///
+    /// ```
+    /// use std::os::unix::net::UnixDatagram;
+    ///
+    /// let socket = UnixDatagram::unbound().unwrap();
+    /// let addr = socket.local_addr().expect("Couldn't get local address");
+    /// assert_eq!(addr.is_unnamed(), true);
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn is_unnamed(&self) -> bool {
+        false
+    }
+}
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl fmt::Debug for SocketAddr {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "SocketAddr")
+    }
+}
+
+/// A Unix stream socket.
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::os::unix::net::UnixStream;
+/// use std::io::prelude::*;
+///
+/// let mut stream = UnixStream::connect("/path/to/my/socket").unwrap();
+/// stream.write_all(b"hello world").unwrap();
+/// let mut response = String::new();
+/// stream.read_to_string(&mut response).unwrap();
+/// println!("{}", response);
+/// ```
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+pub struct UnixStream(FileDesc);
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl fmt::Debug for UnixStream {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut builder = fmt.debug_struct("UnixStream");
+        builder.field("fd", &self.0.raw());
+        if let Ok(addr) = self.local_addr() {
+            builder.field("local", &addr);
+        }
+        if let Ok(addr) = self.peer_addr() {
+            builder.field("peer", &addr);
+        }
+        builder.finish()
+    }
+}
+
+impl UnixStream {
+    /// Connects to the socket named by `path`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// let socket = match UnixStream::connect("/tmp/sock") {
+    ///     Ok(sock) => sock,
+    ///     Err(e) => {
+    ///         println!("Couldn't connect: {:?}", e);
+    ///         return
+    ///     }
+    /// };
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn connect<P: AsRef<Path>>(path: P) -> io::Result<UnixStream> {
+        if let Some(s) = path.as_ref().to_str() {
+            cvt(syscall::open(format!("chan:{}", s), syscall::O_CLOEXEC))
+                .map(FileDesc::new)
+                .map(UnixStream)
+        } else {
+            Err(Error::new(
+                ErrorKind::Other,
+                "UnixStream::connect: non-utf8 paths not supported on redox"
+            ))
+        }
+    }
+
+    /// Creates an unnamed pair of connected sockets.
+    ///
+    /// Returns two `UnixStream`s which are connected to each other.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// let (sock1, sock2) = match UnixStream::pair() {
+    ///     Ok((sock1, sock2)) => (sock1, sock2),
+    ///     Err(e) => {
+    ///         println!("Couldn't create a pair of sockets: {:?}", e);
+    ///         return
+    ///     }
+    /// };
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn pair() -> io::Result<(UnixStream, UnixStream)> {
+        let server = cvt(syscall::open("chan:", syscall::O_CREAT | syscall::O_CLOEXEC))
+            .map(FileDesc::new)?;
+        let client = server.duplicate_path(b"connect")?;
+        let stream = server.duplicate_path(b"listen")?;
+        Ok((UnixStream(client), UnixStream(stream)))
+    }
+
+    /// Creates a new independently owned handle to the underlying socket.
+    ///
+    /// The returned `UnixStream` is a reference to the same stream that this
+    /// object references. Both handles will read and write the same stream of
+    /// data, and options set on one stream will be propagated to the other
+    /// stream.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// let sock_copy = socket.try_clone().expect("Couldn't clone socket");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn try_clone(&self) -> io::Result<UnixStream> {
+        self.0.duplicate().map(UnixStream)
+    }
+
+    /// Returns the socket address of the local half of this connection.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// let addr = socket.local_addr().expect("Couldn't get local address");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        Err(Error::new(ErrorKind::Other, "UnixStream::local_addr unimplemented on redox"))
+    }
+
+    /// Returns the socket address of the remote half of this connection.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// let addr = socket.peer_addr().expect("Couldn't get peer address");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        Err(Error::new(ErrorKind::Other, "UnixStream::peer_addr unimplemented on redox"))
+    }
+
+    /// Sets the read timeout for the socket.
+    ///
+    /// If the provided value is [`None`], then [`read`] calls will block
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method.
+    ///
+    /// [`None`]: ../../../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../../../std/result/enum.Result.html#variant.Err
+    /// [`read`]: ../../../../std/io/trait.Read.html#tymethod.read
+    /// [`Duration`]: ../../../../std/time/struct.Duration.html
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// socket.set_read_timeout(Some(Duration::new(1, 0))).expect("Couldn't set read timeout");
+    /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::os::unix::net::UnixStream;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// let result = socket.set_read_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn set_read_timeout(&self, _timeout: Option<Duration>) -> io::Result<()> {
+        Err(Error::new(ErrorKind::Other, "UnixStream::set_read_timeout unimplemented on redox"))
+    }
+
+    /// Sets the write timeout for the socket.
+    ///
+    /// If the provided value is [`None`], then [`write`] calls will block
+    /// indefinitely. An [`Err`] is returned if the zero [`Duration`] is
+    /// passed to this method.
+    ///
+    /// [`None`]: ../../../../std/option/enum.Option.html#variant.None
+    /// [`Err`]: ../../../../std/result/enum.Result.html#variant.Err
+    /// [`write`]: ../../../../std/io/trait.Write.html#tymethod.write
+    /// [`Duration`]: ../../../../std/time/struct.Duration.html
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// socket.set_write_timeout(Some(Duration::new(1, 0))).expect("Couldn't set write timeout");
+    /// ```
+    ///
+    /// An [`Err`] is returned if the zero [`Duration`] is passed to this
+    /// method:
+    ///
+    /// ```no_run
+    /// use std::io;
+    /// use std::net::UdpSocket;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:34254").unwrap();
+    /// let result = socket.set_write_timeout(Some(Duration::new(0, 0)));
+    /// let err = result.unwrap_err();
+    /// assert_eq!(err.kind(), io::ErrorKind::InvalidInput)
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn set_write_timeout(&self, _timeout: Option<Duration>) -> io::Result<()> {
+        Err(Error::new(ErrorKind::Other, "UnixStream::set_write_timeout unimplemented on redox"))
+    }
+
+    /// Returns the read timeout of this socket.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// socket.set_read_timeout(Some(Duration::new(1, 0))).expect("Couldn't set read timeout");
+    /// assert_eq!(socket.read_timeout().unwrap(), Some(Duration::new(1, 0)));
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn read_timeout(&self) -> io::Result<Option<Duration>> {
+        Err(Error::new(ErrorKind::Other, "UnixStream::read_timeout unimplemented on redox"))
+    }
+
+    /// Returns the write timeout of this socket.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    /// use std::time::Duration;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// socket.set_write_timeout(Some(Duration::new(1, 0))).expect("Couldn't set write timeout");
+    /// assert_eq!(socket.write_timeout().unwrap(), Some(Duration::new(1, 0)));
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn write_timeout(&self) -> io::Result<Option<Duration>> {
+        Err(Error::new(ErrorKind::Other, "UnixStream::write_timeout unimplemented on redox"))
+    }
+
+    /// Moves the socket into or out of nonblocking mode.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// socket.set_nonblocking(true).expect("Couldn't set nonblocking");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        self.0.set_nonblocking(nonblocking)
+    }
+
+    /// Returns the value of the `SO_ERROR` option.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// if let Ok(Some(err)) = socket.take_error() {
+    ///     println!("Got error: {:?}", err);
+    /// }
+    /// ```
+    ///
+    /// # Platform specific
+    /// On Redox this always returns None.
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        Ok(None)
+    }
+
+    /// Shuts down the read, write, or both halves of this connection.
+    ///
+    /// This function will cause all pending and future I/O calls on the
+    /// specified portions to immediately return with an appropriate value
+    /// (see the documentation of [`Shutdown`]).
+    ///
+    /// [`Shutdown`]: ../../../../std/net/enum.Shutdown.html
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixStream;
+    /// use std::net::Shutdown;
+    ///
+    /// let socket = UnixStream::connect("/tmp/sock").unwrap();
+    /// socket.shutdown(Shutdown::Both).expect("shutdown function failed");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn shutdown(&self, _how: Shutdown) -> io::Result<()> {
+        Err(Error::new(ErrorKind::Other, "UnixStream::shutdown unimplemented on redox"))
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl io::Read for UnixStream {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        io::Read::read(&mut &*self, buf)
+    }
+
+    #[inline]
+    unsafe fn initializer(&self) -> Initializer {
+        Initializer::nop()
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl<'a> io::Read for &'a UnixStream {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.read(buf)
+    }
+
+    #[inline]
+    unsafe fn initializer(&self) -> Initializer {
+        Initializer::nop()
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl io::Write for UnixStream {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        io::Write::write(&mut &*self, buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        io::Write::flush(&mut &*self)
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl<'a> io::Write for &'a UnixStream {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.0.write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl AsRawFd for UnixStream {
+    fn as_raw_fd(&self) -> RawFd {
+        self.0.raw()
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl FromRawFd for UnixStream {
+    unsafe fn from_raw_fd(fd: RawFd) -> UnixStream {
+        UnixStream(FileDesc::new(fd))
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl IntoRawFd for UnixStream {
+    fn into_raw_fd(self) -> RawFd {
+        self.0.into_raw()
+    }
+}
+
+/// A structure representing a Unix domain socket server.
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::thread;
+/// use std::os::unix::net::{UnixStream, UnixListener};
+///
+/// fn handle_client(stream: UnixStream) {
+///     // ...
+/// }
+///
+/// let listener = UnixListener::bind("/path/to/the/socket").unwrap();
+///
+/// // accept connections and process them, spawning a new thread for each one
+/// for stream in listener.incoming() {
+///     match stream {
+///         Ok(stream) => {
+///             /* connection succeeded */
+///             thread::spawn(|| handle_client(stream));
+///         }
+///         Err(err) => {
+///             /* connection failed */
+///             break;
+///         }
+///     }
+/// }
+/// ```
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+pub struct UnixListener(FileDesc);
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl fmt::Debug for UnixListener {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut builder = fmt.debug_struct("UnixListener");
+        builder.field("fd", &self.0.raw());
+        if let Ok(addr) = self.local_addr() {
+            builder.field("local", &addr);
+        }
+        builder.finish()
+    }
+}
+
+impl UnixListener {
+    /// Creates a new `UnixListener` bound to the specified socket.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    ///
+    /// let listener = match UnixListener::bind("/path/to/the/socket") {
+    ///     Ok(sock) => sock,
+    ///     Err(e) => {
+    ///         println!("Couldn't connect: {:?}", e);
+    ///         return
+    ///     }
+    /// };
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn bind<P: AsRef<Path>>(path: P) -> io::Result<UnixListener> {
+        if let Some(s) = path.as_ref().to_str() {
+            cvt(syscall::open(format!("chan:{}", s), syscall::O_CREAT | syscall::O_CLOEXEC))
+                .map(FileDesc::new)
+                .map(UnixListener)
+        } else {
+            Err(Error::new(
+                ErrorKind::Other,
+                "UnixListener::bind: non-utf8 paths not supported on redox"
+            ))
+        }
+    }
+
+    /// Accepts a new incoming connection to this listener.
+    ///
+    /// This function will block the calling thread until a new Unix connection
+    /// is established. When established, the corresponding [`UnixStream`] and
+    /// the remote peer's address will be returned.
+    ///
+    /// [`UnixStream`]: ../../../../std/os/unix/net/struct.UnixStream.html
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    ///
+    /// let listener = UnixListener::bind("/path/to/the/socket").unwrap();
+    ///
+    /// match listener.accept() {
+    ///     Ok((socket, addr)) => println!("Got a client: {:?}", addr),
+    ///     Err(e) => println!("accept function failed: {:?}", e),
+    /// }
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn accept(&self) -> io::Result<(UnixStream, SocketAddr)> {
+        self.0.duplicate_path(b"listen").map(|fd| (UnixStream(fd), SocketAddr(())))
+    }
+
+    /// Creates a new independently owned handle to the underlying socket.
+    ///
+    /// The returned `UnixListener` is a reference to the same socket that this
+    /// object references. Both handles can be used to accept incoming
+    /// connections and options set on one listener will affect the other.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    ///
+    /// let listener = UnixListener::bind("/path/to/the/socket").unwrap();
+    ///
+    /// let listener_copy = listener.try_clone().expect("try_clone failed");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn try_clone(&self) -> io::Result<UnixListener> {
+        self.0.duplicate().map(UnixListener)
+    }
+
+    /// Returns the local socket address of this listener.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    ///
+    /// let listener = UnixListener::bind("/path/to/the/socket").unwrap();
+    ///
+    /// let addr = listener.local_addr().expect("Couldn't get local address");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        Err(Error::new(ErrorKind::Other, "UnixListener::local_addr unimplemented on redox"))
+    }
+
+    /// Moves the socket into or out of nonblocking mode.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    ///
+    /// let listener = UnixListener::bind("/path/to/the/socket").unwrap();
+    ///
+    /// listener.set_nonblocking(true).expect("Couldn't set non blocking");
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        self.0.set_nonblocking(nonblocking)
+    }
+
+    /// Returns the value of the `SO_ERROR` option.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::os::unix::net::UnixListener;
+    ///
+    /// let listener = UnixListener::bind("/tmp/sock").unwrap();
+    ///
+    /// if let Ok(Some(err)) = listener.take_error() {
+    ///     println!("Got error: {:?}", err);
+    /// }
+    /// ```
+    ///
+    /// # Platform specific
+    /// On Redox this always returns None.
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        Ok(None)
+    }
+
+    /// Returns an iterator over incoming connections.
+    ///
+    /// The iterator will never return [`None`] and will also not yield the
+    /// peer's [`SocketAddr`] structure.
+    ///
+    /// [`None`]: ../../../../std/option/enum.Option.html#variant.None
+    /// [`SocketAddr`]: struct.SocketAddr.html
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::thread;
+    /// use std::os::unix::net::{UnixStream, UnixListener};
+    ///
+    /// fn handle_client(stream: UnixStream) {
+    ///     // ...
+    /// }
+    ///
+    /// let listener = UnixListener::bind("/path/to/the/socket").unwrap();
+    ///
+    /// for stream in listener.incoming() {
+    ///     match stream {
+    ///         Ok(stream) => {
+    ///             thread::spawn(|| handle_client(stream));
+    ///         }
+    ///         Err(err) => {
+    ///             break;
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    #[stable(feature = "unix_socket_redox", since = "1.29")]
+    pub fn incoming<'a>(&'a self) -> Incoming<'a> {
+        Incoming { listener: self }
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl AsRawFd for UnixListener {
+    fn as_raw_fd(&self) -> RawFd {
+        self.0.raw()
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl FromRawFd for UnixListener {
+    unsafe fn from_raw_fd(fd: RawFd) -> UnixListener {
+        UnixListener(FileDesc::new(fd))
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl IntoRawFd for UnixListener {
+    fn into_raw_fd(self) -> RawFd {
+        self.0.into_raw()
+    }
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl<'a> IntoIterator for &'a UnixListener {
+    type Item = io::Result<UnixStream>;
+    type IntoIter = Incoming<'a>;
+
+    fn into_iter(self) -> Incoming<'a> {
+        self.incoming()
+    }
+}
+
+/// An iterator over incoming connections to a [`UnixListener`].
+///
+/// It will never return [`None`].
+///
+/// [`None`]: ../../../../std/option/enum.Option.html#variant.None
+/// [`UnixListener`]: struct.UnixListener.html
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::thread;
+/// use std::os::unix::net::{UnixStream, UnixListener};
+///
+/// fn handle_client(stream: UnixStream) {
+///     // ...
+/// }
+///
+/// let listener = UnixListener::bind("/path/to/the/socket").unwrap();
+///
+/// for stream in listener.incoming() {
+///     match stream {
+///         Ok(stream) => {
+///             thread::spawn(|| handle_client(stream));
+///         }
+///         Err(err) => {
+///             break;
+///         }
+///     }
+/// }
+/// ```
+#[derive(Debug)]
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+pub struct Incoming<'a> {
+    listener: &'a UnixListener,
+}
+
+#[stable(feature = "unix_socket_redox", since = "1.29")]
+impl<'a> Iterator for Incoming<'a> {
+    type Item = io::Result<UnixStream>;
+
+    fn next(&mut self) -> Option<io::Result<UnixStream>> {
+        Some(self.listener.accept().map(|s| s.0))
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (usize::max_value(), None)
+    }
+}
diff --git a/src/libstd/sys/redox/fd.rs b/src/libstd/sys/redox/fd.rs
index ba7bbdc657f..e04e2791b23 100644
--- a/src/libstd/sys/redox/fd.rs
+++ b/src/libstd/sys/redox/fd.rs
@@ -47,7 +47,10 @@ impl FileDesc {
     }
 
     pub fn duplicate(&self) -> io::Result<FileDesc> {
-        let new_fd = cvt(syscall::dup(self.fd, &[]))?;
+        self.duplicate_path(&[])
+    }
+    pub fn duplicate_path(&self, path: &[u8]) -> io::Result<FileDesc> {
+        let new_fd = cvt(syscall::dup(self.fd, path))?;
         Ok(FileDesc::new(new_fd))
     }
 
diff --git a/src/libstd/sys/redox/net/mod.rs b/src/libstd/sys/redox/net/mod.rs
index 0291d7f0e92..67f22231d5f 100644
--- a/src/libstd/sys/redox/net/mod.rs
+++ b/src/libstd/sys/redox/net/mod.rs
@@ -41,12 +41,12 @@ impl Iterator for LookupHost {
 pub fn lookup_host(host: &str) -> Result<LookupHost> {
     let mut ip_string = String::new();
     File::open("/etc/net/ip")?.read_to_string(&mut ip_string)?;
-    let ip: Vec<u8> = ip_string.trim().split(".").map(|part| part.parse::<u8>()
+    let ip: Vec<u8> = ip_string.trim().split('.').map(|part| part.parse::<u8>()
                                .unwrap_or(0)).collect();
 
     let mut dns_string = String::new();
     File::open("/etc/net/dns")?.read_to_string(&mut dns_string)?;
-    let dns: Vec<u8> = dns_string.trim().split(".").map(|part| part.parse::<u8>()
+    let dns: Vec<u8> = dns_string.trim().split('.').map(|part| part.parse::<u8>()
                                  .unwrap_or(0)).collect();
 
     if ip.len() == 4 && dns.len() == 4 {
diff --git a/src/libstd/sys/redox/net/udp.rs b/src/libstd/sys/redox/net/udp.rs
index 2ed67bd2836..22af02079e7 100644
--- a/src/libstd/sys/redox/net/udp.rs
+++ b/src/libstd/sys/redox/net/udp.rs
@@ -58,7 +58,7 @@ impl UdpSocket {
 
     pub fn recv(&self, buf: &mut [u8]) -> Result<usize> {
         if let Some(addr) = *self.get_conn() {
-            let from = self.0.dup(format!("{}", addr).as_bytes())?;
+            let from = self.0.dup(addr.to_string().as_bytes())?;
             from.read(buf)
         } else {
             Err(Error::new(ErrorKind::Other, "UdpSocket::recv not connected"))
diff --git a/src/libstd/sys/redox/os.rs b/src/libstd/sys/redox/os.rs
index 480765b77a0..5822216779b 100644
--- a/src/libstd/sys/redox/os.rs
+++ b/src/libstd/sys/redox/os.rs
@@ -30,9 +30,6 @@ use sys_common::mutex::Mutex;
 use sys::{cvt, fd, syscall};
 use vec;
 
-const TMPBUF_SZ: usize = 128;
-static ENV_LOCK: Mutex = Mutex::new();
-
 extern {
     #[link_name = "__errno_location"]
     fn errno_location() -> *mut i32;
diff --git a/src/libstd/sys/redox/process.rs b/src/libstd/sys/redox/process.rs
index d0b94e14f54..2037616e6ac 100644
--- a/src/libstd/sys/redox/process.rs
+++ b/src/libstd/sys/redox/process.rs
@@ -13,6 +13,7 @@ use ffi::OsStr;
 use os::unix::ffi::OsStrExt;
 use fmt;
 use io::{self, Error, ErrorKind};
+use iter;
 use libc::{EXIT_SUCCESS, EXIT_FAILURE};
 use path::{Path, PathBuf};
 use sys::fd::FileDesc;
@@ -51,7 +52,7 @@ pub struct Command {
     uid: Option<u32>,
     gid: Option<u32>,
     saw_nul: bool,
-    closures: Vec<Box<FnMut() -> io::Result<()> + Send + Sync>>,
+    closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>,
     stdin: Option<Stdio>,
     stdout: Option<Stdio>,
     stderr: Option<Stdio>,
@@ -122,7 +123,7 @@ impl Command {
     }
 
     pub fn before_exec(&mut self,
-                       f: Box<FnMut() -> io::Result<()> + Send + Sync>) {
+                       f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>) {
         self.closures.push(f);
     }
 
@@ -296,11 +297,11 @@ impl Command {
             t!(callback());
         }
 
-        let mut args: Vec<[usize; 2]> = Vec::new();
-        args.push([self.program.as_ptr() as usize, self.program.len()]);
-        for arg in self.args.iter() {
-            args.push([arg.as_ptr() as usize, arg.len()]);
-        }
+        let args: Vec<[usize; 2]> = iter::once(
+            [self.program.as_ptr() as usize, self.program.len()]
+        ).chain(
+            self.args.iter().map(|arg| [arg.as_ptr() as usize, arg.len()])
+        ).collect();
 
         self.env.apply();
 
diff --git a/src/libstd/sys/redox/syscall/error.rs b/src/libstd/sys/redox/syscall/error.rs
index d8d78d55016..1ef79547431 100644
--- a/src/libstd/sys/redox/syscall/error.rs
+++ b/src/libstd/sys/redox/syscall/error.rs
@@ -48,13 +48,13 @@ impl Error {
 }
 
 impl fmt::Debug for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.write_str(self.text())
     }
 }
 
 impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.write_str(self.text())
     }
 }
diff --git a/src/libstd/sys/redox/thread.rs b/src/libstd/sys/redox/thread.rs
index 110d46ca3ab..f4177087d77 100644
--- a/src/libstd/sys/redox/thread.rs
+++ b/src/libstd/sys/redox/thread.rs
@@ -28,7 +28,7 @@ unsafe impl Send for Thread {}
 unsafe impl Sync for Thread {}
 
 impl Thread {
-    pub unsafe fn new<'a>(_stack: usize, p: Box<FnBox() + 'a>) -> io::Result<Thread> {
+    pub unsafe fn new<'a>(_stack: usize, p: Box<dyn FnBox() + 'a>) -> io::Result<Thread> {
         let p = box p;
 
         let id = cvt(syscall::clone(syscall::CLONE_VM | syscall::CLONE_FS | syscall::CLONE_FILES))?;
diff --git a/src/libstd/sys/redox/time.rs b/src/libstd/sys/redox/time.rs
index cf798500b7f..5c491115c55 100644
--- a/src/libstd/sys/redox/time.rs
+++ b/src/libstd/sys/redox/time.rs
@@ -144,7 +144,7 @@ impl Instant {
 
     pub fn sub_instant(&self, other: &Instant) -> Duration {
         self.t.sub_timespec(&other.t).unwrap_or_else(|_| {
-            panic!("other was less than the current instant")
+            panic!("specified instant was later than self")
         })
     }
 
diff --git a/src/libstd/sys/unix/args.rs b/src/libstd/sys/unix/args.rs
index e1c7ffc19e5..dc1dba6f2f9 100644
--- a/src/libstd/sys/unix/args.rs
+++ b/src/libstd/sys/unix/args.rs
@@ -82,17 +82,15 @@ mod imp {
     static LOCK: Mutex = Mutex::new();
 
     pub unsafe fn init(argc: isize, argv: *const *const u8) {
-        LOCK.lock();
+        let _guard = LOCK.lock();
         ARGC = argc;
         ARGV = argv;
-        LOCK.unlock();
     }
 
     pub unsafe fn cleanup() {
-        LOCK.lock();
+        let _guard = LOCK.lock();
         ARGC = 0;
         ARGV = ptr::null();
-        LOCK.unlock();
     }
 
     pub fn args() -> Args {
@@ -104,13 +102,11 @@ mod imp {
 
     fn clone() -> Vec<OsString> {
         unsafe {
-            LOCK.lock();
-            let ret = (0..ARGC).map(|i| {
+            let _guard = LOCK.lock();
+            (0..ARGC).map(|i| {
                 let cstr = CStr::from_ptr(*ARGV.offset(i) as *const libc::c_char);
                 OsStringExt::from_vec(cstr.to_bytes().to_vec())
-            }).collect();
-            LOCK.unlock();
-            return ret
+            }).collect()
         }
     }
 }
diff --git a/src/libstd/sys/unix/ext/fs.rs b/src/libstd/sys/unix/ext/fs.rs
index 4e981012669..507e9d88171 100644
--- a/src/libstd/sys/unix/ext/fs.rs
+++ b/src/libstd/sys/unix/ext/fs.rs
@@ -59,6 +59,78 @@ pub trait FileExt {
     #[stable(feature = "file_offset", since = "1.15.0")]
     fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize>;
 
+    /// Reads the exact number of byte required to fill `buf` from the given offset.
+    ///
+    /// The offset is relative to the start of the file and thus independent
+    /// from the current cursor.
+    ///
+    /// The current file cursor is not affected by this function.
+    ///
+    /// Similar to [`Read::read_exact`] but uses [`read_at`] instead of `read`.
+    ///
+    /// [`Read::read_exact`]: ../../../../std/io/trait.Read.html#method.read_exact
+    /// [`read_at`]: #tymethod.read_at
+    ///
+    /// # Errors
+    ///
+    /// If this function encounters an error of the kind
+    /// [`ErrorKind::Interrupted`] then the error is ignored and the operation
+    /// will continue.
+    ///
+    /// If this function encounters an "end of file" before completely filling
+    /// the buffer, it returns an error of the kind [`ErrorKind::UnexpectedEof`].
+    /// The contents of `buf` are unspecified in this case.
+    ///
+    /// If any other read error is encountered then this function immediately
+    /// returns. The contents of `buf` are unspecified in this case.
+    ///
+    /// If this function returns an error, it is unspecified how many bytes it
+    /// has read, but it will never read more than would be necessary to
+    /// completely fill the buffer.
+    ///
+    /// [`ErrorKind::Interrupted`]: ../../../../std/io/enum.ErrorKind.html#variant.Interrupted
+    /// [`ErrorKind::UnexpectedEof`]: ../../../../std/io/enum.ErrorKind.html#variant.UnexpectedEof
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(rw_exact_all_at)]
+    /// use std::io;
+    /// use std::fs::File;
+    /// use std::os::unix::prelude::FileExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let mut buf = [0u8; 8];
+    ///     let file = File::open("foo.txt")?;
+    ///
+    ///     // We now read exactly 8 bytes from the offset 10.
+    ///     file.read_exact_at(&mut buf, 10)?;
+    ///     println!("read {} bytes: {:?}", buf.len(), buf);
+    ///     Ok(())
+    /// }
+    /// ```
+    #[unstable(feature = "rw_exact_all_at", issue = "51984")]
+    fn read_exact_at(&self, mut buf: &mut [u8], mut offset: u64) -> io::Result<()> {
+        while !buf.is_empty() {
+            match self.read_at(buf, offset) {
+                Ok(0) => break,
+                Ok(n) => {
+                    let tmp = buf;
+                    buf = &mut tmp[n..];
+                    offset += n as u64;
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
+                Err(e) => return Err(e),
+            }
+        }
+        if !buf.is_empty() {
+            Err(io::Error::new(io::ErrorKind::UnexpectedEof,
+                               "failed to fill whole buffer"))
+        } else {
+            Ok(())
+        }
+    }
+
     /// Writes a number of bytes starting from a given offset.
     ///
     /// Returns the number of bytes written.
@@ -93,6 +165,61 @@ pub trait FileExt {
     /// ```
     #[stable(feature = "file_offset", since = "1.15.0")]
     fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize>;
+
+    /// Attempts to write an entire buffer starting from a given offset.
+    ///
+    /// The offset is relative to the start of the file and thus independent
+    /// from the current cursor.
+    ///
+    /// The current file cursor is not affected by this function.
+    ///
+    /// This method will continuously call [`write_at`] until there is no more data
+    /// to be written or an error of non-[`ErrorKind::Interrupted`] kind is
+    /// returned. This method will not return until the entire buffer has been
+    /// successfully written or such an error occurs. The first error that is
+    /// not of [`ErrorKind::Interrupted`] kind generated from this method will be
+    /// returned.
+    ///
+    /// # Errors
+    ///
+    /// This function will return the first error of
+    /// non-[`ErrorKind::Interrupted`] kind that [`write_at`] returns.
+    ///
+    /// [`ErrorKind::Interrupted`]: ../../../../std/io/enum.ErrorKind.html#variant.Interrupted
+    /// [`write_at`]: #tymethod.write_at
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(rw_exact_all_at)]
+    /// use std::fs::File;
+    /// use std::io;
+    /// use std::os::unix::prelude::FileExt;
+    ///
+    /// fn main() -> io::Result<()> {
+    ///     let file = File::open("foo.txt")?;
+    ///
+    ///     // We now write at the offset 10.
+    ///     file.write_all_at(b"sushi", 10)?;
+    ///     Ok(())
+    /// }
+    /// ```
+    #[unstable(feature = "rw_exact_all_at", issue = "51984")]
+    fn write_all_at(&self, mut buf: &[u8], mut offset: u64) -> io::Result<()> {
+        while !buf.is_empty() {
+            match self.write_at(buf, offset) {
+                Ok(0) => return Err(io::Error::new(io::ErrorKind::WriteZero,
+                                                   "failed to write whole buffer")),
+                Ok(n) => {
+                    buf = &buf[n..];
+                    offset += n as u64
+                }
+                Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
+                Err(e) => return Err(e),
+            }
+        }
+        Ok(())
+    }
 }
 
 #[stable(feature = "file_offset", since = "1.15.0")]
diff --git a/src/libstd/sys/unix/ext/mod.rs b/src/libstd/sys/unix/ext/mod.rs
index c221f7c8cfe..88e4237f8e2 100644
--- a/src/libstd/sys/unix/ext/mod.rs
+++ b/src/libstd/sys/unix/ext/mod.rs
@@ -35,6 +35,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 #![doc(cfg(unix))]
+#![allow(missing_docs)]
 
 pub mod io;
 pub mod ffi;
diff --git a/src/libstd/sys/unix/ext/net.rs b/src/libstd/sys/unix/ext/net.rs
index e277b1aa7b5..55f43ccd7db 100644
--- a/src/libstd/sys/unix/ext/net.rs
+++ b/src/libstd/sys/unix/ext/net.rs
@@ -524,6 +524,9 @@ impl UnixStream {
     ///     println!("Got error: {:?}", err);
     /// }
     /// ```
+    ///
+    /// # Platform specific
+    /// On Redox this always returns None.
     #[stable(feature = "unix_socket", since = "1.10.0")]
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
         self.0.take_error()
@@ -846,6 +849,9 @@ impl UnixListener {
     ///     println!("Got error: {:?}", err);
     /// }
     /// ```
+    ///
+    /// # Platform specific
+    /// On Redox this always returns None.
     #[stable(feature = "unix_socket", since = "1.10.0")]
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
         self.0.take_error()
diff --git a/src/libstd/sys/unix/fast_thread_local.rs b/src/libstd/sys/unix/fast_thread_local.rs
index 6cdbe5df75d..d59d800a579 100644
--- a/src/libstd/sys/unix/fast_thread_local.rs
+++ b/src/libstd/sys/unix/fast_thread_local.rs
@@ -20,7 +20,7 @@
 // fallback implementation to use as well.
 //
 // Due to rust-lang/rust#18804, make sure this is not generic!
-#[cfg(target_os = "linux")]
+#[cfg(any(target_os = "linux", target_os = "fuchsia"))]
 pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
     use libc;
     use mem;
@@ -55,11 +55,6 @@ pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
     _tlv_atexit(dtor, t);
 }
 
-// Just use the thread_local fallback implementation, at least until there's
-// a more direct implementation.
-#[cfg(target_os = "fuchsia")]
-pub use sys_common::thread_local::register_dtor_fallback as register_dtor;
-
 pub fn requires_move_before_drop() -> bool {
     // The macOS implementation of TLS apparently had an odd aspect to it
     // where the pointer we have may be overwritten while this destructor
diff --git a/src/libstd/sys/unix/fd.rs b/src/libstd/sys/unix/fd.rs
index 5dafc3251e7..4830e38d6a9 100644
--- a/src/libstd/sys/unix/fd.rs
+++ b/src/libstd/sys/unix/fd.rs
@@ -75,8 +75,15 @@ impl FileDesc {
         unsafe fn cvt_pread64(fd: c_int, buf: *mut c_void, count: usize, offset: i64)
             -> io::Result<isize>
         {
+            use convert::TryInto;
             use libc::pread64;
-            cvt(pread64(fd, buf, count, offset as i32))
+            // pread64 on emscripten actually takes a 32 bit offset
+            if let Ok(o) = offset.try_into() {
+                cvt(pread64(fd, buf, count, o))
+            } else {
+                Err(io::Error::new(io::ErrorKind::InvalidInput,
+                                   "cannot pread >2GB"))
+            }
         }
 
         #[cfg(not(any(target_os = "android", target_os = "emscripten")))]
@@ -116,8 +123,15 @@ impl FileDesc {
         unsafe fn cvt_pwrite64(fd: c_int, buf: *const c_void, count: usize, offset: i64)
             -> io::Result<isize>
         {
+            use convert::TryInto;
             use libc::pwrite64;
-            cvt(pwrite64(fd, buf, count, offset as i32))
+            // pwrite64 on emscripten actually takes a 32 bit offset
+            if let Ok(o) = offset.try_into() {
+                cvt(pwrite64(fd, buf, count, o))
+            } else {
+                Err(io::Error::new(io::ErrorKind::InvalidInput,
+                                   "cannot pwrite >2GB"))
+            }
         }
 
         #[cfg(not(any(target_os = "android", target_os = "emscripten")))]
@@ -140,6 +154,13 @@ impl FileDesc {
         }
     }
 
+    #[cfg(target_os = "linux")]
+    pub fn get_cloexec(&self) -> io::Result<bool> {
+        unsafe {
+            Ok((cvt(libc::fcntl(self.fd, libc::F_GETFD))? & libc::FD_CLOEXEC) != 0)
+        }
+    }
+
     #[cfg(not(any(target_env = "newlib",
                   target_os = "solaris",
                   target_os = "emscripten",
diff --git a/src/libstd/sys/unix/fs.rs b/src/libstd/sys/unix/fs.rs
index a1ca839dc18..662a76d6725 100644
--- a/src/libstd/sys/unix/fs.rs
+++ b/src/libstd/sys/unix/fs.rs
@@ -25,8 +25,12 @@ use sys_common::{AsInner, FromInner};
 
 #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "l4re"))]
 use libc::{stat64, fstat64, lstat64, off64_t, ftruncate64, lseek64, dirent64, readdir64_r, open64};
+#[cfg(any(target_os = "linux", target_os = "emscripten"))]
+use libc::fstatat64;
+#[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "android"))]
+use libc::dirfd;
 #[cfg(target_os = "android")]
-use libc::{stat as stat64, fstat as fstat64, lstat as lstat64, lseek64,
+use libc::{stat as stat64, fstat as fstat64, fstatat as fstatat64, lstat as lstat64, lseek64,
            dirent as dirent64, open as open64};
 #[cfg(not(any(target_os = "linux",
               target_os = "emscripten",
@@ -48,9 +52,16 @@ pub struct FileAttr {
     stat: stat64,
 }
 
-pub struct ReadDir {
+// all DirEntry's will have a reference to this struct
+struct InnerReadDir {
     dirp: Dir,
-    root: Arc<PathBuf>,
+    root: PathBuf,
+}
+
+#[derive(Clone)]
+pub struct ReadDir {
+    inner: Arc<InnerReadDir>,
+    end_of_stream: bool,
 }
 
 struct Dir(*mut libc::DIR);
@@ -60,8 +71,8 @@ unsafe impl Sync for Dir {}
 
 pub struct DirEntry {
     entry: dirent64,
-    root: Arc<PathBuf>,
-    // We need to store an owned copy of the directory name
+    dir: ReadDir,
+    // We need to store an owned copy of the entry name
     // on Solaris and Fuchsia because a) it uses a zero-length
     // array to store the name, b) its lifetime between readdir
     // calls is not guaranteed.
@@ -207,7 +218,7 @@ impl fmt::Debug for ReadDir {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         // This will only be called from std::fs::ReadDir, which will add a "ReadDir()" frame.
         // Thus the result will be e g 'ReadDir("/home")'
-        fmt::Debug::fmt(&*self.root, f)
+        fmt::Debug::fmt(&*self.inner.root, f)
     }
 }
 
@@ -223,7 +234,7 @@ impl Iterator for ReadDir {
                 // is safe to use in threaded applications and it is generally preferred
                 // over the readdir_r(3C) function.
                 super::os::set_errno(0);
-                let entry_ptr = libc::readdir(self.dirp.0);
+                let entry_ptr = libc::readdir(self.inner.dirp.0);
                 if entry_ptr.is_null() {
                     // NULL can mean either the end is reached or an error occurred.
                     // So we had to clear errno beforehand to check for an error now.
@@ -240,7 +251,7 @@ impl Iterator for ReadDir {
                     entry: *entry_ptr,
                     name: ::slice::from_raw_parts(name as *const u8,
                                                   namelen as usize).to_owned().into_boxed_slice(),
-                    root: self.root.clone()
+                    dir: self.clone()
                 };
                 if ret.name_bytes() != b"." && ret.name_bytes() != b".." {
                     return Some(Ok(ret))
@@ -251,14 +262,25 @@ impl Iterator for ReadDir {
 
     #[cfg(not(any(target_os = "solaris", target_os = "fuchsia")))]
     fn next(&mut self) -> Option<io::Result<DirEntry>> {
+        if self.end_of_stream {
+            return None;
+        }
+
         unsafe {
             let mut ret = DirEntry {
                 entry: mem::zeroed(),
-                root: self.root.clone()
+                dir: self.clone(),
             };
             let mut entry_ptr = ptr::null_mut();
             loop {
-                if readdir64_r(self.dirp.0, &mut ret.entry, &mut entry_ptr) != 0 {
+                if readdir64_r(self.inner.dirp.0, &mut ret.entry, &mut entry_ptr) != 0 {
+                    if entry_ptr.is_null() {
+                        // We encountered an error (which will be returned in this iteration), but
+                        // we also reached the end of the directory stream. The `end_of_stream`
+                        // flag is enabled to make sure that we return `None` in the next iteration
+                        // (instead of looping forever)
+                        self.end_of_stream = true;
+                    }
                     return Some(Err(Error::last_os_error()))
                 }
                 if entry_ptr.is_null() {
@@ -281,13 +303,24 @@ impl Drop for Dir {
 
 impl DirEntry {
     pub fn path(&self) -> PathBuf {
-        self.root.join(OsStr::from_bytes(self.name_bytes()))
+        self.dir.inner.root.join(OsStr::from_bytes(self.name_bytes()))
     }
 
     pub fn file_name(&self) -> OsString {
         OsStr::from_bytes(self.name_bytes()).to_os_string()
     }
 
+    #[cfg(any(target_os = "linux", target_os = "emscripten", target_os = "android"))]
+    pub fn metadata(&self) -> io::Result<FileAttr> {
+        let fd = cvt(unsafe {dirfd(self.dir.inner.dirp.0)})?;
+        let mut stat: stat64 = unsafe { mem::zeroed() };
+        cvt(unsafe {
+            fstatat64(fd, self.entry.d_name.as_ptr(), &mut stat, libc::AT_SYMLINK_NOFOLLOW)
+        })?;
+        Ok(FileAttr { stat: stat })
+    }
+
+    #[cfg(not(any(target_os = "linux", target_os = "emscripten", target_os = "android")))]
     pub fn metadata(&self) -> io::Result<FileAttr> {
         lstat(&self.path())
     }
@@ -441,15 +474,48 @@ impl File {
 
         // Currently the standard library supports Linux 2.6.18 which did not
         // have the O_CLOEXEC flag (passed above). If we're running on an older
-        // Linux kernel then the flag is just ignored by the OS, so we continue
-        // to explicitly ask for a CLOEXEC fd here.
+        // Linux kernel then the flag is just ignored by the OS. After we open
+        // the first file, we check whether it has CLOEXEC set. If it doesn't,
+        // we will explicitly ask for a CLOEXEC fd for every further file we
+        // open, if it does, we will skip that step.
         //
         // The CLOEXEC flag, however, is supported on versions of macOS/BSD/etc
         // that we support, so we only do this on Linux currently.
-        if cfg!(target_os = "linux") {
-            fd.set_cloexec()?;
+        #[cfg(target_os = "linux")]
+        fn ensure_cloexec(fd: &FileDesc) -> io::Result<()> {
+            use sync::atomic::{AtomicUsize, Ordering};
+
+            const OPEN_CLOEXEC_UNKNOWN: usize = 0;
+            const OPEN_CLOEXEC_SUPPORTED: usize = 1;
+            const OPEN_CLOEXEC_NOTSUPPORTED: usize = 2;
+            static OPEN_CLOEXEC: AtomicUsize = AtomicUsize::new(OPEN_CLOEXEC_UNKNOWN);
+
+            let need_to_set;
+            match OPEN_CLOEXEC.load(Ordering::Relaxed) {
+                OPEN_CLOEXEC_UNKNOWN => {
+                    need_to_set = !fd.get_cloexec()?;
+                    OPEN_CLOEXEC.store(if need_to_set {
+                        OPEN_CLOEXEC_NOTSUPPORTED
+                    } else {
+                        OPEN_CLOEXEC_SUPPORTED
+                    }, Ordering::Relaxed);
+                },
+                OPEN_CLOEXEC_SUPPORTED => need_to_set = false,
+                OPEN_CLOEXEC_NOTSUPPORTED => need_to_set = true,
+                _ => unreachable!(),
+            }
+            if need_to_set {
+                fd.set_cloexec()?;
+            }
+            Ok(())
         }
 
+        #[cfg(not(target_os = "linux"))]
+        fn ensure_cloexec(_: &FileDesc) -> io::Result<()> {
+            Ok(())
+        }
+
+        ensure_cloexec(&fd)?;
         Ok(File(fd))
     }
 
@@ -631,14 +697,18 @@ impl fmt::Debug for File {
 }
 
 pub fn readdir(p: &Path) -> io::Result<ReadDir> {
-    let root = Arc::new(p.to_path_buf());
+    let root = p.to_path_buf();
     let p = cstr(p)?;
     unsafe {
         let ptr = libc::opendir(p.as_ptr());
         if ptr.is_null() {
             Err(Error::last_os_error())
         } else {
-            Ok(ReadDir { dirp: Dir(ptr), root: root })
+            let inner = InnerReadDir { dirp: Dir(ptr), root };
+            Ok(ReadDir{
+                inner: Arc::new(inner),
+                end_of_stream: false,
+            })
         }
     }
 }
@@ -733,7 +803,7 @@ pub fn stat(p: &Path) -> io::Result<FileAttr> {
     let p = cstr(p)?;
     let mut stat: stat64 = unsafe { mem::zeroed() };
     cvt(unsafe {
-        stat64(p.as_ptr(), &mut stat as *mut _ as *mut _)
+        stat64(p.as_ptr(), &mut stat)
     })?;
     Ok(FileAttr { stat: stat })
 }
@@ -742,7 +812,7 @@ pub fn lstat(p: &Path) -> io::Result<FileAttr> {
     let p = cstr(p)?;
     let mut stat: stat64 = unsafe { mem::zeroed() };
     cvt(unsafe {
-        lstat64(p.as_ptr(), &mut stat as *mut _ as *mut _)
+        lstat64(p.as_ptr(), &mut stat)
     })?;
     Ok(FileAttr { stat: stat })
 }
@@ -761,8 +831,9 @@ pub fn canonicalize(p: &Path) -> io::Result<PathBuf> {
     Ok(PathBuf::from(OsString::from_vec(buf)))
 }
 
+#[cfg(not(any(target_os = "linux", target_os = "android")))]
 pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
-    use fs::{File, set_permissions};
+    use fs::File;
     if !from.is_file() {
         return Err(Error::new(ErrorKind::InvalidInput,
                               "the source path is not an existing regular file"))
@@ -773,6 +844,100 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
     let perm = reader.metadata()?.permissions();
 
     let ret = io::copy(&mut reader, &mut writer)?;
-    set_permissions(to, perm)?;
+    writer.set_permissions(perm)?;
     Ok(ret)
 }
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
+    use cmp;
+    use fs::File;
+    use sync::atomic::{AtomicBool, Ordering};
+
+    // Kernel prior to 4.5 don't have copy_file_range
+    // We store the availability in a global to avoid unneccessary syscalls
+    static HAS_COPY_FILE_RANGE: AtomicBool = AtomicBool::new(true);
+
+    unsafe fn copy_file_range(
+        fd_in: libc::c_int,
+        off_in: *mut libc::loff_t,
+        fd_out: libc::c_int,
+        off_out: *mut libc::loff_t,
+        len: libc::size_t,
+        flags: libc::c_uint,
+    ) -> libc::c_long {
+        libc::syscall(
+            libc::SYS_copy_file_range,
+            fd_in,
+            off_in,
+            fd_out,
+            off_out,
+            len,
+            flags,
+        )
+    }
+
+    if !from.is_file() {
+        return Err(Error::new(ErrorKind::InvalidInput,
+                              "the source path is not an existing regular file"))
+    }
+
+    let mut reader = File::open(from)?;
+    let mut writer = File::create(to)?;
+    let (perm, len) = {
+        let metadata = reader.metadata()?;
+        (metadata.permissions(), metadata.size())
+    };
+
+    let has_copy_file_range = HAS_COPY_FILE_RANGE.load(Ordering::Relaxed);
+    let mut written = 0u64;
+    while written < len {
+        let copy_result = if has_copy_file_range {
+            let bytes_to_copy = cmp::min(len - written, usize::max_value() as u64) as usize;
+            let copy_result = unsafe {
+                // We actually don't have to adjust the offsets,
+                // because copy_file_range adjusts the file offset automatically
+                cvt(copy_file_range(reader.as_raw_fd(),
+                                    ptr::null_mut(),
+                                    writer.as_raw_fd(),
+                                    ptr::null_mut(),
+                                    bytes_to_copy,
+                                    0)
+                    )
+            };
+            if let Err(ref copy_err) = copy_result {
+                match copy_err.raw_os_error() {
+                    Some(libc::ENOSYS) | Some(libc::EPERM) => {
+                        HAS_COPY_FILE_RANGE.store(false, Ordering::Relaxed);
+                    }
+                    _ => {}
+                }
+            }
+            copy_result
+        } else {
+            Err(io::Error::from_raw_os_error(libc::ENOSYS))
+        };
+        match copy_result {
+            Ok(ret) => written += ret as u64,
+            Err(err) => {
+                match err.raw_os_error() {
+                    Some(os_err) if os_err == libc::ENOSYS
+                                 || os_err == libc::EXDEV
+                                 || os_err == libc::EPERM => {
+                        // Try fallback io::copy if either:
+                        // - Kernel version is < 4.5 (ENOSYS)
+                        // - Files are mounted on different fs (EXDEV)
+                        // - copy_file_range is disallowed, for example by seccomp (EPERM)
+                        assert_eq!(written, 0);
+                        let ret = io::copy(&mut reader, &mut writer)?;
+                        writer.set_permissions(perm)?;
+                        return Ok(ret)
+                    },
+                    _ => return Err(err),
+                }
+            }
+        }
+    }
+    writer.set_permissions(perm)?;
+    Ok(written)
+}
diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index 4c86fddee4b..addf555eb10 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -409,10 +409,9 @@ pub unsafe fn environ() -> *mut *const *const c_char {
 /// environment variables of the current process.
 pub fn env() -> Env {
     unsafe {
-        ENV_LOCK.lock();
+        let _guard = ENV_LOCK.lock();
         let mut environ = *environ();
         if environ == ptr::null() {
-            ENV_LOCK.unlock();
             panic!("os::env() failure getting env string from OS: {}",
                    io::Error::last_os_error());
         }
@@ -423,12 +422,10 @@ pub fn env() -> Env {
             }
             environ = environ.offset(1);
         }
-        let ret = Env {
+        return Env {
             iter: result.into_iter(),
             _dont_send_or_sync_me: PhantomData,
-        };
-        ENV_LOCK.unlock();
-        return ret
+        }
     }
 
     fn parse(input: &[u8]) -> Option<(OsString, OsString)> {
@@ -452,15 +449,14 @@ pub fn getenv(k: &OsStr) -> io::Result<Option<OsString>> {
     // always None as well
     let k = CString::new(k.as_bytes())?;
     unsafe {
-        ENV_LOCK.lock();
+        let _guard = ENV_LOCK.lock();
         let s = libc::getenv(k.as_ptr()) as *const libc::c_char;
         let ret = if s.is_null() {
             None
         } else {
             Some(OsStringExt::from_vec(CStr::from_ptr(s).to_bytes().to_vec()))
         };
-        ENV_LOCK.unlock();
-        return Ok(ret)
+        Ok(ret)
     }
 }
 
@@ -469,10 +465,8 @@ pub fn setenv(k: &OsStr, v: &OsStr) -> io::Result<()> {
     let v = CString::new(v.as_bytes())?;
 
     unsafe {
-        ENV_LOCK.lock();
-        let ret = cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(|_| ());
-        ENV_LOCK.unlock();
-        return ret
+        let _guard = ENV_LOCK.lock();
+        cvt(libc::setenv(k.as_ptr(), v.as_ptr(), 1)).map(|_| ())
     }
 }
 
@@ -480,10 +474,8 @@ pub fn unsetenv(n: &OsStr) -> io::Result<()> {
     let nbuf = CString::new(n.as_bytes())?;
 
     unsafe {
-        ENV_LOCK.lock();
-        let ret = cvt(libc::unsetenv(nbuf.as_ptr())).map(|_| ());
-        ENV_LOCK.unlock();
-        return ret
+        let _guard = ENV_LOCK.lock();
+        cvt(libc::unsetenv(nbuf.as_ptr())).map(|_| ())
     }
 }
 
@@ -572,7 +564,7 @@ fn glibc_version_cstr() -> Option<&'static CStr> {
 // ignoring any extra dot-separated parts. Otherwise return None.
 #[cfg(target_env = "gnu")]
 fn parse_glibc_version(version: &str) -> Option<(usize, usize)> {
-    let mut parsed_ints = version.split(".").map(str::parse::<usize>).fuse();
+    let mut parsed_ints = version.split('.').map(str::parse::<usize>).fuse();
     match (parsed_ints.next(), parsed_ints.next()) {
         (Some(Ok(major)), Some(Ok(minor))) => Some((major, minor)),
         _ => None
diff --git a/src/libstd/sys/unix/pipe.rs b/src/libstd/sys/unix/pipe.rs
index ec9b6f17dca..0a5dccdddda 100644
--- a/src/libstd/sys/unix/pipe.rs
+++ b/src/libstd/sys/unix/pipe.rs
@@ -100,24 +100,6 @@ pub fn read2(p1: AnonPipe,
         // wait for either pipe to become readable using `poll`
         cvt_r(|| unsafe { libc::poll(fds.as_mut_ptr(), 2, -1) })?;
 
-        // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
-        // EAGAIN. If we hit EOF, then this will happen because the underlying
-        // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
-        // this case we flip the other fd back into blocking mode and read
-        // whatever's leftover on that file descriptor.
-        let read = |fd: &FileDesc, dst: &mut Vec<u8>| {
-            match fd.read_to_end(dst) {
-                Ok(_) => Ok(true),
-                Err(e) => {
-                    if e.raw_os_error() == Some(libc::EWOULDBLOCK) ||
-                       e.raw_os_error() == Some(libc::EAGAIN) {
-                        Ok(false)
-                    } else {
-                        Err(e)
-                    }
-                }
-            }
-        };
         if fds[0].revents != 0 && read(&p1, v1)? {
             p2.set_nonblocking(false)?;
             return p2.read_to_end(v2).map(|_| ());
@@ -127,4 +109,23 @@ pub fn read2(p1: AnonPipe,
             return p1.read_to_end(v1).map(|_| ());
         }
     }
+
+    // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
+    // EAGAIN. If we hit EOF, then this will happen because the underlying
+    // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
+    // this case we flip the other fd back into blocking mode and read
+    // whatever's leftover on that file descriptor.
+    fn read(fd: &FileDesc, dst: &mut Vec<u8>) -> Result<bool, io::Error> {
+        match fd.read_to_end(dst) {
+            Ok(_) => Ok(true),
+            Err(e) => {
+                if e.raw_os_error() == Some(libc::EWOULDBLOCK) ||
+                   e.raw_os_error() == Some(libc::EAGAIN) {
+                    Ok(false)
+                } else {
+                    Err(e)
+                }
+            }
+        }
+    }
 }
diff --git a/src/libstd/sys/unix/process/process_common.rs b/src/libstd/sys/unix/process/process_common.rs
index 6396bb3a49e..77f125f3c5b 100644
--- a/src/libstd/sys/unix/process/process_common.rs
+++ b/src/libstd/sys/unix/process/process_common.rs
@@ -52,7 +52,7 @@ pub struct Command {
     uid: Option<uid_t>,
     gid: Option<gid_t>,
     saw_nul: bool,
-    closures: Vec<Box<FnMut() -> io::Result<()> + Send + Sync>>,
+    closures: Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>>,
     stdin: Option<Stdio>,
     stdout: Option<Stdio>,
     stderr: Option<Stdio>,
@@ -155,12 +155,12 @@ impl Command {
         self.gid
     }
 
-    pub fn get_closures(&mut self) -> &mut Vec<Box<FnMut() -> io::Result<()> + Send + Sync>> {
+    pub fn get_closures(&mut self) -> &mut Vec<Box<dyn FnMut() -> io::Result<()> + Send + Sync>> {
         &mut self.closures
     }
 
     pub fn before_exec(&mut self,
-                       f: Box<FnMut() -> io::Result<()> + Send + Sync>) {
+                       f: Box<dyn FnMut() -> io::Result<()> + Send + Sync>) {
         self.closures.push(f);
     }
 
diff --git a/src/libstd/sys/unix/process/process_fuchsia.rs b/src/libstd/sys/unix/process/process_fuchsia.rs
index 06c0540fec0..fa48001179e 100644
--- a/src/libstd/sys/unix/process/process_fuchsia.rs
+++ b/src/libstd/sys/unix/process/process_fuchsia.rs
@@ -56,68 +56,49 @@ impl Command {
                       -> io::Result<zx_handle_t> {
         use sys::process::zircon::*;
 
-        let job_handle = zx_job_default();
         let envp = match maybe_envp {
             Some(envp) => envp.as_ptr(),
             None => ptr::null(),
         };
 
-        // To make sure launchpad_destroy gets called on the launchpad if this function fails
-        struct LaunchpadDestructor(*mut launchpad_t);
-        impl Drop for LaunchpadDestructor {
-            fn drop(&mut self) { unsafe { launchpad_destroy(self.0); } }
-        }
-
-        // Duplicate the job handle
-        let mut job_copy: zx_handle_t = ZX_HANDLE_INVALID;
-        zx_cvt(zx_handle_duplicate(job_handle, ZX_RIGHT_SAME_RIGHTS, &mut job_copy))?;
-        // Create a launchpad
-        let mut launchpad: *mut launchpad_t = ptr::null_mut();
-        zx_cvt(launchpad_create(job_copy, self.get_argv()[0], &mut launchpad))?;
-        let launchpad_destructor = LaunchpadDestructor(launchpad);
-
-        // Set the process argv
-        zx_cvt(launchpad_set_args(launchpad, self.get_argv().len() as i32 - 1,
-                                  self.get_argv().as_ptr()))?;
-        // Setup the environment vars
-        zx_cvt(launchpad_set_environ(launchpad, envp))?;
-        zx_cvt(launchpad_add_vdso_vmo(launchpad))?;
-        // Load the executable
-        zx_cvt(launchpad_elf_load(launchpad, launchpad_vmo_from_file(self.get_argv()[0])))?;
-        zx_cvt(launchpad_load_vdso(launchpad, ZX_HANDLE_INVALID))?;
-        zx_cvt(launchpad_clone(launchpad, LP_CLONE_FDIO_NAMESPACE | LP_CLONE_FDIO_CWD))?;
+        let transfer_or_clone = |opt_fd, target_fd| if let Some(local_fd) = opt_fd {
+            fdio_spawn_action_t {
+                action: FDIO_SPAWN_ACTION_TRANSFER_FD,
+                local_fd,
+                target_fd,
+                ..Default::default()
+            }
+        } else {
+            fdio_spawn_action_t {
+                action: FDIO_SPAWN_ACTION_CLONE_FD,
+                local_fd: target_fd,
+                target_fd,
+                ..Default::default()
+            }
+        };
 
         // Clone stdin, stdout, and stderr
-        if let Some(fd) = stdio.stdin.fd() {
-            zx_cvt(launchpad_transfer_fd(launchpad, fd, 0))?;
-        } else {
-            zx_cvt(launchpad_clone_fd(launchpad, 0, 0))?;
-        }
-        if let Some(fd) = stdio.stdout.fd() {
-            zx_cvt(launchpad_transfer_fd(launchpad, fd, 1))?;
-        } else {
-            zx_cvt(launchpad_clone_fd(launchpad, 1, 1))?;
-        }
-        if let Some(fd) = stdio.stderr.fd() {
-            zx_cvt(launchpad_transfer_fd(launchpad, fd, 2))?;
-        } else {
-            zx_cvt(launchpad_clone_fd(launchpad, 2, 2))?;
-        }
+        let action1 = transfer_or_clone(stdio.stdin.fd(), 0);
+        let action2 = transfer_or_clone(stdio.stdout.fd(), 1);
+        let action3 = transfer_or_clone(stdio.stderr.fd(), 2);
+        let actions = [action1, action2, action3];
 
-        // We don't want FileDesc::drop to be called on any stdio. It would close their fds. The
-        // fds will be closed once the child process finishes.
+        // We don't want FileDesc::drop to be called on any stdio. fdio_spawn_etc
+        // always consumes transferred file descriptors.
         mem::forget(stdio);
 
         for callback in self.get_closures().iter_mut() {
             callback()?;
         }
 
-        // `launchpad_go` destroys the launchpad, so we must not
-        mem::forget(launchpad_destructor);
-
         let mut process_handle: zx_handle_t = 0;
-        let mut err_msg: *const libc::c_char = ptr::null();
-        zx_cvt(launchpad_go(launchpad, &mut process_handle, &mut err_msg))?;
+        zx_cvt(fdio_spawn_etc(
+            0,
+            FDIO_SPAWN_CLONE_JOB | FDIO_SPAWN_CLONE_LDSVC | FDIO_SPAWN_CLONE_NAMESPACE,
+            self.get_argv()[0], self.get_argv().as_ptr(), envp, 3, actions.as_ptr(),
+            &mut process_handle,
+            ptr::null_mut(),
+        ))?;
         // FIXME: See if we want to do something with that err_msg
 
         Ok(process_handle)
diff --git a/src/libstd/sys/unix/process/zircon.rs b/src/libstd/sys/unix/process/zircon.rs
index 90864e6ef3f..a06c73ee263 100644
--- a/src/libstd/sys/unix/process/zircon.rs
+++ b/src/libstd/sys/unix/process/zircon.rs
@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![allow(non_camel_case_types)]
+#![allow(non_camel_case_types, unused)]
 
 use convert::TryInto;
 use io;
@@ -117,75 +117,36 @@ extern {
                               avail: *mut size_t) -> zx_status_t;
 }
 
-// From `enum special_handles` in system/ulib/launchpad/launchpad.c
-// HND_LOADER_SVC = 0
-// HND_EXEC_VMO = 1
-// HND_SEGMENTS_VMAR = 2
-const HND_SPECIAL_COUNT: c_int = 3;
-
+#[derive(Default)]
 #[repr(C)]
-pub struct launchpad_t {
-    argc: u32,
-    envc: u32,
-    args: *const c_char,
-    args_len: size_t,
-    env: *const c_char,
-    env_len: size_t,
-
-    handles: *mut zx_handle_t,
-    handles_info: *mut u32,
-    handle_count: size_t,
-    handle_alloc: size_t,
-
-    entry: zx_vaddr_t,
-    base: zx_vaddr_t,
-    vdso_base: zx_vaddr_t,
-
-    stack_size: size_t,
-
-    special_handles: [zx_handle_t; HND_SPECIAL_COUNT as usize],
-    loader_message: bool,
+pub struct fdio_spawn_action_t {
+    pub action: u32,
+    pub reserved0: u32,
+    pub local_fd: i32,
+    pub target_fd: i32,
+    pub reserved1: u64,
 }
 
 extern {
-    pub fn launchpad_create(job: zx_handle_t, name: *const c_char,
-                            lp: *mut *mut launchpad_t) -> zx_status_t;
-
-    pub fn launchpad_go(lp: *mut launchpad_t,
-                        proc_handle: *mut zx_handle_t,
-                        err_msg: *mut *const c_char) -> zx_status_t;
-
-    pub fn launchpad_destroy(lp: *mut launchpad_t);
-
-    pub fn launchpad_set_args(lp: *mut launchpad_t, argc: c_int,
-                               argv: *const *const c_char) -> zx_status_t;
-
-    pub fn launchpad_set_environ(lp: *mut launchpad_t, envp: *const *const c_char) -> zx_status_t;
-
-    pub fn launchpad_clone(lp: *mut launchpad_t, what: u32) -> zx_status_t;
-
-    pub fn launchpad_clone_fd(lp: *mut launchpad_t, fd: c_int, target_fd: c_int) -> zx_status_t;
-
-    pub fn launchpad_transfer_fd(lp: *mut launchpad_t, fd: c_int, target_fd: c_int) -> zx_status_t;
-
-    pub fn launchpad_elf_load(lp: *mut launchpad_t, vmo: zx_handle_t) -> zx_status_t;
-
-    pub fn launchpad_add_vdso_vmo(lp: *mut launchpad_t) -> zx_status_t;
+    pub fn fdio_spawn_etc(job: zx_handle_t, flags: u32, path: *const c_char,
+                          argv: *const *const c_char, envp: *const *const c_char,
+                          action_count: u64, actions: *const fdio_spawn_action_t,
+                          process: *mut zx_handle_t, err_msg: *mut c_char) -> zx_status_t;
+}
 
-    pub fn launchpad_load_vdso(lp: *mut launchpad_t, vmo: zx_handle_t) -> zx_status_t;
+// fdio_spawn_etc flags
 
-    pub fn launchpad_vmo_from_file(filename: *const c_char) -> zx_handle_t;
-}
+pub const FDIO_SPAWN_CLONE_JOB: u32 = 0x0001;
+pub const FDIO_SPAWN_CLONE_LDSVC: u32 = 0x0002;
+pub const FDIO_SPAWN_CLONE_NAMESPACE: u32 = 0x0004;
+pub const FDIO_SPAWN_CLONE_STDIO: u32 = 0x0008;
+pub const FDIO_SPAWN_CLONE_ENVIRON: u32 = 0x0010;
+pub const FDIO_SPAWN_CLONE_ALL: u32 = 0xFFFF;
 
-// Launchpad clone constants
+// fdio_spawn_etc actions
 
-pub const LP_CLONE_FDIO_NAMESPACE: u32 = 0x0001;
-pub const LP_CLONE_FDIO_CWD: u32 = 0x0002;
-// LP_CLONE_FDIO_STDIO = 0x0004
-// LP_CLONE_FDIO_ALL = 0x00FF
-// LP_CLONE_ENVIRON = 0x0100
-// LP_CLONE_DEFAULT_JOB = 0x0200
-// LP_CLONE_ALL = 0xFFFF
+pub const FDIO_SPAWN_ACTION_CLONE_FD: u32 = 0x0001;
+pub const FDIO_SPAWN_ACTION_TRANSFER_FD: u32 = 0x0002;
 
 // Errors
 
diff --git a/src/libstd/sys/unix/rand.rs b/src/libstd/sys/unix/rand.rs
index caa18945765..01c0ada4ffb 100644
--- a/src/libstd/sys/unix/rand.rs
+++ b/src/libstd/sys/unix/rand.rs
@@ -183,35 +183,10 @@ mod imp {
 mod imp {
     #[link(name = "zircon")]
     extern {
-        fn zx_cprng_draw(buffer: *mut u8, len: usize, actual: *mut usize) -> i32;
-    }
-
-    fn getrandom(buf: &mut [u8]) -> Result<usize, i32> {
-        unsafe {
-            let mut actual = 0;
-            let status = zx_cprng_draw(buf.as_mut_ptr(), buf.len(), &mut actual);
-            if status == 0 {
-                Ok(actual)
-            } else {
-                Err(status)
-            }
-        }
+        fn zx_cprng_draw(buffer: *mut u8, len: usize);
     }
 
     pub fn fill_bytes(v: &mut [u8]) {
-        let mut buf = v;
-        while !buf.is_empty() {
-            let ret = getrandom(buf);
-            match ret {
-                Err(err) => {
-                    panic!("kernel zx_cprng_draw call failed! (returned {}, buf.len() {})",
-                        err, buf.len())
-                }
-                Ok(actual) => {
-                    let move_buf = buf;
-                    buf = &mut move_buf[(actual as usize)..];
-                }
-            }
-        }
+        unsafe { zx_cprng_draw(v.as_mut_ptr(), v.len()) }
     }
 }
diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
index 9e388808030..e26306c045d 100644
--- a/src/libstd/sys/unix/thread.rs
+++ b/src/libstd/sys/unix/thread.rs
@@ -49,7 +49,7 @@ unsafe fn pthread_attr_setstacksize(_attr: *mut libc::pthread_attr_t,
 }
 
 impl Thread {
-    pub unsafe fn new<'a>(stack: usize, p: Box<FnBox() + 'a>)
+    pub unsafe fn new<'a>(stack: usize, p: Box<dyn FnBox() + 'a>)
                           -> io::Result<Thread> {
         let p = box p;
         let mut native: libc::pthread_t = mem::zeroed();
@@ -326,13 +326,22 @@ pub mod guard {
             // Reallocate the last page of the stack.
             // This ensures SIGBUS will be raised on
             // stack overflow.
-            let result = mmap(stackaddr, PAGE_SIZE, PROT_NONE,
+            // Systems which enforce strict PAX MPROTECT do not allow
+            // to mprotect() a mapping with less restrictive permissions
+            // than the initial mmap() used, so we mmap() here with
+            // read/write permissions and only then mprotect() it to
+            // no permissions at all. See issue #50313.
+            let result = mmap(stackaddr, PAGE_SIZE, PROT_READ | PROT_WRITE,
                               MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
-
             if result != stackaddr || result == MAP_FAILED {
                 panic!("failed to allocate a guard page");
             }
 
+            let result = mprotect(stackaddr, PAGE_SIZE, PROT_NONE);
+            if result != 0 {
+                panic!("failed to protect the guard page");
+            }
+
             let guardaddr = stackaddr as usize;
             let offset = if cfg!(target_os = "freebsd") {
                 2
diff --git a/src/libstd/sys/unix/time.rs b/src/libstd/sys/unix/time.rs
index 83127935909..89786eb2a6c 100644
--- a/src/libstd/sys/unix/time.rs
+++ b/src/libstd/sys/unix/time.rs
@@ -289,7 +289,7 @@ mod inner {
 
         pub fn sub_instant(&self, other: &Instant) -> Duration {
             self.t.sub_timespec(&other.t).unwrap_or_else(|_| {
-                panic!("other was less than the current instant")
+                panic!("specified instant was later than self")
             })
         }
 
diff --git a/src/libstd/sys/wasm/thread.rs b/src/libstd/sys/wasm/thread.rs
index 728e678a2e8..8173a624211 100644
--- a/src/libstd/sys/wasm/thread.rs
+++ b/src/libstd/sys/wasm/thread.rs
@@ -19,7 +19,7 @@ pub struct Thread(Void);
 pub const DEFAULT_MIN_STACK_SIZE: usize = 4096;
 
 impl Thread {
-    pub unsafe fn new<'a>(_stack: usize, _p: Box<FnBox() + 'a>)
+    pub unsafe fn new<'a>(_stack: usize, _p: Box<dyn FnBox() + 'a>)
         -> io::Result<Thread>
     {
         unsupported()
diff --git a/src/libstd/sys/windows/backtrace/mod.rs b/src/libstd/sys/windows/backtrace/mod.rs
index 82498ad4d58..7ef4e203571 100644
--- a/src/libstd/sys/windows/backtrace/mod.rs
+++ b/src/libstd/sys/windows/backtrace/mod.rs
@@ -46,110 +46,257 @@ mod printing;
 #[path = "backtrace_gnu.rs"]
 pub mod gnu;
 
-pub use self::printing::{resolve_symname, foreach_symbol_fileline};
+pub use self::printing::{foreach_symbol_fileline, resolve_symname};
+use self::printing::{load_printing_fns_64, load_printing_fns_ex};
 
-pub fn unwind_backtrace(frames: &mut [Frame])
-    -> io::Result<(usize, BacktraceContext)>
-{
+pub fn unwind_backtrace(frames: &mut [Frame]) -> io::Result<(usize, BacktraceContext)> {
     let dbghelp = DynamicLibrary::open("dbghelp.dll")?;
 
     // Fetch the symbols necessary from dbghelp.dll
     let SymInitialize = sym!(dbghelp, "SymInitialize", SymInitializeFn)?;
     let SymCleanup = sym!(dbghelp, "SymCleanup", SymCleanupFn)?;
-    let StackWalkEx = sym!(dbghelp, "StackWalkEx", StackWalkExFn)?;
+
+    // StackWalkEx might not be present and we'll fall back to StackWalk64
+    let sw_var = match sym!(dbghelp, "StackWalkEx", StackWalkExFn) {
+        Ok(StackWalkEx) => {
+            StackWalkVariant::StackWalkEx(StackWalkEx, load_printing_fns_ex(&dbghelp)?)
+        }
+        Err(e) => match sym!(dbghelp, "StackWalk64", StackWalk64Fn) {
+            Ok(StackWalk64) => {
+                StackWalkVariant::StackWalk64(StackWalk64, load_printing_fns_64(&dbghelp)?)
+            }
+            Err(..) => return Err(e),
+        },
+    };
 
     // Allocate necessary structures for doing the stack walk
     let process = unsafe { c::GetCurrentProcess() };
-    let thread = unsafe { c::GetCurrentThread() };
-    let mut context: c::CONTEXT = unsafe { mem::zeroed() };
-    unsafe { c::RtlCaptureContext(&mut context) };
-    let mut frame: c::STACKFRAME_EX = unsafe { mem::zeroed() };
-    frame.StackFrameSize = mem::size_of_val(&frame) as c::DWORD;
-    let image = init_frame(&mut frame, &context);
 
     let backtrace_context = BacktraceContext {
         handle: process,
         SymCleanup,
+        StackWalkVariant: sw_var,
         dbghelp,
     };
 
     // Initialize this process's symbols
     let ret = unsafe { SymInitialize(process, ptr::null_mut(), c::TRUE) };
     if ret != c::TRUE {
-        return Ok((0, backtrace_context))
+        return Ok((0, backtrace_context));
     }
 
     // And now that we're done with all the setup, do the stack walking!
+    match backtrace_context.StackWalkVariant {
+        StackWalkVariant::StackWalkEx(StackWalkEx, _) => {
+            set_frames(StackWalkEx, frames).map(|i| (i, backtrace_context))
+        }
+
+        StackWalkVariant::StackWalk64(StackWalk64, _) => {
+            set_frames(StackWalk64, frames).map(|i| (i, backtrace_context))
+        }
+    }
+}
+
+fn set_frames<W: StackWalker>(StackWalk: W, frames: &mut [Frame]) -> io::Result<usize> {
+    let process = unsafe { c::GetCurrentProcess() };
+    let thread = unsafe { c::GetCurrentProcess() };
+    let mut context: c::CONTEXT = unsafe { mem::zeroed() };
+    unsafe { c::RtlCaptureContext(&mut context) };
+    let mut frame = W::Item::new();
+    let image = frame.init(&context);
+
     let mut i = 0;
-    unsafe {
-        while i < frames.len() &&
-              StackWalkEx(image, process, thread, &mut frame, &mut context,
-                          ptr::null_mut(),
-                          ptr::null_mut(),
-                          ptr::null_mut(),
-                          ptr::null_mut(),
-                          0) == c::TRUE
-        {
-            let addr = (frame.AddrPC.Offset - 1) as *const u8;
-
-            frames[i] = Frame {
-                symbol_addr: addr,
-                exact_position: addr,
-                inline_context: frame.InlineFrameContext,
-            };
-            i += 1;
+    while i < frames.len()
+        && StackWalk.walk(image, process, thread, &mut frame, &mut context) == c::TRUE
+    {
+        let addr = frame.get_addr();
+        frames[i] = Frame {
+            symbol_addr: addr,
+            exact_position: addr,
+            inline_context: 0,
+        };
+
+        i += 1
+    }
+    Ok(i)
+}
+
+type SymInitializeFn = unsafe extern "system" fn(c::HANDLE, *mut c_void, c::BOOL) -> c::BOOL;
+type SymCleanupFn = unsafe extern "system" fn(c::HANDLE) -> c::BOOL;
+
+type StackWalkExFn = unsafe extern "system" fn(
+    c::DWORD,
+    c::HANDLE,
+    c::HANDLE,
+    *mut c::STACKFRAME_EX,
+    *mut c::CONTEXT,
+    *mut c_void,
+    *mut c_void,
+    *mut c_void,
+    *mut c_void,
+    c::DWORD,
+) -> c::BOOL;
+
+type StackWalk64Fn = unsafe extern "system" fn(
+    c::DWORD,
+    c::HANDLE,
+    c::HANDLE,
+    *mut c::STACKFRAME64,
+    *mut c::CONTEXT,
+    *mut c_void,
+    *mut c_void,
+    *mut c_void,
+    *mut c_void,
+) -> c::BOOL;
+
+trait StackWalker {
+    type Item: StackFrame;
+
+    fn walk(&self, c::DWORD, c::HANDLE, c::HANDLE, &mut Self::Item, &mut c::CONTEXT) -> c::BOOL;
+}
+
+impl StackWalker for StackWalkExFn {
+    type Item = c::STACKFRAME_EX;
+    fn walk(
+        &self,
+        image: c::DWORD,
+        process: c::HANDLE,
+        thread: c::HANDLE,
+        frame: &mut Self::Item,
+        context: &mut c::CONTEXT,
+    ) -> c::BOOL {
+        unsafe {
+            self(
+                image,
+                process,
+                thread,
+                frame,
+                context,
+                ptr::null_mut(),
+                ptr::null_mut(),
+                ptr::null_mut(),
+                ptr::null_mut(),
+                0,
+            )
         }
     }
+}
 
-    Ok((i, backtrace_context))
+impl StackWalker for StackWalk64Fn {
+    type Item = c::STACKFRAME64;
+    fn walk(
+        &self,
+        image: c::DWORD,
+        process: c::HANDLE,
+        thread: c::HANDLE,
+        frame: &mut Self::Item,
+        context: &mut c::CONTEXT,
+    ) -> c::BOOL {
+        unsafe {
+            self(
+                image,
+                process,
+                thread,
+                frame,
+                context,
+                ptr::null_mut(),
+                ptr::null_mut(),
+                ptr::null_mut(),
+                ptr::null_mut(),
+            )
+        }
+    }
 }
 
-type SymInitializeFn =
-    unsafe extern "system" fn(c::HANDLE, *mut c_void,
-                              c::BOOL) -> c::BOOL;
-type SymCleanupFn =
-    unsafe extern "system" fn(c::HANDLE) -> c::BOOL;
-
-type StackWalkExFn =
-    unsafe extern "system" fn(c::DWORD, c::HANDLE, c::HANDLE,
-                              *mut c::STACKFRAME_EX, *mut c::CONTEXT,
-                              *mut c_void, *mut c_void,
-                              *mut c_void, *mut c_void, c::DWORD) -> c::BOOL;
-
-#[cfg(target_arch = "x86")]
-fn init_frame(frame: &mut c::STACKFRAME_EX,
-              ctx: &c::CONTEXT) -> c::DWORD {
-    frame.AddrPC.Offset = ctx.Eip as u64;
-    frame.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
-    frame.AddrStack.Offset = ctx.Esp as u64;
-    frame.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
-    frame.AddrFrame.Offset = ctx.Ebp as u64;
-    frame.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
-    c::IMAGE_FILE_MACHINE_I386
+trait StackFrame {
+    fn new() -> Self;
+    fn init(&mut self, ctx: &c::CONTEXT) -> c::DWORD;
+    fn get_addr(&self) -> *const u8;
 }
 
-#[cfg(target_arch = "x86_64")]
-fn init_frame(frame: &mut c::STACKFRAME_EX,
-              ctx: &c::CONTEXT) -> c::DWORD {
-    frame.AddrPC.Offset = ctx.Rip as u64;
-    frame.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
-    frame.AddrStack.Offset = ctx.Rsp as u64;
-    frame.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
-    frame.AddrFrame.Offset = ctx.Rbp as u64;
-    frame.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
-    c::IMAGE_FILE_MACHINE_AMD64
+impl StackFrame for c::STACKFRAME_EX {
+    fn new() -> c::STACKFRAME_EX {
+        unsafe { mem::zeroed() }
+    }
+
+    #[cfg(target_arch = "x86")]
+    fn init(&mut self, ctx: &c::CONTEXT) -> c::DWORD {
+        self.AddrPC.Offset = ctx.Eip as u64;
+        self.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrStack.Offset = ctx.Esp as u64;
+        self.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrFrame.Offset = ctx.Ebp as u64;
+        self.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        c::IMAGE_FILE_MACHINE_I386
+    }
+    #[cfg(target_arch = "x86_64")]
+    fn init(&mut self, ctx: &c::CONTEXT) -> c::DWORD {
+        self.AddrPC.Offset = ctx.Rip as u64;
+        self.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrStack.Offset = ctx.Rsp as u64;
+        self.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrFrame.Offset = ctx.Rbp as u64;
+        self.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        c::IMAGE_FILE_MACHINE_AMD64
+    }
+
+    fn get_addr(&self) -> *const u8 {
+        (self.AddrPC.Offset - 1) as *const u8
+    }
+}
+
+impl StackFrame for c::STACKFRAME64 {
+    fn new() -> c::STACKFRAME64 {
+        unsafe { mem::zeroed() }
+    }
+
+    #[cfg(target_arch = "x86")]
+    fn init(&mut self, ctx: &c::CONTEXT) -> c::DWORD {
+        self.AddrPC.Offset = ctx.Eip as u64;
+        self.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrStack.Offset = ctx.Esp as u64;
+        self.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrFrame.Offset = ctx.Ebp as u64;
+        self.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        c::IMAGE_FILE_MACHINE_I386
+    }
+    #[cfg(target_arch = "x86_64")]
+    fn init(&mut self, ctx: &c::CONTEXT) -> c::DWORD {
+        self.AddrPC.Offset = ctx.Rip as u64;
+        self.AddrPC.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrStack.Offset = ctx.Rsp as u64;
+        self.AddrStack.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        self.AddrFrame.Offset = ctx.Rbp as u64;
+        self.AddrFrame.Mode = c::ADDRESS_MODE::AddrModeFlat;
+        c::IMAGE_FILE_MACHINE_AMD64
+    }
+
+    fn get_addr(&self) -> *const u8 {
+        (self.AddrPC.Offset - 1) as *const u8
+    }
+}
+
+enum StackWalkVariant {
+    StackWalkEx(StackWalkExFn, printing::PrintingFnsEx),
+    StackWalk64(StackWalk64Fn, printing::PrintingFns64),
 }
 
 pub struct BacktraceContext {
     handle: c::HANDLE,
     SymCleanup: SymCleanupFn,
     // Only used in printing for msvc and not gnu
+    // The gnu version is effectively a ZST dummy.
+    #[allow(dead_code)]
+    StackWalkVariant: StackWalkVariant,
+    // keeping DynamycLibrary loaded until its functions no longer needed
     #[allow(dead_code)]
     dbghelp: DynamicLibrary,
 }
 
 impl Drop for BacktraceContext {
     fn drop(&mut self) {
-        unsafe { (self.SymCleanup)(self.handle); }
+        unsafe {
+            (self.SymCleanup)(self.handle);
+        }
     }
 }
diff --git a/src/libstd/sys/windows/backtrace/printing/mod.rs b/src/libstd/sys/windows/backtrace/printing/mod.rs
index 3e566f6e2bd..251d5028aea 100644
--- a/src/libstd/sys/windows/backtrace/printing/mod.rs
+++ b/src/libstd/sys/windows/backtrace/printing/mod.rs
@@ -15,6 +15,20 @@ mod printing;
 #[cfg(target_env = "gnu")]
 mod printing {
     pub use sys_common::gnu::libbacktrace::{foreach_symbol_fileline, resolve_symname};
+
+    // dummy functions to mirror those present in msvc version.
+    use sys::dynamic_lib::DynamicLibrary;
+    use io;
+    pub struct PrintingFnsEx {}
+    pub struct PrintingFns64 {}
+    pub fn load_printing_fns_ex(_: &DynamicLibrary) -> io::Result<PrintingFnsEx> {
+        Ok(PrintingFnsEx{})
+    }
+    pub fn load_printing_fns_64(_: &DynamicLibrary) -> io::Result<PrintingFns64> {
+        Ok(PrintingFns64{})
+    }
 }
 
 pub use self::printing::{foreach_symbol_fileline, resolve_symname};
+pub use self::printing::{load_printing_fns_ex, load_printing_fns_64,
+                         PrintingFnsEx, PrintingFns64};
diff --git a/src/libstd/sys/windows/backtrace/printing/msvc.rs b/src/libstd/sys/windows/backtrace/printing/msvc.rs
index 967df1c8a2d..c8b946bf13a 100644
--- a/src/libstd/sys/windows/backtrace/printing/msvc.rs
+++ b/src/libstd/sys/windows/backtrace/printing/msvc.rs
@@ -10,29 +10,108 @@
 
 use ffi::CStr;
 use io;
-use libc::{c_ulong, c_char};
+use libc::{c_char, c_ulong};
 use mem;
-use sys::c;
 use sys::backtrace::BacktraceContext;
+use sys::backtrace::StackWalkVariant;
+use sys::c;
+use sys::dynamic_lib::DynamicLibrary;
 use sys_common::backtrace::Frame;
 
+// Structs holding printing functions and loaders for them
+// Two versions depending on whether dbghelp.dll has StackWalkEx or not
+// (the former being in newer Windows versions, the older being in Win7 and before)
+pub struct PrintingFnsEx {
+    resolve_symname: SymFromInlineContextFn,
+    sym_get_line: SymGetLineFromInlineContextFn,
+}
+pub struct PrintingFns64 {
+    resolve_symname: SymFromAddrFn,
+    sym_get_line: SymGetLineFromAddr64Fn,
+}
+
+pub fn load_printing_fns_ex(dbghelp: &DynamicLibrary) -> io::Result<PrintingFnsEx> {
+    Ok(PrintingFnsEx {
+        resolve_symname: sym!(dbghelp, "SymFromInlineContext", SymFromInlineContextFn)?,
+        sym_get_line: sym!(
+            dbghelp,
+            "SymGetLineFromInlineContext",
+            SymGetLineFromInlineContextFn
+        )?,
+    })
+}
+pub fn load_printing_fns_64(dbghelp: &DynamicLibrary) -> io::Result<PrintingFns64> {
+    Ok(PrintingFns64 {
+        resolve_symname: sym!(dbghelp, "SymFromAddr", SymFromAddrFn)?,
+        sym_get_line: sym!(dbghelp, "SymGetLineFromAddr64", SymGetLineFromAddr64Fn)?,
+    })
+}
+
+type SymFromAddrFn =
+    unsafe extern "system" fn(c::HANDLE, u64, *mut u64, *mut c::SYMBOL_INFO) -> c::BOOL;
 type SymFromInlineContextFn =
-    unsafe extern "system" fn(c::HANDLE, u64, c::ULONG,
-                              *mut u64, *mut c::SYMBOL_INFO) -> c::BOOL;
-type SymGetLineFromInlineContextFn =
-    unsafe extern "system" fn(c::HANDLE, u64, c::ULONG,
-                              u64, *mut c::DWORD, *mut c::IMAGEHLP_LINE64) -> c::BOOL;
+    unsafe extern "system" fn(c::HANDLE, u64, c::ULONG, *mut u64, *mut c::SYMBOL_INFO) -> c::BOOL;
+
+type SymGetLineFromAddr64Fn =
+    unsafe extern "system" fn(c::HANDLE, u64, *mut u32, *mut c::IMAGEHLP_LINE64) -> c::BOOL;
+type SymGetLineFromInlineContextFn = unsafe extern "system" fn(
+    c::HANDLE,
+    u64,
+    c::ULONG,
+    u64,
+    *mut c::DWORD,
+    *mut c::IMAGEHLP_LINE64,
+) -> c::BOOL;
 
 /// Converts a pointer to symbol to its string value.
-pub fn resolve_symname<F>(frame: Frame,
-                          callback: F,
-                          context: &BacktraceContext) -> io::Result<()>
-    where F: FnOnce(Option<&str>) -> io::Result<()>
+pub fn resolve_symname<F>(frame: Frame, callback: F, context: &BacktraceContext) -> io::Result<()>
+where
+    F: FnOnce(Option<&str>) -> io::Result<()>,
 {
-    let SymFromInlineContext = sym!(&context.dbghelp,
-                                    "SymFromInlineContext",
-                                    SymFromInlineContextFn)?;
+    match context.StackWalkVariant {
+        StackWalkVariant::StackWalkEx(_, ref fns) => resolve_symname_internal(
+            |process: c::HANDLE,
+             symbol_address: u64,
+             inline_context: c::ULONG,
+             info: *mut c::SYMBOL_INFO| unsafe {
+                let mut displacement = 0u64;
+                (fns.resolve_symname)(
+                    process,
+                    symbol_address,
+                    inline_context,
+                    &mut displacement,
+                    info,
+                )
+            },
+            frame,
+            callback,
+            context,
+        ),
+        StackWalkVariant::StackWalk64(_, ref fns) => resolve_symname_internal(
+            |process: c::HANDLE,
+             symbol_address: u64,
+             _inline_context: c::ULONG,
+             info: *mut c::SYMBOL_INFO| unsafe {
+                let mut displacement = 0u64;
+                (fns.resolve_symname)(process, symbol_address, &mut displacement, info)
+            },
+            frame,
+            callback,
+            context,
+        ),
+    }
+}
 
+fn resolve_symname_internal<F, R>(
+    mut symbol_resolver: R,
+    frame: Frame,
+    callback: F,
+    context: &BacktraceContext,
+) -> io::Result<()>
+where
+    F: FnOnce(Option<&str>) -> io::Result<()>,
+    R: FnMut(c::HANDLE, u64, c::ULONG, *mut c::SYMBOL_INFO) -> c::BOOL,
+{
     unsafe {
         let mut info: c::SYMBOL_INFO = mem::zeroed();
         info.MaxNameLen = c::MAX_SYM_NAME as c_ulong;
@@ -41,14 +120,13 @@ pub fn resolve_symname<F>(frame: Frame,
         // due to struct alignment.
         info.SizeOfStruct = 88;
 
-        let mut displacement = 0u64;
-        let ret = SymFromInlineContext(context.handle,
-                                       frame.symbol_addr as u64,
-                                       frame.inline_context,
-                                       &mut displacement,
-                                       &mut info);
-        let valid_range = if ret == c::TRUE &&
-                             frame.symbol_addr as usize >= info.Address as usize {
+        let ret = symbol_resolver(
+            context.handle,
+            frame.symbol_addr as u64,
+            frame.inline_context,
+            &mut info,
+        );
+        let valid_range = if ret == c::TRUE && frame.symbol_addr as usize >= info.Address as usize {
             if info.Size != 0 {
                 (frame.symbol_addr as usize) < info.Address as usize + info.Size as usize
             } else {
@@ -67,30 +145,72 @@ pub fn resolve_symname<F>(frame: Frame,
     }
 }
 
-pub fn foreach_symbol_fileline<F>(frame: Frame,
-                                  mut f: F,
-                                  context: &BacktraceContext)
-    -> io::Result<bool>
-    where F: FnMut(&[u8], u32) -> io::Result<()>
+pub fn foreach_symbol_fileline<F>(
+    frame: Frame,
+    callback: F,
+    context: &BacktraceContext,
+) -> io::Result<bool>
+where
+    F: FnMut(&[u8], u32) -> io::Result<()>,
 {
-    let SymGetLineFromInlineContext = sym!(&context.dbghelp,
-                                    "SymGetLineFromInlineContext",
-                                    SymGetLineFromInlineContextFn)?;
+    match context.StackWalkVariant {
+        StackWalkVariant::StackWalkEx(_, ref fns) => foreach_symbol_fileline_iternal(
+            |process: c::HANDLE,
+             frame_address: u64,
+             inline_context: c::ULONG,
+             line: *mut c::IMAGEHLP_LINE64| unsafe {
+                let mut displacement = 0u32;
+                (fns.sym_get_line)(
+                    process,
+                    frame_address,
+                    inline_context,
+                    0,
+                    &mut displacement,
+                    line,
+                )
+            },
+            frame,
+            callback,
+            context,
+        ),
+        StackWalkVariant::StackWalk64(_, ref fns) => foreach_symbol_fileline_iternal(
+            |process: c::HANDLE,
+             frame_address: u64,
+             _inline_context: c::ULONG,
+             line: *mut c::IMAGEHLP_LINE64| unsafe {
+                let mut displacement = 0u32;
+                (fns.sym_get_line)(process, frame_address, &mut displacement, line)
+            },
+            frame,
+            callback,
+            context,
+        ),
+    }
+}
 
+fn foreach_symbol_fileline_iternal<F, G>(
+    mut line_getter: G,
+    frame: Frame,
+    mut callback: F,
+    context: &BacktraceContext,
+) -> io::Result<bool>
+where
+    F: FnMut(&[u8], u32) -> io::Result<()>,
+    G: FnMut(c::HANDLE, u64, c::ULONG, *mut c::IMAGEHLP_LINE64) -> c::BOOL,
+{
     unsafe {
         let mut line: c::IMAGEHLP_LINE64 = mem::zeroed();
         line.SizeOfStruct = ::mem::size_of::<c::IMAGEHLP_LINE64>() as u32;
 
-        let mut displacement = 0u32;
-        let ret = SymGetLineFromInlineContext(context.handle,
-                                              frame.exact_position as u64,
-                                              frame.inline_context,
-                                              0,
-                                              &mut displacement,
-                                              &mut line);
+        let ret = line_getter(
+            context.handle,
+            frame.exact_position as u64,
+            frame.inline_context,
+            &mut line,
+        );
         if ret == c::TRUE {
             let name = CStr::from_ptr(line.Filename).to_bytes();
-            f(name, line.LineNumber as u32)?;
+            callback(name, line.LineNumber as u32)?;
         }
         Ok(false)
     }
diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index 6d929f21365..30aba2f400f 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -637,6 +637,22 @@ pub struct STACKFRAME_EX {
 
 #[repr(C)]
 #[cfg(feature = "backtrace")]
+pub struct STACKFRAME64 {
+    pub AddrPC: ADDRESS64,
+    pub AddrReturn: ADDRESS64,
+    pub AddrFrame: ADDRESS64,
+    pub AddrStack: ADDRESS64,
+    pub AddrBStore: ADDRESS64,
+    pub FuncTableEntry: *mut c_void,
+    pub Params: [u64; 4],
+    pub Far: BOOL,
+    pub Virtual: BOOL,
+    pub Reserved: [u64; 3],
+    pub KdHelp: KDHELP64,
+}
+
+#[repr(C)]
+#[cfg(feature = "backtrace")]
 pub struct KDHELP64 {
     pub Thread: u64,
     pub ThCallbackStack: DWORD,
diff --git a/src/libstd/sys/windows/ext/mod.rs b/src/libstd/sys/windows/ext/mod.rs
index 4b458d293bc..1f10609f32c 100644
--- a/src/libstd/sys/windows/ext/mod.rs
+++ b/src/libstd/sys/windows/ext/mod.rs
@@ -18,6 +18,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 #![doc(cfg(windows))]
+#![allow(missing_docs)]
 
 pub mod ffi;
 pub mod fs;
diff --git a/src/libstd/sys/windows/process.rs b/src/libstd/sys/windows/process.rs
index be442f41374..4974a8de89c 100644
--- a/src/libstd/sys/windows/process.rs
+++ b/src/libstd/sys/windows/process.rs
@@ -487,9 +487,7 @@ fn make_command_line(prog: &OsStr, args: &[OsString]) -> io::Result<Vec<u16>> {
             } else {
                 if x == '"' as u16 {
                     // Add n+1 backslashes to total 2n+1 before internal '"'.
-                    for _ in 0..(backslashes+1) {
-                        cmd.push('\\' as u16);
-                    }
+                    cmd.extend((0..(backslashes + 1)).map(|_| '\\' as u16));
                 }
                 backslashes = 0;
             }
@@ -498,9 +496,7 @@ fn make_command_line(prog: &OsStr, args: &[OsString]) -> io::Result<Vec<u16>> {
 
         if quote {
             // Add n backslashes to total 2n before ending '"'.
-            for _ in 0..backslashes {
-                cmd.push('\\' as u16);
-            }
+            cmd.extend((0..backslashes).map(|_| '\\' as u16));
             cmd.push('"' as u16);
         }
         Ok(())
diff --git a/src/libstd/sys/windows/thread.rs b/src/libstd/sys/windows/thread.rs
index b6f63303dc2..44ec872b244 100644
--- a/src/libstd/sys/windows/thread.rs
+++ b/src/libstd/sys/windows/thread.rs
@@ -28,7 +28,7 @@ pub struct Thread {
 }
 
 impl Thread {
-    pub unsafe fn new<'a>(stack: usize, p: Box<FnBox() + 'a>)
+    pub unsafe fn new<'a>(stack: usize, p: Box<dyn FnBox() + 'a>)
                           -> io::Result<Thread> {
         let p = box p;