5 files changed, 447 insertions, 0 deletions
diff --git a/src/sys/unix/uds/datagram.rs b/src/sys/unix/uds/datagram.rs
new file mode 100644
index 0000000..d3e5314
--- /dev/null
+++ b/src/sys/unix/uds/datagram.rs
@@ -0,0 +1,56 @@
+use super::{socket_addr, SocketAddr};
+use crate::sys::unix::net::new_socket;
+
+use std::io;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::os::unix::net;
+use std::path::Path;
+
+pub(crate) fn bind(path: &Path) -> io::Result<net::UnixDatagram> {
+    let fd = new_socket(libc::AF_UNIX, libc::SOCK_DGRAM)?;
+    // Ensure the fd is closed.
+    let socket = unsafe { net::UnixDatagram::from_raw_fd(fd) };
+    let (sockaddr, socklen) = socket_addr(path)?;
+    let sockaddr = &sockaddr as *const libc::sockaddr_un as *const _;
+    syscall!(bind(fd, sockaddr, socklen))?;
+    Ok(socket)
+}
+
+pub(crate) fn unbound() -> io::Result<net::UnixDatagram> {
+    new_socket(libc::AF_UNIX, libc::SOCK_DGRAM)
+        .map(|socket| unsafe { net::UnixDatagram::from_raw_fd(socket) })
+}
+
+pub(crate) fn pair() -> io::Result<(net::UnixDatagram, net::UnixDatagram)> {
+    super::pair(libc::SOCK_DGRAM)
+}
+
+pub(crate) fn local_addr(socket: &net::UnixDatagram) -> io::Result<SocketAddr> {
+    super::local_addr(socket.as_raw_fd())
+}
+
+pub(crate) fn peer_addr(socket: &net::UnixDatagram) -> io::Result<SocketAddr> {
+    super::peer_addr(socket.as_raw_fd())
+}
+
+pub(crate) fn recv_from(
+    socket: &net::UnixDatagram,
+    dst: &mut [u8],
+) -> io::Result<(usize, SocketAddr)> {
+    let mut count = 0;
+    let socketaddr = SocketAddr::new(|sockaddr, socklen| {
+        syscall!(recvfrom(
+            socket.as_raw_fd(),
+            dst.as_mut_ptr() as *mut _,
+            dst.len(),
+            0,
+            sockaddr,
+            socklen,
+        ))
+        .map(|c| {
+            count = c;
+            c as libc::c_int
+        })
+    })?;
+    Ok((count as usize, socketaddr))
+}
diff --git a/src/sys/unix/uds/listener.rs b/src/sys/unix/uds/listener.rs
new file mode 100644
index 0000000..b8fb5a9
--- /dev/null
+++ b/src/sys/unix/uds/listener.rs
@@ -0,0 +1,83 @@
+use super::socket_addr;
+use crate::net::{SocketAddr, UnixStream};
+use crate::sys::unix::net::new_socket;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::os::unix::net;
+use std::path::Path;
+use std::{io, mem};
+
+pub(crate) fn bind(path: &Path) -> io::Result<net::UnixListener> {
+    let socket = new_socket(libc::AF_UNIX, libc::SOCK_STREAM)?;
+    let (sockaddr, socklen) = socket_addr(path)?;
+    let sockaddr = &sockaddr as *const libc::sockaddr_un as *const libc::sockaddr;
+
+    syscall!(bind(socket, sockaddr, socklen))
+        .and_then(|_| syscall!(listen(socket, 1024)))
+        .map_err(|err| {
+            // Close the socket if we hit an error, ignoring the error from
+            // closing since we can't pass back two errors.
+            let _ = unsafe { libc::close(socket) };
+            err
+        })
+        .map(|_| unsafe { net::UnixListener::from_raw_fd(socket) })
+}
+
+pub(crate) fn accept(listener: &net::UnixListener) -> io::Result<(UnixStream, SocketAddr)> {
+    let sockaddr = mem::MaybeUninit::<libc::sockaddr_un>::zeroed();
+
+    // This is safe to assume because a `libc::sockaddr_un` filled with `0`
+    // bytes is properly initialized.
+    //
+    // `0` is a valid value for `sockaddr_un::sun_family`; it is
+    // `libc::AF_UNSPEC`.
+    //
+    // `[0; 108]` is a valid value for `sockaddr_un::sun_path`; it begins an
+    // abstract path.
+    let mut sockaddr = unsafe { sockaddr.assume_init() };
+
+    sockaddr.sun_family = libc::AF_UNIX as libc::sa_family_t;
+    let mut socklen = mem::size_of_val(&sockaddr) as libc::socklen_t;
+
+    #[cfg(not(any(
+        target_os = "ios",
+        target_os = "macos",
+        target_os = "netbsd",
+        target_os = "solaris"
+    )))]
+    let socket = {
+        let flags = libc::SOCK_NONBLOCK | libc::SOCK_CLOEXEC;
+        syscall!(accept4(
+            listener.as_raw_fd(),
+            &mut sockaddr as *mut libc::sockaddr_un as *mut libc::sockaddr,
+            &mut socklen,
+            flags
+        ))
+        .map(|socket| unsafe { net::UnixStream::from_raw_fd(socket) })
+    };
+
+    #[cfg(any(
+        target_os = "ios",
+        target_os = "macos",
+        target_os = "netbsd",
+        target_os = "solaris"
+    ))]
+    let socket = syscall!(accept(
+        listener.as_raw_fd(),
+        &mut sockaddr as *mut libc::sockaddr_un as *mut libc::sockaddr,
+        &mut socklen,
+    ))
+    .and_then(|socket| {
+        // Ensure the socket is closed if either of the `fcntl` calls
+        // error below.
+        let s = unsafe { net::UnixStream::from_raw_fd(socket) };
+        syscall!(fcntl(socket, libc::F_SETFD, libc::FD_CLOEXEC)).map(|_| s)
+    });
+
+    socket
+        .map(UnixStream::from_std)
+        .map(|stream| (stream, SocketAddr::from_parts(sockaddr, socklen)))
+}
+
+pub(crate) fn local_addr(listener: &net::UnixListener) -> io::Result<SocketAddr> {
+    super::local_addr(listener.as_raw_fd())
+}
diff --git a/src/sys/unix/uds/mod.rs b/src/sys/unix/uds/mod.rs
new file mode 100644
index 0000000..3ec829f
--- /dev/null
+++ b/src/sys/unix/uds/mod.rs
@@ -0,0 +1,149 @@
+mod socketaddr;
+pub use self::socketaddr::SocketAddr;
+
+/// Get the `sun_path` field offset of `sockaddr_un` for the target OS.
+///
+/// On Linux, this funtion equates to the same value as
+/// `size_of::<sa_family_t>()`, but some other implementations include
+/// other fields before `sun_path`, so the expression more portably
+/// describes the size of the address structure.
+pub(in crate::sys) fn path_offset(sockaddr: &libc::sockaddr_un) -> usize {
+    let base = sockaddr as *const _ as usize;
+    let path = &sockaddr.sun_path as *const _ as usize;
+    path - base
+}
+
+cfg_os_poll! {
+    use std::cmp::Ordering;
+    use std::os::unix::ffi::OsStrExt;
+    use std::os::unix::io::{RawFd, FromRawFd};
+    use std::path::Path;
+    use std::{io, mem};
+
+    pub(crate) mod datagram;
+    pub(crate) mod listener;
+    pub(crate) mod stream;
+
+    pub(in crate::sys) fn socket_addr(path: &Path) -> io::Result<(libc::sockaddr_un, libc::socklen_t)> {
+        let sockaddr = mem::MaybeUninit::<libc::sockaddr_un>::zeroed();
+
+        // This is safe to assume because a `libc::sockaddr_un` filled with `0`
+        // bytes is properly initialized.
+        //
+        // `0` is a valid value for `sockaddr_un::sun_family`; it is
+        // `libc::AF_UNSPEC`.
+        //
+        // `[0; 108]` is a valid value for `sockaddr_un::sun_path`; it begins an
+        // abstract path.
+        let mut sockaddr = unsafe { sockaddr.assume_init() };
+
+        sockaddr.sun_family = libc::AF_UNIX as libc::sa_family_t;
+
+        let bytes = path.as_os_str().as_bytes();
+        match (bytes.get(0), bytes.len().cmp(&sockaddr.sun_path.len())) {
+            // Abstract paths don't need a null terminator
+            (Some(&0), Ordering::Greater) => {
+                return Err(io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "path must be no longer than libc::sockaddr_un.sun_path",
+                ));
+            }
+            (_, Ordering::Greater) | (_, Ordering::Equal) => {
+                return Err(io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "path must be shorter than libc::sockaddr_un.sun_path",
+                ));
+            }
+            _ => {}
+        }
+
+        for (dst, src) in sockaddr.sun_path.iter_mut().zip(bytes.iter()) {
+            *dst = *src as libc::c_char;
+        }
+
+        let offset = path_offset(&sockaddr);
+        let mut socklen = offset + bytes.len();
+
+        match bytes.get(0) {
+            // The struct has already been zeroes so the null byte for pathname
+            // addresses is already there.
+            Some(&0) | None => {}
+            Some(_) => socklen += 1,
+        }
+
+        Ok((sockaddr, socklen as libc::socklen_t))
+    }
+
+    fn pair<T>(flags: libc::c_int) -> io::Result<(T, T)>
+        where T: FromRawFd,
+    {
+        #[cfg(not(any(target_os = "ios", target_os = "macos", target_os = "solaris")))]
+        let flags = flags | libc::SOCK_NONBLOCK | libc::SOCK_CLOEXEC;
+
+        let mut fds = [-1; 2];
+        syscall!(socketpair(libc::AF_UNIX, flags, 0, fds.as_mut_ptr()))?;
+        let pair = unsafe { (T::from_raw_fd(fds[0]), T::from_raw_fd(fds[1])) };
+
+        // Darwin and Solaris do not have SOCK_NONBLOCK or SOCK_CLOEXEC.
+        //
+        // In order to set those flags, additional `fcntl` sys calls must be
+        // performed. If a `fnctl` fails after the sockets have been created,
+        // the file descriptors will leak. Creating `pair` above ensures that if
+        // there is an error, the file descriptors are closed.
+        #[cfg(any(target_os = "ios", target_os = "macos", target_os = "solaris"))]
+        {
+            syscall!(fcntl(fds[0], libc::F_SETFL, libc::O_NONBLOCK))?;
+            syscall!(fcntl(fds[0], libc::F_SETFD, libc::FD_CLOEXEC))?;
+            syscall!(fcntl(fds[1], libc::F_SETFL, libc::O_NONBLOCK))?;
+            syscall!(fcntl(fds[1], libc::F_SETFD, libc::FD_CLOEXEC))?;
+        }
+        Ok(pair)
+    }
+
+    // The following functions can't simply be replaced with a call to
+    // `net::UnixDatagram` because of our `SocketAddr` type.
+
+    fn local_addr(socket: RawFd) -> io::Result<SocketAddr> {
+        SocketAddr::new(|sockaddr, socklen| syscall!(getsockname(socket, sockaddr, socklen)))
+    }
+
+    fn peer_addr(socket: RawFd) -> io::Result<SocketAddr> {
+        SocketAddr::new(|sockaddr, socklen| syscall!(getpeername(socket, sockaddr, socklen)))
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::{path_offset, socket_addr};
+        use std::path::Path;
+        use std::str;
+
+        #[test]
+        fn pathname_address() {
+            const PATH: &str = "./foo/bar.txt";
+            const PATH_LEN: usize = 13;
+
+            // Pathname addresses do have a null terminator, so `socklen` is
+            // expected to be `PATH_LEN` + `offset` + 1.
+            let path = Path::new(PATH);
+            let (sockaddr, actual) = socket_addr(path).unwrap();
+            let offset = path_offset(&sockaddr);
+            let expected = PATH_LEN + offset + 1;
+            assert_eq!(expected as libc::socklen_t, actual)
+        }
+
+        #[test]
+        fn abstract_address() {
+            const PATH: &[u8] = &[0, 116, 111, 107, 105, 111];
+            const PATH_LEN: usize = 6;
+
+            // Abstract addresses do not have a null terminator, so `socklen` is
+            // expected to be `PATH_LEN` + `offset`.
+            let abstract_path = str::from_utf8(PATH).unwrap();
+            let path = Path::new(abstract_path);
+            let (sockaddr, actual) = socket_addr(path).unwrap();
+            let offset = path_offset(&sockaddr);
+            let expected = PATH_LEN + offset;
+            assert_eq!(expected as libc::socklen_t, actual)
+        }
+    }
+}
diff --git a/src/sys/unix/uds/socketaddr.rs b/src/sys/unix/uds/socketaddr.rs
new file mode 100644
index 0000000..69f311a
--- /dev/null
+++ b/src/sys/unix/uds/socketaddr.rs
@@ -0,0 +1,120 @@
+use super::path_offset;
+use std::ffi::OsStr;
+use std::os::unix::ffi::OsStrExt;
+use std::path::Path;
+use std::{ascii, fmt};
+
+/// An address associated with a `mio` specific Unix socket.
+///
+/// This is implemented instead of imported from [`net::SocketAddr`] because
+/// there is no way to create a [`net::SocketAddr`]. One must be returned by
+/// [`accept`], so this is returned instead.
+///
+/// [`net::SocketAddr`]: std::os::unix::net::SocketAddr
+/// [`accept`]: #method.accept
+pub struct SocketAddr {
+    sockaddr: libc::sockaddr_un,
+    socklen: libc::socklen_t,
+}
+
+struct AsciiEscaped<'a>(&'a [u8]);
+
+enum AddressKind<'a> {
+    Unnamed,
+    Pathname(&'a Path),
+    Abstract(&'a [u8]),
+}
+
+impl SocketAddr {
+    fn address(&self) -> AddressKind<'_> {
+        let offset = path_offset(&self.sockaddr);
+        let len = self.socklen as usize - offset;
+        let path = unsafe { &*(&self.sockaddr.sun_path as *const [libc::c_char] as *const [u8]) };
+
+        // macOS seems to return a len of 16 and a zeroed sun_path for unnamed addresses
+        if len == 0
+            || (cfg!(not(any(target_os = "linux", target_os = "android")))
+                && self.sockaddr.sun_path[0] == 0)
+        {
+            AddressKind::Unnamed
+        } else if self.sockaddr.sun_path[0] == 0 {
+            AddressKind::Abstract(&path[1..len])
+        } else {
+            AddressKind::Pathname(OsStr::from_bytes(&path[..len - 1]).as_ref())
+        }
+    }
+}
+
+cfg_os_poll! {
+    use std::{io, mem};
+
+    impl SocketAddr {
+        pub(crate) fn new<F>(f: F) -> io::Result<SocketAddr>
+        where
+            F: FnOnce(*mut libc::sockaddr, &mut libc::socklen_t) -> io::Result<libc::c_int>,
+        {
+            let mut sockaddr = {
+                let sockaddr = mem::MaybeUninit::<libc::sockaddr_un>::zeroed();
+                unsafe { sockaddr.assume_init() }
+            };
+
+            let raw_sockaddr = &mut sockaddr as *mut libc::sockaddr_un as *mut libc::sockaddr;
+            let mut socklen = mem::size_of_val(&sockaddr) as libc::socklen_t;
+
+            f(raw_sockaddr, &mut socklen)?;
+            Ok(SocketAddr::from_parts(sockaddr, socklen))
+        }
+
+        pub(crate) fn from_parts(sockaddr: libc::sockaddr_un, socklen: libc::socklen_t) -> SocketAddr {
+            SocketAddr { sockaddr, socklen }
+        }
+
+        /// Returns `true` if the address is unnamed.
+        ///
+        /// Documentation reflected in [`SocketAddr`]
+        ///
+        /// [`SocketAddr`]: std::os::unix::net::SocketAddr
+        pub fn is_unnamed(&self) -> bool {
+            if let AddressKind::Unnamed = self.address() {
+                true
+            } else {
+                false
+            }
+        }
+
+        /// Returns the contents of this address if it is a `pathname` address.
+        ///
+        /// Documentation reflected in [`SocketAddr`]
+        ///
+        /// [`SocketAddr`]: std::os::unix::net::SocketAddr
+        pub fn as_pathname(&self) -> Option<&Path> {
+            if let AddressKind::Pathname(path) = self.address() {
+                Some(path)
+            } else {
+                None
+            }
+        }
+    }
+}
+
+impl fmt::Debug for SocketAddr {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.address() {
+            AddressKind::Unnamed => write!(fmt, "(unnamed)"),
+            AddressKind::Abstract(name) => write!(fmt, "{} (abstract)", AsciiEscaped(name)),
+            AddressKind::Pathname(path) => write!(fmt, "{:?} (pathname)", path),
+        }
+    }
+}
+
+// ===== impl AsciiEscaped =====
+
+impl<'a> fmt::Display for AsciiEscaped<'a> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "\"")?;
+        for byte in self.0.iter().cloned().flat_map(ascii::escape_default) {
+            write!(fmt, "{}", byte as char)?;
+        }
+        write!(fmt, "\"")
+    }
+}
diff --git a/src/sys/unix/uds/stream.rs b/src/sys/unix/uds/stream.rs
new file mode 100644
index 0000000..149dd14
--- /dev/null
+++ b/src/sys/unix/uds/stream.rs
@@ -0,0 +1,39 @@
+use super::{socket_addr, SocketAddr};
+use crate::sys::unix::net::new_socket;
+
+use std::io;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::os::unix::net;
+use std::path::Path;
+
+pub(crate) fn connect(path: &Path) -> io::Result<net::UnixStream> {
+    let socket = new_socket(libc::AF_UNIX, libc::SOCK_STREAM)?;
+    let (sockaddr, socklen) = socket_addr(path)?;
+    let sockaddr = &sockaddr as *const libc::sockaddr_un as *const libc::sockaddr;
+
+    match syscall!(connect(socket, sockaddr, socklen)) {
+        Ok(_) => {}
+        Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {}
+        Err(e) => {
+            // Close the socket if we hit an error, ignoring the error
+            // from closing since we can't pass back two errors.
+            let _ = unsafe { libc::close(socket) };
+
+            return Err(e);
+        }
+    }
+
+    Ok(unsafe { net::UnixStream::from_raw_fd(socket) })
+}
+
+pub(crate) fn pair() -> io::Result<(net::UnixStream, net::UnixStream)> {
+    super::pair(libc::SOCK_STREAM)
+}
+
+pub(crate) fn local_addr(socket: &net::UnixStream) -> io::Result<SocketAddr> {
+    super::local_addr(socket.as_raw_fd())
+}
+
+pub(crate) fn peer_addr(socket: &net::UnixStream) -> io::Result<SocketAddr> {
+    super::peer_addr(socket.as_raw_fd())
+}