Implementation of `try_clone` for posix.

src/lib.rs

@@ -737,6 +737,14 @@ pub trait SerialPort: Send + io::Read + io::Write {
     /// * `NoDevice` if the device was disconnected.
     /// * `Io` for any other type of I/O error.
     fn read_carrier_detect(&mut self) -> ::Result<bool>;
+
+    // Misc methods
+    /// Attempts to clone the SerialPort. This allow you to write and read simultaneously from the
+    /// same serial connection.
+    ///
+    fn try_clone(&mut self) -> ::Result<Box<SerialPort>>;
+    //
+
 }
 
 #[derive(Debug,Clone,PartialEq,Eq)]

src/posix/tty.rs

@@ -5,6 +5,7 @@ use std::ffi::OsStr;
 use std::io;
 #[cfg(target_os = "macos")]
 use std::mem;
+use std::sync::Arc;
 use std::os::unix::prelude::*;
 use std::path::Path;
 use std::time::Duration;
@@ -44,6 +45,23 @@ fn close(fd: RawFd){
     let _ = unistd::close(fd);
 }
 
+/// Holds a file descriptor, and call `close` on it when it goes out of scope.
+struct FdCloser {
+    pub fd : RawFd
+}
+
+impl FdCloser {
+    fn new(fd : RawFd) -> FdCloser{
+        FdCloser{fd:fd}
+    }
+}
+
+impl Drop for FdCloser {
+    fn drop(&mut self) {
+        close(self.fd);
+    }
+}
+
 /// A TTY-based serial port implementation.
 ///
 /// The port will be closed when the value is dropped. However, this struct
@@ -51,6 +69,7 @@ fn close(fd: RawFd){
 /// the cross-platform `serialport::open()` or
 /// `serialport::open_with_settings()`.
 pub struct TTYPort {
+    closer : Arc<FdCloser>,
     fd: RawFd,
     termios: nix::sys::termios::Termios,
     timeout: Duration,
@@ -142,7 +161,9 @@ impl TTYPort {
             e
         })?;
 
+        let fd_closer = FdCloser::new(fd.clone());
         let mut port = TTYPort {
+            closer : Arc::new(fd_closer),
             fd: fd,
             termios: termios,
             timeout: Duration::from_millis(100),
@@ -275,11 +296,14 @@ impl TTYPort {
         // Open the slave port using default settings
         let slave_tty = TTYPort::open(Path::new(&ptty_name), &Default::default())?;
 
+        let fd = next_pty_fd.into_raw_fd();
+        let fd_closer = FdCloser::new(fd.clone());
         // Manually construct the master port here because the
         // `tcgetattr()` doesn't work on Mac, Solaris, and maybe other
         // BSDs when used on the master port.
         let master_tty = TTYPort {
-            fd: next_pty_fd.into_raw_fd(),
+            closer : Arc::new(fd_closer),
+            fd: fd,
             termios: slave_tty.termios.clone(),
             timeout: Duration::from_millis(100),
             exclusive: true,
@@ -425,11 +449,13 @@ impl TTYPort {
     }
 }
 
+/*
 impl Drop for TTYPort {
     fn drop(&mut self) {
         close(self.fd);
     }
 }
+*/
 
 impl AsRawFd for TTYPort {
     fn as_raw_fd(&self) -> RawFd {
@@ -441,7 +467,7 @@ impl IntoRawFd for TTYPort {
     fn into_raw_fd(self) -> RawFd {
         // Pull just the file descriptor out.  Let the
         // rest of the member fields drop.
-        let TTYPort { fd, .. } = self;
+        let TTYPort { fd, closer,.. } = self;
         fd
     }
 }
@@ -458,10 +484,12 @@ impl FromRawFd for TTYPort {
             Err(_) => false,
         };
 
+        let fd_closer = FdCloser::new(fd.clone());
+
         // It is not trivial to get the file path corresponding to a file descriptor.
         // We'll punt and set it None here.
-
         TTYPort {
+            closer : Arc::new(fd_closer),
             fd: fd,
             termios: termios,
             timeout: Duration::from_millis(100),
@@ -714,6 +742,18 @@ impl SerialPort for TTYPort {
     fn read_carrier_detect(&mut self) -> ::Result<bool> {
         self.read_pin(ioctl::DATA_CARRIER_DETECT)
     }
+
+    fn try_clone(&mut self) -> ::Result<Box<SerialPort>> {
+        let fd_cloned : i32 = fcntl(self.fd,nix::fcntl::F_DUPFD(self.fd))?;
+        Ok(Box::new(TTYPort {
+            closer : Arc::clone(&self.closer),
+            fd : fd_cloned,
+            termios : self.termios.clone(),
+            exclusive : self.exclusive,
+            port_name : self.port_name.clone(), 
+            timeout : self.timeout,
+        }))
+    }
 }
 
 /// Retrieves the udev property value named by `key`. If the value exists, then it will be

src/windows/com.rs

@@ -416,6 +416,11 @@ impl SerialPort for COMPort {
 
         self.write_settings()
     }
+
+    // TODO : Implement me
+    fn try_clone(&mut self) {
+        unimplemented!()
+    }
 }
 
 // According to the MSDN docs, we should use SetupDiGetClassDevs, SetupDiEnumDeviceInfo