Add openpty()

Add documentation for openpty

Fix mutability problem with openpty FFI

src/lib.rs

@@ -44,6 +44,8 @@ pub mod mount;
 #[cfg(target_os = "linux")]
 pub mod mqueue;
 
+pub mod pty;
+
 #[cfg(any(target_os = "linux", target_os = "macos"))]
 pub mod poll;
 

src/pty.rs

@@ -0,0 +1,50 @@
+use libc;
+
+use {Errno, Result};
+use std::os::unix::io::RawFd;
+
+use sys::termios::Termios;
+
+pub use libc::pid_t as SessionId;
+pub use libc::winsize as Winsize;
+
+pub struct OpenptyResult {
+    pub master: RawFd,
+    pub slave: RawFd,
+}
+
+/// Create a new pseudoterminal, returning the slave and master file descriptors
+/// in `OpenptyResult`
+/// (see [openpty](http://man7.org/linux/man-pages/man3/openpty.3.html)). 
+///
+/// If `winsize` is not `None`, the window size of the slave will be set to
+/// the values in `winsize`. If `termios` is not `None`, the pseudoterminal's
+/// terminal settings of the slave will be set to the values in `termios`.
+#[inline]
+pub fn openpty(winsize: Option<Winsize>, termios: Option<Termios>) -> Result<OpenptyResult> {
+    let mut slave: libc::c_int = -1;
+    let mut master: libc::c_int = -1;
+    let c_termios = match &termios {
+        &Some(ref termios) => termios as *const Termios,
+        &None => 0 as *const Termios,
+    };
+    let c_winsize = match &winsize {
+        &Some(ref ws) => ws as *const Winsize,
+        &None => 0 as *const Winsize,
+    };
+    let ret = unsafe {
+        libc::openpty(
+            &mut master as *mut libc::c_int,
+            &mut slave as *mut libc::c_int,
+            0 as *mut libc::c_char,
+            c_termios as *mut libc::termios,
+            c_winsize as *mut Winsize)
+    };
+
+    let _ = try!(Errno::result(ret));
+
+    Ok(OpenptyResult {
+        master: master,
+        slave: slave,
+    })
+}

test/test.rs

@@ -13,6 +13,7 @@ mod sys;
 mod test_fcntl;
 mod test_net;
 mod test_nix_path;
+mod test_pty;
 #[cfg(any(target_os = "linux", target_os = "android"))]
 mod test_sendfile;
 mod test_stat;

test/test_pty.rs

@@ -0,0 +1,36 @@
+use nix::pty::openpty;
+use nix::unistd::{read, write, close};
+
+#[test]
+fn test_openpty() {
+    // TODO: figure out the right termios settings to pass in here
+    let pty = openpty(None, None).unwrap();
+    assert!(pty.master > 0); // must be valid file descriptors
+    assert!(pty.slave > 0);
+
+    // writing to one should be readable on the other one
+    let string = "foofoofoo\n";
+    let mut buf = [0u8; 16];
+    write(pty.master, string.as_bytes()).unwrap();
+    let len = read(pty.slave, &mut buf).unwrap();
+
+    assert_eq!(len, string.len());
+    assert_eq!(&buf[0..len], string.as_bytes());
+
+    // read the echo as well
+    let echoed_string = "foofoofoo\r\n";
+    let len = read(pty.master, &mut buf).unwrap();
+    assert_eq!(len, echoed_string.len());
+    assert_eq!(&buf[0..len], echoed_string.as_bytes());
+
+    let string2 = "barbarbarbar\n";
+    let echoed_string2 = "barbarbarbar\r\n";
+    write(pty.slave, string2.as_bytes()).unwrap();
+    let len = read(pty.master, &mut buf).unwrap();
+
+    assert_eq!(len, echoed_string2.len());
+    assert_eq!(&buf[0..len], echoed_string2.as_bytes());
+
+    close(pty.master).unwrap();
+    close(pty.slave).unwrap();
+}