Hide unnecessary error checking from the user

src/libstd/sys/common/net.rs

@@ -503,7 +503,7 @@ pub fn connect_timeout(fd: sock_t,
     #[cfg(windows)] use libc::WSAEWOULDBLOCK as WOULDBLOCK;
 
     // Make sure the call to connect() doesn't block
-    try!(set_nonblocking(fd, true));
+    set_nonblocking(fd, true);
 
     let ret = match unsafe { libc::connect(fd, addrp, len) } {
         // If the connection is in progress, then we need to wait for it to
@@ -533,7 +533,7 @@ pub fn connect_timeout(fd: sock_t,
     };
 
     // be sure to turn blocking I/O back on
-    try!(set_nonblocking(fd, false));
+    set_nonblocking(fd, false);
     return ret;
 
     #[cfg(unix)]
@@ -626,7 +626,7 @@ pub struct Guard<'a> {
 #[unsafe_destructor]
 impl<'a> Drop for Guard<'a> {
     fn drop(&mut self) {
-        assert!(set_nonblocking(self.fd, false).is_ok());
+        set_nonblocking(self.fd, false);
     }
 }
 
@@ -723,7 +723,7 @@ impl TcpStream {
             fd: self.fd(),
             guard: self.inner.lock.lock().unwrap(),
         };
-        assert!(set_nonblocking(self.fd(), true).is_ok());
+        set_nonblocking(self.fd(), true);
         ret
     }
 
@@ -862,7 +862,7 @@ impl UdpSocket {
             fd: self.fd(),
             guard: self.inner.lock.lock().unwrap(),
         };
-        assert!(set_nonblocking(self.fd(), true).is_ok());
+        set_nonblocking(self.fd(), true);
         ret
     }
 
@@ -887,9 +887,7 @@ impl UdpSocket {
                            storagep,
                            &mut addrlen) as libc::c_int
         }));
-        sockaddr_to_addr(&storage, addrlen as uint).and_then(|addr| {
-            Ok((n as uint, addr))
-        })
+        Ok((n as uint, sockaddr_to_addr(&storage, addrlen as uint).unwrap()))
     }
 
     pub fn send_to(&mut self, buf: &[u8], dst: SocketAddr) -> IoResult<()> {
@@ -910,11 +908,8 @@ impl UdpSocket {
         };
 
         let n = try!(write(fd, self.write_deadline, buf, false, dolock, dowrite));
-        if n != buf.len() {
-            Err(short_write(n, "couldn't send entire packet at once"))
-        } else {
-            Ok(())
-        }
+        assert!(n == buf.len(), "UDP packet not completely written.");
+        Ok(())
     }
 
     pub fn join_multicast(&mut self, multi: IpAddr) -> IoResult<()> {

src/libstd/sys/unix/mod.rs

@@ -214,9 +214,9 @@ pub fn wouldblock() -> bool {
     err == libc::EWOULDBLOCK as i32 || err == libc::EAGAIN as i32
 }
 
-pub fn set_nonblocking(fd: sock_t, nb: bool) -> IoResult<()> {
+pub fn set_nonblocking(fd: sock_t, nb: bool) {
     let set = nb as libc::c_int;
-    mkerr_libc(retry(|| unsafe { c::ioctl(fd, c::FIONBIO, &set) }))
+    mkerr_libc(retry(|| unsafe { c::ioctl(fd, c::FIONBIO, &set) })).unwrap();
 }
 
 // nothing needed on unix platforms

src/libstd/sys/unix/pipe.rs

@@ -235,9 +235,9 @@ impl UnixListener {
 
             _ => {
                 let (reader, writer) = try!(unsafe { sys::os::pipe() });
-                try!(set_nonblocking(reader.fd(), true));
-                try!(set_nonblocking(writer.fd(), true));
-                try!(set_nonblocking(self.fd(), true));
+                set_nonblocking(reader.fd(), true);
+                set_nonblocking(writer.fd(), true);
+                set_nonblocking(self.fd(), true);
                 Ok(UnixAcceptor {
                     inner: Arc::new(AcceptorInner {
                         listener: self,

src/libstd/sys/unix/process.rs

@@ -345,8 +345,8 @@ impl Process {
             unsafe {
                 let mut pipes = [0; 2];
                 assert_eq!(libc::pipe(pipes.as_mut_ptr()), 0);
-                set_nonblocking(pipes[0], true).ok().unwrap();
-                set_nonblocking(pipes[1], true).ok().unwrap();
+                set_nonblocking(pipes[0], true);
+                set_nonblocking(pipes[1], true);
                 WRITE_FD = pipes[1];
 
                 let mut old: c::sigaction = mem::zeroed();
@@ -362,7 +362,7 @@ impl Process {
         fn waitpid_helper(input: libc::c_int,
                           messages: Receiver<Req>,
                           (read_fd, old): (libc::c_int, c::sigaction)) {
-            set_nonblocking(input, true).ok().unwrap();
+            set_nonblocking(input, true);
             let mut set: c::fd_set = unsafe { mem::zeroed() };
             let mut tv: libc::timeval;
             let mut active = Vec::<(libc::pid_t, Sender<ProcessExit>, u64)>::new();

src/libstd/sys/unix/tcp.rs

@@ -67,9 +67,9 @@ impl TcpListener {
             -1 => Err(last_net_error()),
             _ => {
                 let (reader, writer) = try!(unsafe { sys::os::pipe() });
-                try!(set_nonblocking(reader.fd(), true));
-                try!(set_nonblocking(writer.fd(), true));
-                try!(set_nonblocking(self.fd(), true));
+                set_nonblocking(reader.fd(), true);
+                set_nonblocking(writer.fd(), true);
+                set_nonblocking(self.fd(), true);
                 Ok(TcpAcceptor {
                     inner: Arc::new(AcceptorInner {
                         listener: self,

src/libstd/sys/windows/mod.rs

@@ -192,12 +192,12 @@ pub fn wouldblock() -> bool {
     err == libc::WSAEWOULDBLOCK as i32
 }
 
-pub fn set_nonblocking(fd: sock_t, nb: bool) -> IoResult<()> {
+pub fn set_nonblocking(fd: sock_t, nb: bool) {
     let mut set = nb as libc::c_ulong;
-    if unsafe { c::ioctlsocket(fd, c::FIONBIO, &mut set) != 0 } {
-        Err(last_error())
-    } else {
-        Ok(())
+    if unsafe { c::ioctlsocket(fd, c::FIONBIO, &mut set) } != 0 {
+        // The above function should not return an error unless we passed it
+        // invalid parameters. Panic on errors.
+        Err(last_error()).unwrap();
     }
 }
 

src/libstd/sys/windows/net.rs

@@ -25,6 +25,8 @@ pub type wrlen_t = i32;
 
 pub struct Socket(libc::SOCKET);
 
+/// Checks whether the Windows socket interface has been started already, and
+/// if not, starts it.
 pub fn init() {
     static START: Once = ONCE_INIT;
 
@@ -38,10 +40,16 @@ pub fn init() {
     });
 }
 
+/// Returns the last error from the Windows socket interface.
 fn last_error() -> io::Error {
     io::Error::from_os_error(unsafe { c::WSAGetLastError() })
 }
 
+/// Checks if the signed integer is the Windows constant `SOCKET_ERROR` (-1)
+/// and if so, returns the last error from the Windows socket interface. . This
+/// function must be called before another call to the socket API is made.
+///
+/// FIXME: generics needed?
 pub fn cvt<T: SignedInt>(t: T) -> io::Result<T> {
     let one: T = Int::one();
     if t == -one {
@@ -51,11 +59,14 @@ pub fn cvt<T: SignedInt>(t: T) -> io::Result<T> {
     }
 }
 
+/// Provides the functionality of `cvt` for the return values of `getaddrinfo`
+/// and similar, meaning that they return an error if the return value is 0.
 pub fn cvt_gai(err: c_int) -> io::Result<()> {
     if err == 0 { return Ok(()) }
     cvt(err).map(|_| ())
 }
 
+/// Provides the functionality of `cvt` for a closure.
 pub fn cvt_r<T: SignedInt, F>(mut f: F) -> io::Result<T> where F: FnMut() -> T {
     cvt(f())
 }
@@ -112,7 +123,7 @@ impl Socket {
 
 impl Drop for Socket {
     fn drop(&mut self) {
-        unsafe { let _ = libc::closesocket(self.0); }
+        unsafe { cvt(libc::closesocket(self.0)).unwrap(); }
     }
 }
 

src/libstd/sys/windows/tcp.rs

@@ -192,7 +192,7 @@ impl TcpAcceptor {
                         c::WSAEventSelect(socket, events[1], 0)
                     };
                     if ret != 0 { return Err(last_net_error()) }
-                    try!(set_nonblocking(socket, false));
+                    set_nonblocking(socket, false);
                     return Ok(stream)
                 }
             }