std: Add an experimental connect_timeout function

This adds a `TcpStream::connect_timeout` function in order to assist opening
connections with a timeout (cc #13523). There isn't really much design space for
this specific operation (unlike timing out normal blocking reads/writes), so I
am fairly confident that this is the correct interface for this function.

The function is marked #[experimental] because it takes a u64 timeout argument,
and the u64 type is likely to change in the future.

src/libnative/io/c_unix.rs

@@ -0,0 +1,76 @@
+// Copyright 2014 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.
+
+//! C definitions used by libnative that don't belong in liblibc
+
+pub use self::select::fd_set;
+
+use libc;
+
+#[cfg(target_os = "macos")]
+#[cfg(target_os = "freebsd")]
+pub static FIONBIO: libc::c_ulong = 0x8004667e;
+#[cfg(target_os = "linux")]
+#[cfg(target_os = "android")]
+pub static FIONBIO: libc::c_ulong = 0x5421;
+#[cfg(target_os = "macos")]
+#[cfg(target_os = "freebsd")]
+pub static FIOCLEX: libc::c_ulong = 0x20006601;
+#[cfg(target_os = "linux")]
+#[cfg(target_os = "android")]
+pub static FIOCLEX: libc::c_ulong = 0x5451;
+
+extern {
+    pub fn gettimeofday(timeval: *mut libc::timeval,
+                        tzp: *libc::c_void) -> libc::c_int;
+    pub fn select(nfds: libc::c_int,
+                  readfds: *fd_set,
+                  writefds: *fd_set,
+                  errorfds: *fd_set,
+                  timeout: *libc::timeval) -> libc::c_int;
+    pub fn getsockopt(sockfd: libc::c_int,
+                      level: libc::c_int,
+                      optname: libc::c_int,
+                      optval: *mut libc::c_void,
+                      optlen: *mut libc::socklen_t) -> libc::c_int;
+    pub fn ioctl(fd: libc::c_int, req: libc::c_ulong, ...) -> libc::c_int;
+
+}
+
+#[cfg(target_os = "macos")]
+mod select {
+    pub static FD_SETSIZE: uint = 1024;
+
+    pub struct fd_set {
+        fds_bits: [i32, ..(FD_SETSIZE / 32)]
+    }
+
+    pub fn fd_set(set: &mut fd_set, fd: i32) {
+        set.fds_bits[(fd / 32) as uint] |= 1 << (fd % 32);
+    }
+}
+
+#[cfg(target_os = "android")]
+#[cfg(target_os = "freebsd")]
+#[cfg(target_os = "linux")]
+mod select {
+    use std::uint;
+
+    pub static FD_SETSIZE: uint = 1024;
+
+    pub struct fd_set {
+        fds_bits: [uint, ..(FD_SETSIZE / uint::BITS)]
+    }
+
+    pub fn fd_set(set: &mut fd_set, fd: i32) {
+        let fd = fd as uint;
+        set.fds_bits[fd / uint::BITS] |= 1 << (fd % uint::BITS);
+    }
+}