1 files changed, 110 insertions, 14 deletions

diff --git a/ctr-std/src/sys/unix/pipe.rs b/ctr-std/src/sys/unix/pipe.rs
index 992e1ac..0a5dccd 100644
--- a/ctr-std/src/sys/unix/pipe.rs
+++ b/ctr-std/src/sys/unix/pipe.rs
@@ -1,4 +1,4 @@
-// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -9,27 +9,123 @@
 // except according to those terms.
 
 use io;
-use sys::Void;
+use libc::{self, c_int};
+use mem;
+use sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering};
+use sys::fd::FileDesc;
+use sys::{cvt, cvt_r};
 
-pub struct AnonPipe(Void);
+////////////////////////////////////////////////////////////////////////////////
+// Anonymous pipes
+////////////////////////////////////////////////////////////////////////////////
 
-impl AnonPipe {
-    pub fn read(&self, _buf: &mut [u8]) -> io::Result<usize> {
-        match self.0 {}
+pub struct AnonPipe(FileDesc);
+
+pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
+    weak! { fn pipe2(*mut c_int, c_int) -> c_int }
+    static INVALID: AtomicBool = ATOMIC_BOOL_INIT;
+
+    let mut fds = [0; 2];
+
+    // Unfortunately the only known way right now to create atomically set the
+    // CLOEXEC flag is to use the `pipe2` syscall on Linux. This was added in
+    // 2.6.27, however, and because we support 2.6.18 we must detect this
+    // support dynamically.
+    if cfg!(any(target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "linux",
+                target_os = "netbsd",
+                target_os = "openbsd")) &&
+       !INVALID.load(Ordering::SeqCst)
+    {
+
+        if let Some(pipe) = pipe2.get() {
+            // Note that despite calling a glibc function here we may still
+            // get ENOSYS. Glibc has `pipe2` since 2.9 and doesn't try to
+            // emulate on older kernels, so if you happen to be running on
+            // an older kernel you may see `pipe2` as a symbol but still not
+            // see the syscall.
+            match cvt(unsafe { pipe(fds.as_mut_ptr(), libc::O_CLOEXEC) }) {
+                Ok(_) => {
+                    return Ok((AnonPipe(FileDesc::new(fds[0])),
+                               AnonPipe(FileDesc::new(fds[1]))));
+                }
+                Err(ref e) if e.raw_os_error() == Some(libc::ENOSYS) => {
+                    INVALID.store(true, Ordering::SeqCst);
+                }
+                Err(e) => return Err(e),
+            }
+        }
     }
+    cvt(unsafe { libc::pipe(fds.as_mut_ptr()) })?;
+
+    let fd0 = FileDesc::new(fds[0]);
+    let fd1 = FileDesc::new(fds[1]);
+    fd0.set_cloexec()?;
+    fd1.set_cloexec()?;
+    Ok((AnonPipe(fd0), AnonPipe(fd1)))
+}
 
-    pub fn write(&self, _buf: &[u8]) -> io::Result<usize> {
-        match self.0 {}
+impl AnonPipe {
+    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.0.read(buf)
     }
 
-    pub fn diverge(&self) -> ! {
-        match self.0 {}
+    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
+        self.0.write(buf)
     }
+
+    pub fn fd(&self) -> &FileDesc { &self.0 }
+    pub fn into_fd(self) -> FileDesc { self.0 }
 }
 
 pub fn read2(p1: AnonPipe,
-             _v1: &mut Vec<u8>,
-             _p2: AnonPipe,
-             _v2: &mut Vec<u8>) -> io::Result<()> {
-    match p1.0 {}
+             v1: &mut Vec<u8>,
+             p2: AnonPipe,
+             v2: &mut Vec<u8>) -> io::Result<()> {
+
+    // Set both pipes into nonblocking mode as we're gonna be reading from both
+    // in the `select` loop below, and we wouldn't want one to block the other!
+    let p1 = p1.into_fd();
+    let p2 = p2.into_fd();
+    p1.set_nonblocking(true)?;
+    p2.set_nonblocking(true)?;
+
+    let mut fds: [libc::pollfd; 2] = unsafe { mem::zeroed() };
+    fds[0].fd = p1.raw();
+    fds[0].events = libc::POLLIN;
+    fds[1].fd = p2.raw();
+    fds[1].events = libc::POLLIN;
+    loop {
+        // wait for either pipe to become readable using `poll`
+        cvt_r(|| unsafe { libc::poll(fds.as_mut_ptr(), 2, -1) })?;
+
+        if fds[0].revents != 0 && read(&p1, v1)? {
+            p2.set_nonblocking(false)?;
+            return p2.read_to_end(v2).map(|_| ());
+        }
+        if fds[1].revents != 0 && read(&p2, v2)? {
+            p1.set_nonblocking(false)?;
+            return p1.read_to_end(v1).map(|_| ());
+        }
+    }
+
+    // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
+    // EAGAIN. If we hit EOF, then this will happen because the underlying
+    // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
+    // this case we flip the other fd back into blocking mode and read
+    // whatever's leftover on that file descriptor.
+    fn read(fd: &FileDesc, dst: &mut Vec<u8>) -> Result<bool, io::Error> {
+        match fd.read_to_end(dst) {
+            Ok(_) => Ok(true),
+            Err(e) => {
+                if e.raw_os_error() == Some(libc::EWOULDBLOCK) ||
+                   e.raw_os_error() == Some(libc::EAGAIN) {
+                    Ok(false)
+                } else {
+                    Err(e)
+                }
+            }
+        }
+    }
 }