1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
15 use libc::{self, c_int};
18 use sys::fd::FileDesc;
20 ////////////////////////////////////////////////////////////////////////////////
22 ////////////////////////////////////////////////////////////////////////////////
24 pub struct AnonPipe(FileDesc);
26 pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
29 // Unfortunately the only known way right now to create atomically set the
30 // CLOEXEC flag is to use the `pipe2` syscall on Linux. This was added in
31 // 2.6.27, however, and because we support 2.6.18 we must detect this
32 // support dynamically.
33 if cfg!(target_os = "linux") {
34 weak! { fn pipe2(*mut c_int, c_int) -> c_int }
35 if let Some(pipe) = pipe2.get() {
36 match cvt_r(|| unsafe { pipe(fds.as_mut_ptr(), libc::O_CLOEXEC) }) {
38 return Ok((AnonPipe(FileDesc::new(fds[0])),
39 AnonPipe(FileDesc::new(fds[1]))))
41 Err(ref e) if e.raw_os_error() == Some(libc::ENOSYS) => {}
42 Err(e) => return Err(e),
46 if unsafe { libc::pipe(fds.as_mut_ptr()) == 0 } {
47 let fd0 = FileDesc::new(fds[0]);
48 let fd1 = FileDesc::new(fds[1]);
49 Ok((AnonPipe::from_fd(fd0)?, AnonPipe::from_fd(fd1)?))
51 Err(io::Error::last_os_error())
56 pub fn from_fd(fd: FileDesc) -> io::Result<AnonPipe> {
61 pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
65 pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
66 self.0.read_to_end(buf)
69 pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
73 pub fn fd(&self) -> &FileDesc { &self.0 }
74 pub fn into_fd(self) -> FileDesc { self.0 }
77 pub fn read2(p1: AnonPipe,
80 v2: &mut Vec<u8>) -> io::Result<()> {
81 // Set both pipes into nonblocking mode as we're gonna be reading from both
82 // in the `select` loop below, and we wouldn't want one to block the other!
83 let p1 = p1.into_fd();
84 let p2 = p2.into_fd();
85 p1.set_nonblocking(true)?;
86 p2.set_nonblocking(true)?;
88 let max = cmp::max(p1.raw(), p2.raw());
90 // wait for either pipe to become readable using `select`
92 let mut read: libc::fd_set = mem::zeroed();
93 libc::FD_SET(p1.raw(), &mut read);
94 libc::FD_SET(p2.raw(), &mut read);
95 libc::select(max + 1, &mut read, 0 as *mut _, 0 as *mut _,
99 // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
100 // EAGAIN. If we hit EOF, then this will happen because the underlying
101 // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
102 // this case we flip the other fd back into blocking mode and read
103 // whatever's leftover on that file descriptor.
104 let read = |fd: &FileDesc, dst: &mut Vec<u8>| {
105 match fd.read_to_end(dst) {
108 if e.raw_os_error() == Some(libc::EWOULDBLOCK) ||
109 e.raw_os_error() == Some(libc::EAGAIN) {
118 p2.set_nonblocking(false)?;
119 return p2.read_to_end(v2).map(|_| ());
122 p1.set_nonblocking(false)?;
123 return p1.read_to_end(v1).map(|_| ());