| use crate::io::{self, IoSlice, IoSliceMut}; |
| use crate::mem; |
| use crate::sync::atomic::{AtomicBool, Ordering}; |
| use crate::sys::fd::FileDesc; |
| use crate::sys::{cvt, cvt_r}; |
| |
| use libc::c_int; |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Anonymous pipes |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| pub struct AnonPipe(FileDesc); |
| |
| pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> { |
| syscall! { fn pipe2(fds: *mut c_int, flags: c_int) -> c_int } |
| static INVALID: AtomicBool = AtomicBool::new(false); |
| |
| 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", |
| target_os = "redox" |
| )) && !INVALID.load(Ordering::SeqCst) |
| { |
| // 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 { pipe2(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))) |
| } |
| |
| impl AnonPipe { |
| pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> { |
| self.0.read(buf) |
| } |
| |
| pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> { |
| self.0.read_vectored(bufs) |
| } |
| |
| #[inline] |
| pub fn is_read_vectored(&self) -> bool { |
| self.0.is_read_vectored() |
| } |
| |
| pub fn write(&self, buf: &[u8]) -> io::Result<usize> { |
| self.0.write(buf) |
| } |
| |
| pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> { |
| self.0.write_vectored(bufs) |
| } |
| |
| #[inline] |
| pub fn is_write_vectored(&self) -> bool { |
| self.0.is_write_vectored() |
| } |
| |
| 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<()> { |
| // 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(drop); |
| } |
| if fds[1].revents != 0 && read(&p2, v2)? { |
| p1.set_nonblocking(false)?; |
| return p1.read_to_end(v1).map(drop); |
| } |
| } |
| |
| // 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) |
| } |
| } |
| } |
| } |
| } |