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use crate::io::{self, IoSlice, IoSliceMut};
use crate::mem;
use crate::sys::fd::FileDesc;
use crate::sys::{cvt, cvt_r};
////////////////////////////////////////////////////////////////////////////////
// Anonymous pipes
////////////////////////////////////////////////////////////////////////////////
pub struct AnonPipe(FileDesc);
pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
let mut fds = [0; 2];
// The only known way right now to create atomically set the CLOEXEC flag is
// to use the `pipe2` syscall. This was added to Linux in 2.6.27, glibc 2.9
// and musl 0.9.3, and some other targets also have it.
cfg_if::cfg_if! {
if #[cfg(any(
target_os = "dragonfly",
target_os = "freebsd",
target_os = "linux",
target_os = "netbsd",
target_os = "openbsd",
target_os = "redox"
))] {
cvt(unsafe { libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC) })?;
Ok((AnonPipe(FileDesc::new(fds[0])), AnonPipe(FileDesc::new(fds[1]))))
} else {
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)
}
}
}
}
}
|
