std/sys/pal/unix/
pipe.rs

Help
1use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
2use crate::mem;
3use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
4use crate::sys::fd::FileDesc;
5use crate::sys::{cvt, cvt_r};
6use crate::sys_common::{FromInner, IntoInner};
7
8////////////////////////////////////////////////////////////////////////////////
9// Anonymous pipes
10////////////////////////////////////////////////////////////////////////////////
11
12#[derive(Debug)]
13pub struct AnonPipe(FileDesc);
14
15pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
16    let mut fds = [0; 2];
17
18    // The only known way right now to create atomically set the CLOEXEC flag is
19    // to use the `pipe2` syscall. This was added to Linux in 2.6.27, glibc 2.9
20    // and musl 0.9.3, and some other targets also have it.
21    cfg_if::cfg_if! {
22        if #[cfg(any(
23            target_os = "dragonfly",
24            target_os = "freebsd",
25            target_os = "hurd",
26            target_os = "illumos",
27            target_os = "linux",
28            target_os = "netbsd",
29            target_os = "openbsd",
30            target_os = "redox"
31        ))] {
32            unsafe {
33                cvt(libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC))?;
34                Ok((AnonPipe(FileDesc::from_raw_fd(fds[0])), AnonPipe(FileDesc::from_raw_fd(fds[1]))))
35            }
36        } else {
37            unsafe {
38                cvt(libc::pipe(fds.as_mut_ptr()))?;
39
40                let fd0 = FileDesc::from_raw_fd(fds[0]);
41                let fd1 = FileDesc::from_raw_fd(fds[1]);
42                fd0.set_cloexec()?;
43                fd1.set_cloexec()?;
44                Ok((AnonPipe(fd0), AnonPipe(fd1)))
45            }
46        }
47    }
48}
49
50impl AnonPipe {
51    #[allow(dead_code)]
52    // FIXME: This function seems legitimately unused.
53    pub fn try_clone(&self) -> io::Result<Self> {
54        self.0.duplicate().map(Self)
55    }
56
57    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
58        self.0.read(buf)
59    }
60
61    pub fn read_buf(&self, buf: BorrowedCursor<'_>) -> io::Result<()> {
62        self.0.read_buf(buf)
63    }
64
65    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
66        self.0.read_vectored(bufs)
67    }
68
69    #[inline]
70    pub fn is_read_vectored(&self) -> bool {
71        self.0.is_read_vectored()
72    }
73
74    pub fn read_to_end(&self, buf: &mut Vec<u8>) -> io::Result<usize> {
75        self.0.read_to_end(buf)
76    }
77
78    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
79        self.0.write(buf)
80    }
81
82    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
83        self.0.write_vectored(bufs)
84    }
85
86    #[inline]
87    pub fn is_write_vectored(&self) -> bool {
88        self.0.is_write_vectored()
89    }
90
91    #[allow(dead_code)]
92    // FIXME: This function seems legitimately unused.
93    pub fn as_file_desc(&self) -> &FileDesc {
94        &self.0
95    }
96}
97
98impl IntoInner<FileDesc> for AnonPipe {
99    fn into_inner(self) -> FileDesc {
100        self.0
101    }
102}
103
104pub fn read2(p1: AnonPipe, v1: &mut Vec<u8>, p2: AnonPipe, v2: &mut Vec<u8>) -> io::Result<()> {
105    // Set both pipes into nonblocking mode as we're gonna be reading from both
106    // in the `select` loop below, and we wouldn't want one to block the other!
107    let p1 = p1.into_inner();
108    let p2 = p2.into_inner();
109    p1.set_nonblocking(true)?;
110    p2.set_nonblocking(true)?;
111
112    let mut fds: [libc::pollfd; 2] = unsafe { mem::zeroed() };
113    fds[0].fd = p1.as_raw_fd();
114    fds[0].events = libc::POLLIN;
115    fds[1].fd = p2.as_raw_fd();
116    fds[1].events = libc::POLLIN;
117    loop {
118        // wait for either pipe to become readable using `poll`
119        cvt_r(|| unsafe { libc::poll(fds.as_mut_ptr(), 2, -1) })?;
120
121        if fds[0].revents != 0 && read(&p1, v1)? {
122            p2.set_nonblocking(false)?;
123            return p2.read_to_end(v2).map(drop);
124        }
125        if fds[1].revents != 0 && read(&p2, v2)? {
126            p1.set_nonblocking(false)?;
127            return p1.read_to_end(v1).map(drop);
128        }
129    }
130
131    // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
132    // EAGAIN. If we hit EOF, then this will happen because the underlying
133    // reader will return Ok(0), in which case we'll see `Ok` ourselves. In
134    // this case we flip the other fd back into blocking mode and read
135    // whatever's leftover on that file descriptor.
136    fn read(fd: &FileDesc, dst: &mut Vec<u8>) -> Result<bool, io::Error> {
137        match fd.read_to_end(dst) {
138            Ok(_) => Ok(true),
139            Err(e) => {
140                if e.raw_os_error() == Some(libc::EWOULDBLOCK)
141                    || e.raw_os_error() == Some(libc::EAGAIN)
142                {
143                    Ok(false)
144                } else {
145                    Err(e)
146                }
147            }
148        }
149    }
150}
151
152impl AsRawFd for AnonPipe {
153    #[inline]
154    fn as_raw_fd(&self) -> RawFd {
155        self.0.as_raw_fd()
156    }
157}
158
159impl AsFd for AnonPipe {
160    fn as_fd(&self) -> BorrowedFd<'_> {
161        self.0.as_fd()
162    }
163}
164
165impl IntoRawFd for AnonPipe {
166    fn into_raw_fd(self) -> RawFd {
167        self.0.into_raw_fd()
168    }
169}
170
171impl FromRawFd for AnonPipe {
172    unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
173        Self(FromRawFd::from_raw_fd(raw_fd))
174    }
175}
176
177impl FromInner<FileDesc> for AnonPipe {
178    fn from_inner(fd: FileDesc) -> Self {
179        Self(fd)
180    }
181}
std/sys/pal/unix/pipe.rs

std/sys/pal/unix/
pipe.rs
