Struct PipeReader

pub struct PipeReader(pub(crate) FileDesc);

Read end of an anonymous pipe.

Tuple Fields

0: FileDesc

Implementations

impl PipeReader

pub fn try_clone(&self) -> Result<Self>

Create a new PipeReader instance that shares the same underlying file description.

Examples

use std::fs;
use std::io::{pipe, Write};
use std::process::Command;
const NUM_SLOT: u8 = 2;
const NUM_PROC: u8 = 5;
const OUTPUT: &str = "work.txt";

let mut jobs = vec![];
let (reader, mut writer) = pipe()?;

// Write NUM_SLOT characters the pipe.
writer.write_all(&[b'|'; NUM_SLOT as usize])?;

// Spawn several processes that read a character from the pipe, do some work, then
// write back to the pipe. When the pipe is empty, the processes block, so only
// NUM_SLOT processes can be working at any given time.
for _ in 0..NUM_PROC {
    jobs.push(
        Command::new("bash")
            .args(["-c",
                &format!(
                     "read -n 1\n\
                      echo -n 'x' >> '{OUTPUT}'\n\
                      echo -n '|'",
                ),
            ])
            .stdin(reader.try_clone()?)
            .stdout(writer.try_clone()?)
            .spawn()?,
    );
}

// Wait for all jobs to finish.
for mut job in jobs {
    job.wait()?;
}

// Check our work and clean up.
let xs = fs::read_to_string(OUTPUT)?;
fs::remove_file(OUTPUT)?;
assert_eq!(xs, "x".repeat(NUM_PROC.into()));

Trait Implementations

impl AsFd for PipeReader

fn as_fd(&self) -> BorrowedFd<'_>

Borrows the file descriptor.

impl AsHandle for PipeReader

Available on Windows only.

fn as_handle(&self) -> BorrowedHandle<'_>

Borrows the handle.

impl AsRawFd for PipeReader

fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor.

impl AsRawHandle for PipeReader

Available on Windows only.

fn as_raw_handle(&self) -> RawHandle

Extracts the raw handle.

impl CopyRead for &PipeReader

fn properties(&self) -> CopyParams

Extracts the file descriptor and hints/metadata, delegating through wrappers if necessary.

fn drain_to<W: Write>(&mut self, _writer: &mut W, _limit: u64) -> Result<u64>

Implementations that contain buffers (i.e. BufReader) must transfer data from their internal buffers into writer until either the buffers are emptied or limit bytes have been transferred, whichever occurs sooner. If nested buffers are present the outer buffers must be drained first.

fn taken(&mut self, _bytes: u64)

Updates Take wrappers to remove the number of bytes copied.

fn min_limit(&self) -> u64

The minimum of the limit of all Take<_> wrappers, u64::MAX otherwise. This method does not account for data BufReader buffers and would underreport the limit of a Take<BufReader<Take<_>>> type. Thus its result is only valid after draining the buffers via drain_to.

impl CopyRead for PipeReader

fn properties(&self) -> CopyParams

Extracts the file descriptor and hints/metadata, delegating through wrappers if necessary.

fn drain_to<W: Write>(&mut self, _writer: &mut W, _limit: u64) -> Result<u64>

Implementations that contain buffers (i.e. BufReader) must transfer data from their internal buffers into writer until either the buffers are emptied or limit bytes have been transferred, whichever occurs sooner. If nested buffers are present the outer buffers must be drained first.

fn taken(&mut self, _bytes: u64)

Updates Take wrappers to remove the number of bytes copied.

fn min_limit(&self) -> u64

The minimum of the limit of all Take<_> wrappers, u64::MAX otherwise. This method does not account for data BufReader buffers and would underreport the limit of a Take<BufReader<Take<_>>> type. Thus its result is only valid after draining the buffers via drain_to.

impl Debug for PipeReader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<OwnedFd> for PipeReader

fn from(owned_fd: OwnedFd) -> Self

Converts to this type from the input type.

impl From<OwnedHandle> for PipeReader

Available on Windows only.

fn from(owned_handle: OwnedHandle) -> Self

Converts to this type from the input type.

impl From<PipeReader> for OwnedFd

fn from(pipe: PipeReader) -> Self

Converts to this type from the input type.

impl From<PipeReader> for OwnedHandle

Available on Windows only.

fn from(pipe: PipeReader) -> Self

Converts to this type from the input type.

impl From<PipeReader> for Stdio

fn from(pipe: PipeReader) -> Self

Converts to this type from the input type.

impl FromInner<FileDesc> for PipeReader

fn from_inner(inner: FileDesc) -> Self

impl FromRawFd for PipeReader

unsafe fn from_raw_fd(raw_fd: RawFd) -> Self

Constructs a new instance of Self from the given raw file descriptor.

impl FromRawHandle for PipeReader

Available on Windows only.

unsafe fn from_raw_handle(raw_handle: RawHandle) -> Self

Constructs a new I/O object from the specified raw handle.

impl IntoInner<FileDesc> for PipeReader

fn into_inner(self) -> FileDesc

impl IntoRawFd for PipeReader

fn into_raw_fd(self) -> RawFd

Consumes this object, returning the raw underlying file descriptor.

impl IntoRawHandle for PipeReader

Available on Windows only.

fn into_raw_handle(self) -> RawHandle

Consumes this object, returning the raw underlying handle.

impl Read for &PipeReader

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Reads all bytes until EOF in this source, placing them into buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Pull some bytes from this source into the specified buffer.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Reads all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>

Reads the exact number of bytes required to fill buf.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Reads the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R: Read>(self, next: R) -> Chain<Self, R>

where Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.

impl Read for PipeReader

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Reads all bytes until EOF in this source, placing them into buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Pull some bytes from this source into the specified buffer.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Reads all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>

Reads the exact number of bytes required to fill buf.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Reads the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R: Read>(self, next: R) -> Chain<Self, R>

where Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.