4156bc4417
This commit adds a `AsInner` trait to `sys_common` and provides implementations on many `std::io` types. This is a building block for exposing platform-specific APIs that hook into `std::io` types.
136 lines
3.7 KiB
Rust
136 lines
3.7 KiB
Rust
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Synchronous, in-memory pipes.
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//!
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//! Currently these aren't particularly useful, there only exists bindings
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//! enough so that pipes can be created to child processes.
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#![allow(missing_docs)]
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use prelude::*;
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use io::IoResult;
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use libc;
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use sync::Arc;
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use sys_common;
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use sys;
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use sys::fs::FileDesc as FileDesc;
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/// A synchronous, in-memory pipe.
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pub struct PipeStream {
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inner: Arc<FileDesc>
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}
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pub struct PipePair {
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pub reader: PipeStream,
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pub writer: PipeStream,
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}
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impl PipeStream {
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/// Consumes a file descriptor to return a pipe stream that will have
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/// synchronous, but non-blocking reads/writes. This is useful if the file
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/// descriptor is acquired via means other than the standard methods.
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///
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/// This operation consumes ownership of the file descriptor and it will be
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/// closed once the object is deallocated.
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///
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/// # Example
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///
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/// ```{rust,no_run}
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/// # #![allow(unused_must_use)]
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/// extern crate libc;
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///
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/// use std::io::pipe::PipeStream;
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///
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/// fn main() {
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/// let mut pipe = PipeStream::open(libc::STDERR_FILENO);
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/// pipe.write(b"Hello, stderr!");
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/// }
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/// ```
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pub fn open(fd: libc::c_int) -> IoResult<PipeStream> {
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Ok(PipeStream::from_filedesc(FileDesc::new(fd, true)))
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}
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// FIXME: expose this some other way
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/// Wrap a FileDesc directly, taking ownership.
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#[doc(hidden)]
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pub fn from_filedesc(fd: FileDesc) -> PipeStream {
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PipeStream { inner: Arc::new(fd) }
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}
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/// Creates a pair of in-memory OS pipes for a unidirectional communication
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/// stream.
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///
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/// The structure returned contains a reader and writer I/O object. Data
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/// written to the writer can be read from the reader.
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///
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/// # Errors
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///
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/// This function can fail to succeed if the underlying OS has run out of
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/// available resources to allocate a new pipe.
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pub fn pair() -> IoResult<PipePair> {
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let (reader, writer) = try!(unsafe { sys::os::pipe() });
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Ok(PipePair {
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reader: PipeStream::from_filedesc(reader),
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writer: PipeStream::from_filedesc(writer),
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})
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}
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}
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impl sys_common::AsInner<sys::fs::FileDesc> for PipeStream {
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fn as_inner(&self) -> &sys::fs::FileDesc {
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&*self.inner
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}
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}
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impl Clone for PipeStream {
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fn clone(&self) -> PipeStream {
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PipeStream { inner: self.inner.clone() }
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}
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}
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impl Reader for PipeStream {
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fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
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self.inner.read(buf)
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}
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}
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impl Writer for PipeStream {
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fn write(&mut self, buf: &[u8]) -> IoResult<()> {
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self.inner.write(buf)
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}
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}
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#[cfg(test)]
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mod test {
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use prelude::*;
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#[test]
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fn partial_read() {
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use os;
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use io::pipe::PipeStream;
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let os::Pipe { reader, writer } = unsafe { os::pipe().unwrap() };
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let out = PipeStream::open(writer);
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let mut input = PipeStream::open(reader);
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let (tx, rx) = channel();
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spawn(proc() {
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let mut out = out;
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out.write(&[10]).unwrap();
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rx.recv(); // don't close the pipe until the other read has finished
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});
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let mut buf = [0, ..10];
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input.read(&mut buf).unwrap();
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tx.send(());
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}
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}
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