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// run-pass
// ignore-emscripten no processes
// ignore-sgx no processes
// ignore-fuchsia Child I/O swaps not privileged
// Previously libstd would set stdio descriptors of a child process
// by `dup`ing the requested descriptors to inherit directly into the
// stdio descriptors. This, however, would incorrectly handle cases
// where the descriptors to inherit were already stdio descriptors.
// This test checks to avoid that regression.
#![cfg_attr(unix, feature(rustc_private))]
#![cfg_attr(not(unix), allow(unused_imports))]
#[cfg(unix)]
extern crate libc;
use std::fs::File;
use std::io::{Read, Write};
use std::io::{stdout, stderr};
use std::process::{Command, Stdio};
#[cfg(unix)]
use std::os::unix::io::FromRawFd;
#[cfg(not(unix))]
fn main() {
// Bug not present in Windows
}
#[cfg(unix)]
fn main() {
let mut args = std::env::args();
let name = args.next().unwrap();
let args: Vec<String> = args.collect();
if let Some("--child") = args.get(0).map(|s| &**s) {
return child();
} else if !args.is_empty() {
panic!("unknown options");
}
let stdout_backup = unsafe { libc::dup(libc::STDOUT_FILENO) };
let stderr_backup = unsafe { libc::dup(libc::STDERR_FILENO) };
assert!(stdout_backup > -1);
assert!(stderr_backup > -1);
let (stdout_reader, stdout_writer) = pipe();
let (stderr_reader, stderr_writer) = pipe();
assert!(unsafe { libc::dup2(stdout_writer, libc::STDOUT_FILENO) } > -1);
assert!(unsafe { libc::dup2(stderr_writer, libc::STDERR_FILENO) } > -1);
// Make sure we close any duplicates of the writer end of the pipe,
// otherwise we can get stuck reading from the pipe which has open
// writers but no one supplying any input
assert_eq!(unsafe { libc::close(stdout_writer) }, 0);
assert_eq!(unsafe { libc::close(stderr_writer) }, 0);
stdout().write_all("parent stdout\n".as_bytes()).expect("failed to write to stdout");
stderr().write_all("parent stderr\n".as_bytes()).expect("failed to write to stderr");
let child = {
Command::new(name)
.arg("--child")
.stdin(Stdio::inherit())
.stdout(unsafe { Stdio::from_raw_fd(libc::STDERR_FILENO) })
.stderr(unsafe { Stdio::from_raw_fd(libc::STDOUT_FILENO) })
.spawn()
};
// The Stdio passed into the Command took over (and closed) std{out, err}
// so we should restore them as they were.
assert!(unsafe { libc::dup2(stdout_backup, libc::STDOUT_FILENO) } > -1);
assert!(unsafe { libc::dup2(stderr_backup, libc::STDERR_FILENO) } > -1);
// Using File as a shim around the descriptor
let mut read = String::new();
let mut f: File = unsafe { FromRawFd::from_raw_fd(stdout_reader) };
f.read_to_string(&mut read).expect("failed to read from stdout file");
assert_eq!(read, "parent stdout\nchild stderr\n");
// Using File as a shim around the descriptor
read.clear();
let mut f: File = unsafe { FromRawFd::from_raw_fd(stderr_reader) };
f.read_to_string(&mut read).expect("failed to read from stderr file");
assert_eq!(read, "parent stderr\nchild stdout\n");
assert!(child.expect("failed to execute child process").wait().unwrap().success());
}
#[cfg(unix)]
fn child() {
stdout().write_all("child stdout\n".as_bytes()).expect("child failed to write to stdout");
stderr().write_all("child stderr\n".as_bytes()).expect("child failed to write to stderr");
}
#[cfg(unix)]
/// Returns a pipe (reader, writer combo)
fn pipe() -> (i32, i32) {
let mut fds = [0; 2];
assert_eq!(unsafe { libc::pipe(fds.as_mut_ptr()) }, 0);
(fds[0], fds[1])
}
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