diff --git a/src/libstd/sys/unix/process.rs b/src/libstd/sys/unix/process.rs
index 407fcb0a1b8f1..671cfbd361316 100644
--- a/src/libstd/sys/unix/process.rs
+++ b/src/libstd/sys/unix/process.rs
@@ -288,6 +288,32 @@ impl Process {
unsafe { libc::_exit(1) }
}
+ // Make sure that the source descriptors are not an stdio descriptor,
+ // otherwise the order which we set the child's descriptors may blow
+ // away a descriptor which we are hoping to save. For example,
+ // suppose we want the child's stderr to be the parent's stdout, and
+ // the child's stdout to be the parent's stderr. No matter which we
+ // dup first, the second will get overwritten prematurely.
+ let maybe_migrate = |src: Stdio, output: &mut AnonPipe| {
+ match src {
+ Stdio::Raw(fd @ libc::STDIN_FILENO) |
+ Stdio::Raw(fd @ libc::STDOUT_FILENO) |
+ Stdio::Raw(fd @ libc::STDERR_FILENO) => {
+ let fd = match cvt_r(|| libc::dup(fd)) {
+ Ok(fd) => fd,
+ Err(_) => fail(output),
+ };
+ let fd = FileDesc::new(fd);
+ fd.set_cloexec();
+ Stdio::Raw(fd.into_raw())
+ },
+
+ s @ Stdio::None |
+ s @ Stdio::Inherit |
+ s @ Stdio::Raw(_) => s,
+ }
+ };
+
let setup = |src: Stdio, dst: c_int| {
match src {
Stdio::Inherit => true,
@@ -313,6 +339,12 @@ impl Process {
}
};
+ // Make sure we migrate all source descriptors before
+ // we start overwriting them
+ let in_fd = maybe_migrate(in_fd, &mut output);
+ let out_fd = maybe_migrate(out_fd, &mut output);
+ let err_fd = maybe_migrate(err_fd, &mut output);
+
if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) }
if !setup(out_fd, libc::STDOUT_FILENO) { fail(&mut output) }
if !setup(err_fd, libc::STDERR_FILENO) { fail(&mut output) }
diff --git a/src/test/run-pass/issue-30490.rs b/src/test/run-pass/issue-30490.rs
new file mode 100644
index 0000000000000..ea603fc665dda
--- /dev/null
+++ b/src/test/run-pass/issue-30490.rs
@@ -0,0 +1,107 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// 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(libc))]
+#![cfg_attr(windows, 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 { FromRawFd::from_raw_fd(libc::STDERR_FILENO) })
+ .stderr(unsafe { FromRawFd::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])
+}