1 files changed, 101 insertions, 0 deletions
diff --git a/rust/minijail/tests/fork_remap.rs b/rust/minijail/tests/fork_remap.rs
new file mode 100644
index 0000000..6cf3415
--- /dev/null
+++ b/rust/minijail/tests/fork_remap.rs
@@ -0,0 +1,101 @@
+// Copyright 2021 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+//! A test of Minijail::fork_remap.
+//!
+//! It needs to be run on its own because it forks the process and by default cargo test is
+//! multi-threaded, and we do not want copies of the other worker threads leaking into the child
+//! process.
+
+use std::fs::{read_link, File, OpenOptions};
+use std::io::{self, Read};
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+use std::path::Path;
+
+use minijail::Minijail;
+
+const DEV_NULL: &str = "/dev/null";
+const DEV_ZERO: &str = "/dev/zero";
+const PROC_CMDLINE: &str = "/proc/self/cmdline";
+
+fn open_path(path: &str) -> Result<File, io::Error> {
+    OpenOptions::new()
+        .read(true)
+        .write(false)
+        .open(Path::new(path))
+}
+
+fn main() {
+    let mut check_file1 = open_path(DEV_ZERO).unwrap();
+    let mut check_file2 = open_path(PROC_CMDLINE).unwrap();
+    let j = Minijail::new().unwrap();
+
+    let mut stdio_expected = String::new();
+    let mut file2_expected = String::new();
+    for &p in &[0, 1, 2, check_file1.as_raw_fd(), check_file2.as_raw_fd()] {
+        let path = format!("/proc/self/fd/{}", p);
+        let target = read_link(Path::new(&path));
+        eprintln!("P: {} -> {:?}", p, &target);
+        if p == 2 {
+            stdio_expected = target.unwrap().to_string_lossy().to_string();
+        } else if p == check_file2.as_raw_fd() {
+            file2_expected = target.unwrap().to_string_lossy().to_string();
+        }
+    }
+
+    // Swap fd1 and fd2.
+    let dest_fd1: RawFd = check_file2.as_raw_fd();
+    let dest_fd2: RawFd = check_file1.as_raw_fd();
+
+    if unsafe {
+        j.fork_remap(&[
+            // fd 0 tests stdio mapped to /dev/null.
+            (2, 1),                              // One-to-many.
+            (2, 2),                              // Identity.
+            (check_file1.as_raw_fd(), dest_fd1), // Cross-over.
+            (check_file2.as_raw_fd(), dest_fd2), // Cross-over.
+        ])
+    }
+    .unwrap()
+        != 0
+    {
+        j.wait().unwrap();
+        eprintln!("Parent done.");
+        return;
+    }
+
+    // Safe because we are re-taking ownership of remapped fds after forking.
+    unsafe {
+        check_file1.into_raw_fd();
+        check_file1 = File::from_raw_fd(dest_fd1);
+
+        check_file2.into_raw_fd();
+        check_file2 = File::from_raw_fd(dest_fd2);
+    }
+
+    for (p, expected) in &[
+        (0, DEV_NULL),
+        (1, &stdio_expected),
+        (2, &stdio_expected),
+        (dest_fd1, DEV_ZERO),
+        (dest_fd2, &file2_expected),
+    ] {
+        let path = format!("/proc/self/fd/{}", p);
+        let target = read_link(Path::new(&path));
+        eprintln!("  C: {} -> {:?}", p, &target);
+        if !matches!(&target, Ok(p) if p == Path::new(expected)) {
+            panic!("  C: got {:?}; expected Ok({:?})", target, expected);
+        }
+    }
+
+    const BUFFER_LEN: usize = 16;
+    let mut buffer = [0xffu8; BUFFER_LEN];
+    check_file1.read_exact(&mut buffer).unwrap();
+    assert_eq!(&buffer, &[0u8; BUFFER_LEN]);
+
+    let mut file2_contents = Vec::<u8>::new();
+    check_file2.read_to_end(&mut file2_contents).unwrap();
+
+    eprintln!("  Child done.");
+}