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#![allow(clippy::expect_used)]
#![allow(clippy::unwrap_used)]
#![allow(clippy::panic)]
#![allow(clippy::match_wild_err_arm)]
#![allow(clippy::similar_names)]
#![allow(clippy::uninlined_format_args)]
#![allow(clippy::cast_ptr_alignment)]
#![allow(clippy::ptr_as_ptr)]
#![allow(clippy::doc_markdown)]
/// Tests for stdio redirection to /dev/null
/// These tests verify that file descriptors 0,1,2 are not reused after closing stdio
use std::{fs::File, io::Write, os::unix::io::AsRawFd, process::exit};
use fork::{Fork, close_fd, fork, waitpid};
/// Test that demonstrates the fd reuse bug with close_fd()
///
/// This test SHOULD FAIL with current implementation because:
/// - close_fd() closes fd 0,1,2
/// - Next File::create() will get fd=0, then fd=1, then fd=2
/// - This test expects fd >= 3
#[test]
#[should_panic(expected = "File descriptors were reused")]
fn test_close_fd_allows_fd_reuse() {
match fork() {
Ok(Fork::Parent(child)) => {
let result = waitpid(child);
// If child exited with error, the bug exists
if result.is_err()
|| std::fs::read_to_string("/tmp/fork_test_fd_marker.txt")
.unwrap_or_default()
.contains("REUSED")
{
// Cleanup
let _ = std::fs::remove_file("/tmp/fork_test_fd_marker.txt");
panic!("File descriptors were reused (bug exists)");
}
}
Ok(Fork::Child) => {
// Close stdio
close_fd().unwrap();
// Open files - with current implementation, they WILL get fd 0,1,2
let f1 = File::create("/tmp/fork_test_fd1.txt").unwrap();
let f2 = File::create("/tmp/fork_test_fd2.txt").unwrap();
let f3 = File::create("/tmp/fork_test_fd3.txt").unwrap();
let fd1 = f1.as_raw_fd();
let fd2 = f2.as_raw_fd();
let fd3 = f3.as_raw_fd();
// Check if any fd is < 3 (the bug)
if fd1 < 3 || fd2 < 3 || fd3 < 3 {
// Write marker file to signal bug to parent
std::fs::write("/tmp/fork_test_fd_marker.txt", "REUSED").ok();
exit(1);
}
// If we get here, fds are >= 3 (the fix is working)
exit(0);
}
Err(_) => panic!("Fork failed"),
}
}
/// Test file descriptor reuse scenario
///
/// This test demonstrates that println! would write to wrong file
#[test]
fn test_fd_reuse_corruption_scenario() {
match fork() {
Ok(Fork::Parent(child)) => {
waitpid(child).unwrap();
// Check what was written to the files
let content1 = std::fs::read_to_string("/tmp/fork_test_corruption1.txt").ok();
let content2 = std::fs::read_to_string("/tmp/fork_test_corruption2.txt").ok();
if let (Some(c1), Some(c2)) = (content1, content2) {
// With close_fd(), these files will contain the debug output!
// With redirect_stdio(), they will only contain intended data
if c1.contains("This should NOT") || c2.contains("This should NOT") {
eprintln!("BUG DETECTED: Debug output leaked to data files!");
eprintln!("File 1: {}", c1);
eprintln!("File 2: {}", c2);
// Don't panic - this is expected with close_fd()
} else {
println!("GOOD: Files only contain intended data");
}
}
// Cleanup
let _ = std::fs::remove_file("/tmp/fork_test_corruption1.txt");
let _ = std::fs::remove_file("/tmp/fork_test_corruption2.txt");
}
Ok(Fork::Child) => {
// Close stdio
close_fd().unwrap();
// Open files - they will get fd 0,1,2 with current implementation
let mut f1 = File::create("/tmp/fork_test_corruption1.txt").unwrap();
let mut f2 = File::create("/tmp/fork_test_corruption2.txt").unwrap();
// Try to write debug output to stderr (fd=2)
// With close_fd(), this might go to one of the files above!
// We can't use eprintln! here because it might corrupt the files
// Instead, directly write to demonstrate the issue
let fd1 = f1.as_raw_fd();
let fd2 = f2.as_raw_fd();
// If files got fd 0 or 1, then fd=2 might be another file or free
// Write a marker to show potential corruption
if fd1 <= 2 || fd2 <= 2 {
// Simulate what eprintln! would do
let stderr_msg = b"This should NOT appear in data files\n";
unsafe {
libc::write(2, stderr_msg.as_ptr() as *const _, stderr_msg.len());
}
}
// Write intended data
f1.write_all(b"data1\n").unwrap();
f2.write_all(b"data2\n").unwrap();
exit(0);
}
Err(_) => panic!("Fork failed"),
}
}
#[test]
fn test_redirect_stdio_prevents_fd_reuse() {
match fork() {
Ok(Fork::Parent(child)) => {
waitpid(child).unwrap();
}
Ok(Fork::Child) => {
// Redirect stdio to /dev/null
fork::redirect_stdio().unwrap();
// Open files - should get fd >= 3
let f1 = File::create("/tmp/fork_test_redirect1.txt").unwrap();
let f2 = File::create("/tmp/fork_test_redirect2.txt").unwrap();
let f3 = File::create("/tmp/fork_test_redirect3.txt").unwrap();
let fd1 = f1.as_raw_fd();
let fd2 = f2.as_raw_fd();
let fd3 = f3.as_raw_fd();
// With redirect_stdio(), these should all be >= 3
assert!(fd1 >= 3, "File 1 got fd < 3: {}", fd1);
assert!(fd2 >= 3, "File 2 got fd < 3: {}", fd2);
assert!(fd3 >= 3, "File 3 got fd < 3: {}", fd3);
// Cleanup
drop(f1);
drop(f2);
drop(f3);
let _ = std::fs::remove_file("/tmp/fork_test_redirect1.txt");
let _ = std::fs::remove_file("/tmp/fork_test_redirect2.txt");
let _ = std::fs::remove_file("/tmp/fork_test_redirect3.txt");
exit(0);
}
Err(_) => panic!("Fork failed"),
}
}
#[test]
fn test_redirect_stdio_println_safety() {
match fork() {
Ok(Fork::Parent(child)) => {
waitpid(child).unwrap();
// Verify files only contain intended data
let content = std::fs::read_to_string("/tmp/fork_test_println_safe.txt").unwrap();
assert!(!content.contains("debug"), "Debug output leaked to file!");
assert_eq!(content, "data\n", "File content is correct");
// Cleanup
let _ = std::fs::remove_file("/tmp/fork_test_println_safe.txt");
}
Ok(Fork::Child) => {
// Redirect stdio to /dev/null
fork::redirect_stdio().unwrap();
// Open file - gets fd >= 3
let mut f = File::create("/tmp/fork_test_println_safe.txt").unwrap();
// This println! will go to /dev/null (fd=1), not to the file
println!("debug message that should not appear in file");
// Write intended data
f.write_all(b"data\n").unwrap();
exit(0);
}
Err(_) => panic!("Fork failed"),
}
}
#[test]
fn test_daemon_uses_redirect_stdio() {
// Test that daemon() correctly uses redirect_stdio() internally
// We do this by manually testing the double-fork pattern with redirect_stdio()
match fork() {
Ok(Fork::Parent(child)) => {
waitpid(child).unwrap();
// Give daemon time to write file
std::thread::sleep(std::time::Duration::from_millis(100));
// Check file was created and has correct content
let content = std::fs::read_to_string("/tmp/fork_test_daemon_redirect.txt")
.expect("Daemon should have created file");
assert!(
!content.contains("Should not appear"),
"println! should have gone to /dev/null, not to file"
);
assert_eq!(
content.trim(),
"daemon data",
"File should have correct data"
);
// Cleanup
let _ = std::fs::remove_file("/tmp/fork_test_daemon_redirect.txt");
}
Ok(Fork::Child) => {
// Simulate what daemon() does
fork::setsid().unwrap();
fork::redirect_stdio().unwrap(); // This is what daemon() now uses
match fork() {
Ok(Fork::Parent(_)) => exit(0), // First child exits
Ok(Fork::Child) => {
// Grandchild (daemon) continues
let mut f = File::create("/tmp/fork_test_daemon_redirect.txt").unwrap();
// Verify file got fd >= 3
assert!(f.as_raw_fd() >= 3, "File should get fd >= 3");
// This println! goes to /dev/null
println!("Should not appear in file");
// Write actual data
f.write_all(b"daemon data\n").unwrap();
f.flush().unwrap();
exit(0);
}
Err(_) => exit(1),
}
}
Err(_) => panic!("Fork failed"),
}
}
#[test]
fn test_redirect_stdio_error_handling() {
// Test that redirect_stdio returns proper io::Error
match fork() {
Ok(Fork::Parent(child)) => {
waitpid(child).unwrap();
}
Ok(Fork::Child) => {
// Call redirect_stdio - should succeed
let result = fork::redirect_stdio();
assert!(result.is_ok(), "redirect_stdio should succeed");
// Verify we can access errno if needed (though it won't be set on success)
if let Err(e) = result {
// If it somehow fails, verify it's a proper io::Error
let _os_error = e.raw_os_error();
let _error_msg = format!("{}", e);
}
exit(0);
}
Err(_) => panic!("Fork failed"),
}
}
#[test]
fn test_redirect_stdio_idempotent() {
// Test that calling redirect_stdio multiple times is safe
match fork() {
Ok(Fork::Parent(child)) => {
waitpid(child).unwrap();
}
Ok(Fork::Child) => {
// First call
fork::redirect_stdio().unwrap();
// Second call should also work
fork::redirect_stdio().unwrap();
// Files should still get fd >= 3
let f = File::create("/tmp/fork_test_idempotent.txt").unwrap();
assert!(f.as_raw_fd() >= 3, "File should get fd >= 3");
// Cleanup
drop(f);
let _ = std::fs::remove_file("/tmp/fork_test_idempotent.txt");
exit(0);
}
Err(_) => panic!("Fork failed"),
}
}