Hi Ludo, it does pretty much the equvalent of this Python program, in Rust:
------------------------ #!/usr/bin/env python3 import os import subprocess import signal signal.pthread_sigmask(signal.SIG_BLOCK, [signal.SIGINT]) p = subprocess.Popen(["cat"], stdin=subprocess.PIPE, stdout=subprocess.PIPE) signal.pthread_sigmask(signal.SIG_UNBLOCK, [signal.SIGINT]) os.kill(p.pid, signal.SIGINT) stdout, stderr = p.communicate(b"hello\n", timeout=1) assert stdout == b"" p.wait() ------------------------ The goal of it is to test this feature: Their "Popen" implementation uses something like spawnvp, only they have overwritten it in order to clear the signal mask for the child. In Rust the test is: ------------------------------------------------------ fn test_process_mask() { unsafe { // Test to make sure that a signal mask does not get inherited. let mut cmd = Command::new(OsStr::new("cat")); let mut set: libc::sigset_t = mem::uninitialized(); let mut old_set: libc::sigset_t = mem::uninitialized(); t!(cvt(libc::sigemptyset(&mut set))); t!(cvt(sigaddset(&mut set, libc::SIGINT))); t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &set, &mut old_set))); cmd.stdin(Stdio::MakePipe); cmd.stdout(Stdio::MakePipe); let (mut cat, mut pipes) = t!(cmd.spawn(Stdio::Null, true)); let stdin_write = pipes.stdin.take().unwrap(); let stdout_read = pipes.stdout.take().unwrap(); t!(cvt(libc::pthread_sigmask(libc::SIG_SETMASK, &old_set, ptr::null_mut()))); t!(cvt(libc::kill(cat.id() as libc::pid_t, libc::SIGINT))); // We need to wait until SIGINT is definitely delivered. The // easiest way is to write something to cat, and try to read it // back: if SIGINT is unmasked, it'll get delivered when cat is // next scheduled. let _ = stdin_write.write(b"Hello"); drop(stdin_write); // Either EOF or failure (EPIPE) is okay. let mut buf = [0; 5]; if let Ok(ret) = stdout_read.read(&mut buf) { assert!(ret == 0); } t!(cat.wait()); } ------------------------------------------------------ and the implementation that clears the mask is https://github.com/rust-lang/rust/blob/1.16.0/src/libstd/sys/unix/process/process_unix.rs#L144 (line 144ff, bottom of "fn do_exec")