1 // run-pass
2 // only-linux - pidfds are a linux-specific concept
3 
4 #![feature(linux_pidfd)]
5 #![feature(rustc_private)]
6 
7 extern crate libc;
8 
9 use std::io::Error;
10 use std::os::linux::process::{ChildExt, CommandExt};
11 use std::process::Command;
12 
has_clone3() -> bool13 fn has_clone3() -> bool {
14     let res = unsafe { libc::syscall(libc::SYS_clone3, 0, 0) };
15     let err = (res == -1)
16         .then(|| Error::last_os_error())
17         .expect("probe syscall should not succeed");
18 
19     // If the `clone3` syscall is not implemented in the current kernel version it should return an
20     // `ENOSYS` error. Docker also blocks the whole syscall inside unprivileged containers, and
21     // returns `EPERM` (instead of `ENOSYS`) when a program tries to invoke the syscall. Because of
22     // that we need to check for *both* `ENOSYS` and `EPERM`.
23     //
24     // Note that Docker's behavior is breaking other projects (notably glibc), so they're planning
25     // to update their filtering to return `ENOSYS` in a future release:
26     //
27     //     https://github.com/moby/moby/issues/42680
28     //
29     err.raw_os_error() != Some(libc::ENOSYS) && err.raw_os_error() != Some(libc::EPERM)
30 }
31 
main()32 fn main() {
33     // pidfds require the clone3 syscall
34     if !has_clone3() {
35         return;
36     }
37 
38     // We don't assert the precise value, since the standard library
39     // might have opened other file descriptors before our code runs.
40     let _ = Command::new("echo")
41         .create_pidfd(true)
42         .spawn()
43         .unwrap()
44         .pidfd().expect("failed to obtain pidfd");
45 
46     let _ = Command::new("echo")
47         .create_pidfd(false)
48         .spawn()
49         .unwrap()
50         .pidfd().expect_err("pidfd should not have been created when create_pid(false) is set");
51 
52     let _ = Command::new("echo")
53         .spawn()
54         .unwrap()
55         .pidfd().expect_err("pidfd should not have been created");
56 }
57