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use std::{mem, process};
use nix::{
errno, sched,
unistd::{self, Pid},
};
#[repr(C)]
#[derive(Debug, Default)]
struct CloneArgs {
flags: u64,
pidfd: u64,
child_tid: u64,
parent_tid: u64,
exit_signal: u64,
stack: u64,
stack_size: u64,
tls: u64,
}
pub unsafe fn clone(flags: sched::CloneFlags) -> nix::Result<unistd::ForkResult> {
let mut args = CloneArgs {
flags: flags.bits() as u64,
exit_signal: libc::SIGCHLD as u64,
..CloneArgs::default()
};
let size = mem::size_of_val(&args) as libc::size_t;
let pid = libc::syscall(libc::SYS_clone3, &mut args, size);
if pid < 0 {
Err(errno::Errno::last())
} else if pid == 0 {
Ok(unistd::ForkResult::Child)
} else {
Ok(unistd::ForkResult::Parent {
child: Pid::from_raw(pid as libc::pid_t),
})
}
}
pub unsafe fn spawn<F>(flags: Option<sched::CloneFlags>, f: F) -> nix::Result<Pid>
where
F: FnOnce(),
{
let res = if let Some(flags) = flags {
clone(flags)
} else {
unistd::fork()
};
match res? {
unistd::ForkResult::Parent { child } => Ok(child),
unistd::ForkResult::Child => {
f();
process::exit(0)
}
}
}
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