1 files changed, 59 insertions, 0 deletions
diff --git a/crates/rebel-runner/src/util/clone.rs b/crates/rebel-runner/src/util/clone.rs
new file mode 100644
index 0000000..51a31c3
--- /dev/null
+++ b/crates/rebel-runner/src/util/clone.rs
@@ -0,0 +1,59 @@
+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);
+
+	#[allow(clippy::comparison_chain)]
+	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)
+		}
+	}
+}