runner: get rid of spawn argument funnelling

5 files changed, 32 insertions, 34 deletions

diff --git a/crates/runner/src/lib.rs b/crates/runner/src/lib.rs
index 8066c58..636c112 100644
--- a/crates/runner/src/lib.rs
+++ b/crates/runner/src/lib.rs
@@ -11,7 +11,7 @@ use std::{
 	fs::File,
 	net,
 	os::unix::{net::UnixStream, prelude::*},
-	slice,
+	process, slice,
 };
 
 use capctl::prctl;
@@ -55,7 +55,7 @@ fn handle_sigchld(ctx: &mut RunnerContext) -> Result<()> {
 }
 
 fn handle_request(ctx: &mut RunnerContext, request_socket: UnixStream) {
-	let run = |()| {
+	let run = || {
 		ctx.socket.steal();
 
 		let task: Task =
@@ -68,7 +68,7 @@ fn handle_request(ctx: &mut RunnerContext, request_socket: UnixStream) {
 		drop(request_socket);
 	};
 
-	let pid = unsafe { clone::spawn(None, (), run) }.expect("fork()").0;
+	let pid = unsafe { clone::spawn(None, run) }.expect("fork()");
 	assert!(ctx.tasks.insert(pid));
 }
 
@@ -91,7 +91,7 @@ fn handle_socket(ctx: &mut RunnerContext) -> bool {
 	true
 }
 
-fn runner(uid: Uid, gid: Gid, socket: UnixSeqpacketConn, _lockfile: File, options: &Options) {
+fn runner(uid: Uid, gid: Gid, socket: UnixSeqpacketConn, _lockfile: File, options: &Options) -> ! {
 	ns::mount_proc();
 	ns::setup_userns(Uid::from_raw(0), Gid::from_raw(0), uid, gid);
 
@@ -144,6 +144,8 @@ fn runner(uid: Uid, gid: Gid, socket: UnixSeqpacketConn, _lockfile: File, option
 			panic!("Unexpected error status for socket file descriptor");
 		}
 	}
+
+	process::exit(0);
 }
 
 pub struct Runner {
@@ -165,18 +167,17 @@ impl Runner {
 
 		let (local, remote) = UnixSeqpacketConn::pair().expect("socketpair()");
 
-		let (local, _remote) = clone::spawn(
-			Some(CloneFlags::CLONE_NEWUSER | CloneFlags::CLONE_NEWNS | CloneFlags::CLONE_NEWPID),
-			(local, remote),
-			|(local, remote)| {
-				drop(local);
-				runner(uid, gid, remote, lockfile, options);
-			},
+		match clone::clone(
+			CloneFlags::CLONE_NEWUSER | CloneFlags::CLONE_NEWNS | CloneFlags::CLONE_NEWPID,
 		)
 		.expect("clone()")
-		.1;
-
-		Ok(Runner { socket: local })
+		{
+			unistd::ForkResult::Parent { .. } => Ok(Runner { socket: local }),
+			unistd::ForkResult::Child => {
+				drop(local);
+				runner(uid, gid, remote, lockfile, options);
+			}
+		}
 	}
 
 	pub fn spawn(&self, task: &Task) -> UnixStream {
diff --git a/crates/runner/src/ns.rs b/crates/runner/src/ns.rs
index a075931..3a8b51f 100644
--- a/crates/runner/src/ns.rs
+++ b/crates/runner/src/ns.rs
@@ -27,17 +27,17 @@ pub fn setup_userns(inner_uid: Uid, inner_gid: Gid, outer_uid: Uid, outer_gid: G
 	.expect("Failed to write /proc/self/gid_map");
 }
 
-pub unsafe fn spawn<T, F>(flags: CloneFlags, arg: T, f: F) -> nix::Result<(Pid, T)>
+pub unsafe fn spawn<F>(flags: CloneFlags, f: F) -> nix::Result<Pid>
 where
-	F: FnOnce(T),
+	F: FnOnce(),
 {
 	assert!(flags.contains(CloneFlags::CLONE_NEWNS) || !flags.contains(CloneFlags::CLONE_NEWPID));
 
-	clone::spawn(Some(flags), arg, |arg| {
+	clone::spawn(Some(flags), || {
 		if flags.contains(CloneFlags::CLONE_NEWPID) {
 			mount_proc();
 		}
-		f(arg)
+		f()
 	})
 }
 
diff --git a/crates/runner/src/tar.rs b/crates/runner/src/tar.rs
index 4bc343f..3fd21e7 100644
--- a/crates/runner/src/tar.rs
+++ b/crates/runner/src/tar.rs
@@ -55,9 +55,8 @@ pub fn pack<W: Write, P: AsRef<Path>>(archive: &mut W, source: P) -> Result<()>
 		process::exit(127);
 	};
 
-	let pid = unsafe { ns::spawn(CloneFlags::CLONE_NEWNS, (), |()| exec_tar().unwrap()) }
-		.context("Failed to run tar")?
-		.0;
+	let pid = unsafe { ns::spawn(CloneFlags::CLONE_NEWNS, || exec_tar().unwrap()) }
+		.context("Failed to run tar")?;
 
 	let result = io::copy(&mut piper, archive).context("Failed to write TAR archive");
 
diff --git a/crates/runner/src/task.rs b/crates/runner/src/task.rs
index 2b0070b..dc15ec5 100644
--- a/crates/runner/src/task.rs
+++ b/crates/runner/src/task.rs
@@ -319,15 +319,14 @@ fn run_task(input_hash: &InputHash, task: &Task, jobserver: &mut Jobserver) -> R
 		process::exit(127);
 	};
 
-	let (pid, ()) = unsafe {
+	let pid = unsafe {
 		ns::spawn(
 			CloneFlags::CLONE_NEWNS
 				| CloneFlags::CLONE_NEWPID
 				| CloneFlags::CLONE_NEWIPC
 				| CloneFlags::CLONE_NEWNET
 				| CloneFlags::CLONE_NEWUTS,
-			(),
-			|()| exec_cmd().unwrap(),
+			|| exec_cmd().unwrap(),
 		)
 	}
 	.context("Failed to run task container")?;
diff --git a/crates/runner/src/util/clone.rs b/crates/runner/src/util/clone.rs
index 4835b53..0af9e4d 100644
--- a/crates/runner/src/util/clone.rs
+++ b/crates/runner/src/util/clone.rs
@@ -1,6 +1,9 @@
 use std::{mem, process};
 
-use nix::{errno, sched, unistd};
+use nix::{
+	errno, sched,
+	unistd::{self, Pid},
+};
 
 #[repr(C)]
 #[derive(Debug, Default)]
@@ -30,18 +33,14 @@ pub unsafe fn clone(flags: sched::CloneFlags) -> nix::Result<unistd::ForkResult>
 		Ok(unistd::ForkResult::Child)
 	} else {
 		Ok(unistd::ForkResult::Parent {
-			child: unistd::Pid::from_raw(pid as libc::pid_t),
+			child: Pid::from_raw(pid as libc::pid_t),
 		})
 	}
 }
 
-pub unsafe fn spawn<T, F>(
-	flags: Option<sched::CloneFlags>,
-	arg: T,
-	f: F,
-) -> nix::Result<(unistd::Pid, T)>
+pub unsafe fn spawn<F>(flags: Option<sched::CloneFlags>, f: F) -> nix::Result<Pid>
 where
-	F: FnOnce(T),
+	F: FnOnce(),
 {
 	let res = if let Some(flags) = flags {
 		clone(flags)
@@ -49,9 +48,9 @@ where
 		unistd::fork()
 	};
 	match res? {
-		unistd::ForkResult::Parent { child } => Ok((child, arg)),
+		unistd::ForkResult::Parent { child } => Ok(child),
 		unistd::ForkResult::Child => {
-			f(arg);
+			f();
 			process::exit(0)
 		}
 	}