Add fail-closed Linux process and descriptor primitives

crates/lazaret-linux/src/ipc.rs

@@ -0,0 +1,36 @@
+use std::os::fd::OwnedFd;
+
+use rustix::net::{AddressFamily, SocketFlags, SocketType, socketpair};
+
+/// # Errors
+/// Returns an error when the private sequenced-packet pair cannot be created.
+pub fn private_seqpacket_pair() -> std::io::Result<(OwnedFd, OwnedFd)> {
+    socketpair(
+        AddressFamily::UNIX,
+        SocketType::SEQPACKET,
+        SocketFlags::CLOEXEC,
+        None,
+    )
+    .map_err(Into::into)
+}
+
+#[cfg(test)]
+mod tests {
+    use std::os::fd::AsFd;
+
+    use rustix::net::{RecvFlags, SendFlags, recv, send};
+
+    use super::private_seqpacket_pair;
+
+    #[test]
+    fn preserves_message_boundaries() {
+        let (left, right) = private_seqpacket_pair().unwrap();
+        send(left.as_fd(), b"first", SendFlags::empty()).unwrap();
+        send(left.as_fd(), b"second", SendFlags::empty()).unwrap();
+        let mut buffer = [0_u8; 16];
+        let (_, first) = recv(right.as_fd(), &mut buffer, RecvFlags::empty()).unwrap();
+        assert_eq!(&buffer[..first], b"first");
+        let (_, second) = recv(right.as_fd(), &mut buffer, RecvFlags::empty()).unwrap();
+        assert_eq!(&buffer[..second], b"second");
+    }
+}