Add thread spawn with proper trait checks.

rust/lib/mammoth/src/thread.rs

@@ -42,3 +42,43 @@ impl Thread {
         syscall::thread_wait(&self.cap)
     }
 }
+
+pub struct JoinHandle {
+    cap: Capability,
+}
+
+impl JoinHandle {
+    pub fn join(&self) -> Result<(), zion::ZError> {
+        syscall::thread_wait(&self.cap)
+    }
+}
+
+#[no_mangle]
+extern "C" fn entry_point(func: *mut c_void) -> ! {
+    unsafe {
+        Box::from_raw(func as *mut Box<dyn FnOnce()>)();
+    }
+
+    syscall::thread_exit()
+}
+
+pub fn spawn<F>(f: F) -> JoinHandle
+where
+    F: FnOnce() + Send + 'static,
+{
+    // This is very tricky.
+    // If we have been passed a closure that doesn't capture
+    // anything it will be 0 size and creating a Box of it
+    // will create a pointer with address 0x1.
+    // So we create this "main" closure that captures f to get around this.
+    // Also somehow having the explicit type annotation here is important.
+    let main: Box<dyn FnOnce()> = Box::new(move || {
+        f();
+    });
+    let raw_main = Box::into_raw(Box::new(main));
+    let proc_cap = Capability::take_copy(unsafe { crate::init::SELF_PROC_CAP }).unwrap();
+    let cap = syscall::thread_create(&proc_cap).unwrap();
+    syscall::thread_start(&cap, entry_point as u64, raw_main as u64, 0).unwrap();
+
+    JoinHandle { cap }
+}

rust/usr/testbed/src/main.rs

@@ -3,6 +3,7 @@
 
 extern crate alloc;
 
+use alloc::boxed::Box;
 use alloc::string::ToString;
 use mammoth::debug;
 use mammoth::define_entry;
@@ -12,6 +13,10 @@ use yellowstone_yunq::GetEndpointRequest;
 
 define_entry!();
 
+pub fn testthread() {
+    debug!("Testing 1, 8 ,9");
+}
+
 #[no_mangle]
 pub extern "C" fn main() -> z_err_t {
     debug!("Testing!");
@@ -28,11 +33,24 @@ pub extern "C" fn main() -> z_err_t {
 
     debug!("Got endpoint w/ cap: {:#x}", endpoint.endpoint);
 
+    let a = Box::new(1);
+    let b = Box::new(1);
+    debug!("Addrs: {:p} {:p}", a, b);
+
     let e: thread::ThreadEntry = |_| {
         debug!("Testing 1 2 3");
     };
     let t = thread::Thread::spawn(e, core::ptr::null()).expect("Failed to spawn thread");
+    t.join().expect("Failed to wait.");
 
+    let x = Box::new(|| 1);
+    debug!("Addr: {:p}", x);
+    debug!("Addr: {:p}", &x);
+
+    let t = thread::spawn(testthread);
+    t.join().expect("Failed to wait.");
+
+    let t = thread::spawn(|| debug!("Testing 4, 5, 6"));
     t.join().expect("Failed to wait.");
 
     0