//go:build linux || darwin

package runtime

import "unsafe"

// SpawnBinary forks and execs an installed binary as a new domain.
// binPath is the absolute path to the binary in the mxinstall cache.
// hash is the .mxh content hash embedded at compile time for this spawn site,
// verified by SpawnHandshake on both sides.
// Returns the parent's IPC fd on success, -1 on error.
//
// Child stderr/stdout are inherited from the parent. Child panic traces and
// debug output will appear on the parent's terminal. This is intentional.
func SpawnBinary(binPath string, hash string) int32 {
	var fds [2]int32
	r := moxie_socketpair(1, 1, 0, unsafe.Pointer(&fds[0])) // AF_UNIX=1, SOCK_STREAM=1
	if r < 0 {
		println("spawn: socketpair failed for", binPath)
		return -1
	}
	moxie_set_spawn_bufs(fds[0], fds[1])

	pid := moxie_fork()
	if pid < 0 {
		moxie_close(fds[0])
		moxie_close(fds[1])
		println("spawn: fork failed for", binPath)
		return -1
	}

	if pid == 0 {
		// Child: moxie_exec_binary closes all fds except fds[1] (IPC fd),
		// sets MOXIE_IPC_FD, then execs the binary. Does not return on success.
		moxie_close(fds[0]) // close parent's end before exec
		moxie_exec_binary(binPath, fds[1])
		println("spawn: exec failed for", binPath)
		exit(1)
	}

	// Parent: close child's fd.
	moxie_close(fds[1])

	// Perform handshake over the parent's fd.
	if errMsg := SpawnHandshake(fds[0], []string{hash}); errMsg != "" {
		println("spawn:", errMsg)
		moxie_close(fds[0])
		moxie_kill(pid, 9)
		var status int32
		moxie_waitpid(pid, unsafe.Pointer(&status), 0)
		return -1
	}

	// Register with domain list so domainReapChildren handles cleanup.
	domainRegister(pid, fds[0], -1)
	return fds[0]
}

//export moxie_exec_binary
func moxie_exec_binary(path string, ipcFd int32) int32