plugins 2.0 update

plugins/sample-wasm-hostinfo/native/main.go

@@ -0,0 +1,93 @@
+package main
+
+import "unsafe"
+
+//go:wasmimport env overlord_emit
+func overlordEmit(eventPtr, eventLen, payloadPtr, payloadLen uint32) int32
+
+//go:wasmimport env overlord_host_info
+func overlordHostInfo(outPtr, outLen uint32) int32
+
+var heap = make([]byte, 64*1024)
+var heapOffset uint32 = 8
+
+var hostInfo [1024]byte
+var hostInfoLen uint32
+
+//go:export overlord_alloc
+func overlordAlloc(size uint32) uint32 {
+	if size == 0 {
+		size = 1
+	}
+	ptr := (heapOffset + 7) &^ 7
+	next := ptr + size
+	if next >= uint32(len(heap)) {
+		return 0
+	}
+	heapOffset = next
+	return uint32(uintptr(unsafe.Pointer(&heap[ptr])))
+}
+
+//go:export overlord_free
+func overlordFree(ptr, size uint32) {
+	_, _ = ptr, size
+}
+
+//go:export overlord_on_load
+func overlordOnLoad(hostPtr, hostLen uint32) int32 {
+	n := hostLen
+	if n > uint32(len(hostInfo)) {
+		n = uint32(len(hostInfo))
+	}
+	copy(hostInfo[:n], bytesAt(hostPtr, n))
+	hostInfoLen = n
+	emit("ready", hostInfo[:hostInfoLen])
+	return 0
+}
+
+//go:export overlord_on_event
+func overlordOnEvent(eventPtr, eventLen, payloadPtr, payloadLen uint32) int32 {
+	_, _ = payloadPtr, payloadLen
+	event := string(bytesAt(eventPtr, eventLen))
+	if event != "query_host" {
+		return 0
+	}
+
+	var buf [1024]byte
+	n := overlordHostInfo(uint32(uintptr(unsafe.Pointer(&buf[0]))), uint32(len(buf)))
+	if n < 0 {
+		emitString("host_info", `{"error":"host info buffer too small"}`)
+		return 0
+	}
+	emit("host_info", buf[:uint32(n)])
+	return 0
+}
+
+//go:export overlord_on_unload
+func overlordOnUnload() {}
+
+func emitString(event string, payload string) {
+	emit(event, []byte(payload))
+}
+
+func emit(event string, payload []byte) {
+	eventBytes := []byte(event)
+	var eventPtr uint32
+	var payloadPtr uint32
+	if len(eventBytes) > 0 {
+		eventPtr = uint32(uintptr(unsafe.Pointer(&eventBytes[0])))
+	}
+	if len(payload) > 0 {
+		payloadPtr = uint32(uintptr(unsafe.Pointer(&payload[0])))
+	}
+	overlordEmit(eventPtr, uint32(len(eventBytes)), payloadPtr, uint32(len(payload)))
+}
+
+func bytesAt(ptr, length uint32) []byte {
+	if length == 0 {
+		return nil
+	}
+	return unsafe.Slice((*byte)(unsafe.Pointer(uintptr(ptr))), length)
+}
+
+func main() {}