From e8f054d59880f0bf459dacb6a80bea3626ca83d8 Mon Sep 17 00:00:00 2001
From: rrai35 <ritesh.rai@aexp.com>
Date: Fri, 29 Sep 2023 10:16:43 -0400
Subject: [PATCH] feat(syswall): Adding syswall, rand and time capability to
 wazero

---
 engines/wazero/wazero.go | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/engines/wazero/wazero.go b/engines/wazero/wazero.go
index 7b9dd72..9f6b46d 100644
--- a/engines/wazero/wazero.go
+++ b/engines/wazero/wazero.go
@@ -2,6 +2,7 @@ package wazero
 
 import (
 	"context"
+	"crypto/rand"
 	"errors"
 	"fmt"
 	"sync/atomic"
@@ -124,7 +125,7 @@ func (e *engine) New(ctx context.Context, host wapc.HostCallHandler, guest []byt
 	m := &Module{runtime: r, wapcHostCallHandler: host}
 
 	m.config = wazero.NewModuleConfig().
-		WithStartFunctions(functionStart, functionInit) // Call any WASI or waPC start functions on instantiate.
+		WithStartFunctions() // Manually call _start and _init
 
 	if config.Stdout != nil {
 		m.config = m.config.WithStdout(config.Stdout)
@@ -132,6 +133,8 @@ func (e *engine) New(ctx context.Context, host wapc.HostCallHandler, guest []byt
 	if config.Stderr != nil {
 		m.config = m.config.WithStderr(config.Stderr)
 	}
+	m.config = m.config.WithRandSource(rand.Reader).WithSysNanosleep().WithSysNanotime().WithSysWalltime()
+
 	mod = m
 
 	if _, err = instantiateWapcHost(ctx, r, m.wapcHostCallHandler, config.Logger); err != nil {
@@ -371,6 +374,21 @@ func (m *Module) Instantiate(ctx context.Context) (wapc.Instance, error) {
 		return nil, err
 	}
 
+	// Call any WASI or waPC start functions on instantiate.
+	funcs := []string{functionStart, functionInit}
+	for _, f := range funcs {
+		exportedFunc := module.ExportedFunction(f)
+		if exportedFunc != nil {
+			ic := invokeContext{operation: f, guestReq: nil}
+			ictx := newInvokeContext(ctx, &ic)
+			if _, err := exportedFunc.Call(ictx); err != nil {
+				module.Close(ctx)
+
+				return nil, fmt.Errorf("error calling %s: %v", f, err)
+			}
+		}
+	}
+
 	instance := Instance{name: moduleName, m: module}
 
 	if instance.guestCall = module.ExportedFunction(functionGuestCall); instance.guestCall == nil {