The use of eval in vm is restricted

[LoyDgIk]

runtime.getExecutor("""
    const vm = require('node:vm');
    const script = new vm.Script("eval('1+1')");
    script.runInNewContext();
""".trimIndent()).setModule(true).executeVoid()

It's normal to write like this.
But

runtime.getExecutor("""
    const vm = require('node:vm');
    const script = new vm.Script("eval('1+1')");
    script.runInNewContext();
""".trimIndent()).compileV8Module().execute();

Will throw an error:EvalError: Code generation from strings disallowed for this context

So this is a bug?

[caoccao]

It seems you are using the engine pool which disables eval() by default. Please check this page out to allow eval().

[LoyDgIk]

I set allowEval to true, but it doesn't seem to work.

[caoccao]

It's more like a JS trick as follows.

nodeRuntime.allowEval(true);
nodeRuntime.getExecutor("const vm = require(\"node:vm\");\n" +
        "const script = new vm.Script(\"eval('1+1')\");\n" +
        "console.log(script.runInThisContext());\n" +
        "console.log(script.runInNewContext(vm.createContext({eval})));").executeVoid();
// Output
2
2

[LoyDgIk]

Have you tried .compileV8Module().execute()? This is when an error would be thrown, whereas .executeVoid() works without issues. I needed to use .compileV8Module() in IV8ModuleResolver.resolve() and that's how I discovered this problem.

[caoccao]

Those API require certain understanding on how V8 works internally. Please let your code.

[LoyDgIk]

fun resolve(runtime: V8Runtime, resourceName: String, v8ModuleReferrer: IV8Module): Any? {
    return when {
        resourceName.startsWith("/") || resourceName.startsWith("./") || resourceName.startsWith("../") -> {
            val parentModuleName = v8ModuleReferrer.getResourceName()
            val moduleRelativePath = Paths.get(parentModuleName).parent.resolve(resourceName).normalize()
            val moduleFile = Paths.get(localRelativePath).resolve(moduleRelativePath).toFile()

            if (moduleFile.exists() && moduleFile.isFile) {
                val url = "file://${moduleFile.canonicalPath}"
                val code = readFile(url)
                runtime.getExecutor("import.meta.url=${Json.encodeToString(url)};$code")
                    .setResourceName(moduleRelativePath.toString()).compileV8Module()
            } else {
                null
            }
        }
        resourceName.startsWith("node:") -> nodeResolve.resolve(runtime, resourceName, v8ModuleReferrer)
        else -> {
            val moduleObject = runtime.getNodeModule(resourceName, nodeModuleAnyClazz).getModuleObject()
            moduleObject.set("default", moduleObject)
            runtime.createV8Module(resourceName, moduleObject)
        }
    }
}

This is my code.
So, how do we address the issues with eval?

[caoccao]

It doesn't seem to be a complete reproducible code. Could you leave a repo with the issue?

[LoyDgIk]

It's more like a JS trick as follows.

nodeRuntime.allowEval(true);
nodeRuntime.getExecutor("const vm = require(\"node:vm\");\n" +
        "const script = new vm.Script(\"eval('1+1')\");\n" +
        "console.log(script.runInThisContext());\n" +
        "console.log(script.runInNewContext(vm.createContext({eval})));").executeVoid();
// Output
2
2

I just realized that this eval is manually injected into the vm context, while in fact, native Node.js does not require such an operation.
native Node.js:

javet:

[LoyDgIk]

It's more like a JS trick as follows.

nodeRuntime.allowEval(true);
nodeRuntime.getExecutor("const vm = require(\"node:vm\");\n" +
        "const script = new vm.Script(\"eval('1+1')\");\n" +
        "console.log(script.runInThisContext());\n" +
        "console.log(script.runInNewContext(vm.createContext({eval})));").executeVoid();
// Output
2
2

Can you take a look at it for me?

[FoxNick]

const vm = require('vm');

// 创建一个沙箱上下文
const sandbox = { x: 1, y: 2 };

// 创建一个虚拟机上下文，允许执行 eval
vm.createContext(sandbox);

// 使用 vm.runInContext 执行代码
const code = 'eval("x + y")'; // 使用 eval 来执行动态代码
const result = vm.runInContext(code, sandbox);

console.log(result); // 输出: 3
在这个例子中，通过 vm.createContext 创建了一个沙箱，并在该上下文中执行了一个包含 eval() 的动态代码。正常环境 这个代码被允许执行，因为 eval 在上下文中没有被禁用。但是javet 运行结果是eval不能正确执行, 可能是处于禁用。

[FoxNick]

v8Isolate->SetModifyCodeGenerationFromStringsCallback(nullptr);
不知道这段代码是用来干什么的 注释掉 vm eavl 开启和禁用 问题解决