从WebAssembly .wasm模块获取JavaScript导入对象条目 [英] Obtaining JavaScript import object entries from a WebAssembly .wasm module

问题描述

我想了解Rust程序在编译成wasm文件时实际导出的内容，因此我可以为实例化函数提供有效的 importObject :

I want to understand what a Rust program actually exports when it is compiled to a wasm file so I can provide a valid importObject to the instantiate function:

WebAssembly.instantiate(bufferSource, importObject);

据我了解，做到这一点的唯一方法是通过导出类似于s语法的已编译代码文件.我无法在他们的文档中或通过网络搜索找到方法.

As far as I understand, the only way to do this is by exporting an s-syntax like file of the compiled code. I can't find how to do this in their docs or through web searches.

推荐答案

您可以使用 wabt 的 wasm2wast 将 .wasm 文件转换为等效的 .wast .那会满足您的要求.

You can use a tool such as wabt's wasm2wast to translate a .wasm file to the equivalent .wast. That would do what you ask for.

但是，您不一定需要这样做！JavaScript API为您提供了所需的最多:

However, you don't necessarily need to do this! The JavaScript API gives you most of what you want:

let arrayBuffer = ...; // Somehow get your .wasm file into an ArrayBuffer. XHR, from a string, or what have you.
let module = WebAssembly.Module(arrayBuffer); // This is the synchronous API! Only use it for testing / offline things.

let importObject = {};
for (let imp of WebAssembly.Module.imports(module)) {
    if (typeof importObject[imp.module] === "undefined")
        importObject[imp.module] = {};
    switch (imp.kind) {
    case "function": importObject[imp.module][imp.name] = () => {}; break;
    case "table": importObject[imp.module][imp.name] = new WebAssembly.Table({ initial: ???, maximum: ???, element: "anyfunc" }); break;
    case "memory": importObject[imp.module][imp.name] = new WebAssembly.Memory({ initial: ??? }); break;
    case "global": importObject[imp.module][imp.name] = 0; break;
    }
}

请注意，表和内存的初始/最大值当前是猜测！我建议我们将缺少的信息添加到JS API中.我认为在下一次WebAssembly会议上可能是讨论添加此类内容的好时机.

Note that Table and Memory initial / maximum are currently guesses! I'm proposing that we add the missing information to the JS API. I think at the next WebAssembly meeting may be a good time to discuss such an addition.

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