nstdlib-nightly/lib/internal/wasm_web_api.mjs

Node.js standard library converted to runtime-agnostic ES modules.

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/internal/wasm_web_api.js

import { codes as __codes__ } from "nstdlib/lib/internal/errors";
import * as __hoisted_internal_deps_undici_undici__ from "nstdlib/stub/internal/deps/undici/undici";

const { ERR_INVALID_ARG_TYPE, ERR_WEBASSEMBLY_RESPONSE } = __codes__;

let undici;
function lazyUndici() {
  return (undici ??= __hoisted_internal_deps_undici_undici__);
}

// This is essentially an implementation of a v8::WasmStreamingCallback, except
// that it is implemented in JavaScript because the fetch() implementation is
// difficult to use from C++. See lib/internal/process/pre_execution.js and
// src/node_wasm_web_api.cc that interact with this function.
function wasmStreamingCallback(streamState, source) {
  (async () => {
    const response = await Promise.resolve(source);
    if (!(response instanceof lazyUndici().Response)) {
      throw new ERR_INVALID_ARG_TYPE(
        "source",
        ["Response", "Promise resolving to Response"],
        response,
      );
    }

    const contentType = response.headers.get("Content-Type");
    if (contentType !== "application/wasm") {
      throw new ERR_WEBASSEMBLY_RESPONSE(
        `has unsupported MIME type '${contentType}'`,
      );
    }

    if (!response.ok) {
      throw new ERR_WEBASSEMBLY_RESPONSE(`has status code ${response.status}`);
    }

    if (response.bodyUsed !== false) {
      throw new ERR_WEBASSEMBLY_RESPONSE("body has already been used");
    }

    if (response.url) {
      streamState.setURL(response.url);
    }

    // Pass all data from the response body to the WebAssembly compiler.
    const { body } = response;
    if (body != null) {
      for await (const chunk of body) {
        streamState.push(chunk);
      }
    }
  })().then(
    () => {
      // No error occurred. Tell the implementation that the stream has ended.
      streamState.finish();
    },
    (err) => {
      // An error occurred, either because the given object was not a valid
      // and usable Response or because a network error occurred.
      streamState.abort(err);
    },
  );
}

export { wasmStreamingCallback };