In Oniguruma LoadWasm function, node fs buffer works fine but vscode.workspace.fs buffer does not work.

[leodevbro]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.65.0-insider (user setup)
• OS Version: Windows 10 Pro 21H2

I'm not sure that it is a bug, but it is a very strange behavior. I'm building a VSCode extension. I'm trying to load oniguruma wasm with vscode.workspace.fs buffer, it does not work, but node fs buffer works fine. I don't want to use node fs, because I want my extension to be a web extension (as well as desktop extension).

Steps to Reproduce (See full code down below, after the gif):

The code:

import * as vscode from "vscode";
import * as path from "path";
import * as nodeFs from "fs";

import myOniguruma = require("vscode-oniguruma");
const myOnigurumaPath = require.resolve("vscode-oniguruma");

const myWasmPath = path.join(
    myOnigurumaPath.slice(0, myOnigurumaPath.length - 7),
    "onig.wasm",
);
const myWasmPathUri = vscode.Uri.file(myWasmPath);

vscode.workspace.fs.readFile(myWasmPathUri).then((myUint8Array) => {
    const vscodeFsBuffer = myUint8Array.buffer;
    console.log("vscodeFsBuffer: ", vscodeFsBuffer);

    const nodeFsBuffer = nodeFs.readFileSync(myWasmPath).buffer;
    console.log("nodeFsBuffer: ", nodeFsBuffer);

    myOniguruma.loadWASM(nodeFsBuffer) // this works fine --------------------------------
    // myOniguruma.loadWASM(vscodeFsBuffer) // this does not work ----------------------------
        .then((x) => {
            console.log("successful");
        })
        .catch((error) => {
            console.log("error: ", error);
        });
});

The error:

message:'WebAssembly.instantiate(): expected magic word 00 61 73 6d, found 01 00 00 03 @+0'
stack:'CompileError: WebAssembly.instantiate(): expected magic word 00 61 73 6d, found 01 00 00 03 @+0'

rejected promise not handled within 1 second: Error: Must invoke loadWASM first.

[alexdima]

@leodevbro Uint8Array is a view on an ArrayBuffer. That means that the Uint8Array can use only a part of its underlying .buffer, namely the part from .byteOffset and of length .byteLength:

interface ArrayBufferView {
    /**
     * The ArrayBuffer instance referenced by the array.
     */
    buffer: ArrayBufferLike;

    /**
     * The length in bytes of the array.
     */
    byteLength: number;

    /**
     * The offset in bytes of the array.
     */
    byteOffset: number;
}

So in this particular case this is a programming mistake. To correct it, you would need to create a new Buffer of the right size and copy the parts of the other Buffer into the new one.

To allow supporting 0-copy, I have pushed a change to vscode-oniguruma to accept an ArrayBufferView, so with the latest vscode-oniguruma, you will be able to use myOniguruma.loadWASM(myUint8Array)

[leodevbro]

@alexdima, huge thanks, it's working, really appreciate that you updated vscode-oniguruma package.