Add tickybox for unsafe (fix #3)

This `twelf.wasm` build was made against an unlanded PR
standardml/twelf#19 . However,
this (`twelf-wasm`) change itself is deployable despite that PR not
having landed yet.

Just for historical interest: the thing I did to build against that PR
was putting
```
RUN git clone -b jcreed/wasi-unsafe https://github.com/standardml/twelf && \
```
in the `Dockerfile`.

public/css/style.css

@@ -206,6 +206,10 @@ label {
   user-select: none;
 }
 
+label {
+  user-select: none;
+}
+
 .server-status::after {
   content: '';
   display: block;

public/index.html

@@ -30,6 +30,7 @@ <h1>Twelf Sandbox</h1>
       <div class="wrap" id="twelf-response-wrap">
         <textarea readonly id="twelf-response" spellcheck="false"></textarea>
       </div>
+		<div><input id="unsafe" type="checkbox"></input><label for="unsafe">Enable Unsafe</label></div>
     </div>
     <div style="margin-left: 3em; margin-top: 3em; font-size: 0.8rem;">
       <a href="http://twelf.org/wiki/Main_Page">Twelf</a> on Wasm is made possible by <a href="https://twelf-live.onrender.com/">Twelf Live</a> and

src/index.ts

@@ -104,7 +104,9 @@ async function initTwelf(editor: EditorView) {
     }
 
     document.getElementById('running-indicator')!.classList.remove('hidden');
-    const result = await (workerRef.worker).exec(text);
+    const result = await (workerRef.worker).exec(text, {
+      unsafe: (document.getElementById('unsafe')! as HTMLInputElement).checked
+    });
     document.getElementById('running-indicator')!.classList.add('hidden');
 
     if (result.status.t == 'timeout') {

src/twelf-service.ts

@@ -6,6 +6,7 @@ type TwelfExports = {
   twelf_open(argc: number, argv: number): void;
   allocate(size: number): number;
   execute(): TwelfStatus;
+  unsafe(u: boolean): void;
 };
 
 function debug(_x: string): void {
@@ -59,6 +60,11 @@ export class TwelfService {
 
   constructor(public instance: WebAssembly.Instance) { }
 
+  unsafe(u: boolean): void {
+    const exports = this.instance.exports as TwelfExports;
+    exports.unsafe(u);
+  }
+
   async exec(input: string): Promise<TwelfStatus> {
     const exports = this.instance.exports as TwelfExports;
     const mem = exports.memory;

src/twelf-worker-types.ts

@@ -3,6 +3,10 @@ export enum TwelfStatus {
   ABORT = 1,
 }
 
+export type TwelfOptions = {
+  unsafe: boolean,
+}
+
 export type TwelfExecStatus =
   | { t: 'twelfStatus', status: TwelfStatus }
   | { t: 'timeout' }
@@ -16,6 +20,7 @@ export type WithId<T> = { id: number, body: T };
 
 export type TwelfExecRequest = {
   input: string,
+  options: TwelfOptions,
 }
 
 export type TwelfSideEffectData = {

src/twelf-worker.ts

@@ -1,4 +1,4 @@
-import { TwelfExecRequest, TwelfExecResponse, WorkerMessage, WithId, TwelfSideEffectData, TwelfError } from "./twelf-worker-types";
+import { TwelfExecRequest, TwelfExecResponse, WorkerMessage, WithId, TwelfSideEffectData, TwelfError, TwelfOptions } from "./twelf-worker-types";
 
 export async function mkTwelfWorker(): Promise<TwelfWorker> {
   const worker = new TwelfWorker();
@@ -36,10 +36,10 @@ export class TwelfWorker {
     this._readyPromise = readyPromise;
   }
 
-  mkRequest(input: string): WithId<TwelfExecRequest> {
+  mkRequest(input: string, options: TwelfOptions): WithId<TwelfExecRequest> {
     return {
       id: this.requestIdCounter++,
-      body: { input },
+      body: { input, options },
     };
   }
 
@@ -64,10 +64,10 @@ export class TwelfWorker {
     }
   }
 
-  async exec(input: string): Promise<TwelfExecResponse> {
+  async exec(input: string, options: TwelfOptions): Promise<TwelfExecResponse> {
     this.output.splice(0); // clear output
 
-    const req = this.mkRequest(input);
+    const req = this.mkRequest(input, options);
     const prom = new Promise<WorkerMessage>((res, rej) => {
       this.responseMap[req.id] = res;
     });

src/worker.ts

@@ -12,6 +12,7 @@ async function go() {
 
   self.onmessage = async event => {
     const { body, id } = event.data as WithId<TwelfExecRequest>;
+    await service.unsafe(body.options.unsafe);
     post({ t: 'execResponse', id, response: await service.exec(body.input) });
   };