fix stdin for multiple read

Author: kateinoigakukun

src/features/fd.ts

@@ -30,28 +30,33 @@ class WritableTextProxy implements FdEntry {
     close(): void {}
 }
 
-class ReadableTextProxy implements FdEntry {
+export class ReadableTextProxy implements FdEntry {
     private encoder = new TextEncoder();
-    private pending: Uint8Array | null;
+    private pending: Uint8Array | null = null;
     constructor(private readonly consume: () => string) { }
 
     writev(_iovs: Uint8Array[]): number {
         return 0;
     }
+    consumePending(pending: Uint8Array, requestLength: number): Uint8Array {
+        if (pending.byteLength < requestLength) {
+            this.pending = null
+            return pending;
+        } else {
+            const result = pending.slice(0, requestLength);
+            this.pending = pending.slice(requestLength);
+            return result;
+        }
+    }
     readv(iovs: Uint8Array[]): number {
         let read = 0;
         for (const buffer of iovs) {
             let remaining = buffer.byteLength;
             if (this.pending) {
-                const reading = Math.min(remaining, this.pending.byteLength);
-                buffer.set(this.pending.slice(0, reading), 0);
-                remaining -= reading;
-                if (remaining < this.pending.byteLength) {
-                    this.pending = this.pending.slice(reading);
-                    continue;
-                } else {
-                    this.pending = null;
-                }
+                const consumed = this.consumePending(this.pending, remaining);
+                buffer.set(consumed, 0);
+                remaining -= consumed.byteLength;
+                read += consumed.byteLength;
             }
             while (remaining > 0) {
                 const newText = this.consume();

src/index.ts

@@ -5,7 +5,7 @@ export * from "./features/all";
 export * from "./features/args";
 export * from "./features/clock";
 export * from "./features/environ";
-export * from "./features/fd";
+export { useFS, useStdio } from "./features/fd";
 export * from "./features/proc";
 export * from "./features/random";
 export * from "./features/tracing";

test/fd.test.ts

@@ -0,0 +1,27 @@
+import { ReadableTextProxy } from "../src/features/fd"
+
+describe("fd.ReadableTextProxy", () => {
+    it("readv single buffer", () => {
+        const input = "hello";
+        const inputs = [input];
+        const proxy = new ReadableTextProxy(() => inputs.shift() || "");
+        const buffer = new Uint8Array(10);
+        const read = proxy.readv([buffer]);
+        expect(read).toBe(5);
+        const expected = new TextEncoder().encode(input)
+        expect(buffer.slice(0, 5)).toEqual(expected);
+    })
+
+    it("readv 2 buffer", () => {
+        const input = "hello";
+        const inputs = [input];
+        const proxy = new ReadableTextProxy(() => inputs.shift() || "");
+        const buf0 = new Uint8Array(2);
+        const buf1 = new Uint8Array(2);
+        const read = proxy.readv([buf0, buf1]);
+        expect(read).toBe(4);
+        const expected = new TextEncoder().encode(input)
+        expect(buf0).toEqual(expected.slice(0, 2));
+        expect(buf1).toEqual(expected.slice(2, 4));
+    })
+})

test/wasi-test-suite/harness.ts

@@ -6,7 +6,7 @@ import { readFile } from "fs/promises";
 export async function runTest(filePath: string) {
     let stdout = "";
     let stderr = "";
-    const stdin = await (async () => {
+    let stdin = await (async () => {
         const path = filePath.replace(/\.wasm$/, ".stdin");
         if (!existsSync(path)) {
             return "";
@@ -16,7 +16,11 @@ export async function runTest(filePath: string) {
     const features = [
         useEnviron, useArgs, useClock, useProc,
         useRandom(), useStdio({
-            stdin: () => { return stdin },
+            stdin: () => {
+                const result = stdin;
+                stdin = "";
+                return result;
+            },
             stdout: (lines) => { stdout += lines },
             stderr: (lines) => { stderr += lines },
         })