Merge pull request #4 from arjunbajaj/stdio-buffers-support

README.md

@@ -99,6 +99,20 @@ const wasi = new WASI({
 });
 ```
 
+By default, the `stdout` and `stderr` handlers are passed strings. You can pass `outputBuffers: true` to get `Uint8Array` buffers instead. Along with that, you can also pass `Uint8Array` buffers to `stdin`.
+
+```js
+import { WASI, useStdio } from "uwasi";
+const wasi = new WASI({
+ features: [useStdio({
+ outputBuffers: true,
+ stdin: () => new Uint8Array([1, 2, 3, 4, 5]),
+ stdout: (buf) => console.log(buf),
+ stderr: (buf) => console.error(buf),
+ })],
+});
+```
+
 ## Implementation Status
 
 Some of WASI system calls are not implemented yet. Contributions are welcome!

src/features/fd.ts

@@ -9,7 +9,10 @@ interface FdEntry {
 
 class WritableTextProxy implements FdEntry {
  private decoder = new TextDecoder('utf-8');
- constructor(private readonly handler: (lines: string) => void) { }
+ constructor(
+ private readonly handler: (lines: string | Uint8Array) => void,
+ private readonly outputBuffers: boolean
+ ) { }
 
  writev(iovs: Uint8Array[]): number {
  const totalBufferSize = iovs.reduce((acc, iov) => acc + iov.byteLength, 0);
@@ -20,8 +23,13 @@ class WritableTextProxy implements FdEntry {
  offset += buffer.byteLength;
  }
 
- const lines = this.decoder.decode(concatBuffer);
- this.handler(lines);
+ if (this.outputBuffers) {
+ this.handler(concatBuffer);
+ } else {
+ const lines = this.decoder.decode(concatBuffer);
+ this.handler(lines);
+ }
+
  return concatBuffer.length;
  }
  readv(_iovs: Uint8Array[]): number {
@@ -33,7 +41,7 @@ class WritableTextProxy implements FdEntry {
 export class ReadableTextProxy implements FdEntry {
  private encoder = new TextEncoder();
  private pending: Uint8Array | null = null;
- constructor(private readonly consume: () => string) { }
+ constructor(private readonly consume: () => string | Uint8Array) { }
 
  writev(_iovs: Uint8Array[]): number {
  return 0;
@@ -59,8 +67,15 @@ export class ReadableTextProxy implements FdEntry {
  read += consumed.byteLength;
  }
  while (remaining > 0) {
- const newText = this.consume();
- const bytes = this.encoder.encode(newText);
+ const newData = this.consume();
+ let bytes: Uint8Array;
+
+ if (newData instanceof Uint8Array) {
+ bytes = newData;
+ } else {
+ bytes = this.encoder.encode(newData);
+ }
+
  if (bytes.length == 0) {
  return read;
  }
@@ -108,16 +123,19 @@ export class ReadableTextProxy implements FdEntry {
  */
 export function useStdio(
  useOptions: {
- stdin?: () => string,
- stdout?: (lines: string) => void,
- stderr?: (lines: string) => void,
+ stdin?: () => string | Uint8Array,
+ stdout?: (lines: string | Uint8Array) => void,
+ stderr?: (lines: string | Uint8Array) => void,
+ outputBuffers?: boolean,
  } = {}
 ): WASIFeatureProvider {
  return (options, abi, memoryView) => {
+ const outputBuffers = useOptions.outputBuffers || false;
+
  const fdTable = [
  new ReadableTextProxy(useOptions.stdin || (() => { return "" })),
- new WritableTextProxy(useOptions.stdout || console.log),
- new WritableTextProxy(useOptions.stderr || console.error),
+ new WritableTextProxy(useOptions.stdout || console.log, outputBuffers),
+ new WritableTextProxy(useOptions.stderr || console.error, outputBuffers),
  ]
  return {
  fd_fdstat_get: (fd: number, buf: number) => {