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Handle stdio/stderr consistently in Example/src/index.js #17

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Merged
kateinoigakukun merged 2 commits into from
Jun 21, 2020
Merged

Handle stdio/stderr consistently in Example/src/index.js #17

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9ef7981
Make stdio/stderr handling consistent in Example/src/index.js
MaxDesiatov Jun 21, 2020
f91841b
Update formatting in Example/src/index.js
MaxDesiatov Jun 21, 2020
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25 changes: 21 additions & 4 deletions Example/src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,27 @@ import { WasmFs } from "@wasmer/wasmfs";
const swift = new SwiftRuntime();
// Instantiate a new WASI Instance
const wasmFs = new WasmFs();

// Output stdout and stderr to console
const originalWriteSync = wasmFs.fs.writeSync;
wasmFs.fs.writeSync = (fd, buffer, offset, length, position) => {
const text = new TextDecoder("utf-8").decode(buffer);

// Filter out standalone "\n" added by every `print`, `console.log`
// always adds its own "\n" on top.
if (text !== "\n") {
switch (fd) {
case 1:
console.log(text);
break;
case 2:
console.error(text);
break;
}
}
return originalWriteSync(fd, buffer, offset, length, position);
};

let wasi = new WASI({
args: [],
env: {},
Expand All @@ -30,9 +51,5 @@ const startWasiTask = async () => {
swift.setInstance(instance);
// Start the WebAssembly WASI instance!
wasi.start(instance);

// Output what's inside of /dev/stdout!
const stdout = await wasmFs.getStdOut();
console.log(stdout);
};
startWasiTask();