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'use strict';
const common = require('../common');
const assert = require('assert');
const path = require('path');
const fs = require('fs');
const spawn = require('child_process').spawn;
const tmpdir = require('../common/tmpdir');
let cat, grep, wc;
const KB = 1024;
const MB = KB * KB;
// Make sure process chaining allows desired data flow:
// check cat <file> | grep 'x' | wc -c === 1MB
// This helps to make sure no data is lost between pipes.
{
tmpdir.refresh();
const file = path.resolve(tmpdir.path, 'data.txt');
const buf = Buffer.alloc(MB).fill('x');
// Most OS commands that deal with data, attach special
// meanings to new line - for example, line buffering.
// So cut the buffer into lines at some points, forcing
// data flow to be split in the stream.
for (let i = 0; i < KB; i++)
buf[i * KB] = 10;
fs.writeFileSync(file, buf.toString());
cat = spawn('cat', [file]);
grep = spawn('grep', ['x'], { stdio: [cat.stdout, 'pipe', 'pipe'] });
wc = spawn('wc', ['-c'], { stdio: [grep.stdout, 'pipe', 'pipe'] });
// Extra checks: We never try to start reading data ourselves.
cat.stdout._handle.readStart = common.mustNotCall();
grep.stdout._handle.readStart = common.mustNotCall();
// Keep an array of error codes and assert on them during process exit. This
// is because stdio can still be open when a child process exits, and we don't
// want to lose information about what caused the error.
const errors = [];
process.on('exit', () => {
assert.deepStrictEqual(errors, []);
});
[cat, grep, wc].forEach((child, index) => {
const errorHandler = (thing, type) => {
// Don't want to assert here, as we might miss error code info.
console.error(`unexpected ${type} from child #${index}:\n${thing}`);
};
child.stderr.on('data', (d) => { errorHandler(d, 'data'); });
child.on('error', (err) => { errorHandler(err, 'error'); });
child.on('exit', common.mustCall((code) => {
if (code !== 0) {
errors.push(`child ${index} exited with code ${code}`);
}
}));
});
wc.stdout.on('data', common.mustCall((data) => {
assert.strictEqual(data.toString().trim(), MB.toString());
}));
}
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