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var assert = require('assert'),
util = require('util'),
spawn = require('child_process').spawn;
// We're trying to reproduce:
// $ echo "hello\nnode\nand\nworld" | grep o | sed s/o/a/
var echo = spawn('echo', ['hello\nnode\nand\nworld\n']),
grep = spawn('grep', ['o']),
sed = spawn('sed', ['s/o/O/']);
/*
* grep and sed hang if the spawn function leaks file descriptors to child
* processes.
* This happens when calling pipe(2) and then forgetting to set the
* FD_CLOEXEC flag on the resulting file descriptors.
*
* This test checks child processes exit, meaning they don't hang like
* explained above.
*/
// pipe echo | grep
echo.stdout.on('data', function(data) {
if (!grep.stdin.write(data)) {
echo.stdout.pause();
}
});
grep.stdin.on('drain', function(data) {
echo.stdout.resume();
});
// propagate end from echo to grep
echo.stdout.on('end', function(code) {
grep.stdin.end();
});
// pipe grep | sed
grep.stdout.on('data', function(data) {
if (!sed.stdin.write(data)) {
grep.stdout.pause();
}
});
sed.stdin.on('drain', function(data) {
grep.stdout.resume();
});
// propagate end from grep to sed
grep.stdout.on('end', function(code) {
sed.stdin.end();
});
var result = '';
// print sed's output
sed.stdout.on('data', function(data) {
result += data.toString('utf8', 0, data.length);
util.print(data);
});
sed.stdout.on('end', function(code) {
assert.equal(result, 'hellO\nnOde\nwOrld\n');
});
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