Stdin from node to PHP script hangs - php

Question

I'm attempting to pipe contents from a node process into a PHP script, but for some reason it hangs in PHP and never seems to exit the while loop in test-stdin.php and therefore the final echo statement echo('Total input from stdin: ' . $text) is never run.
run.js
const { spawn } = require('child_process');
const php = spawn('php', ['test-stdin.php'], {});
php.stdin.write('some input');
php.stdin.write("\n"); // As I understand, EOL is needed to stop processing
// Also tried the below, didn't work.
// ls.stdin.write(require('os').EOL);
php.stdout.on('data', (data) => {
console.log(`stdout: ${data}`);
});
php.on('close', (code) => {
console.log(`child process exited with code ${code}`);
});
test-stdin.php
$input_stream = fopen("php://stdin","r");
stream_set_blocking($input_stream, 0); // Also tried: stream_set_blocking(STDIN, 0);
$text="";
// It never exits this loop, for some reason?
while(($line = fgets($input_stream,4096)) !== false) {
var_dump('Read from fgets: ', $line); // This dumps successfully "some input"
$text .= $line;
}
// The below code is never reached, as it seems it's hanging in the loop above.
fclose($input_stream);
echo('Total input from stdin: ' . $text);
Any ideas why it's hanging inside that loop and not hitting the final echo? I tried setting stream to "non blocking" mode and it didn't seem to have any effect.

Answer 1

This only hangs for me if I set the PHP stdin stream as blocking instead of unblocking as your example has e.g stream_set_blocking($input_stream, 1);.
With that set it hangs for ever as I would expect as nothing on the NodeJS side is ending the stdin stream.
Calling .end() on stdin from NodeJS seems to be all that's missing e.g:
const { spawn } = require('child_process');
const php = spawn('php', ['test-stdin.php'], {});
php.stdin.write('some input');
php.stdin.write("\n"); // As I understand, EOL is needed to stop processing
// Also tried the below, didn't work.
// ls.stdin.write(require('os').EOL);
php.stdin.end();
php.stdout.on('data', (data) => {
console.log(`stdout: ${data}`);
});
php.on('close', (code) => {
console.log(`child process exited with code ${code}`);
});