PHP: Deadlock through using proc_open("ssh hostname 'tail -F ~somefile' ") - php

Question

Happens that i need to track file status through ssh by php(using phpunit). But when i trying to launch this code:
$descriptorspec = array(
0 => array('pipe', 'r'),
1 => array('pipe', 'w'),
2 => array('pipe', 'w'),
);
$cmd = "ssh hostname 'tail -F ~/test.file'";
$proc = proc_open($cmd, $descriptorspec, $pipes, null);
$str = fgets($pipes[1]);
echo $str;
if (!fclose($pipes[0])) {
throw new Exception("Can't close pipe 0");
}
if (!fclose($pipes[1])) {
throw new Exception("pipe 1");
}
if (!fclose($pipes[2])) {
throw new Exception("pipe 2");
}
$res = proc_close($proc);
nothing happens - no output, and i guess deadlock exucuted: script doesn't exit.
Have any ideas? or suggestions?

Answer 1

tail -F doesn't actually "end" - it just keeps dumping output as it becomes available. That's probably the problem. It's blocking on the fgets().
My recommendation: use phpseclib, a pure PHP SSH2 implementation. eg.
<?php
include('Net/SSH2.php');
$ssh = new Net_SSH2('www.domain.tld');
if (!$ssh->login('username', 'password')) {
exit('Login Failed');
}
function packet_handler($str)
{
echo $str;
}
$ssh->exec('tail -F ~/test.file', 'packet_handler');
?>
Although looking at the implementation, now... it doesn't look like it provides you with any mechanism to prematurely quit either. It'd be nice if it was like "if packet_handler returns false then exec() stops running" or something.
I guess in lieu of that you can use ->setTimeout().