Script fails if fread is great than 1

[Boxerman]

Hi guys,

 

Tricky one to explain here so first sorry if i do not provide everything.

 

The below script is set to create a new user by passing PHP variables into a powershell script. The powershell has been tested manually and works perfectly:

 //cmd to run
$runCMD = "powershell -Command './MasterScript.ps1 -ucr -udn \"$user\" -pas \"$pass\" -loc \"$loc\"'";
// exec a command and return a stream
$stream = ssh2_exec($connection, $runCMD);
// force PHP to wait for the output
stream_set_blocking($stream, true);
// read the output into a variable
$data = '';
while($buffer = fread($stream, 4096)) {
    $data .= $buffer;
}
// close the stream
fclose($stream);
// print the response
echo $data;

As you can see the fread leagth is set to 4096, the webpage just sits at refreshing but never compeletes, however the the user gets created, but the page does not return the echo'ed $data (it doesn't display anything it is just sitting at refreshing the page).

 

If i set this to 1, it works as expected, however does not show the full stack trace (completed output which contains the username generated which is what i need to get. I have tried setting this to 2 but it just keeps waiting for the script to finish, but i can confirm i see the users. So this doesnt appear to be a powershell issue, more of a php code issue. Can anyone see a mistake in the above? 

 

Let me know if you require any more information. 

[scootstah]

You have an infinite loop. It should be like this:

while(feof($stream) === false) {

    $data .= fread($buffer, 4096);

}

[Boxerman]

Thanks for the reply, im looking at your suggestion, but im getting the following:

 

Warning: fread() expects parameter 1 to be resource, null given in /srv/www/htdocs/newuserphp/test.php on line 31

Notice: Undefined variable: buffer in /srv/www/htdocs/newuserphp/test.php on line 31

any advise?

[Barand]

Replace $buffer with $stream

[scootstah]

Oops, my bad. Updated:

while(feof($stream) === false) {

    $data .= fread($stream, 4096);

}

[Boxerman]

Thanks! however, the page is not outputting (its still refreshing) but when i check AD i see the new user account has been created!?

 

This is confusing me, so much, im sorry!

[scootstah]

Are you sure that $stream is what you think it is? And do you have error reporting on?

Edited August 8, 2015 by scootstah

[Boxerman]

When i revert back to my old code i get an output if the user exists (full stack trace of what i need), if i create a new user, it only shows part of the stack trace (i presume related to the value of 1 needing to be increased?) but if its set above on, it just gets stuck on refreshing and never returns anything, yet the script does exactly what its suppose to (powershell wise).

 

Hopefully this makes sense.

[scootstah]

Yes that makes sense that it would refresh and never return anything, because you had an infinite loop going.

[Boxerman]

But with the new code provided with the feof in, it does exactly the same?

[Barand]

nm!

Edited August 8, 2015 by Barand

[scootstah]

When I create a test stream, everything works perfectly.

$stream = fopen('data://text/plain,This is a sample stream of text', 'r');

$data = '';
while(feof($stream) === false) {
    $data .= fread($stream, 4096);
}

echo $data;

I get "This is a sample stream of text" output.

 

I would suggest inspecting $stream to make sure that it is in fact what you think it is, and also to make sure error reporting is turned on.

[scootstah]

nm!

No, feof() returns true once it reaches the end of the file.

[Barand]

I know. I usually use !feof() and was confusing myself.

[Boxerman]

How would one work out if stream is the correct one? 

[scootstah]

Something I just thought of: you can try stream_get_contents instead of all the fread stuff.

 

$stream = ssh2_exec($connection, $runCMD);
echo stream_get_contents($stream);

See if that works.

[Boxerman]

New code:

$stream = ssh2_exec($connection, $runCMD);
stream_set_blocking($stream, true);
echo stream_get_contents($stream);

Still just stays at refreshing its so confusing, im sorry all...

[scootstah]

I would say it probably has to do with the blocking, then. The blocking says that PHP has to wait for output, so it seems to be stuck there.

[Boxerman]

Any advise on what one would do to work around this issue? OR is there another way?

Edited August 8, 2015 by Boxerman

[Boxerman]

Anyone got advise? 

[Boxerman]

Fixed the issue:

 

Adding [[ \"$-\" != *i* ]] && echo '\n' before the Powershell command fixed this issue.

 

Thanks for all the help and i hope my fix helps someone one day!