Feof generates an endless loop.

Question

So, I do one simple thing, firstly, I execute the command through ssh2_exec (after successful authentication), and then I read the response in a variable. My code is below (no authentication)

try {
        $stdout_stream = ssh2_exec($this->connection, $_cmd);
        $stderr_stream = ssh2_fetch_stream($stdout_stream, \SSH2_STREAM_STDERR);
    } catch (Exception $e) {
        $std_output = $e->getMessage();
        return false;
    }

    $output = "";

    while (!feof($stdout_stream)) {
        $output .= fgets($stdout_stream, 4096);
    }

    while (!feof($stderr_stream)) {
        $output .= fgets($stderr_stream, 4096);
    }

    fclose($stdout_stream);
    fclose($stderr_stream);     

    return $output;

For example, I try to execute such cmd:

sudo service httpd stop && sudo service httpd start

So, when the command is executed well, everything is fine, the answer

Shutdown httpd: [OK] Start httpd: [OK]

But when I try, for example, to execute such a command without sudo

service httpd stop && service httpd start

I know that the server says something like “command not found” or something like this, but I cannot get this error, this script runs endlessly.

I tried to rewrite my code this way (or with others similar to this)

    $dataString = fgets($stdout_stream);
        if($dataString == "\n" || $dataString == "\r\n" || $dataString == "") {
            //var_dump("Empty line found.");
        }

        if($dataString === false && !feof($stdout_stream)) {
            //var_dump("not string");
        } elseif($dataString === false && feof($stdout_stream)) {
            //var_dump("We are at the end of the file.\n");
            break;
        } else {
            //else all is good, process line read in
            $output .= $dataString;
        }
    }

but the result is the same.

So, the problem is that we cannot say in advance what an infinite loop $stdout_streamor follows $stderr_stream.

PHP 5.3.

Answer 1

, ~ 2 , . secod. . , ...

    try {
        $stdout_stream = ssh2_exec($this->connection, $_cmd);
        $stderr_stream = ssh2_fetch_stream($stdout_stream, \SSH2_STREAM_STDERR);
    } catch (Exception $e) {
        $std_output = $e->getMessage();
        return false;
    }

    $output = "";

    $start_time = time();
    $max_time = 2; //time in seconds

    while(((time()-$start_time) < $max_time)) {
        $output .= fgets($stderr_stream, 4096);
    }

    if(empty($output)) {
        $start_time = time();
        $max_time = 10; //time in seconds

        while (!feof($stdout_stream)) {
            $output .= fgets($stdout_stream, 4096);
            if((time()-$start_time) > $max_time) break;
        }
    }

    fclose($stdout_stream);
    fclose($stderr_stream);     

    return $output;