How to make fread blocking and read until the end ?

Question

Hello,

I am executing a TCL script from PHP using proc_open.

1. I first open the TCL shell 2) Send a command using fwrite 3) What I need is fread to wait/block until the command sent by fwrite is complete and get all the contents .The command may take some time to complete. (I am able to read just 2 lines and then it is going off to the next loop)

Can someone guide me.

The present code is

<?php

$app = 'tclsh84';
$descriptorspec = array(
0 => array("pipe","r"),
1 => array("pipe","w"),
2 => array("file","C:/wamp/www/tcl/bin/g.txt","w")
) ;
$process = proc_open($app, $descriptorspec, $pipes);
if (is_resource($process)) 
{


for($i=0;$i<4;$i++)
{

 fwrite($pipes[0], 'source c:/wamp/www/tcl/bin/test.tcl'."\n");
$content= fread($pipes[1],8192)
print "$content";

}    
   fclose($pipes[0]);    

   fclose($pipes[1]);


   proc_close($process);
}
?>

Answer 1

try:

$content = '';
while(!feof($pipes[1]))
  $content .= fread($pipes[1],8192);

Does that wait?

Answer 2

I'm thinking about a combination of

• stream_select and/or feof()
• fread() and concatenation of the partial results ($result .= fread())
• and maybe proc_get_status() to determine the end of the process

You want to wait until the tcl application doesn't write something to its stdout for a certain amount of time (presuming that this means the end of the last command) and then send the next command/line to its stdin?

edit:
Seems like you can send all commands to the tcl shell at once and they are processed one by one, i.e. the shell reads the next input line/command when it's done with the previous one. I've tested this with the script.

incr a 1
after 1000
puts [concat [clock seconds] $a]

and

<?php
$app = 'c:/programme/tcl/bin/tclsh85.exe';
$descriptorspec = array(
  0 => array("pipe","r"),
  1 => array("pipe","w"),
  2 => array("file","C:/god.txt","w")
) ;
$process = proc_open($app, $descriptorspec, $pipes);
if (is_resource($process)) {
  fwrite($pipes[0], "set a 1\n");
  for($i=0;$i<4;$i++) {
    fwrite($pipes[0], "source c:/helloworld.tcl\n");
  }
  // when all scripts are done the shell shall exit
  fwrite($pipes[0], "exit\n");
  fclose($pipes[0]);

  do {
    $read=array($pipes[1]); $write=array(); $except=array($pipes[1]);
    // wait up to 1 second for new output of the tcl process
    $ready = stream_select($read, $write, $except, 1, 0);
    if ( $ready && $read /* is not empty */) {
      // get the partial output
      $r = fread($pipes[1], 2048);
      echo $r;
    }
    // is the process still running?
    $status = proc_get_status($process);
  } while($status['running']);
  fclose($pipes[1]);
  proc_close($process);
}
?>

You probably want to add some more error handling. E.g. if stream_select() returns x times with an timeout something might have gone wrong.

edit2:
Let the shell print something you can scan for after each script.

<?php
// something that's not in the "normal" output of the scripts
$id = 'done'. time();

$app = 'c:/programme/tcl/bin/tclsh85.exe';
$descriptorspec = array(
  0 => array("pipe","r"),
  1 => array("pipe","w"),
  2 => array("file","C:/god.txt","w")
) ;
$process = proc_open($app, $descriptorspec, $pipes);
if (is_resource($process)) {
  fwrite($pipes[0], "set a 1\n");
  for($i=0;$i<4;$i++) {
    $output = '';
    $continue = true;
    $cTimeout = 0;
    echo 'loop ', $i, "\n";
    fwrite($pipes[0], "source c:/helloworld.tcl\n");
    fwrite($pipes[0], "puts $id\n");
    echo "waiting for idle\n";
    do {
      $read=array($pipes[1]);
      $write=array();
      $except=array($pipes[1]);
      $ready = stream_select($read, $write, $except, 1, 0);
      if ( $ready && $read ) {
        $output .= fread($pipes[1], 2048);
        // if the delimiter id shows up in $output
        if ( false!==strpos($output, $id) ) {
            // the script is done
          $continue = false;
        }
      }
    } while($continue);
    echo 'loop ', $i, " finished\n";
  }
  proc_close($process);
}
?>