Description:
------------
The file pointer position is not changed when a file opened in append mode is truncated using ftruncate() function. As per the documentation of ftruncate() function, the file pointer should be changed.

http://in2.php.net/manual/en/function.ftruncate.php
from doumentation: 
...
Note:  The file pointer is changed only in append mode. In write mode, additional fseek()  call is needed.
...

This is applicable to php5 as well as php6. 
checked it on WinXP and RHEL 5.

Reproduce code:
---------------
<?php
  $fp = fopen("test.txt", "w");
  fwrite($fp, "testing ftrucate function with append mode");
  fclose($fp);
  var_dump( filesize("test.txt") );

  $fp = fopen ("test.txt", "a");
  var_dump( ftell($fp) );
  var_dump( ftruncate($fp, 10) );
  var_dump( ftell($fp) );
  fclose($fp);

  clearstatcache();
  var_dump( filesize("test.txt") );
?>


Expected result:
----------------
int(42)
int(0)
bool(true)
int(10)
int(10)



Actual result:
--------------
int(42)
int(0)
bool(true)
int(0)
int(10)