Description:
------------
Opening a file for appending does not move the file pointer to 
the end of file before the first I/O operation is performed.

That makes ftell() return zero directly after the fopen() 
call.

The workaround, if you need to call ftell() immediately after 
the fopen(), is to use a no-operation I/O call fseek() that 
don't do anything. Thus, the file pointer is updated and 
returns correct position information.

Reproduce code:
---------------
// create or open a file, and write some stuff to it.
$filename = "/path/to/file.txt";
$fp = fopen($filename, "a+");
fwrite($fp, "Sample text");
fclose($fp);

// re-open it and check what ftell() returns
$fp = fopen($filename, "a+");
echo " pre-fseek: " . ftell($fp) . "\n"; // ftell returns 0
fseek($fp, 0, SEEK_END);
echo "post-fseek: " . ftell($fp) . "\n"; // ftell now ok


Expected result:
----------------
The snippet should print the file size of the file:

 pre-fseek: 11
post-fseek: 11

Actual result:
--------------
The snippet should print the correct file size only after the 
first I/O operation:

 pre-fseek: 0
post-fseek: 11