Description:
------------
This code does not work on Windows:
 
<?
$f1 = fopen("/tmp/a", "a+b");
flock($f1, LOCK_SH);
$f2 = fopen("/tmp/a", "r+b");
fwrite($f2, "test");
?>
 
It creates zero-length file. On Linux everything is OK.
 
If I delete flock() or call flock($f1, LOCK_UN) just after first flock(), all works correctly.

Flock() is ADVISORY lock, but it works as mandatory lock. Bad luck.

Reproduce code:
---------------
$f1 = fopen("/tmp/a", "a+b");
flock($f1, LOCK_SH);
$f2 = fopen("/tmp/a", "r+b");
fwrite($f2, "test");


Expected result:
----------------
Create non-empty file.

Actual result:
--------------
Creates empty file.