rmdir() bug with particular filename? Permission denied - php

Question

First, let's get these out of the way:
There are no open handles on the directory.
There are no files in the directory.
chmod ing the permissions to 0777 does not prevent the error.
the directory name is correct.
Now then, here's my problem. rmdir() is throwing this error when trying to delete the directory:
rmdir(098f6bcd4621d373cade4e832627b4f6) [function.rmdir]: Permission denied in path\to\administrate.php on line 124
098f6bcd4621d373cade4e832627b4f6 is the name of the directory.
Here is the relevant portion of the script.
if(is_dir($userhash)) :
foreach (new DirectoryIterator($userhash) as $fileInfo) {
$fileName = $fileInfo->getFilename();
if($fileInfo->isDot()) continue;
if(!rename($userhash.'/'.$fileName , 'trashcan/'.$username.'/'.$fileName)) {
echo '<p class="error">Could not move '.$fileName.'</p>';
$err = 1;
}
}
else :
echo '<p class="error">Unable to delete files! error: 67</p>';
$err = 1;
endif;
//JUST TO BE SURE
chmod('./',0777);
chmod($userhash,0777);
// RMDIR ONCE THE DIR IS EMPTY.
if(rmdir($userhash))
echo '<p class="success">Deleted the user directory. The files are in the trash.</p>';
else {
echo '<p class="error">Could not remove the user directory. Error: 656</p>';
$err = 1;
}
Update
I manually created the dir 'jake' in the same directory. I did rmdir('jake'); and it worked great. Now, I manually created a dir '098f6bcd4621d373cade4e832627b4f6' in the same directory. I did rmdir('098f6bcd4621d373cade4e832627b4f6'); and it errored!
Update 2
This is beginning to look like some weird rmdir() bug, as unlikely as that seems. Here are directory names I've created and then tried to remove with rmdir;
098f6bcd4621d373cade4e832627b4f6 | didn't work (quintuple checked)
098f6bcd4621d373cade4e832627b4f7 | worked
098f6bcd4621d373cade4e832627b4f | worked
098f6bcd4621d373cade4e832627b4f66 | worked

Answer 1

In order to be able remove file:
user should have write permissions to PARENT directory
restricted deletion flag should NOT be set for PARENT directory
UPDATE:
About restricted deletion flag - from man chmod:
RESTRICTED DELETION FLAG OR STICKY BIT
The restricted deletion flag or sticky
bit is a single bit, whose
interpretation depends on the file
type. For directories, it prevents
unprivi‐leged users from removing
or renaming a file in the directory
unless they own the file or the
directory; this is called the
restricted deletion flag for the
directory, and is commonly found on
world-writable directories like /tmp.
For regular files on some older
systems, the bit saves the program's
text image on the swap device so it
will load more quickly when run; this
is called the sticky bit.
You may SET it by adding 1 to the first octal digit in mode, for example:
chmod 1xxx dirname
UPDATE 2:
Does user, under which php is executed, has permissions to chmod parent directory?
In other words, are you sure that first chmod call returns true?
chmod('./',0777);