Home » Internationalization » Translation2 » Bug #3420

[2005-02-09 22:49 UTC] ylf at xung dot org

Description:
------------
Hi,

Translation2 version : 2.0.0beta6

AFAIK, flock() provides _advisory_ locks. In Translation2/Admin/Container/xml.php, line 340, you state :

@flock($f, LOCK_EX);
fwrite ($f, $xml);
@flock($f, LOCK_UN);
fclose ($f);

Sidenote: @flock ($f,LOCK_UN) is useless, fclose() unlocks the file.

An "exclusive" (LOCK_EX) advisory lock does not forbid other processes to read from the file. These processes need to explicitly acquire a shared lock.

From the flock Linux manpage :
"flock(2) places advisory locks only; given suitable permissions on a file, a process is free to ignore the use of flock(2) and perform I/O on the file."

In our case it means that you correctly acquire an exclusive lock when writing to the xml file, but you forget to acquire a shared lock when reading.

Consequence : the lock is ignored by reading processes. The call to flock($f,LOCK_EX) should protect the file from getting corrupted, but there are chances to read junk from it.

You should turn, in Container/xml.php, line 137 :

$unserializer = &new XML_Unserializer (array('keyAttribute' => $keyAttr));
if (PEAR::isError($status = $unserializer->unserialize($this->_filename, true))) {
return $status;
}

into :

if (!$fp = @fopen ($this->_filename, 'r')) {
return new PEAR_Error ("Can\'t read from the XML source : {$this->_filename}");
}
@flock ($fp, LOCK_SH);
$unserializer = &new XML_Unserializer (array('keyAttribute' => $keyAttr));
if (PEAR::isError($status = $unserializer->unserialize($this->_filename, true))) {
fclose ($fp);
return $status;
}
fclose($fp);

Cheers