Write to file sometimes deletes EVERYTHING, leaving empty file

[wallaby]

I've used PHP to save raw data from Flash to an XML in the past. Load the XML into flash, update a couple variables, then send it to PHP to completely overwrite the old .xml file. This works great most of time, but sometimes after a few days, I'll check the .xml and it will be empty (0 bytes). Not sure if this is caused by a user who aborted during the writing process, or simultaneous connections, etc. Been thinking about doing a backup every day using CRON, but that's a mission and I'd like for it not to happen full stop. Any suggestions?

[Glyde]

I have no idea why it owuld just go this randomly, but you can try this:

 

<?php
// Delete below here if you have PHP 5
if (!function_exists('file_get_contents')) {
     function file_get_contents($file) {
          return implode("\n", file($file));
     }
}
// Delete above here if you have PHP 5

function writeContents($file, $contents) {
     $fHandle = fopen($file, "w");
     fwrite($fHandle, $contents);
     fclose($fHandle);
}

// Get the old file contents
$oldContents = file_get_contents("file.xml");
writeContents("file.xml", "new contents");

// Write old contents if it failed
if (!filesize("file.xml")) writeContents("file.xml", $oldContents);
?>