[RESOLVED] dir "locker" creating 21mb CORE file.

[exponder]

Alright, a friend and myself where working on writing this file to search child directories for index files, and then create one if the there wasn't one.

The results where equal every time we tweaked the script. The script would write the index file in the same directory the script was in, but wouldn't mess with the child directories.

I tested it on a Hosted server, running in Safe_mode, and the script created a file with no extention called "core". The file was 21mb's, and I only got a peice of it. What is the core file? And why is the script making the server write it? Here's the script, and peices of the core file.

function do_the_dir($dir) {
       if ($dh = opendir($dir)) {
           while (($file = readdir($dh)) !== false) {
          echo "Checking file $file<br>\n";
    if(is_dir($file)) {
        echo " <b>Found Directory $file</b><br>\n";
    $testies = @fopen("$file"."index.html", 'r');
    $testies2 = @fopen("$file"."index.php", 'r');
    $testies3 = @fopen("$file"."index.asp", 'r');
    $testies4 = @fopen("$file"."index.cgi", 'r');
    $testies5 = @fopen("$file"."index.htm", 'r');
    $testies6 = @fopen("$file"."index.shtml", 'r');
        if(!$testies && !$testies6 && !$testies5 && !$testies4 && !$testies3 && ! $testies2) { 
    //if the directory is without balls
        echo "  Found no index in $file, creating one<br>\n";
            $indexFile="index.html";
        $data = "Index File - \n<br>Created by..";
            $fp = fopen("
        $file$indexFile", "w");
            fwrite($fp,$data);
                fclose($fp);
}
   do_the_dir($file);
} else
   echo " No dir found, continuing search";
}
   closedir($dh);
   }
}
            do_the_dir('.');

(It seems as if it's an error log, but the server generates them as error_log)

Core contents:

ELF 4 4 ^ ô H € @9 À= À À à €A €Ë €Ë Ï @ Ï@ pÏ p@ €Ï €@ ......

[Weedpacket]

http://acs.ucsd.edu/info/coredump.php

You're hitting a bug in PHP (or perhaps the web server), and that is what is causing the program to dump core.

The problem is that your code gets into an instant infinite loop; you forget that the first file found in a directory listing is . - which is the current directory. So the first file it looks at is '.' ... and eventually PHP falls over because of the effectively infinite amount of work you've given it to do.

function do_the_dir($dir)
{
	if ($dh = opendir($dir))
	{
		while (($file = readdir($dh)) !== false)
		{
			if($file=='.' || $file=='..') continue;
			echo "Checking file $file<br>\n";
			if(is_dir($file))
			{
				echo " <b>Found Directory $file</b><br>\n";
				$testies = @fopen("$file"."index.html", 'r');
				$testies2 = @fopen("$file"."index.php", 'r');
				$testies3 = @fopen("$file"."index.asp", 'r');
				$testies4 = @fopen("$file"."index.cgi", 'r');
				$testies5 = @fopen("$file"."index.htm", 'r');
				$testies6 = @fopen("$file"."index.shtml", 'r');
				if(!$testies && !$testies6 && !$testies5 && !$testies4 && !$testies3 && ! $testies2)
				{
					//if the directory is without balls
					echo "  Found no index in $file, creating one<br>\n";
					$indexFile="index.html";
					$data = "Index File - \n<br>Created by..";
					$fp = fopen("$file$indexFile", "w");
					fwrite($fp,$data);
					fclose($fp);
				}
				do_the_dir($file);
			}
			else
				echo " No dir found, continuing search";
		}
		closedir($dh);
	}
}
do_the_dir('.');

Core dumps should not happen - they're indicative of bugs in the application - but to defend against every possible instance would itself require an effectively infinite amount of work, so it's really down to the PHP programmer to make sure their code doesn't explode.

[exponder]

Ah, thank you greatly Weedpacket, I'm reading the link you gave me currently.

I've talked to other people about it, but they'd only say "it's an error", over and over, and never give me a reason why. Anyway, thanks for your time taken!! 🆒