How to delete specific files from timthumb's cache?

Question

I have a photo sharing app and I use timthumb to display the thumbnails. When a user delete a photo, I want the cached images also deleted from the timthumb's cache directory to save space. Currently I can only delete all files from cache, but it is less than ideal.

How to delete only specific files from timthumb's cache given the original image?

Answer 1

I came to this solution. I have to make little modifications to the timthumb.php file so I can include the file and instantiate the class from another file.

timthumb.php:

<?php

// If this file is included from other script, don't start timthumb
if (basename($_SERVER['SCRIPT_NAME']) == basename(__FILE__)) {
  timthumb::start();
}

class timthumb {
  ...
  // $cachefile is protected so I create a getter function
  public function getCacheFile() {
    return $this->cachefile;
  }
}

Now I can get the cache filename for a given image and delete it. The code is not pretty, but I need to save space.

delete_cache.php:

<?php
require 'timthumb.php';

// Fake the query string
$_SERVER['QUERY_STRING'] = 'src=path/to/src/image.jpg&w=200&h=150';
parse_str($_SERVER['QUERY_STRING'], $_GET);

// When instantiated, timthumb will generate some properties: 
// salt, directories, cachefile, etc.
$t = new timthumb();

// Get the cache file name
$f = $t->getCacheFile();

// Delete the file
if (file_exists($f)) {
    unlink($f);
}

Answer 2

asuming we want to delete the cache file of a local image:

first thing we need is the cacheDirectory = './cache'
second, the FILE_CACHE_PREFIX = 'timthumb'
then that it is internal (_int_)
then there is an md5 hash of:

• timthumb.php's modification time
• char '-'
• timthumb.php's inode
• image's modification time
• the $_SERVER ['QUERY_STRING'] when you call the image
• the 'fileCacheVersion' which is always the nubmer 1

and lastly, the FILE_CACHE_SUFFIX = '.timthumb.txt'

for example:

HTML:

<img src='timthumb.php?src=images/example.png&w=150'>

PHP:

$cachefile = 'cache/timthumb_int_'.md5(filemtime('timthumb.php') . '-' . fileinode('timthumb.php') . filemtime("images/example.png"). "src=images/example.png&w=150" . 1) . '.timthumb.txt';
unlink($cachefile);