+/*
+
+ Protect against directory traversal.
+ Changes all not POSIX compatible chars to underscore.
+*/
+function clean_file_name($filename) {
+ $filename = str_replace(chr(0), '', $filename);
+ return preg_replace('/[^a-zA-Z0-9.\-_]/', '_', $filename);
+}
+
+/*
+ Simple random password generator.
+*/
+function generate_password()
+{
+ if (PHP_VERSION >= '5.3')
+ $bytes = openssl_random_pseudo_bytes(8, $cstrong);
+ else
+ $bytes = sprintf("08%x", mt_rand(0,0xffffffff));
+
+ return base64_encode($bytes);
+}
+
+if (!function_exists('array_fill_keys')) // since 5.2
+{
+ function array_fill_keys($keys, $value)
+ {
+ return (object)array_combine($keys, array_fill(count($keys), $value));
+ }
+}
+
+/*
+ This function aims to generate cryptographically strong random identifier.
+ Result identifier has length 4[strength/8/3]
+*/
+function random_id($strength = 128)
+{
+ $n = ceil($strength/8);
+
+ if (function_exists('openssl_random_pseudo_bytes'))
+ $bin = openssl_random_pseudo_bytes($n, $cstrong); // openssl on php 5.3 and up
+ else if (file_exists('/dev/urandom'))
+ $bin = file_get_contents('/dev/urandom', false, null, -1, $n); // linux std random device
+ else {
+ $bin = '';
+ for($i=0; $i < $n; $i++)
+ $bin .= chr(mt_rand(0, 255)); // Mersene Twister generator
+ }
+ $id = strtr(base64_encode($bin), '+/=', '-_x'); // see RFC 4648 Section 5