Add backward compatibility support for PHP 5.3.3 (#164)

* Add backward compatibility support for PHP 5.3
* Re-activate Travis for PHP 5.3
* Downgrade to PHP 5.3 in the composer
* PHPDoc should be above the function definition
* Remove useless code related to PHP < 5.3
* Increase minor version required to 5.3.3 and remove duplicate check about it
* Simplify hex2bin since PHP >= 5.3
* Increase requirement in composer to 5.3.3 as well
* Update the message about requirement too
* Improve credits from PHP doc

.travis.yml

@@ -7,6 +7,7 @@ php:
   - 5.6
   - 5.5
   - 5.4
+  - 5.3
 
 before_script:
   - sudo apt-get update > /dev/null

composer.json

@@ -18,7 +18,7 @@
   },
   "minimum-stability": "dev",
   "require": {
-    "php": ">= 5.4.0, <= 7.1.99"
+    "php": ">= 5.3.3, <= 7.1.99"
   },
   "require-dev": {
     "behat/mink": "~1.4",

public_html/lists/admin/inc/php_compat.php

@@ -52,3 +52,36 @@ function hash_equals($known_string, $user_string)
         return $ret === 0;
     }
 }
+
+if (!function_exists('hex2bin')) { // PHP 5.4 and up
+    /**
+     * Convert hexadecimal values to ASCII characters.
+     *
+     * Credits: Walf's user note from PHP Documentation Group - http://php.net/manual/en/function.hex2bin.php#113472
+     * License: CC-BY 3.0 (http://creativecommons.org/licenses/by/3.0/)
+     * Changes: The original part of the code has been simplified assuming PHP >= 5.3.3
+     *
+     * @param string $data The hexadecimal representation of data to be converted
+     *
+     * @return string Returns the binary representation of the given data or FALSE on failure. 
+     */
+    function hex2bin($data) {
+        if (is_scalar($data) || (method_exists($data, '__toString'))) {
+            $data = (string) $data;
+        }
+        else {
+            trigger_error(__FUNCTION__.'() expects parameter 1 to be string, ' . gettype($data) . ' given', E_USER_WARNING);
+            return;//null in this case
+        }
+        $len = strlen($data);
+        if ($len % 2) {
+            trigger_error(__FUNCTION__.'(): Hexadecimal input string must have an even length', E_USER_WARNING);
+            return false;
+        }
+        if (strspn($data, '0123456789abcdefABCDEF') != $len) {
+            trigger_error(__FUNCTION__.'(): Input string must be hexadecimal string', E_USER_WARNING);
+            return false;
+        }
+        return pack('H*', $data);
+    }
+}

public_html/lists/admin/index.php

@@ -1,6 +1,6 @@
 <?php
 
-if (!defined('PHP_VERSION_ID') || PHP_VERSION_ID < 50300) {
+if (!defined('PHP_VERSION_ID') || PHP_VERSION_ID < 50303) {
     die('Your PHP version is too old. Please upgrade PHP before continuing.');
 }
 
@@ -499,8 +499,8 @@ function mb_strtolower($string)
     if (TEST) {
         echo Info($GLOBALS['I18N']->get('Running in testmode, no emails will be sent. Check your config file.'));
     }
-    if (version_compare(PHP_VERSION, '5.4.0', '<') && WARN_ABOUT_PHP_SETTINGS) {
-        Error(s('Your PHP version is out of date. phpList requires PHP version 5.4.0 or higher.'));
+    if (version_compare(PHP_VERSION, '5.3.3', '<') && WARN_ABOUT_PHP_SETTINGS) {
+        Error(s('Your PHP version is out of date. phpList requires PHP version 5.3.3 or higher.'));
     }
     if (defined('RELEASEDATE') && ((time() - RELEASEDATE) / 31536000) > 2) {
         Fatal_Error(s('Your phpList version is older than two years. Please %supgrade phpList</a> before continuing.</br>
@@ -509,10 +509,6 @@ function mb_strtolower($string)
         return;
     }
 
-    if (!defined('PHP_VERSION_ID') || PHP_VERSION_ID < 50300) {
-        Fatal_Error(s('Your PHP version is too old. Please upgrade PHP before continuing'));
-        return;
-    }
     if (defined('ENABLE_RSS') && ENABLE_RSS && !function_exists('xml_parse') && WARN_ABOUT_PHP_SETTINGS) {
         Warn($GLOBALS['I18N']->get('You are trying to use RSS, but XML is not included in your PHP'));
     }