added PMA_getenv() as a wrapper to $_SERVER, $_ENV, getenv() and apache_getenv()

libraries/common.lib.php

@@ -545,6 +545,30 @@ function PMA_checkPageValidity(&$page, $whitelist)
     return false;
 }
 
+/**
+ * trys to find the value for the given environment vriable name
+ *
+ * searchs in $_SERVER, $_ENV than trys getenv() and apache_getenv()
+ * in this order
+ *
+ * @param   string  $var_name   variable name
+ * @return  string  value of $var or empty string
+ */
+function PMA_getenv($var_name) {
+    if (isset($_SERVER[$var_name])) {
+        return $_SERVER[$var_name];
+    } elseif (isset($_ENV[$var_name])) {
+        return $_ENV[$var_name];
+    } elseif (getenv($var_name)) {
+        return getenv($var_name);
+    } elseif (function_exists('apache_getenv')
+     && apache_getenv($var_name, true)) {
+        return apache_getenv($var_name, true);
+    }
+
+    return '';
+}
+
 /**
  * include here only libraries which contain only function definitions
  * no code im main()!