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<?php |
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/** |
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* Smarty plugin |
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* @package Smarty |
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* @subpackage plugins |
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*/ |
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/** |
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* Smarty {math} function plugin |
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* |
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* Type: function<br> |
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* Name: math<br> |
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* Purpose: handle math computations in template<br> |
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* @link http://smarty.php.net/manual/en/language.function.math.php {math} |
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* (Smarty online manual) |
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* @author Monte Ohrt <monte at ohrt dot com> |
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* @param array |
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* @param Smarty |
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* @return string |
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*/ |
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function smarty_function_math($params, &$smarty) |
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{ |
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// be sure equation parameter is present |
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if (empty($params['equation'])) { |
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$smarty->trigger_error("math: missing equation parameter"); |
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return; |
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} |
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// strip out backticks, not necessary for math |
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$equation = str_replace('`','',$params['equation']); |
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// make sure parenthesis are balanced |
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if (substr_count($equation,"(") != substr_count($equation,")")) { |
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$smarty->trigger_error("math: unbalanced parenthesis"); |
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return; |
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} |
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// match all vars in equation, make sure all are passed |
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preg_match_all("!(?:0x[a-fA-F0-9]+)|([a-zA-Z][a-zA-Z0-9_]*)!",$equation, $match); |
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$allowed_funcs = array('int','abs','ceil','cos','exp','floor','log','log10', |
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'max','min','pi','pow','rand','round','sin','sqrt','srand','tan'); |
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foreach($match[1] as $curr_var) { |
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if ($curr_var && !in_array($curr_var, array_keys($params)) && !in_array($curr_var, $allowed_funcs)) { |
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$smarty->trigger_error("math: function call $curr_var not allowed"); |
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return; |
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} |
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} |
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foreach($params as $key => $val) { |
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if ($key != "equation" && $key != "format" && $key != "assign") { |
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// make sure value is not empty |
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if (strlen($val)==0) { |
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$smarty->trigger_error("math: parameter $key is empty"); |
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return; |
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} |
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if (!is_numeric($val)) { |
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$smarty->trigger_error("math: parameter $key: is not numeric"); |
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return; |
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} |
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$equation = preg_replace("/\b$key\b/", " \$params['$key'] ", $equation); |
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} |
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} |
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eval("\$smarty_math_result = ".$equation.";"); |
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if (empty($params['format'])) { |
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if (empty($params['assign'])) { |
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return $smarty_math_result; |
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} else { |
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$smarty->assign($params['assign'],$smarty_math_result); |
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} |
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} else { |
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if (empty($params['assign'])){ |
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printf($params['format'],$smarty_math_result); |
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} else { |
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$smarty->assign($params['assign'],sprintf($params['format'],$smarty_math_result)); |
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} |
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} |
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} |
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/* vim: set expandtab: */ |
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?> |
On one hand,
eval
might be exploited by malicious users if they somehow manage to inject dynamic content. On the other hand, with the emergence of faster PHP runtimes like the HHVM,eval
prevents some optimization that they perform.