php intval() 小数时安全漏洞分析_PHP教程

PHP_FUNCTION(intval)

{

zval **num, **arg_base;

int base;

switch (ZEND_NUM_ARGS()) {

case 1:

if (zend_get_parameters_ex(1, &num) == FAILURE) {

WRONG_PARAM_COUNT;

}

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base = 10;

break;

case 2:

if (zend_get_parameters_ex(2, &num, &arg_base) == FAILURE) {

WRONG_PARAM_COUNT;

}

convert_to_long_ex(arg_base);

base = Z_LVAL_PP(arg_base);

break;

default:

WRONG_PARAM_COUNT;

}

RETVAL_ZVAL(*num, 1, 0);

convert_to_long_base(return_value, base);

}

Zend/zend_operators.c->>convert_to_long_base()

……

case IS_STRING:

strval = Z_STRVAL_P(op);

Z_LVAL_P(op) = strtol(strval, NULL, base);

STR_FREE(strval);

break;

$o = 0.1;
for($a = 1; $a $o += 0.1;
echo “
intval($o) = “.intval($o);
if(intval($o)){
print(“ true”);
}else{
print(“ false”);
}
}?>

输出结果：

intval(0.2) = 0 false
intval(0.3) = 0 false
intval(0.4) = 0 false
intval(0.5) = 0 false
intval(0.6) = 0 false
intval(0.7) = 0 false
intval(0.8) = 0 false
intval(0.9) = 0 false
intval(1) = 0 false
intval(1.1) = 1 true
intval(1.2) = 1 true
intval(1.3) = 1 true
intval(1.4) = 1 true
intval(1.5) = 1 true
intval(1.6) = 1 true
intval(1.7) = 1 true
intval(1.8) = 1 true
intval(1.9) = 1 true
intval(2) = 2 true
…..

$t ='165';

echo gettype((int)($t));
echo '

//输出结果:integer integer value:165

$t ='a165';

echo gettype((int)($t));
echo '

//结果 integer integer value:0,0

$string="2a";
$string1=intval($string);
echo '$string1的值：'.$string1.'$string2的值：';//单引号不会输出变量，将原样输出
$string2=(int)($string);
echo $string2