(转)addslashes与mysql_real_escape_string的区别
我们为了更深层次的探究这两个函数的不同..还是去看一看PHP的源码吧..
这是PHP的addslashes函数..
PHP_FUNCTION(addslashes)
{
zval **str;
if (ZEND_NUM_ARGS() != 1 || zend_get_parameters_ex(1, &str) == FAILURE) {
WRONG_PARAM_COUNT;
}
convert_to_string_ex(str);
if (Z_STRLEN_PP(str) == 0) {
RETURN_EMPTY_STRING();
}
RETURN_STRING(php_addslashes(Z_STRVAL_PP(str),
Z_STRLEN_PP(str),
&Z_STRLEN_P(return_value), 0
TSRMLS_CC), 0);
}
很显然.它调用了php_addslashes.我们继续看这个函数
PHPAPI char *php_addslashes(char *str, int length, int *new_length, int should_free TSRMLS_DC)
{
return php_addslashes_ex(str, length, new_length, should_free, 0 TSRMLS_CC);
}
结果又是是在调用php_addslashes_ex 我们就像在剥洋葱一样..一步一步的接近真理..
PHPAPI char *php_addslashes_ex(char *str, int length, int *new_length, int should_free, int ignore_sybase TSRMLS_DC)
{
/* maximum string length, worst case situation */
char *new_str;
char *source, *target;
char *end;
int local_new_length;
if (!new_length) {
new_length = &local_new_length;
}
if (!str) {
*new_length = 0;
return str;
}
new_str = (char *) safe_emalloc(2, (length ? length : (length = strlen(str))), 1);
source = str;
end = source + length;
target = new_str;
if (!ignore_sybase && PG(magic_quotes_sybase)) {
while (source < end) {
switch (*source) {
case ‘/0’:
*target++ = ‘//’;
*target++ = ‘0’;
break;
case ‘/”:
*target++ = ‘/”;
*target++ = ‘/”;
break;
default:
*target++ = *source;
break;
}
source++;
}
} else {
while (source < end) {
switch (*source) {
case ‘/0’:
*target++ = ‘//’;
*target++ = ‘0’;
break;
case ‘/”:
case ‘/”‘:
case ‘//’:
*target++ = ‘//’;
/* break is missing *intentionally* */
default:
*target++ = *source;
break;
}
source++;
}
}
*target = 0;
*new_length = target – new_str;
if (should_free) {
STR_FREE(str);
}
new_str = (char *) erealloc(new_str, *new_length + 1);
return new_str;
}
上面的函数已经非常清楚的描述出都要转义哪些字符了..现在我们去看一看mysql_real_escape_string
这个不在string.c里了..是在mysql扩展中.
PHP_FUNCTION(mysql_real_escape_string)
{
zval *mysql_link = NULL;
char *str;
char *new_str;
int id = -1, str_len, new_str_len;
php_mysql_conn *mysql;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, “s|r”, &str, &str_len, &mysql_link) == FAILURE) {
return;
}
if (ZEND_NUM_ARGS() == 1) {
id = php_mysql_get_default_link(INTERNAL_FUNCTION_PARAM_PASSTHRU);
CHECK_LINK(id);
}
ZEND_FETCH_RESOURCE2(mysql, php_mysql_conn *, &mysql_link, id, “MySQL-Link”, le_link, le_plink);
new_str = safe_emalloc(str_len, 2, 1);
new_str_len = mysql_real_escape_string(&mysql->conn, new_str, str, str_len);
new_str = erealloc(new_str, new_str_len + 1);
RETURN_STRINGL(new_str, new_str_len, 0);
}
这个函数并没有像上面的那样剥洋葱..
而是直接调用了MySql的C的API.mysql_real_escape_string()..
需要注意的是.这个函数在调用mysql_real_escape_string这个API之前.先是判断了是否连接上了数据库
CHECK_LINK(id); //就是这句
所以这就意味着mysql_real_escape_string必须是连接数据库之后才能使用.为了证实这一点.
我们来简单的实验下.
<?php
echo mysql_real_escape_string(“fdsafda’fdsa”);
结果
Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: Access denied for user ‘ODBC’@’localhost’ (using password: NO) in PHPDocument1 on line 2
Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: A link to the server could not be established in PHPDocument1 on line 2
果然报错了..显示没有链接上数据库..
好了..总结就先告一段落..
我们终于明白为什么那么多开源的程序比如Discuz用addslashes而不用mysql_real_escape_string了.
所以呢.以后也就用addslashes好了..暂时可以忘记掉mysql_real_escape_string了:)
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