PHP. Extension. Call existing PHP function

c, php, php-extension

Solution

The easiest way to figure out how a function works is to search for it on lxr.php.net. The first example that turns up is in readline: http://lxr.php.net/xref/PHP_TRUNK/ext/readline/readline.c#474

The use for `mail` is analogous. Given the arguments as zvals (`to_zval`, `from_zval`, `msg_zval`) the call is very simple:

zval *params = { to_zval, from_zval, msg_zval };
zend_uint param_count = 3;
zval *retval_ptr;

zval function_name;
INIT_ZVAL(function_name);
ZVAL_STRING(&function_name, "mail", 1);

if (call_user_function(
        CG(function_table), NULL /* no object */, &function_name,
        retval_ptr, param_count, params TSRMLS_CC
    ) == SUCCESS
) {
    /* do something with retval_ptr here if you like */
}

/* don't forget to free the zvals */
zval_ptr_dtor(&retval_ptr);
zval_dtor(&function_name);

If you don't have the parameters as zvals already, then you can create them using `MAKE_STD_ZVAL` and `ZVAL_STRING`.

Problem

So I decided to write an extension for php. Everything seems to be fine except I'm stuck on a tiny problem. I have `php-5.4.9` source codes. There is file `ext/standard/mail.c` with awesome function ``` PHPAPI int php_mail(char *to, char *subject, char *message, char *headers, char *extra_cmd TSRMLS_DC) ``` In my extension, in `acme.c` I have includes ``` ... #include "php.h" #include "ext/standard/php_mail.h" #include "php_ini.h" ... ``` So `php_mail` feels good and works fine. But, obviously, I want to use the code from `mail.c` starting on line 101 and ending on 189 (http://pastie.org/5444192 5-93 corresponding lines in the paste). So I caught myself on idea (it is awkward in some point though) why not to call `PHP_FUNCTION(mail)`? By the moment I could not locate that macros, and actually I'd like to know the best way to implement the idea. My inner zend engineer (which is newbie) recommends me to use call_user_function ``` ZEND_API int call_user_function(HashTable *function_table, zval **object_pp, zval *function_name, zval *retval_ptr, zend_uint param_count, zval *params[] TSRMLS_DC); ``` But I can not figure it out how to call it. The question! How (an example with `mail` function is very welcomed) to call functions defined by `PHP_FUNCTION`?

Original source