calling a script function via call_user_function

Hi All,

I'm building an embedded application that uses PHP scripting for internal
data processing. It behaves as follows:

1. Provide arbitrary application-specified input parameters.
2. Execute a PHP script that manipulates those input parameters.
3. Retrieve the resulting return value.

I've attempted three possible approaches for achieving this goal. Please
bear with me as I explain each of these approaches -- it's necessary in
order to understand the question :-)

Approach A:

Parse a script containing a PHP function, and then call that PHP function.

On the PHP side:

// some arbitrary user-defined PHP function
function myfunction( $pArg ) { return strtoupper( $pArg ); }

On the application side:

// do something to parse "myfunction" and cause it to be available via
call_user_function()
php_lint_script(&file_handle TSRMLS_CC);

zval funcname, retval;
zval *args[1];

INIT_ZVAL(retval);
INIT_ZVAL(funcname);

MAKE_STD_ZVAL(args[1]);
ZVAL_STRING(args[1], "the string to make uppercase", 0);

ZVAL_STRING(&funcname, "myfunction", 0);

// call the user function
if(call_user_function(EG(function_table), NULL, &funcname, &retval, 1, args
TSRMLS_CC) != FAILURE)
{
// it worked
}

My problem with Approach A is that "php_lint_script", "php_execute_script",
etc, do not add the PHP function "myfunction" to the EG(function_table)
hash, so call_user_function() always fails.

Approach B:

Execute a PHP script and retrieve the return value without calling a
particular PHP function.

On the PHP side:

return strtoupper( $GLOBAL_VARIABLE );

On the application side:

php_register_variable("GLOBAL_VARIABLE", "the string to make uppercase",
NULL TSRMLS_CC);

zval *retval;
php_execute_simple_script(&file_handle, &retval TSRMLS_CC);

My problem with Approach B is that the return zval from the
php_execute_simple_script() function always contains a true/false value
instead of whatever was returned using the 'return' construct from the code.

Approach C:

Similar to approach B, except call a module function to record the result.

On the PHP side:

record_return( strtoupper( $GLOBAL_VARIABLE ) );

On the application side, create a module that provides the "record_return"
function to record the return value for later usage. This approach works.
However, if at all possible, I would prefer to use the PHP language 'return'
construct and somehow retrieve the resulting value.

Does anyone have any suggestions on how I could get either approach A or
approach B working? Any input would be greatly appreciated.

I'm currently using PHP 5.2.4 for development -- I can upgrade to a newer
version if that would be beneficial.

Thanks,
Marshall