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Re: [PHP] 7.1 extension writing, output parameter remains unchanged




Hi
Hi Jan

2017-07-19 12:17 GMT+02:00 Jan Vávra <vavra@xxxxxx>:
Hello,
  I'm porting our extension from php5.6 to php7.1 x64 Windows, Visual Studio
2015.
I'd like to write an extension function that has one input / output
parameter type of long. But the parameter value changed in extension is not
changed in php. What I'm doing wrong?
The php code is:

$a = 3;
$r = hello_square($a);
var_export($a); echo "\n"; //value of $a still remains 3, should be 9.

The c code is:

PHP_FUNCTION(hello_square)
{
   long a = 0;
   zval *b;

   if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "z", &b) == FAILURE)
{
     return;
   }

   a = Z_LVAL_P(b);
   ZVAL_LONG(b, a*a);

   RETURN_BOOL(1);
}

----

I also implemented hello_square this way
PHP_FUNCTION(hello_square)
{
   zend_long b;

   if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &b) == FAILURE)
{
     return;
   }

   b = b * b;
   RETURN_BOOL(1);
}

And the value of $a remains unchanged.
What you should do is to make the parameter sent to hello_square() a
reference, this is done by the following (keep in mind this uses the
new and fast parameter parsing API, but it is still do-able with the
old zend_parse_parameters()):

https://gist.github.com/KalleZ/69f9ca1895bcac945e110b7777104203

Take a look at the README.PARAMETER_PARSING_API in the root of
php-src, this includes all possible values that
zend_parse_parameters() can accept
I've fixed line 10 from your sample to
ZVAL_LONG(b, Z_LVAL_P(b) * Z_LVAL_P(b));

or put a constant
ZVAL_LONG(b, 20);

But in php $a variable remains unchanged.

Full c source is:

PHP_FUNCTION(hello_square)
{
  zval *b;

  ZEND_PARSE_PARAMETERS_START(1, 1)
  Z_PARAM_ZVAL_DEREF(b)
  ZEND_PARSE_PARAMETERS_END();

  zval_dtor(b);
  ZVAL_LONG(b, Z_LVAL_P(b) * Z_LVAL_P(b));

  RETURN_TRUE;
}

Jan.

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