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Linking problem with extension written in C++

php.internals

Grzegorz Godlewski

23 years ago
I have written an extension. Unfortunatelly I had to use some C++. After building I have some problems with 3 functions: zval_add_ref, REGISTER_LONG_CONSTANT, php_error_docref. If I include their body within my extension, it's Ok. Otherwise I got memory fault under PHP 4.3.0 and relocation error: /usr/lib/php/xerces.so: undefined symbol: _Z12zval_add_refPP12_zval_struct under 4.3.1. It has been built by gcc 3.2.2. Could anyone spend few minutes on it: http://ggodlewski.host.sk/download/php-xerces/php-xerces-0.1.tar.gz It requires xerces-c-2.2.0. Problematic places are marked by MEM_FAULT_HACK macro. Thanks, Grzegorz Godlewski

J Smith

23 years ago
There are a few header files that you have to include with extern "C" so their names get mangled properly into C++. Try wrapping php.h, php_ini.h and info.h in extern "C" and see how that goes. I wrote up a little article on this sort of thing, so if you're interested, check out http://www.tutorbuddy.com/software/phpcpp/phpcpp/. J Grzegorz Godlewski wrote:

Per Lundberg

23 years ago
On Mon, 2003-04-14 at 16:19, Jay Smith wrote:
> There are a few header files that you have to include with extern "C" so > their names get mangled properly into C++. Try wrapping php.h, php_ini.h > and info.h in extern "C" and see how that goes.
How come we don't have extern C wrapped in #ifdef __cplusplus in these files already, so they can just be included straight away? Like this: #ifdef __cplusplus extern "C" { #endif // yadda yadda #ifdef __cplusplus }; #endif
-- Best regards, Per Lundberg / Capio ApS Phone: +46-18-4186040 Fax: +46-18-4186049 Web: http://www.nobolt.com

J Smith

23 years ago
It kind of seems messy to wrap everything in extern "C". It would probably be better to weed out the individual API functions that need to be extern C'd. I'll try and seek out the offending functions. There aren't too many of them AFAIK... J Per Lundberg wrote:

Per Lundberg

23 years ago
On Mon, 2003-04-14 at 18:26, Jay Smith wrote:
> It kind of seems messy to wrap everything in extern "C".
Well, I think it's kind of standard procedure when writing C APIs. Do a grep on __cplusplus in your /usr/include for example. But do it any way you like, as long as it works...
-- Best regards, Per Lundberg / Capio ApS Phone: +46-18-4186040 Fax: +46-18-4186049 Web: http://www.nobolt.com

J Smith

23 years ago
I believe Zeev suggested doing it on a per API function basis. Should be in the archives some place, so I can't take credit for the suggestion. I don't really care how it's done either, so long as it works. Looking over the Zend code, it seems that most of the ZEND_API are wrapped in BEGIN/END_EXTERN_C(), so for the sake of consistency that's probably the way to go. J Per Lundberg wrote: