custom PHP extension - php

Question

I need to create custom extension for PHP. All things are going well till I want to load compiled extension into PHP. Than I'm getting this error message (by using php -m): "Warning: PHP Startup: Invalid library (maybe not a PHP library) 'first.so' in Unknown on line 0"
OS:
OS X 10.8.5
Here is my compiling process thru which there is no error at all :
$ phpize54
$ sudo ./configure --with-php-config=/opt/local/bin/php-config54
$ sudo make install
I'm registering the extension by .ini file in dir for additional .ini files
extension=first.so
I'm using no another additional tools. Whan I was trying to comtile some extension right from the extensions included in sources of PHP distribution (posix, to be concrete) in this way, everything works and extension was loaded correctly.
Does anybody see any mistake in my source code below? Thank U for hellp.
config.m4:
PHP_ARG_ENABLE(first,whether to enable FIRST functions,
[ --disable-first Disable FIRST functions], yes)
if test "$PHP_FIRST" = "yes"; then
AC_DEFINE(HAVE_FIRST, 1, [whether to include FIRST functions])
PHP_NEW_EXTENSION(first, first.c, $ext_shared)
fi
first.c
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "php.h"
#include "ext/standard/info.h"
extern zend_module_entry first_module_entry;
#define first_module_ptr &first_module_entry
#define phpext_first_ptr first_module_ptr
static PHP_MINFO_FUNCTION(first)
{
php_info_print_table_start();
php_info_print_table_row(2, "Revision", "$Id: 01 $");
php_info_print_table_end();
}
static PHP_MINIT_FUNCTION(first)
{
return SUCCESS;
}
PHP_FUNCTION(hallo)
{
RETURN_STRING("FIRST extension function works\n", 1);
}
ZEND_BEGIN_ARG_INFO_EX(arginfo_hallo, 0, 0, 0)
ZEND_END_ARG_INFO()
const zend_function_entry first_functions[] =
{
PHP_FE(hallo, arginfo_hallo)
PHP_FE_END
};
zend_module_entry first_module_entry = {
STANDARD_MODULE_HEADER,
"first",
first_functions,
PHP_MINIT(first),
NULL,
NULL,
NULL,
PHP_MINFO(first),
NO_VERSION_YET,
STANDARD_MODULE_PROPERTIES
};
#ifdef COMPILE_DL_POSIX
ZEND_GET_MODULE(first)
#endif

Answer 1

#ifdef COMPILE_DL_POSIX
ZEND_GET_MODULE(first)
#endif
This looks wrong. In config.m4 you claim your extension is called first (PHP_NEW_EXTENSION(first, ...) but there you are checking whether an extension called posix is built shared.
Background: PHP can load extensions (meaning PHP modules not to be confused with Zend Extensions like xdebug or opcache - they are a different topi) in two ways. Either statically compiled into PHP or shared.
Statically means that your extension is built as part of PHP and built right in the php binary. (put it in php-src/ext/, run buildconf, configure) This works by configure creating a file main/internal_functions.c which includes all php_foo.h files and creating an array of module_entry which is processed at PHP start.
If an extension is build shared (using --with-foo=shared in php-src or phpize) and loading it via php.ini PHP will look for a function get_module() using dlopen() and dlsym() system apis (or LoadDll on Windows) which will return the module structure. In order to not habe to write that function get_module() all the time the macro ZEND_GET_MODULE does that. But get_module is a common name, and during a static build it has to be prevented that each extension creates it as that would cause a conflict to have the same function multiple times in the same binary, that's why the build system creates COMPILED_DL_FOO defines which can be used as guards.
So in your case PHP opens the library, looks for a get_module() but can't find it, shrugs and reports an error.
References:
http://lxr.php.net/xref/PHP_TRUNK/ext/standard/dl.c#100 - PHP's module loading routine
http://lxr.php.net/xref/PHP_TRUNK/Zend/zend_API.h#135 - ZEND_GET_MODULE
The config.h file in your tree after running configure (search for COMPILE_DL there)