The Minimal PHP5 Extension Skeleton for Starters

To create an extension, you will need at least three files:

• config.m4
• ext_foo.c
• ext_foo.h

Here is a initial content of config.m4:

PHP_ARG_ENABLE(foo, whether to enable foo extension support, 
  [--enable-foo Enable foo extension support])
PHP_NEW_EXTENSION(foo, php_foo.c, $ext_shared)

The PHP_ARG_ENABLE macro enables the option from ./configure script, you can do:

./configure --enable-foo

And you can add extra script in your config.m4 to check weather to compile your extension. The value of the configuration will be stored in $PHP_FOO variable. Since it’s boolean option, there will only be “yes” or “no”:

if test $PHP_FOO != "no"; then
  PHP_NEW_EXTENSION(foo, php_foo.c, $ext_shared)
fi

However the code above is usually not used since your extension will be installed directly, not from the php-src build system.

./configure

Would just work for you.

And here is the minimal content of ext_foo.h

#ifndef _PHP_FOO_H
  #define _PHP_FOO_H
  #ifdef HAVE_CONFIG_H
  #include “config.h”
#endif
#ifdef ZTS
  #warning php_ext_uv module will *NEVER* be thread-safe
  #include <TSRM.h>
#endif
#include <php.h>
extern zend_module_entry foo_module_entry;
PHP_FUNCTION(foo_hello);
#endif

Here is the content of php_foo.c, a minimal extension source code must contains a zend_module_entry, And you usually need to define zend_function_entry to declare your extension functions:

#include "php_foo.h"
PHP_MINIT_FUNCTION(foo);
PHP_MSHUTDOWN_FUNCTION(foo);
PHP_MINFO_FUNCTION(foo);
#if COMPILE_DL_FOO
ZEND_GET_MODULE(foo)
#endif
static const zend_function_entry foo_functions[] = {
  PHP_FE(foo_hello, NULL)
  PHP_FE_END
};
zend_module_entry foo_module_entry = {
  STANDARD_MODULE_HEADER,
  "Foo", // your extension name
  foo_functions, // where you define your functions
  PHP_MINIT(foo),
  PHP_MSHUTDOWN(foo),
  NULL, // PHP_RINIT(foo)
  NULL, // PHP_RSHUTDOWN(foo)
  PHP_MINFO(foo),
  "0.1",
  STANDARD_MODULE_PROPERTIES
};
PHP_MINIT_FUNCTION(foo) {
  return SUCCESS;
}
PHP_MSHUTDOWN_FUNCTION(foo) {
  return SUCCESS;
}
PHP_MINFO_FUNCTION(foo) {
}
PHP_FUNCTION(foo_hello) {
  RETURN_TRUE;
}

Finally just run commands to build your extension file:

phpize
./configure
make

One more thing, to customize the extension name instead of using “foo”, you can some perl commands to replace the identifiers:

perl -i -pe 's/foo/bar/g' config.m4 *.h *.c
perl -i -pe 's/Foo/Bar/g' config.m4 *.h *.c
perl -i -pe 's/FOO/BAR/g' config.m4 *.h *.c

Just replace “bar”, “Bar”, “BAR” with your new name and it will just work.