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HOW TO CREATE A SELF-CONTAINED PHP EXTENSION
A self-contained extension can be distributed independently of
the PHP source. To create such an extension, two things are
required:
- Configuration file (config.m4)
- Source code for your module
We will describe now how to create these and how to put things
together.
PREPARING YOUR SYSTEM
While the result will run on any system, a developer's setup needs these
tools:
GNU autoconf
GNU libtool
GNU m4
All of these are available from
ftp://ftp.gnu.org/pub/gnu/
CONVERTING AN EXISTING EXTENSION
Just to show you how easy it is to create a self-contained
extension, we will convert an embedded extension into a
self-contained one. Install PHP and execute the following
commands.
$ mkdir /tmp/newext
$ cd /tmp/newext
You now have an empty directory. We will copy the files from
the mysql extension:
$ cp -rp php-4.0.X/ext/mysql/* .
It is time to finish the module. Run:
$ phpize
You can now ship the contents of the directory - the extension
can live completely on its own.
The user instructions boil down to
$ ./configure \
[--with-php-config=/path/to/php-config] \
[--with-mysql=MYSQL-DIR]
$ make install
The MySQL module will either use the embedded MySQL client
library or the MySQL installation in MYSQL-DIR.
DEFINING THE NEW EXTENSION
Our demo extension is called "foobar".
It consists of two source files "foo.c" and "bar.c"
(and any arbitrary amount of header files, but that is not
important here).
The demo extension does not reference any external
libraries (that is important, because the user does not
need to specify anything).
LTLIBRARY_SOURCES specifies the names of the sources files. You can
name an arbitrary number of source files here.
CREATING THE M4 CONFIGURATION FILE
The m4 configuration can perform additional checks. For a
self-contained extension, you do not need more than a few
macro calls.
------------------------------------------------------------------------------
PHP_ARG_ENABLE([foobar],
[whether to enable foobar],
[AS_HELP_STRING([--enable-foobar],
[Enable foobar])])
if test "$PHP_FOOBAR" != "no"; then
PHP_NEW_EXTENSION(foobar, foo.c bar.c, $ext_shared)
fi
------------------------------------------------------------------------------
PHP_ARG_ENABLE will automatically set the correct variables, so
that the extension will be enabled by PHP_NEW_EXTENSION in shared mode.
The first argument of PHP_NEW_EXTENSION describes the name of the
extension. The second names the source-code files. The third passes
$ext_shared which is set by PHP_ARG_ENABLE/WITH to PHP_NEW_EXTENSION.
Please use always PHP_ARG_ENABLE or PHP_ARG_WITH. Even if you do not
plan to distribute your module with PHP, these facilities allow you
to integrate your module easily into the main PHP module framework.
CREATING SOURCE FILES
ext_skel can be of great help when creating the common code for all modules
in PHP for you and also writing basic function definitions and C code for
handling arguments passed to your functions. See README.EXT_SKEL for further
information.
As for the rest, you are currently alone here. There are a lot of existing
modules, use a simple module as a starting point and add your own code.
CREATING THE SELF-CONTAINED EXTENSION
Put config.m4 and the source files into one directory. Then, run phpize
(this is installed during make install by PHP 4.0).
For example, if you configured PHP with --prefix=/php, you would run
$ /php/bin/phpize
This will automatically copy the necessary build files and create
configure from your config.m4.
And that's it. You now have a self-contained extension.
INSTALLING A SELF-CONTAINED EXTENSION
An extension can be installed by running:
$ ./configure \
[--with-php-config=/path/to/php-config]
$ make install
ADDING SHARED MODULE SUPPORT TO A MODULE
In order to be useful, a self-contained extension must be loadable
as a shared module. I will explain now how you can add shared module
support to an existing module called foo.
1. In config.m4, use PHP_ARG_WITH/PHP_ARG_ENABLE. Then you will
automatically be able to use --with-foo=shared[,..] or
--enable-foo=shared[,..].
2. In config.m4, use PHP_NEW_EXTENSION(foo,.., $ext_shared) to enable
building the extension.
3. Add the following lines to your C source file:
#ifdef COMPILE_DL_FOO
ZEND_GET_MODULE(foo)
#endif
PECL SITE CONFORMITY
If you plan to release an extension to the PECL website, there are several
points to be regarded.
1. Add LICENSE or COPYING to the package.xml
2. The following should be defined in one of the extension header files
#define PHP_FOO_VERSION "1.2.3"
This macros has to be used within your foo_module_entry to indicate the
extension version.
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