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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, three things are
required:
- Makefile template (Makefile.in)
- 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 automake
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).
CREATING THE MAKEFILE TEMPLATE
The Makefile Template (Makefile.in) contains three lines:
------------------------------------------------------------------------------
LTLIBRARY_SHARED_NAME = foobar.la
LTLIBRARY_SOURCES = foo.c bar.c
include $(top_srcdir)/build/dynlib.mk
------------------------------------------------------------------------------
LTLIBRARY_SHARED_NAME specifies the name of the extension.
It must be of the form `ext-name.la'.
LTLIBRARY_SOURCES specifies the names of the sources files. You can
name an arbitrary number of source files here.
The final include directive includes the build rules (you usually
don't need to care about what happens there). rules.mk and other
files are installed by phpize which we will cover later.
CREATING THE M4 CONFIGURATION FILE
The m4 configuration can perform additional checks. For a
self-contained extension, you do not need more than a few
macro calls.
------------------------------------------------------------------------------
PHP_ARG_ENABLE(foobar,whether to enable foobar,
[ --enable-foobar Enable foobar])
if test "$PHP_FOOBAR" != "no"; then
PHP_EXTENSION(foobar, $ext_shared)
fi
------------------------------------------------------------------------------
PHP_ARG_ENABLE will automatically set the correct variables, so
that the extension will be enabled by PHP_EXTENSION in shared mode.
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 Makefile.in, 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_EXTENSION(foo, $ext_shared) to enable
building the extension.
3. Add the following line to Makefile.in:
LTLIBRARY_SHARED_NAME = foo.la
4. Add the following lines to your C source file:
#ifdef COMPILE_DL_FOO
ZEND_GET_MODULE(foo)
#endif
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