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Editing: self-contained-extensions.md
# 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. ```bash mkdir /tmp/newext cd /tmp/newext ``` You now have an empty directory. We will copy the files from the mysqli extension: ```bash cp -rp php-src/ext/mysqli/* . ``` It is time to finish the module. Run: ```bash phpize ``` You can now ship the contents of the directory - the extension can live completely on its own. The user instructions boil down to ```bash ./configure \ [--with-php-config=/path/to/php-config] \ [--with-mysqli=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. ```m4 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. ## Create source files `ext_skel.php` 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 `./ext/ext_skel.php --help` 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). For example, if you configured PHP with `--prefix=/php`, you would run ```bash /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: ```bash ./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. The following 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: ```c #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 ```c #define PHP_FOO_VERSION "1.2.3" ``` This macro has to be used within your foo_module_entry to indicate the extension version.
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