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