How to create a custom PHP extension

In PHP, extension refers to a way to add new functions to PHP, which can expand PHP's capabilities and adapt to various application scenarios. PHP extensions are written in C language, so familiarity with C language is a basic requirement for extension development.

If you want to make your code available to others as a PHP extension, you need to create a custom PHP extension. This article will show you how to create a basic PHP extension.

1. Install the PHP development environment

Before you start developing extensions, you need to install the PHP development environment, which includes PHP itself and related tool chains. You can go to the PHP official website to download the PHP source code and compile and install it, or directly use the compiled binary package.

After installing PHP, you also need to install PHP development tool kits, such as PHP C/C extension development kit, phpize and other tools. These tools help you quickly compile and build PHP extensions.

2. Writing extended C code

Since PHP extensions are written in C language, you need to learn C language and be familiar with the API and data types required for the extension, To write extended C code. Here, we take creating a simple addition function as an example:

In the extended directory, create a new source code file addition.c and write the following content:

#include "php.h"

// 定义函数原型
PHP_FUNCTION(addition);

// 定义模块信息结构体
zend_module_entry addition_module_entry = {
    STANDARD_MODULE_HEADER,
    "addition",
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    "1.0",
    STANDARD_MODULE_PROPERTIES
};

// 定义函数参数
ZEND_BEGIN_ARG_INFO_EX(arginfo_addition, 0, 0, 2)
    ZEND_ARG_INFO(0, a)
    ZEND_ARG_INFO(0, b)
ZEND_END_ARG_INFO()

// 定义函数
PHP_FUNCTION(addition)
{
    // 定义变量
    int a, b;
    long result;

    // 从参数中获取值
    ZEND_PARSE_PARAMETERS_START(2, 2)
        Z_PARAM_LONG(a)
        Z_PARAM_LONG(b)
    ZEND_PARSE_PARAMETERS_END();

    // 计算结果
    result = a + b;

    // 返回结果
    RETURN_LONG(result);
}

// 注册函数入口
zend_function_entry addition_functions[] = {
    PHP_FE(addition, arginfo_addition)
    PHP_FE_END
};

// 构造扩展
zend_module_entry *get_module(void)
{
    return &addition_module_entry;
}

// 扩展初始化函数
PHP_MINIT_FUNCTION(addition)
{
    return SUCCESS;
}

// 扩展关闭函数
PHP_MSHUTDOWN_FUNCTION(addition)
{
    return SUCCESS;
}

// 扩展信息函数
PHP_MINFO_FUNCTION(addition)
{
    php_info_print_table_start();
    php_info_print_table_header(2, "addition support", "enabled");
    php_info_print_table_end();
}

// 定义模块
zend_module_entry addition_module_entry = {
    STANDARD_MODULE_HEADER,
    "addition",
    addition_functions,  // 注册扩展的函数入口
    PHP_MINIT(addition),
    PHP_MSHUTDOWN(addition),
    NULL,
    NULL,
    PHP_MINFO(addition),
    "1.0",
    STANDARD_MODULE_PROPERTIES
};

// 将扩展注册到PHP中
ZEND_GET_MODULE(addition)

3. Building and installing extensions

Building extensions is mainly done using the command line tool that comes with PHP. In the extension directory, execute the following commands:

phpize
./configure
make

These commands will automatically generate Makefile, compile and link, and generate a dynamic link library (extension file) addition.so. At this point you can use the phpinfo() function to check whether the extension has been generated.

Finally, you need to copy the generated extension file addition.so to the PHP module directory and edit the php.ini file to enable the extension:

sudo cp ./modules/addition.so /path/to/php/modules/
sudo echo "extension=addition.so" >> /path/to/php/php.ini

Now your custom extension is ready If used, you can call the addition() function in PHP code to perform addition calculations.

Summary

Creating a custom PHP extension requires familiarity with C language and the API and data types required for PHP extensions, as well as knowledge of compiling and installing extensions. If you are new to PHP extension development, you can start with some simple extensions and gradually improve your programming skills.

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