The first useful PHP extension

C/C++ to develop PHP extensions

I feel that for PHP developers, there are very complex and many things to learn. Of course, developing PHP extensions is also a skill that must be mastered. Here I pay homage to the great bird brother ( Laruence)~
The first functional extension to be developed today. Its main function is to generate the date part in front of the log when recording the log

<code>#即使当前的时间，年-月-日 时：分：秒 时间戳.微妙数 
[2015-05-19 20:39:32 1432039172.968199]</code>

Prelude to the php extension function

First generate the "skeleton":

<code>1. 进入php源码src/ext目录下面
2. 运行./ext_skel --extname=mytest
3. 进入src/ext/mytest/目录
4. 在编写扩展的时候要先修改下config.me文件的10-12行，去掉前面的dnl注释，这个网上一搜一大把。</code>

In the header file Declare the name of the PHP extension function to be written in php_mttest.h

<code>PHP_FUNCTION(get_log_title);
#PHP_FUNCTION是PHP内核中声明的一个宏
#define PHP_FUNCTION 		ZEND_FUNCTION    //在文件src/main/php.h : 347行
#define ZEND_FUNCTION(name) ZEND_NAMED_FUNCTION(ZEND_FN(name))		//文件src/Zend/zend_API.h : 68行
#define ZEND_FN(name) 		zif_##name		//文件src/Zend/zend_API.h : 65行
#define ZEND_NAMED_FUNCTION(name) void name(INTERNAL_FUNCTION_PARAMETERS)	//文件src/Zend/zend_API.h : 67行
#define INTERNAL_FUNCTION_PARAMETERS int ht, zval *return_value, zval **return_value_ptr, zval *this_ptr, int return_value_used TSRMLS_DC	//src/Zend/zend.h : 290行</code>

The above declaration function macro is expanded to:

<code>void zif_get_log_title( int ht, zval *return_value, zval **return_value_ptr, zval *this_ptr, int return_value_used TSRMLS_DC)</code>

Add the declaration of the get_log_title function to the zend_function_entry declaration in mytest.c

<code>const zend_function_entry logs_functions[] = {
        PHP_FE(confirm_logs_compiled,   NULL)           /* For testing, remove later. */
		PHP_FE(get_log_title, NULL)
        PHP_FE_END      /* Must be the last line in logs_functions[] */
};
#编写函数
PHP_FUNCTION(get_log_title)
{
    struct timeval tv;
    time_t rawtime;
    struct tm *timeinfo;
    char *formatinfo;
    time(&rawtime);
    timeinfo = localtime(&rawtime);
    gettimeofday(&tv, NULL);
    spprintf(&formatinfo, 0, "[%4d-%02d-%02d %d:%d:%d %d.%d]", 1900 + timeinfo->tm_year, 1 + timeinfo->tm_mon, timeinfo->tm_mday, timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec, tv.tv_sec, tv.tv_usec);
    RETURN_STRING(formatinfo, 1);
}</code>

There is also a macro to look at here RETURN_STRING

<code>#define RETURN_STRING(s, duplicate) 	{ RETVAL_STRING(s, duplicate); return; }		//文件src/Zend/zend_API.h : 635行
#define RETVAL_STRING(s, duplicate) 	ZVAL_STRING(return_value, s, duplicate)			//文件src/Zend/zend_API.h : 623行
#define ZVAL_STRING(z, s, duplicate) do {	\	//文件src/Zend/zend_API.h : 577-583行，这个的作用其实是给一个string类型zval变量赋值
	const char *__s=(s);				\		
	zval *__z = (z);					\
	Z_STRLEN_P(__z) = strlen(__s);		\		//设置zval字符串长度
	Z_STRVAL_P(__z) = (duplicate?estrndup(__s, Z_STRLEN_P(__z)):(char*)__s);\	//设置zval字符串的值
	Z_TYPE_P(__z) = IS_STRING;			\		//设置zval字符串的类型为字符串
} while (0)</code>

Therefore, RETURN_STRING(formatinfo, 1) is expanded to:

<code>do {
	const char *__s=(formatinfo);
	zval *__z = (return_value);			//这里面的return_value估计是内核定义的，类似 zval *return_value;
	(*__z).value.str.len = strlrn(__s);		//等价于__z->value.str.len
	(*__z).value.str.val = (1?estrndup(__s, (*__z).value.str.len):(char*)__s);
	(*__z).type = 6;	
}</code>

Compile and test

<code>编译的时候需要安装好的php，比如我的php安装在/usr/local/php/目录下面

cd mytest;		//今日刚才编写的函数扩展目录
/usr/local/php/bin/phpize 	//运行phpize，生成configure文件
./configure --with-php-config=/usr/local/php/bin/php-config 	//configure，后面的--with-php-config会生成so文件到安装好的扩展目录，当然也可以不用加，声称之后手动copy过去
make	//有错误的话修正
make install 	//运行之后会提示类似下面的内容
#Installing shared extensions:     /usr/local/php/lib/php/extensions/no-debug-non-zts-20100525/
#修改配置文件php.ini添加extension = mytest.so
#测试
php -r 'var_dump(log_get_title());'</code>

If you output the following content, congratulations on your success

<code>[root@iforever logs]# php -r 'var_dump(get_log_title());' && date
string(39) "[2015-05-19 22:52:29 1432047149.755613]"
2015年 05月 19日 星期二 22:52:29 CST</code>

5/19/2015 10:54:38 PM

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The above introduces the first useful PHP extension, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.