SAPI

Zend VM

内部扩展

全局变量的定义，通常是zend_modulename_globals

模块的初始化，包括资源/类/常量/ini配置等模块级的初始化

请求的初始化，包括与单次请求相关的一些初始化

请求的结束，清理单次请求相关的数据/内存

模块的卸载，清理模块相关的数据/内存

基本上我们要做的就是按照上面的流程，实现相关的内置函数，定义自己的资源/全局变量/类/函数等。值得注意的地方是在在嵌入其他语言如Python或者被嵌入其他组件如apache时，要小心多进程多线程相关的问题。

php-src/ext/ext_skel可以生成PHP扩展的框架

./ext_skel --extname=myext
[tan@tan ~/software/needbak/php-5.5.20/ext 12:24]$==> ls myext/
config.m4  config.w32  CREDITS  EXPERIMENTAL  myext.c  myext.php  php_myext.h  tests

比较重要的文件是config.m4（当然还有源码），config.m4文件可以使用phpize命令生成configure文件，其中说明了我们是否开启模块，以及外部依赖的库。

//config.m4
//如果你的扩展依赖其他外部库
dnl PHP_ARG_WITH(myext, for myext support,
dnl Make sure that the comment is aligned:
dnl [  --with-myext             Include myext support])

//扩展不依赖外部库
dnl PHP_ARG_ENABLE(myext, whether to enable myext support,
dnl Make sure that the comment is aligned:
dnl [  --enable-myext           Enable myext support])

//寻找并包含头文件
if test "$PHP_MYEXT" != "no"; then
  dnl Write more examples of tests here...

  dnl # --with-myext -> check with-path
  dnl SEARCH_PATH="/usr/local /usr"     # you might want to change this
  dnl SEARCH_FOR="/include/myext.h"  # you most likely want to change this
  dnl if test -r $PHP_MYEXT/$SEARCH_FOR; then # path given as parameter
  dnl   MYEXT_DIR=$PHP_MYEXT
  dnl else # search default path list
  dnl   AC_MSG_CHECKING([for myext files in default path])
  dnl   for i in $SEARCH_PATH ; do
  dnl     if test -r $i/$SEARCH_FOR; then
  dnl       MYEXT_DIR=$i
  dnl       AC_MSG_RESULT(found in $i)
  dnl     fi
  dnl   done
  dnl fi
  dnl
  dnl if test -z "$MYEXT_DIR"; then
  dnl   AC_MSG_RESULT([not found])
  dnl   AC_MSG_ERROR([Please reinstall the myext distribution])
  dnl fi

  dnl # --with-myext -> add include path
  dnl PHP_ADD_INCLUDE($MYEXT_DIR/include)

  //加载的lib位置
  dnl # --with-myext -> check for lib and symbol presence
  dnl LIBNAME=myext # you may want to change this
  dnl LIBSYMBOL=myext # you most likely want to change this 

  dnl PHP_CHECK_LIBRARY($LIBNAME,$LIBSYMBOL,
  dnl [
  dnl   PHP_ADD_LIBRARY_WITH_PATH($LIBNAME, $MYEXT_DIR/$PHP_LIBDIR, MYEXT_SHARED_LIBADD)
  dnl   AC_DEFINE(HAVE_MYEXTLIB,1,[ ])
  dnl ],[
  dnl   AC_MSG_ERROR([wrong myext lib version or lib not found])
  dnl ],[
  dnl   -L$MYEXT_DIR/$PHP_LIBDIR -lm
  dnl ])
  dnl
  dnl PHP_SUBST(MYEXT_SHARED_LIBADD)

  PHP_NEW_EXTENSION(myext, myext.c, $ext_shared)
fi

//php_myext.h
#ifndef PHP_MYEXT_H
#define PHP_MYEXT_H
extern zend_module_entry myext_module_entry;
#define phpext_myext_ptr &myext_module_entry
//导出符号，在链接的时候有用
#ifdef PHP_WIN32
#   define PHP_MYEXT_API __declspec(dllexport)
#elif defined(__GNUC__) && __GNUC__ >= 4
#   define PHP_MYEXT_API __attribute__ ((visibility("default")))
#else
#   define PHP_MYEXT_API
#endif
#ifdef ZTS
#include "TSRM.h"
#endif
//几个核心函数的声明
PHP_MINIT_FUNCTION(myext);
PHP_MSHUTDOWN_FUNCTION(myext);
PHP_RINIT_FUNCTION(myext);
PHP_RSHUTDOWN_FUNCTION(myext);
PHP_MINFO_FUNCTION(myext);
//自动生成的测试函数声明，我们自己定义的模块函数需要在此声明
PHP_FUNCTION(confirm_myext_compiled);   
//全局变量在这定义，展开后是zend_myext_globals结构体
ZEND_BEGIN_MODULE_GLOBALS(myext)
  long  global_value;
  char *global_string;
ZEND_END_MODULE_GLOBALS(myext)
//线程安全与非线程安全下获取全局变量的方式
#ifdef ZTS
#define MYEXT_G(v) TSRMG(myext_globals_id, zend_myext_globals *, v)
#else
#define MYEXT_G(v) (myext_globals.v)
#endif
#endif  /* PHP_MYEXT_H */

//myext.c
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "php.h"
#include "php_ini.h"
#include "ext/standard/info.h"
#include "php_myext.h"
//全局变量声明
ZEND_DECLARE_MODULE_GLOBALS(myext)
/* True global resources - no need for thread safety here */
static int le_myext;
//模块函数的导出
const zend_function_entry myext_functions[] = {
  PHP_FE(confirm_myext_compiled,  NULL)	   /* For testing, remove later. */
    PHP_FE_END  /* Must be the last line in myext_functions[] */
};
//模块结构
zend_module_entry myext_module_entry = {
#if ZEND_MODULE_API_NO >= 20010901
  STANDARD_MODULE_HEADER,
#endif
  "myext",
  myext_functions,
  PHP_MINIT(myext),
  PHP_MSHUTDOWN(myext),
  PHP_RINIT(myext),	   /* Replace with NULL if there\'s nothing to do at request start */
  PHP_RSHUTDOWN(myext),   /* Replace with NULL if there\'s nothing to do at request end */
  PHP_MINFO(myext),
#if ZEND_MODULE_API_NO >= 20010901
  PHP_MYEXT_VERSION,
#endif
  STANDARD_MODULE_PROPERTIES
};
#ifdef COMPILE_DL_MYEXT
ZEND_GET_MODULE(myext)
#endif
//ini配置文件的设置
PHP_INI_BEGIN()
  STD_PHP_INI_ENTRY("myext.global_value",	  "42", PHP_INI_ALL, OnUpdateLong, global_value, zend_myext_globals, myext_globals)
  STD_PHP_INI_ENTRY("myext.global_string", "foobar", PHP_INI_ALL, OnUpdateString, global_string, zend_myext_globals, myext_globals)
PHP_INI_END()
//初始化全局变量
static void php_myext_init_globals(zend_myext_globals *myext_globals)
{
  myext_globals->global_value = 0;
  myext_globals->global_string = NULL;
}
//模块加载时的函数
PHP_MINIT_FUNCTION(myext)
{
  /* If you have INI entries, uncomment these lines 
  REGISTER_INI_ENTRIES();
  */
  return SUCCESS;
}
//模块卸载时函数
PHP_MSHUTDOWN_FUNCTION(myext)
{
  /* uncomment this line if you have INI entries
  UNREGISTER_INI_ENTRIES();
  */
  return SUCCESS;
}
//请求初始化函数
PHP_RINIT_FUNCTION(myext)
{
  return SUCCESS;
}
//请求关闭函数
PHP_RSHUTDOWN_FUNCTION(myext)
{
  return SUCCESS;
}
//模块信息，phpinfo
PHP_MINFO_FUNCTION(myext)
{
  php_info_print_table_start();
  php_info_print_table_header(2, "myext support", "enabled");
  php_info_print_table_end();
  /* Remove comments if you have entries in php.ini
  DISPLAY_INI_ENTRIES();
  */
}
//测试函数
PHP_FUNCTION(confirm_myext_compiled)
{
  char *arg = NULL;
  int arg_len, len;
  char *strg;
  if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &arg, &arg_len) == FAILURE) {
    return;
  }
  len = spprintf(&strg, 0, "Congratulations! You have successfully modified ext/%.78s/config.m4. Module %.78s is now compiled into PHP.", "myext", arg);
  RETURN_STRINGL(strg, len, 0);
}