A brief analysis of the basics of PHP Extension development (2)_PHP tutorial

如果你懒得弄清楚PHP扩展包目录结构的全部内容，那么里面有三个文件你必须注意：

config.m4：这是Unix环境下的Build System配置文件，后面将会通过它生成配置和安装。

php_say_hello.h：这个文件是扩展模块的头文件。遵循C语言一贯的作风，这个里面可以放置一些自定义的结构体、全局变量等等。

say_hello.c：这个就是扩展模块的主程序文件了，最终的扩展模块各个函数入口都在这里。当然，你可以将所有程序代码都塞到这里面，也可以遵循模块化思想，将各个功能模块放到不同文件中。

下面的内容主要围绕这三个文件展开。

Unix Build System配置

开发PHP扩展组件的第一步不是写实现代码，而是要先配置好Build System选项。由于我们是在Linux下开发，所以这里的配置主要与config.m4有关。

关于Build System配置这一块，要是写起来能写一大堆，而且与Unix系统很多东西相关，就算我有兴趣写估计大家也没兴趣看，所以这里我们从略，只拣关键地方说一下，关于config.m4更多细节可以参考这里。

打开生成的config.m4文件，内容大致如下：

dnl $Id___FCKpd___4nbsp;   dnl config.m4 for extension say_hello    dnl Comments in this file start with the string dnl.    dnl Remove where necessary. This file will not work     dnl without editing.     dnl If your extension references something external, use with:    dnl PHP_ARG_WITH(say_hello, for say_hello support,    dnl Make sure that the comment is aligned:    dnl [  --with-say_hello             Include say_hello support])    dnl Otherwise use enable:    dnl PHP_ARG_ENABLE(say_hello, whether to enable say_hello support,    dnl Make sure that the comment is aligned:    dnl [  --enable-say_hello           Enable say_hello support])    if test "$PHP_SAY_HELLO" != "no"; then    dnl Write more examples of tests here...     dnl # --with-say_hello -> check with-path     dnl SEARCH_PATH="/usr/local /usr"     # you might want to change this     dnl SEARCH_FOR="/include/say_hello.h"  # you most likely want to change this    dnl if test -r $PHP_SAY_HELLO/$SEARCH_FOR; then # path given as parameter     dnl   SAY_HELLO_DIR=$PHP_SAY_HELLO     dnl else # search default path list    dnl   AC_MSG_CHECKING([for say_hello files in default path])     dnl   for i in $SEARCH_PATH ; do   dnl     if test -r $i/$SEARCH_FOR; then    dnl       SAY_HELLO_DIR=$i     dnl       AC_MSG_RESULT(found in $i)     dnl     fi    dnl   done    dnl fi   dnl     dnl if test -z "$SAY_HELLO_DIR"; then    dnl   AC_MSG_RESULT([not found])     dnl   AC_MSG_ERROR([Please reinstall the say_hello distribution])     dnl fi    dnl # --with-say_hello -> add include path     dnl PHP_ADD_INCLUDE($SAY_HELLO_DIR/include)     dnl # --with-say_hello -> check for lib and symbol presence      dnl LIBNAME=say_hello # you may want to change this       dnl LIBSYMBOL=say_hello # you most likely want to change this      dnl PHP_CHECK_LIBRARY($LIBNAME,$LIBSYMBOL,     dnl [     dnl   PHP_ADD_LIBRARY_WITH_PATH($LIBNAME, $SAY_HELLO_DIR/lib, SAY_HELLO_SHARED_LIBADD)      dnl   AC_DEFINE(HAVE_SAY_HELLOLIB,1,[ ])      dnl ],[      dnl   AC_MSG_ERROR([wrong say_hello lib version or lib not found])      dnl ],[      dnl   -L$SAY_HELLO_DIR/lib -lm      dnl ])       dnl       dnl PHP_SUBST(SAY_HELLO_SHARED_LIBADD)       PHP_NEW_EXTENSION(say_hello, say_hello.c, $ext_shared)     fi  不要看这么多，因为所有以“dnl”开头的全是注释，所以真正起作用没几行。这里需要配置的只有下面几行：

 dnl If your extension references something external, use with:     dnl PHP_ARG_WITH(say_hello, for say_hello support,    dnl Make sure that the comment is aligned:    dnl [  --with-say_hello             Include say_hello support])    dnl Otherwise use enable:    dnl PHP_ARG_ENABLE(say_hello, whether to enable say_hello support,    dnl Make sure that the comment is aligned:     dnl [  --enable-say_hello           Enable say_hello support])  我想大家也都能看明白，意思就是“如果你的扩展引用了外部组件，使用…，否则使用…”。我们的say_hello扩展并没有引用外部组件，所以将“Otherwise use enable”下面三行的“dnl”去掉，改为：

dnl Otherwise use enable: PHP_ARG_ENABLE(say_hello, whether to enable say_hello support, Make sure that the comment is aligned: [ --enable-say_hello Enable say_hello support]) Save, and the Build System configuration is complete.

PHP Extension and Zend_Module Structural Analysis

The above can be seen as preparations for developing PHP extensions, and the core code will be written next. As mentioned above, writing PHP extensions is based on Zend API and some macros, so if we want to write core code, we must first figure out the structure of PHP Extension. Because a PHP Extension is actually a zend_module_entry structure at the C language level, which can be confirmed from "php_say_hello.h". Open "php_say_hello.h" and you will see a line in it:

extern zend_module_entry say_hello_module_entry; say_hello_module_entry is the C language corresponding element of the say_hello extension, and the definition of its type zend_module_entry can be found in the "Zend/zend_modules.h" file of the PHP source code. The following code is the definition of zend_module_entry:

typedef struct _zend_module_entry zend_module_entry; struct _zend_module_entry { unsigned short size; unsigned int zend_api; unsigned char zend_debug; unsigned char zts; const struct _zend_ini_entry *ini_entry; const struct _zend_module_dep *deps; const char *name; const struct _zend_function_entry *functions; int (*module_startup_func)(INIT_FUNC_ARGS); int (*module_shutdown_func)(SHUTDOWN_FUNC_ARGS); int (*request_startup_func)(INIT_FUNC_ARGS); GS);         void (*info_func)(ZEND_MODULE_INFO_FUNC_ARGS);         const char *version; size_t globals_size; #ifdef ZTS ts_rsrc_id* globals_id_ptr; #else &n

http://www.bkjia.com/PHPjc/478780.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/478780.htmlTechArticleIf you are too lazy to figure out the entire contents of the PHP extension package directory structure, then there are three files in it that you must pay attention to: config .m4: This is the Build System configuration file under Unix environment, which will be later...