PHP扩展开发-内核执行流程与扩展结构
SAPI
Zend VM
内部扩展
关于各种SAPI或者PHP本身的生命周期，可能会和其他组件如apache耦合，后续再细谈。关于PHP扩展的生命周期，这里借用一张图。流程应该是很容易明白的，关于这个过程，网上也有很多资料，不再赘述。我们开发扩展需要注意的几个地方也可以对应到图中的某些节点：
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。 
使用php-src/ext/ext_skel可以生成PHP扩展的框架
<code class=" hljs avrasm">./ext_skel --extname=myext[[email protected] ~/software/needbak/php-<span class="hljs-number">5.5</span><span class="hljs-number">.20</span>/ext <span class="hljs-number">12</span>:<span class="hljs-number">24</span>]$==> ls myext/config<span class="hljs-preprocessor">.m</span>4 config<span class="hljs-preprocessor">.w</span>32 CREDITS EXPERIMENTAL myext<span class="hljs-preprocessor">.c</span> myext<span class="hljs-preprocessor">.php</span> php_myext<span class="hljs-preprocessor">.h</span> tests</code>
比较重要的文件是config.m4（当然还有源码），config.m4文件可以使用phpize命令生成configure文件，其中说明了我们是否开启模块，以及外部依赖的库。
<code class=" hljs bash">//config.m4//如果你的扩展依赖其他外部库dnl PHP_ARG_WITH(myext, <span class="hljs-keyword">for</span> myext support,dnl Make sure that the comment is aligned:dnl [ --with-myext Include myext support])//扩展不依赖外部库dnl PHP_ARG_ENABLE(myext, whether to enable myext support,dnl Make sure that the comment is aligned:dnl [ --enable-myext Enable myext support])//寻找并包含头文件<span class="hljs-keyword">if</span> test <span class="hljs-string">"<span class="hljs-variable">$PHP_MYEXT</span>"</span> != <span class="hljs-string">"no"</span>; <span class="hljs-keyword">then</span> dnl Write more examples of tests here... dnl <span class="hljs-comment"># --with-myext -> check with-path</span> dnl SEARCH_PATH=<span class="hljs-string">"/usr/local /usr"</span> <span class="hljs-comment"># you might want to change this</span> dnl SEARCH_FOR=<span class="hljs-string">"/include/myext.h"</span> <span class="hljs-comment"># you most likely want to change this</span> dnl <span class="hljs-keyword">if</span> test -r <span class="hljs-variable">$PHP_MYEXT</span>/<span class="hljs-variable">$SEARCH_FOR</span>; <span class="hljs-keyword">then</span> <span class="hljs-comment"># path given as parameter</span> dnl MYEXT_DIR=<span class="hljs-variable">$PHP_MYEXT</span> dnl <span class="hljs-keyword">else</span> <span class="hljs-comment"># search default path list</span> dnl AC_MSG_CHECKING([<span class="hljs-keyword">for</span> myext files <span class="hljs-keyword">in</span> default path]) dnl <span class="hljs-keyword">for</span> i <span class="hljs-keyword">in</span> <span class="hljs-variable">$SEARCH_PATH</span> ; <span class="hljs-keyword">do</span> dnl <span class="hljs-keyword">if</span> test -r <span class="hljs-variable">$i</span>/<span class="hljs-variable">$SEARCH_FOR</span>; <span class="hljs-keyword">then</span> dnl MYEXT_DIR=<span class="hljs-variable">$i</span> dnl AC_MSG_RESULT(found <span class="hljs-keyword">in</span> <span class="hljs-variable">$i</span>) dnl <span class="hljs-keyword">fi</span> dnl <span class="hljs-keyword">done</span> dnl <span class="hljs-keyword">fi</span> dnl dnl <span class="hljs-keyword">if</span> test -z <span class="hljs-string">"<span class="hljs-variable">$MYEXT_DIR</span>"</span>; <span class="hljs-keyword">then</span> dnl AC_MSG_RESULT([not found]) dnl AC_MSG_ERROR([Please reinstall the myext distribution]) dnl <span class="hljs-keyword">fi</span> dnl <span class="hljs-comment"># --with-myext -> add include path</span> dnl PHP_ADD_INCLUDE(<span class="hljs-variable">$MYEXT_DIR</span>/include) //加载的lib位置 dnl <span class="hljs-comment"># --with-myext -> check for lib and symbol presence</span> dnl LIBNAME=myext <span class="hljs-comment"># you may want to change this</span> dnl LIBSYMBOL=myext <span class="hljs-comment"># you most likely want to change this </span> dnl PHP_CHECK_LIBRARY(<span class="hljs-variable">$LIBNAME</span>,<span class="hljs-variable">$LIBSYMBOL</span>, dnl [ dnl PHP_ADD_LIBRARY_WITH_PATH(<span class="hljs-variable">$LIBNAME</span>, <span class="hljs-variable">$MYEXT_DIR</span>/<span class="hljs-variable">$PHP_LIBDIR</span>, MYEXT_SHARED_LIBADD) dnl AC_DEFINE(HAVE_MYEXTLIB,<span class="hljs-number">1</span>,[ ]) dnl ],[ dnl AC_MSG_ERROR([wrong myext lib version or lib not found]) dnl ],[ dnl -L<span class="hljs-variable">$MYEXT_DIR</span>/<span class="hljs-variable">$PHP_LIBDIR</span> -lm dnl ]) dnl dnl PHP_SUBST(MYEXT_SHARED_LIBADD) PHP_NEW_EXTENSION(myext, myext.c, <span class="hljs-variable">$ext_shared</span>)<span class="hljs-keyword">fi</span></code>
<code class=" hljs vala"><span class="hljs-comment">//php_myext.h</span><span class="hljs-preprocessor">#ifndef PHP_MYEXT_H</span><span class="hljs-preprocessor">#define PHP_MYEXT_H</span>extern zend_module_entry myext_module_entry;<span class="hljs-preprocessor">#define phpext_myext_ptr &myext_module_entry</span><span class="hljs-comment">//导出符号，在链接的时候有用</span><span class="hljs-preprocessor">#ifdef PHP_WIN32</span><span class="hljs-preprocessor"># define PHP_MYEXT_API __declspec(dllexport)</span><span class="hljs-preprocessor">#elif defined(__GNUC__) && __GNUC__ >= 4</span><span class="hljs-preprocessor"># define PHP_MYEXT_API __attribute__ ((visibility("default")))</span><span class="hljs-preprocessor">#else</span><span class="hljs-preprocessor"># define PHP_MYEXT_API</span><span class="hljs-preprocessor">#endif</span><span class="hljs-preprocessor">#ifdef ZTS</span><span class="hljs-preprocessor">#include "TSRM.h"</span><span class="hljs-preprocessor">#endif</span><span class="hljs-comment">//几个核心函数的声明</span>PHP_MINIT_FUNCTION(myext);PHP_MSHUTDOWN_FUNCTION(myext);PHP_RINIT_FUNCTION(myext);PHP_RSHUTDOWN_FUNCTION(myext);PHP_MINFO_FUNCTION(myext);<span class="hljs-comment">//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</span>PHP_FUNCTION(confirm_myext_compiled); <span class="hljs-comment">//全局变量在这定义，展开后是zend_myext_globals结构体</span>ZEND_BEGIN_MODULE_GLOBALS(myext) <span class="hljs-keyword">long</span> global_value; <span class="hljs-keyword">char</span> *global_string;ZEND_END_MODULE_GLOBALS(myext)<span class="hljs-comment">//线程安全与非线程安全下获取全局变量的方式</span><span class="hljs-preprocessor">#ifdef ZTS</span><span class="hljs-preprocessor">#define MYEXT_G(v) TSRMG(myext_globals_id, zend_myext_globals *, v)</span><span class="hljs-preprocessor">#else</span><span class="hljs-preprocessor">#define MYEXT_G(v) (myext_globals.v)</span><span class="hljs-preprocessor">#endif</span><span class="hljs-preprocessor">#endif /* PHP_MYEXT_H */</span></code><code class=" hljs vala"><span class="hljs-comment">//myext.c</span><span class="hljs-preprocessor">#ifdef HAVE_CONFIG_H</span><span class="hljs-preprocessor">#include "config.h"</span><span class="hljs-preprocessor">#endif</span><span class="hljs-preprocessor">#include "php.h"</span><span class="hljs-preprocessor">#include "php_ini.h"</span><span class="hljs-preprocessor">#include "ext/standard/info.h"</span><span class="hljs-preprocessor">#include "php_myext.h"</span><span class="hljs-comment">//全局变量声明</span>ZEND_DECLARE_MODULE_GLOBALS(myext)<span class="hljs-comment">/* True global resources - no need for thread safety here */</span><span class="hljs-keyword">static</span> <span class="hljs-keyword">int</span> le_myext;<span class="hljs-comment">//模块函数的导出</span><span class="hljs-keyword">const</span> zend_function_entry myext_functions[] = { PHP_FE(confirm_myext_compiled, NULL) <span class="hljs-comment">/* For testing, remove later. */</span> <span class="hljs-constant"> PHP_FE_END </span> <span class="hljs-comment">/* Must be the last line in myext_functions[] */</span>};<span class="hljs-comment">//模块结构</span>zend_module_entry myext_module_entry = {<span class="hljs-preprocessor">#if ZEND_MODULE_API_NO >= 20010901</span> STANDARD_MODULE_HEADER,<span class="hljs-preprocessor">#endif</span> <span class="hljs-string">"myext"</span>, myext_functions, PHP_MINIT(myext), PHP_MSHUTDOWN(myext), PHP_RINIT(myext), <span class="hljs-comment">/* Replace with NULL if there's nothing to do at request start */</span> PHP_RSHUTDOWN(myext), <span class="hljs-comment">/* Replace with NULL if there's nothing to do at request end */</span> PHP_MINFO(myext),<span class="hljs-preprocessor">#if ZEND_MODULE_API_NO >= 20010901</span> PHP_MYEXT_VERSION,<span class="hljs-preprocessor">#endif</span> STANDARD_MODULE_PROPERTIES};<span class="hljs-preprocessor">#ifdef COMPILE_DL_MYEXT</span>ZEND_GET_MODULE(myext)<span class="hljs-preprocessor">#endif</span><span class="hljs-comment">//ini配置文件的设置</span>PHP_INI_BEGIN() STD_PHP_INI_ENTRY(<span class="hljs-string">"myext.global_value"</span>, <span class="hljs-string">"42"</span>, PHP_INI_ALL, OnUpdateLong, global_value, zend_myext_globals, myext_globals) STD_PHP_INI_ENTRY(<span class="hljs-string">"myext.global_string"</span>, <span class="hljs-string">"foobar"</span>, PHP_INI_ALL, OnUpdateString, global_string, zend_myext_globals, myext_globals)PHP_INI_END()<span class="hljs-comment">//初始化全局变量</span><span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> php_myext_init_globals(zend_myext_globals *myext_globals){ myext_globals->global_value = <span class="hljs-number">0</span>; myext_globals->global_string = NULL;}<span class="hljs-comment">//模块加载时的函数</span>PHP_MINIT_FUNCTION(myext){ <span class="hljs-comment">/* If you have INI entries, uncomment these lines REGISTER_INI_ENTRIES(); */</span> <span class="hljs-keyword">return</span> SUCCESS;}<span class="hljs-comment">//模块卸载时函数</span>PHP_MSHUTDOWN_FUNCTION(myext){ <span class="hljs-comment">/* uncomment this line if you have INI entries UNREGISTER_INI_ENTRIES(); */</span> <span class="hljs-keyword">return</span> SUCCESS;}<span class="hljs-comment">//请求初始化函数</span>PHP_RINIT_FUNCTION(myext){ <span class="hljs-keyword">return</span> SUCCESS;}<span class="hljs-comment">//请求关闭函数</span>PHP_RSHUTDOWN_FUNCTION(myext){ <span class="hljs-keyword">return</span> SUCCESS;}<span class="hljs-comment">//模块信息，phpinfo</span>PHP_MINFO_FUNCTION(myext){ php_info_print_table_start(); php_info_print_table_header(<span class="hljs-number">2</span>, <span class="hljs-string">"myext support"</span>, <span class="hljs-string">"enabled"</span>); php_info_print_table_end(); <span class="hljs-comment">/* Remove comments if you have entries in php.ini DISPLAY_INI_ENTRIES(); */</span>}<span class="hljs-comment">//测试函数</span>PHP_FUNCTION(confirm_myext_compiled){ <span class="hljs-keyword">char</span> *arg = NULL; <span class="hljs-keyword">int</span> arg_len, len; <span class="hljs-keyword">char</span> *strg; if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, <span class="hljs-string">"s"</span>, &arg, &arg_len) == FAILURE) { <span class="hljs-keyword">return</span>; } len = spprintf(&strg, <span class="hljs-number">0</span>, <span class="hljs-string">"Congratulations! You have successfully modified ext/%.78s/config.m4. Module %.78s is now compiled into PHP."</span>, <span class="hljs-string">"myext"</span>, arg); RETURN_STRINGL(strg, len, <span class="hljs-number">0</span>);}</code>
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