开发PHP扩展是一件很COOL的事情。不过难度自然要比开发PHP程序要复杂很多。毕竟是C语言。
我打一开始学习编程就是用的最笨的办法。由于学习的不是计算机专业，所以学编程甚是头大。和大多数哥哥姐姐弟弟妹妹一样，我也是买了一本谭浩强的C语言，当然这个一方面是大家推荐，另外一方面谭老师的书在编程的书架上面放在了最醒目的位置，其他版本的在我们这个小地方也太难买到。
学习编程，开始就是抄代码删代码，我觉得学这个开发扩展，开始不明白无所谓，先把编写的过程结构给弄清楚，这个应该比较简单，就是在什么位置，写什么代码，哪些可以修改，哪些不可以修改。熟悉过程了之后在去弄明白这段代码是什么意思，而且在删除代码的过程也就明白这段代码所起的作用。
今天写个‘hello world’，和所有的编程语言开始一样。如何写出来一个返回“hello world”的函数。
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首先，在终端中找到PHP源码的目录，然后在ext目录里，输入如下内容，其中"helloworld"为今天的函数名称
./ext_skel --extname=helloworld
接下来一起来见证奇迹的诞生，ext目录下有了helloworld目录。这个是没有任何功能的扩展，下面我们为其添加功能。
打开php_helloworld.h文件,在其中添加如下代码
PHP_FUNCTION(hellworld);
添加后的文件如下
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/* +----------------------------------------------------------------------+ | PHP Version 5 | +----------------------------------------------------------------------+ | Copyright (c) 1997-2015 The PHP Group | +----------------------------------------------------------------------+ | This source file is subject to version 3.01 of the PHP license, | | that is bundled with this package in the file LICENSE, and is | | available through the world-wide-web at the following url: | | http://www.php.net/license/3_01.txt | | If you did not receive a copy of the PHP license and are unable to | | obtain it through the world-wide-web, please send a note to | | license@php.net so we can mail you a copy immediately. | +----------------------------------------------------------------------+ | Author: | +----------------------------------------------------------------------+*//* $Id$ */#ifndef PHP_HELLOWORLD_H#define PHP_HELLOWORLD_Hextern zend_module_entry helloworld_module_entry;#define phpext_helloworld_ptr &helloworld_module_entry#define PHP_HELLOWORLD_VERSION "0.1.0" /* Replace with version number for your extension */#ifdef PHP_WIN32# define PHP_HELLOWORLD_API __declspec(dllexport)#elif defined(__GNUC__) && __GNUC__ >= 4# define PHP_HELLOWORLD_API __attribute__ ((visibility("default")))#else# define PHP_HELLOWORLD_API#endif#ifdef ZTS#include "TSRM.h"#endifPHP_MINIT_FUNCTION(helloworld);PHP_MSHUTDOWN_FUNCTION(helloworld);PHP_RINIT_FUNCTION(helloworld);PHP_RSHUTDOWN_FUNCTION(helloworld);PHP_MINFO_FUNCTION(helloworld);PHP_FUNCTION(confirm_helloworld_compiled); /* For testing, remove later. *///-----------------------------------------------------------start---------------------------------------------//这里是我添加内容的开始PHP_FUNCTION(hellworld);//这里结束//-----------------------------------------------------end------------------------------------------------/* Declare any global variables you may need between the BEGIN and END macros here: ZEND_BEGIN_MODULE_GLOBALS(helloworld) long global_value; char *global_string;ZEND_END_MODULE_GLOBALS(helloworld)*//* In every utility function you add that needs to use variables in php_helloworld_globals, call TSRMLS_FETCH(); after declaring other variables used by that function, or better yet, pass in TSRMLS_CC after the last function argument and declare your utility function with TSRMLS_DC after the last declared argument. Always refer to the globals in your function as HELLOWORLD_G(variable). You are encouraged to rename these macros something shorter, see examples in any other php module directory.*/#ifdef ZTS#define HELLOWORLD_G(v) TSRMG(helloworld_globals_id, zend_helloworld_globals *, v)#else#define HELLOWORLD_G(v) (helloworld_globals.v)#endif#endif /* PHP_HELLOWORLD_H *//* * Local variables: * tab-width: 4 * c-basic-offset: 4 * End: * vim600: noet sw=4 ts=4 fdm=marker * vim<600: noet sw=4 ts=4 */ 下面打开helloworld.c，修改后如下
/* +----------------------------------------------------------------------+ | PHP Version 5 | +----------------------------------------------------------------------+ | Copyright (c) 1997-2015 The PHP Group | +----------------------------------------------------------------------+ | This source file is subject to version 3.01 of the PHP license, | | that is bundled with this package in the file LICENSE, and is | | available through the world-wide-web at the following url: | | http://www.php.net/license/3_01.txt | | If you did not receive a copy of the PHP license and are unable to | | obtain it through the world-wide-web, please send a note to | | license@php.net so we can mail you a copy immediately. | +----------------------------------------------------------------------+ | Author: | +----------------------------------------------------------------------+*//* $Id$ */#ifdef HAVE_CONFIG_H#include "config.h"#endif#include "php.h"#include "php_ini.h"#include "ext/standard/info.h"#include "php_helloworld.h"/* If you declare any globals in php_helloworld.h uncomment this:ZEND_DECLARE_MODULE_GLOBALS(helloworld)*//* True global resources - no need for thread safety here */static int le_helloworld;/* {{{ helloworld_functions[] * * Every user visible function must have an entry in helloworld_functions[]. */const zend_function_entry helloworld_functions[] = { PHP_FE(confirm_helloworld_compiled, NULL) /* For testing, remove later. */ PHP_FE(helloworld, NULL) /* 在这里添加代码 ，和上个文件中的函数名要一致*/ PHP_FE_END /* Must be the last line in helloworld_functions[] */};/* }}} *//* {{{ helloworld_module_entry */zend_module_entry helloworld_module_entry = {#if ZEND_MODULE_API_NO >= 20010901 STANDARD_MODULE_HEADER,#endif "helloworld", helloworld_functions, PHP_MINIT(helloworld), PHP_MSHUTDOWN(helloworld), PHP_RINIT(helloworld), /* Replace with NULL if there's nothing to do at request start */ PHP_RSHUTDOWN(helloworld), /* Replace with NULL if there's nothing to do at request end */ PHP_MINFO(helloworld),#if ZEND_MODULE_API_NO >= 20010901 PHP_HELLOWORLD_VERSION,#endif STANDARD_MODULE_PROPERTIES};/* }}} */#ifdef COMPILE_DL_HELLOWORLDZEND_GET_MODULE(helloworld)#endif/* {{{ PHP_INI *//* Remove comments and fill if you need to have entries in php.iniPHP_INI_BEGIN() STD_PHP_INI_ENTRY("helloworld.global_value", "42", PHP_INI_ALL, OnUpdateLong, global_value, zend_helloworld_globals, helloworld_globals) STD_PHP_INI_ENTRY("helloworld.global_string", "foobar", PHP_INI_ALL, OnUpdateString, global_string, zend_helloworld_globals, helloworld_globals)PHP_INI_END()*//* }}} *//* {{{ php_helloworld_init_globals *//* Uncomment this function if you have INI entriesstatic void php_helloworld_init_globals(zend_helloworld_globals *helloworld_globals){ helloworld_globals->global_value = 0; helloworld_globals->global_string = NULL;}*//* }}} *//* {{{ PHP_MINIT_FUNCTION */PHP_MINIT_FUNCTION(helloworld){ /* If you have INI entries, uncomment these lines REGISTER_INI_ENTRIES(); */ return SUCCESS;}/* }}} *//* {{{ PHP_MSHUTDOWN_FUNCTION */PHP_MSHUTDOWN_FUNCTION(helloworld){ /* uncomment this line if you have INI entries UNREGISTER_INI_ENTRIES(); */ return SUCCESS;}/* }}} *//* Remove if there's nothing to do at request start *//* {{{ PHP_RINIT_FUNCTION */PHP_RINIT_FUNCTION(helloworld){ return SUCCESS;}/* }}} *//* Remove if there's nothing to do at request end *//* {{{ PHP_RSHUTDOWN_FUNCTION */PHP_RSHUTDOWN_FUNCTION(helloworld){ return SUCCESS;}/* }}} *//* {{{ PHP_MINFO_FUNCTION */PHP_MINFO_FUNCTION(helloworld){ php_info_print_table_start(); php_info_print_table_header(2, "helloworld support", "enabled"); php_info_print_table_end(); /* Remove comments if you have entries in php.ini DISPLAY_INI_ENTRIES(); */}/* }}} *//* Remove the following function when you have successfully modified config.m4 so that your module can be compiled into PHP, it exists only for testing purposes. *//* Every user-visible function in PHP should document itself in the source *//* {{{ proto string confirm_helloworld_compiled(string arg) Return a string to confirm that the module is compiled in */PHP_FUNCTION(confirm_helloworld_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.", "helloworld", arg); RETURN_STRINGL(strg, len, 0);}/* }}} *//* The previous line is meant for vim and emacs, so it can correctly fold and unfold functions in source code. See the corresponding marks just before function definition, where the functions purpose is also documented. Please follow this convention for the convenience of others editing your code.*//* * Local variables: * tab-width: 4 * c-basic-offset: 4 * End: * vim600: noet sw=4 ts=4 fdm=marker * vim<600: noet sw=4 ts=4 */ /* 这里是功能 这个函数不接收参数，只有返回值。 */ PHP_FUNCTION(helloworld){ int len; char *strg; len = spprintf(&strg, 0, "%.78s", "helloworld"); RETURN_STRINGL(strg, len, 0);}在编译之前还需要修改一个文件，就是config.m4，将10、11、12三行最前面的dnl删除掉。这里删除这几个注释，是编译的时候让编译这个扩展，不然就忽略了。
dnl $Id$dnl config.m4 for extension helloworlddnl Comments in this file start with the string 'dnl'.dnl Remove where necessary. This file will not workdnl without editing.dnl If your extension references something external, use with:PHP_ARG_WITH(helloworld, for helloworld support,Make sure that the comment is aligned:[ --with-helloworld Include helloworld support])dnl Otherwise use enable:dnl PHP_ARG_ENABLE(helloworld, whether to enable helloworld support,dnl Make sure that the comment is aligned:dnl [ --enable-helloworld Enable helloworld support])if test "$PHP_HELLOWORLD" != "no"; then dnl Write more examples of tests here... dnl # --with-helloworld -> check with-path dnl SEARCH_PATH="/usr/local /usr" # you might want to change this dnl SEARCH_FOR="/include/helloworld.h" # you most likely want to change this dnl if test -r $PHP_HELLOWORLD/$SEARCH_FOR; then # path given as parameter dnl HELLOWORLD_DIR=$PHP_HELLOWORLD dnl else # search default path list dnl AC_MSG_CHECKING([for helloworld files in default path]) dnl for i in $SEARCH_PATH ; do dnl if test -r $i/$SEARCH_FOR; then dnl HELLOWORLD_DIR=$i dnl AC_MSG_RESULT(found in $i) dnl fi dnl done dnl fi dnl dnl if test -z "$HELLOWORLD_DIR"; then dnl AC_MSG_RESULT([not found]) dnl AC_MSG_ERROR([Please reinstall the helloworld distribution]) dnl fi dnl # --with-helloworld -> add include path dnl PHP_ADD_INCLUDE($HELLOWORLD_DIR/include) dnl # --with-helloworld -> check for lib and symbol presence dnl LIBNAME=helloworld # you may want to change this dnl LIBSYMBOL=helloworld # you most likely want to change this dnl PHP_CHECK_LIBRARY($LIBNAME,$LIBSYMBOL, dnl [ dnl PHP_ADD_LIBRARY_WITH_PATH($LIBNAME, $HELLOWORLD_DIR/$PHP_LIBDIR, HELLOWORLD_SHARED_LIBADD) dnl AC_DEFINE(HAVE_HELLOWORLDLIB,1,[ ]) dnl ],[ dnl AC_MSG_ERROR([wrong helloworld lib version or lib not found]) dnl ],[ dnl -L$HELLOWORLD_DIR/$PHP_LIBDIR -lm dnl ]) dnl dnl PHP_SUBST(HELLOWORLD_SHARED_LIBADD) PHP_NEW_EXTENSION(helloworld, helloworld.c, $ext_shared)fi
到这里就大功告成了。这里开发工具已经做完了，剩下就是编译了。在该扩展目录下，依次执行如下命令
phpize
./configure --withphp-config=php-config
make
sudo make install
安装之后，需要在PHP.INI文件当中将扩展启用，在该文件最后一行添加
extension=helloworld.so
接下来一起见证奇迹的诞生
<?phpecho helloworld();
这就是第一个PHP扩展。
