Summary of PHP extension development, PHP extension summary

1. Thread-safe macro definition

There is the following definition in the TSRM/TSRM.h file

#define TSRMLS_FETCH()       void ***tsrm_ls = (void ***) ts_resource_ex(0, NULL)
#define TSRMLS_FETCH_FROM_CTX(ctx) void ***tsrm_ls = (void ***) ctx
#define TSRMLS_SET_CTX(ctx)   ctx = (void ***) tsrm_ls
#define TSRMG(id, type, element)   (((type) (*((void ***) tsrm_ls))[TSRM_UNSHUFFLE_RSRC_ID(id)])->element)
#define TSRMLS_D   void ***tsrm_ls
#define TSRMLS_DC  , TSRMLS_D
#define TSRMLS_C   tsrm_ls
#define TSRMLS_CC  , TSRMLS_C

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There is such a passage in ext/xsl/php_xsl.h

/* In every utility function you add that needs to use variables.                                                                     
   in php_xsl_globals, call TSRM_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 XSL_G(variable).  You are.
   encouraged to rename these macros something shorter, see
   examples in any other php module directory.
*/

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1. Add TSRMLS_D (use this if the method has no parameters) or TSRMLS_DC (with more than 1 parameter) when defining the method
2. Use TSRMLS_C (use this if the method has no parameters) or when calling the method TSRMLS_CC (has more than 1 parameter)

It should be understood this way

The first suffix letter D means definition, that is, D=Define, the first suffix letter C means call, that is, C=Call, and does the second suffix letter C mean a comma? C=Comma (comma)

TSRMLS_D就是定义了，所以是  void ***tsrm_ls

TSRMLS_DC是带逗号的定义，所以是 , void ***tsrm_ls

TSRMLS_C是调用，即tsrm_ls

TSRMLS_CC是调用并带逗号，即 ,tsrm_ls

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So one is a formal parameter and the other is an actual parameter

You can use it like this

int php_myext_action(int action_id, char *message TSRMLS_DC);
php_myext_action(42, "The meaning of life" TSRMLS_CC);

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It is generally recommended to use the tsrm_ls pointer definition method to ensure thread safety

TSRMLS_FETCH call requires a certain amount of processing time. This isn't noticeable in a single iteration, but as your thread count increases, and as the points at which you call TSRMLS_FETCH() increase, your scaling will reveal this bottleneck. Therefore, please use it with caution. Note: For compatibility with c compilers, make sure to place TSRMLS_FETCH() and all variable definitions at the top of the given block scope (before any other statements). Because the TSRMLS_FETCH() macro itself can be parsed in many different ways, it is best to use it as the last line of the variable definition

2. PHP life cycle

The two most common operating modes of PHP are WEB mode and CLI mode. No matter which mode, PHP works on the same principle, running as a SAPI.

1. When we type the php command in the terminal, it uses the CLI.
It is like a web server to support PHP to complete the request. After the request is completed, control is returned to the terminal.
2. When using Apache as the host, when a request comes, PHP will support the completion of the request

PHP_MINIT_FUNCTION  初始化module时运行  
PHP_MSHUTDOWN_FUNCTION  当module被卸载时运行  
PHP_RINIT_FUNCTION  当一个REQUEST请求初始化时运行  
PHP_RSHUTDOWN_FUNCTION  当一个REQUEST请求结束时运行  
PHP_MINFO_FUNCTION  这个是设置phpinfo中这个模块的信息  
PHP_GINIT_FUNCTION  初始化全局变量时  
PHP_GSHUTDOWN_FUNCTION  释放全局变量时

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For example PHP_GINIT_FUNCTION

比如PHP_GINIT_FUNCTION

PHP_GINIT_FUNCTION(test)
{
    /** 初始化全局变量 */
}
//对应的C代码
void zm_globals_ctor_test (zend_test_globals *test_globals TSRMLS_DC)
{
    /** 初始化全局变量 */
}
//在线程退出时，需要将之前自己申请的资源释放时，可以使用 PHP_GSHUTDOWN_FUNCTION来注册析构函数。
PHP_GSHUTDOWN_FUNCTION(test)
{
    /** 清除全局变量 */
}

//对应的C代码
void zm_globals_dtor_test (zend_test_globals *test_globals TSRMLS_DC)
{
    /** 清除全局变量 */
}

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Here is a piece of code that you can test

int minit_time;
PHP_MINIT_FUNCTION(test)
{
    minit_time = time(NULL);
    return SUCCESS;
}

PHP_MSHUTDOWN_FUNCTION(test)
{
    FILE *fp=fopen("mshutdown.txt","a+");
    fprintf(fp,"%ld\n",time(NULL));
    fclose(fp);
    return SUCCESS;
}

int rinit_time;
PHP_RINIT_FUNCTION(test)
{
    rinit_time = time(NULL);
    return SUCCESS;
}


PHP_RSHUTDOWN_FUNCTION(test)
{
    FILE *fp=fopen("rshutdown.txt","a+");
    fprintf(fp,"%ld\n",time(NULL));
    fclose(fp);
    return SUCCESS;
}

PHP_MINFO_FUNCTION(test)
{
    php_info_print_table_start();
    php_info_print_table_header(2, "module info", "enabled");
    php_info_print_table_end();

    /* Remove comments if you have entries in php.ini
    DISPLAY_INI_ENTRIES();
    */
}


PHP_FUNCTION(test)
{
    php_printf("%d",time_of_minit);
    php_printf("%d",time_of_rinit);
    return;
}

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3. Segmentation fault debugging

C programs under Linux often cause segment faults due to memory access errors and other reasons. At this time, if the system core dump function is turned on, the memory image will be dumped to the hard disk, and then gdb can be used Analyze the core file and restore the stack situation when the system segmentation fault occurred. This is very helpful for us to find program bugs.
Use ulimit -a to view the size limit of the system core file; use ulimit -c [kbytes] to set the size of the core file that the system allows to generate.

ulimit -c 0 does not generate core files
ulimit -c 100 sets the maximum core file size to 100k
ulimit -c unlimited does not limit the core file size

Steps:

1. When a segmentation fault occurs, we check ulimit -a (core file size (blocks, -c) 0) and there is no file.
2. Setting: ulimit -c unlimited does not limit the core file size
3. Run the program. When a segmentation fault occurs, it will be automatically recorded in the core (php -f WorkWithArray.php)
4. ls -al core.* in that file (-rw------- 1 leconte leconte 139264 01-06 22:3 1 core.2065)
5. Use gdb to run the program and record the file with segmentation fault. (gdb ./test core.2065)
6. Will mention which line is wrong.

The default core file size of many systems is 0. We can specify it by adding the ulimit -c command to the shell startup script /etc/bashrc or ~/.bashrc. The size of the core file to ensure that the core file can be generated.
In addition, you can also set the file name template of the core file in /proc/sys/kernel/core_pattern. For details, please see the official man manual of core.

4. Common variable operation macros

CG    -> Complier Global      编译时信息，包括函数表等(zend_globals_macros.h:32)
EG    -> Executor Global      执行时信息(zend_globals_macros.h:43)
PG    -> PHP Core Global      主要存储php.ini中的信息
SG    -> SAPI Global          SAPI信息

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1. SG for SAPI information in the main/SAPI.h file

typedef struct _sapi_globals_struct {
    void *server_context;
    sapi_request_info request_info;
    sapi_headers_struct sapi_headers;
    int read_post_bytes;
    unsigned char headers_sent;
    struct stat global_stat;
    char *default_mimetype;
    char *default_charset;
    HashTable *rfc1867_uploaded_files;
    long post_max_size;
    int options;
    zend_bool sapi_started;
    double global_request_time;
    HashTable known_post_content_types;
    zval *callback_func;
    zend_fcall_info_cache fci_cache;
    zend_bool callback_run;
} sapi_globals_struct;

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Look at the definition of SG

BEGIN_EXTERN_C()
#ifdef ZTS
# define SG(v) TSRMG(sapi_globals_id, sapi_globals_struct *, v)
SAPI_API extern int sapi_globals_id;
#else
# define SG(v) (sapi_globals.v)
extern SAPI_API sapi_globals_struct sapi_globals;
#endif

SAPI_API void sapi_startup(sapi_module_struct *sf);
SAPI_API void sapi_shutdown(void);
SAPI_API void sapi_activate(TSRMLS_D);
SAPI_API void sapi_deactivate(TSRMLS_D);
SAPI_API void sapi_initialize_empty_request(TSRMLS_D);
END_EXTERN_C()

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The members are all here in sapi_globals_struct

Then can we call it like this

SG(default_mimetype)
SG(request_info).request_uri

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You can feel this piece of code

static int sapi_cgi_send_headers(sapi_headers_struct *sapi_headers TSRMLS_DC)
{
    char buf[SAPI_CGI_MAX_HEADER_LENGTH];
    sapi_header_struct *h;
    zend_llist_position pos;
    long rfc2616_headers = 0;

    if(SG(request_info).no_headers == 1) {
        return  SAPI_HEADER_SENT_SUCCESSFULLY;
    }

    if (SG(sapi_headers).http_response_code != 200) {
        int len;
        len = sprintf(buf, "Status: %d\r\n", SG(sapi_headers).http_response_code);
        PHPWRITE_H(buf, len);
    }
    if (SG(sapi_headers).send_default_content_type) {
        char *hd;
        hd = sapi_get_default_content_type(TSRMLS_C);
        PHPWRITE_H("Content-type:", sizeof("Content-type: ")-1);
        PHPWRITE_H(hd, strlen(hd));
        PHPWRITE_H("\r\n", 2);
        efree(hd);
    }
    h = zend_llist_get_first_ex(&sapi_headers->headers, &pos);
    while (h) {
        PHPWRITE_H(h->header, h->header_len);
        PHPWRITE_H("\r\n", 2);
        h = zend_llist_get_next_ex(&sapi_headers->headers, &pos);
    }
    PHPWRITE_H("\r\n", 2);
    return SAPI_HEADER_SENT_SUCCESSFULLY;
}

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2. EG Executor Globals

EG obtains the data in the struct _zend_execution_globals structure

struct _zend_execution_globals {
  ...
  HashTable symbol_table;   /* 全局作用域，如果没有进入函数内部，全局＝活动 */
  HashTable *active_symbol_table; /* 活动作用域，当前作用域 */
  ...
}

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Usually, use EG(symbol_table) to get the symbol table in the global scope, use EG(active_symbol_table) to get the symbol table in the current scope

For example, to define $foo = 'bar'

zval *fooval;

MAKE_STD_ZVAL(fooval);
ZVAL_STRING(fooval, "bar", 1);
ZEND_SET_SYMBOL(EG(active_symbol_table), "foo", fooval);

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or find $foo

from the symbol table

zval **fooval;
if(zend_hash_find(&EG(symbol_table), "foo", sizeof("foo"), (void **)&fooval) == SUCCESS) {
	RETURN_STRINGL(Z_STRVAL_PP(fooval), Z_STRLEN_PP(fooval));
} else {
	RETURN_FALSE;
}

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In the above code, EG(active_symbol_table) == &EG(symbol_table)

3. CG() is used to access core global variables. (zend/zend_globals_macros.h)

4. PG() PHP global variable. We know that php.ini will map one or more PHP global structures. (main/php_globals.h)

5. FG() file global variable. Most data streams for file I/O or related global variables are plugged into the standard extension exit structure. (ext/standard/file.h)

5. Get the type and value of the variable

#define Z_TYPE(zval)        (zval).type
#define Z_TYPE_P(zval_p)    Z_TYPE(*zval_p)
#define Z_TYPE_PP(zval_pp)  Z_TYPE(**zval_pp)

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For example, getting the type of a variable

void describe_zval(zval *foo)
{
    if ( Z_TYPE_P(foo) == IS_NULL )
    {
        php_printf("这个变量的数据类型是： NULL");
    }
    else
    {
        php_printf("这个变量的数据类型不是NULL，这种数据类型对应的数字是： %d", Z_TYPE_P(foo));
    }
}

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There are several types

#define IS_NULL     0
#define IS_LONG     1
#define IS_DOUBLE   2
#define IS_BOOL     3
#define IS_ARRAY    4
#define IS_OBJECT   5
#define IS_STRING   6
#define IS_RESOURCE 7
#define IS_CONSTANT 8
#define IS_CONSTANT_ARRAY   9
#define IS_CALLABLE 10

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php_printf()函数是内核对printf()函数的一层封装，我们可以像使用printf()函数那样使用它，以一个P结尾的宏的参数大多是*zval型变量。此外获取变量类型的宏还有两个，分别是Z_TYPE和Z_TYPE_PP，前者的参数是zval型，而后者的参数则是**zval

比如gettype函数的实现

//开始定义php语言中的函数gettype
PHP_FUNCTION(gettype)
{
    //arg间接指向调用gettype函数时所传递的参数。是一个zval**结构
    //所以我们要对他使用__PP后缀的宏。
    zval **arg;

    //这个if的操作主要是让arg指向参数～
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "Z", &arg) == FAILURE) {
        return;
    }

    //调用Z_TYPE_PP宏来获取arg指向zval的类型。
    //然后是一个switch结构，RETVAL_STRING宏代表这gettype函数返回的字符串类型的值
    switch (Z_TYPE_PP(arg)) {
        case IS_NULL:
            RETVAL_STRING("NULL", 1);
            break;

        case IS_BOOL:
            RETVAL_STRING("boolean", 1);
            break;

        case IS_LONG:
            RETVAL_STRING("integer", 1);
            break;

        case IS_DOUBLE:
            RETVAL_STRING("double", 1);
            break;

        case IS_STRING:
            RETVAL_STRING("string", 1);
            break;

        case IS_ARRAY:
            RETVAL_STRING("array", 1);
            break;

        case IS_OBJECT:
            RETVAL_STRING("object", 1);
            break;

        case IS_RESOURCE:
            {
                char *type_name;
                type_name = zend_rsrc_list_get_rsrc_type(Z_LVAL_PP(arg) TSRMLS_CC);
                if (type_name) {
                    RETVAL_STRING("resource", 1);
                    break;
                }
            }

        default:
            RETVAL_STRING("unknown type", 1);
    }
}

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获取变量的值，有这么多宏来获取

Long	Boolean	Double	String value	String length
<pre class="code">Z_LVAL( ) Copy after login	<pre class="code">Z_BVAL( ) Copy after login	<pre class="code">Z_DVAL( ) Copy after login	<pre class="code">Z_STRVAL( ) Copy after login	<pre class="code">Z_STRLEN( ) Copy after login
<pre class="code">Z_LVAL_P( ) Copy after login	<pre class="code">Z_BVAL_P( ) Copy after login	<pre class="code">Z_DVAL_P( ) Copy after login	<pre class="code">Z_STRVAL_P( ) Copy after login	<pre class="code">Z_STRLEN_P( ) Copy after login
<pre class="code">Z_LVAL_PP( ) Copy after login	<pre class="code">Z_BVAL_PP( ) Copy after login	<pre class="code">Z_DVAL_PP( ) Copy after login	<pre class="code">Z_STRVAL_PP( ) Copy after login	<pre class="code">Z_STRLEN_PP( ) Copy after login
HashTable	Object	Object properties	Object class entry	Resource value
<pre class="code">Z_ARRVAL( ) Copy after login	<pre class="code">Z_OBJ( ) Copy after login	<pre class="code">Z_OBJPROP( ) Copy after login	<pre class="code">Z_OBJCE( ) Copy after login	<pre class="code">Z_RESVAL( ) Copy after login
<pre class="code">Z_ARRVAL_P( ) Copy after login	<pre class="code">Z_OBJ_P( ) Copy after login	<pre class="code">Z_OBJPROP_P( ) Copy after login	<pre class="code">Z_OBJCE_P( ) Copy after login	<pre class="code">Z_RESVAL_P( ) Copy after login
<pre class="code">Z_ARRVAL_PP( ) Copy after login	<pre class="code">Z_OBJ_PP( ) Copy after login	<pre class="code">Z_OBJPROP_PP( ) Copy after login	<pre class="code">Z_OBJCE_PP( ) Copy after login	<pre class="code">Z_RESVAL_PP( ) Copy after login

rot13函数的实现

PHP_FUNCTION(rot13)
{
  zval **arg;
  char *ch, cap;
  int i;
  
  if (ZEND_NUM_ARGS( ) != 1 || zend_get_parameters_ex(1, &arg) == FAILURE) {
      WRONG_PARAM_COUNT;
  }
  *return_value = **arg;
  zval_copy_ctor(return_value);
  convert_to_string(return_value);
  
  for(i=0, ch=return_value->value.str.val;
      i<return_value->value.str.len; i++, ch++) {
        cap = *ch & 32;
        *ch &= ~cap;
        *ch = ((*ch>='A') && (*ch<='Z') ? ((*ch-'A'+13) % 26 + 'A') : *ch) | cap;
    }
}

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要获取变量的值，也应该使用Zend定义的宏进行访问。对于简单的标量数据类型、Boolean，long，double，使用Z_BVAL, Z_LVAL, Z_DVAL

void display_values(zval boolzv, zval *longpzv, zval **doubleppzv)
{
  if (Z_TYPE(boolzv) == IS_BOOL) {
    php_printf("The value of the boolean is : %s\n", Z_BVAL(boolzv) ? "true" : "false");
  }
  if(Z_TYPE_P(longpzv) == IS_LONG) {
    php_printf("The value of the long is: %ld\n", Z_LVAL_P(longpzv));
  }
  if(Z_TYPE_PP(doubleppzv) == IS_DOUBLE) {
    php_printf("The value of the double is : %f\n", Z_DVAL_PP(doubleppzv));
  }
}

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对于字符串类型，因为它含有两个字段char * (Z_STRVAL) 和 int (Z_STRLEN)，因此需要用两个宏来进行取值，因为需要二进制安全的输出这个字符串

void display_string(zval *zstr)
{
  if (Z_TYPE_P(zstr) != IS_STRING) {
    php_printf("The wronng datatype was passed!\n");
    return ;
  }
  PHPWRITE(Z_STRVAL_P(zstr), Z_STRLEN_P(zstr));
}

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因为数组在zval中是以HashTable形式存在的，因此使用Z_ARRVAL()进行访问

void display_zval(zval *value)
{
    switch (Z_TYPE_P(value)) {
        case IS_NULL:
            /* 如果是NULL，则不输出任何东西 */
            break;

        case IS_BOOL:
            /* 如果是bool类型，并且true，则输出1，否则什么也不干 */
            if (Z_BVAL_P(value)) {
                php_printf("1");
            }
            break;
        case IS_LONG:
            /* 如果是long整型，则输出数字形式 */
            php_printf("%ld", Z_LVAL_P(value));
            break;
        case IS_DOUBLE:
            /* 如果是double型，则输出浮点数 */
            php_printf("%f", Z_DVAL_P(value));
            break;
        case IS_STRING:
            /* 如果是string型，则二进制安全的输出这个字符串 */
            PHPWRITE(Z_STRVAL_P(value), Z_STRLEN_P(value));
            break;
        case IS_RESOURCE:
            /* 如果是资源，则输出Resource #10 格式的东东 */
            php_printf("Resource #%ld", Z_RESVAL_P(value));
            break;
        case IS_ARRAY:
            /* 如果是Array，则输出Array5个字母！ */
            php_printf("Array");
            break;
        case IS_OBJECT:
            php_printf("Object");
            break;
        default:
            /* Should never happen in practice,
             * but it's dangerous to make assumptions
             */
             php_printf("Unknown");
             break;
    }
}

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一些类型转换函数

ZEND_API void convert_to_long(zval *op);
ZEND_API void convert_to_double(zval *op);
ZEND_API void convert_to_null(zval *op);
ZEND_API void convert_to_boolean(zval *op);
ZEND_API void convert_to_array(zval *op);
ZEND_API void convert_to_object(zval *op);
ZEND_API void _convert_to_string(zval *op ZEND_FILE_LINE_DC);

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6、常量的实例化

我们可以这样实例化

PHP_MINIT_FUNCTION(consts) //模块初始化时定义常量
{
    REGISTER_LONG_CONSTANT("CONSTS_MEANING_OF_LIFE", 42, CONST_CS | CONST_PERSISTENT);
    REGISTER_DOUBLE_CONSTANT("CONSTS_PI", 3.1415926, CONST_PERSISTENT);
    REGISTER_STRING_CONSTANT("CONSTS_NAME", "leon", CONST_CS|CONST_PERSISTENT);
}

PHP_RINIT_FUNCTION(consts) //每次请求时定义常量
{
    char buffer[40];
    srand((int)time(NULL));
    snprintf(buffer, sizeof(buffer), "%d", rand());
    REGISTER_STRING_CONSTANT("CONSTS_RAND", estrdup(buffer), CONST_CS);
    return SUCCESS;
}

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常见的宏

/*注册LONG类型常量*/
#define REGISTER_LONG_CONSTANT(name, lval, flags)  zend_register_long_constant((name), sizeof(name), (lval), (flags), module_number TSRMLS_CC)

/*注册double类型常量*/
#define REGISTER_DOUBLE_CONSTANT(name, dval, flags)  zend_register_double_constant((name), sizeof(name), (dval), (flags), module_number TSRMLS_CC)

/*注册STRING类型常量*/
#define REGISTER_STRING_CONSTANT(name, str, flags)  zend_register_string_constant((name), sizeof(name), (str), (flags), module_number TSRMLS_CC)

/*注册STRING类型常量*/
#define REGISTER_STRINGL_CONSTANT(name, str, len, flags)  zend_register_stringl_constant((name), sizeof(name), (str), (len), (flags), module_number TSRMLS_CC)

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7、全局变量

#php-fpm 生成 POST|GET|COOKIE|SERVER|ENV|REQUEST|FILES全局变量的流程
php_cgi_startup() -> php_module_startup() -> php_startup_auto_globals() -> 保存变量到symbol_table符号表

php_cgi_startup()在 fpm/fpm/fpm_main.c中定义
php_module_startup() 在main/main.c中定义
php_startup_auto_globals() 在main/php_variables.h中定义
zend_hash_update(&EG(symbol_table), "_GET", sizeof("_GET") + 1, &vars, sizeof(zval *), NULL);

/* 读取$_SERVER变量 */
static PHP_FUNCTION(print_server_vars) {
    zval **val;
    if (zend_hash_find(&EG(symbol_table), "_SERVER", sizeof("_SERVER"), (void **)&val) == SUCCESS) {
        RETURN_ZVAL(*val, 1, 0);
    }else{
     RETURN_FALSE;
    }
}


/* 读取$_SERVER[$name] */

ZEND_BEGIN_ARG_INFO(print_server_var_arginfo, 0)
    ZEND_ARG_INFO(0, "name")
ZEND_END_ARG_INFO()

static PHP_FUNCTION(print_server_var) {
    char *name;
    int name_len;
    zval **val;
    HashTable *ht_vars = NULL;
    HashPosition pos;
    zval **ret_val;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|s!", &name, &name_len) == FAILURE) {
        RETURN_NULL();
    }

    if (zend_hash_find(&EG(symbol_table), "_SERVER", sizeof("_SERVER"), (void **)&val) == SUCCESS) {
        ht_vars = Z_ARRVAL_PP(val);

        //此处需传入大于name长度+1的值，因为字符串值后面需要'\0'

        if (zend_hash_find(ht_vars, name, name_len+1, (void **)&ret_val) == SUCCESS) {              RETURN_STRING(Z_STRVAL_PP(ret_val), 0);
        }else{
            RETURN_NULL();
        }
    }else{
        RETURN_NULL();
    }
}

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8、包装第三方库

配置(config.m4)

SEARCH_PATH="/usr/local /usr"     #lib搜索的目录
SEARCH_FOR="/include/curl/curl.h"  #lib头文件的路径
if test -r $PHP_LIBS/$SEARCH_FOR; then 
    LIBS_DIR=$PHP_LIBS
else # search default path list
    AC_MSG_CHECKING([for libs files in default path])
    for i in $SEARCH_PATH ; do
        if test -r $i/$SEARCH_FOR; then
            LIBS_DIR=$i                #搜索到的lib的路径
            AC_MSG_RESULT(found in $i)
        fi
    done
fi

/*验证lib是否存在*/
if test -z "$LIBS_DIR"; then
    AC_MSG_RESULT([not found])
    AC_MSG_ERROR([Please reinstall the libs distribution])
fi


/*编译的时候添加lib的include目录,  -I/usr/include*/
PHP_ADD_INCLUDE($LIBS_DIR/include) 

LIBNAME=curl            #lib名称  
LIBSYMBOL=curl_version  #lib的一个函数，用来PHP_CHECK_LIBRARY验证lib

/*验证lib*/
PHP_CHECK_LIBRARY($LIBNAME,$LIBSYMBOL,  
[
    PHP_ADD_LIBRARY_WITH_PATH($LIBNAME, $LIBS_DIR/$PHP_LIBDIR, LIBS_SHARED_LIBADD) #编译的时候链接lib, -llibcurl
    AC_DEFINE(HAVE_LIBSLIB,1,[ ])
],[
    AC_MSG_ERROR([wrong libs lib version or lib not found])
],[
    -L$LIBS_DIR/$PHP_LIBDIR -lm
])  


PHP_SUBST(LIBS_SHARED_LIBADD)

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9、用于返回的宏

//这些宏都定义在Zend/zend_API.h文件里
#define RETVAL_RESOURCE(l)              ZVAL_RESOURCE(return_value, l)
#define RETVAL_BOOL(b)                  ZVAL_BOOL(return_value, b)
#define RETVAL_NULL()                   ZVAL_NULL(return_value)
#define RETVAL_LONG(l)                  ZVAL_LONG(return_value, l)
#define RETVAL_DOUBLE(d)                ZVAL_DOUBLE(return_value, d)
#define RETVAL_STRING(s, duplicate)         ZVAL_STRING(return_value, s, duplicate)
#define RETVAL_STRINGL(s, l, duplicate)     ZVAL_STRINGL(return_value, s, l, duplicate)
#define RETVAL_EMPTY_STRING()           ZVAL_EMPTY_STRING(return_value)
#define RETVAL_ZVAL(zv, copy, dtor)     ZVAL_ZVAL(return_value, zv, copy, dtor)
#define RETVAL_FALSE                    ZVAL_BOOL(return_value, 0)
#define RETVAL_TRUE                     ZVAL_BOOL(return_value, 1)

#define RETURN_RESOURCE(l)              { RETVAL_RESOURCE(l); return; }
#define RETURN_BOOL(b)                  { RETVAL_BOOL(b); return; }
#define RETURN_NULL()                   { RETVAL_NULL(); return;}
#define RETURN_LONG(l)                  { RETVAL_LONG(l); return; }
#define RETURN_DOUBLE(d)                { RETVAL_DOUBLE(d); return; }
#define RETURN_STRING(s, duplicate)     { RETVAL_STRING(s, duplicate); return; }
#define RETURN_STRINGL(s, l, duplicate) { RETVAL_STRINGL(s, l, duplicate); return; }
#define RETURN_EMPTY_STRING()           { RETVAL_EMPTY_STRING(); return; }
#define RETURN_ZVAL(zv, copy, dtor)     { RETVAL_ZVAL(zv, copy, dtor); return; }
#define RETURN_FALSE                    { RETVAL_FALSE; return; }
#define RETURN_TRUE                     { RETVAL_TRUE; return; }

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其实，除了这些标量类型，还有很多php语言中的复合类型我们需要在函数中返回，如数组和对象，我们可以通过RETVAL_ZVAL与RETURN_ZVAL来操作它们

10、`hashTable的遍历函数`

//基于long key的操作函数

zval *v3;
MAKE_STD_ZVAL(v3);
ZVAL_STRING(v3, "value3", 1);
zend_hash_index_update(names, 0, &v3, sizeof(zval *), NULL);//按数字索引键更新HashTable元素的值

zval **v4;
zend_hash_index_find(names, 1, &v4); //按数字索引获取HashTable元素的值
php_printf("v4 : ");
PHPWRITE(Z_STRVAL_PP(v4), Z_STRLEN_PP(v4));
php_printf("\n");

ulong idx;
idx = zend_hash_index_exists(names, 10);//按数字索引查找HashTable，如果找到返回 1， 反之则返回 0

zend_hash_index_del(names, 2);    //按数字索引删除HashTable元素


//hashTable的遍历函数

zend_hash_internal_pointer_reset(names); //初始化hash指针
zend_hash_internal_pointer_reset_ex(names, &pos);//初始化hash指针，并付值给pos

zend_hash_get_current_data(names, (void**) &val); //获取当前hash存储值,data should be cast to void**, ie: (void**) &data
zend_hash_get_current_data_ex(names, (void**) &val, &pos) == SUCCESS; //获取当前hash存储值

zend_hash_get_current_key(names, &key, &klen, &index, 0) == HASH_KEY_IS_LONG
zend_hash_get_current_key_ex(names, &key, &klen, &index, 0, &pos) == HASH_KEY_IS_LONG; //读取hashtable当前的KEY，返回值会有两种 HASH_KEY_IS_LONG | HASH_KEY_IS_STRING ，分别对应array("value")，array("key"=>"value")两种hashtable

zend_hash_move_forward(names); 
zend_hash_move_forward_ex(names, &pos); //hash指针移至下一位

//HashTable长度
php_printf("%*carray(%d) {\n", depth * 2, ' ', zend_hash_num_elements(Z_ARRVAL_P(zv))

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一个简单的函数

function hello_array_strings($arr) {
    if (!is_array($arr)) return NULL;
    printf("The array passed contains %d elements ", count($arr));

    foreach($arr as $data) {
        if (is_string($data)) echo "$data ";
    }
}

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PHP内核实现

PHP_FUNCTION(hello_array_strings)
{
    zval *arr, **data;
    HashTable *arr_hash;
    HashPosition pointer;
    int array_count;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "a", &arr) == FAILURE) {
        RETURN_NULL();
    }

    arr_hash = Z_ARRVAL_P(arr);
    array_count = zend_hash_num_elements(arr_hash);
    php_printf("The array passed contains %d elements ", array_count);

    for(zend_hash_internal_pointer_reset_ex(arr_hash, &pointer); zend_hash_get_current_data_ex(arr_hash, (void**) &data, &pointer) == SUCCESS; zend_hash_move_forward_ex(arr_hash, &pointer)) {
        if (Z_TYPE_PP(data) == IS_STRING) {

            PHPWRITE(Z_STRVAL_PP(data), Z_STRLEN_PP(data));

            php_printf(" ");

        }
    }

    RETURN_TRUE;
}

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参考文章　

http://php.find-info.ru/php/016/ch23lev1sec1.html

http://docstore.mik.ua/orelly/webprog/php/ch14_10.htm

http://wiki.jikexueyuan.com/project/extending-embedding-php/2.4.html

http://www.php-internals.com/book/?p=chapt02/02-03-02-opcode

http://blog.csdn.net/phpkernel/article/details/5721134

https://github.com/chenpingzhao/php-ext-trie-filter/blob/master/trie_filter.c

http://aicode.cc/tags/php%E6%89%A9%E5%B1%95/

http://www.phpboy.net/2013-12/28-php-stream-wrapper.html

http://thiniki.sinaapp.com/?p=163

http://top.jobbole.com/26400/