PHP Kernel-SAPI_PHP Tutorial for Apache2

We know that before defining SAPI, we must first define the sapi_module_struct structure. Looking at the source code: /soft/php-5.2.9/sapi/apache2handler/sapi_apache2.c, you can see that the structure is defined. I copied it directly:

[cpp] 
static sapi_module_struct apache2_sapi_module = { 
        "apache2handler", 
        "Apache 2.0 Handler", 
 
        php_apache2_startup,                            /* startup */ 
        php_module_shutdown_wrapper,                    /* shutdown */ 
 
        NULL,                                           /* activate */ 
        NULL,                                           /* deactivate */ 
 
        php_apache_sapi_ub_write,                       /* unbuffered write */ 
        php_apache_sapi_flush,                          /* flush */ 
        php_apache_sapi_get_stat,                       /* get uid */ 
        php_apache_sapi_getenv,                         /* getenv */ 
 
        php_error,                                      /* error handler */ 
 
        php_apache_sapi_header_handler,                 /* header handler */ 
        php_apache_sapi_send_headers,                   /* send headers handler */ 
        NULL,                                           /* send header handler */ 
 
        php_apache_sapi_read_post,                      /* read POST data */ 
        php_apache_sapi_read_cookies,                   /* read Cookies */ 
 
        php_apache_sapi_register_variables, 
        php_apache_sapi_log_message,                    /* Log message */ 
        php_apache_sapi_get_request_time,               /* Request Time */ 
 
        STANDARD_SAPI_MODULE_PROPERTIES 
}; 
1，php_apache2_startup：当通过apache调用PHP时，这个函数会被调用。该函数定义如下，主要是对PHP进行初始化。
[cpp]
static int php_apache2_startup(sapi_module_struct *sapi_module) 
{ 
        if (php_module_startup(sapi_module, &php_apache_module, 1)==FAILURE) { 
                   return FAILURE;
         } 
         return SUCCESS;
}

2, php_module_shutdown_wrapper: PHP shutdown function.
3. PHP will handle some initialization and resource allocation transactions at each request. This part is what the activate field is defined for.

4. The function of activate is deactive, which will provide a handler to handle the finishing work.

5. php_apache_sapi_ub_write: Provides an interface for writing Response data.

[cpp]
static int
php_apache_sapi_ub_write(const char *str, uint str_length TSRMLS_DC)
{
request_rec *r;
​​​​ php_struct *ctx;

​​​ ctx = SG(server_context);
r = ctx->r;

If (ap_rwrite(str, str_length, r)                   php_handle_aborted_connection();
         } 

          return str_length; /* we always consume all the data passed to us. */
}

6. php_apache_sapi_flush: Provides the handle to zend to refresh the cache.

[cpp]
static void 
php_apache_sapi_flush(void *server_context) 
{ 
        php_struct *ctx; 
        request_rec *r; 
        TSRMLS_FETCH(); 
 
        ctx = server_context; 
 
        /* If we haven't registered a server_context yet,
         * then don't bother flushing. */ 
        if (!server_context) { 
                return; 
        } 
 
        r = ctx->r; 
 
        sapi_send_headers(TSRMLS_C); 
 
        r->status = SG(sapi_headers).http_response_code; 
        SG(headers_sent) = 1; 
 
        if (ap_rflush(r) connection->aborted) { 
                php_handle_aborted_connection(); 
        } 
} 
7，php_apache_sapi_get_stat：这部分用来让Zend可以验证一个要执行脚本文件的state，从而判断文件是否据有执行权限等等。
[cpp]
static struct stat* 
php_apache_sapi_get_stat(TSRMLS_D) 
{ 
        php_struct *ctx = SG(server_context); 
 
        ctx->finfo.st_uid = ctx->r->finfo.user; 
        ctx->finfo.st_gid = ctx->r->finfo.group; 
        ctx->finfo.st_dev = ctx->r->finfo.device; 
        ctx->finfo.st_ino = ctx->r->finfo.inode; 
#if defined(NETWARE) && defined(CLIB_STAT_PATCH) 
        ctx->finfo.st_atime.tv_sec = apr_time_sec(ctx->r->finfo.atime); 
        ctx->finfo.st_mtime.tv_sec = apr_time_sec(ctx->r->finfo.mtime); 
        ctx->finfo.st_ctime.tv_sec = apr_time_sec(ctx->r->finfo.ctime); 
#else 
        ctx->finfo.st_atime = apr_time_sec(ctx->r->finfo.atime); 
        ctx->finfo.st_mtime = apr_time_sec(ctx->r->finfo.mtime); 
        ctx->finfo.st_ctime = apr_time_sec(ctx->r->finfo.ctime); 
#endif 
 
        ctx->finfo.st_size = ctx->r->finfo.size; 
        ctx->finfo.st_nlink = ctx->r->finfo.nlink; 
 
        return &ctx->finfo; 
} 

8，php_apache_sapi_getenv：为Zend提供了一个根据name来查找环境变量的接口，当我们在脚本中调用getenv的时候，就会间接的调用这个句柄。
[cpp] 
static char * 
php_apache_sapi_getenv(char *name, size_t name_len TSRMLS_DC) 
{ 
        php_struct *ctx = SG(server_context); 
        const char *env_var; 
 
        env_var = apr_table_get(ctx->r->subprocess_env, name); 
 
        return (char *) env_var; 
} 

9，php_error：错误处理函数，直接调用PHP错误处理函数。
10，php_apache_sapi_header_handler：在调用PHP的header()函数时，会调用这个函数。

[cpp]
static int 
php_apache_sapi_header_handler(sapi_header_struct *sapi_header,sapi_headers_struct *sapi_headers TSRMLS_DC) 
{ 
        php_struct *ctx; 
        char *val, *ptr; 
 
        ctx = SG(server_context); 
 
        val = strchr(sapi_header->header, ':'); 
 
        if (!val) { 
                sapi_free_header(sapi_header); 
                return 0; 
        } 
        ptr = val; 
 
        *val = '