PHP内核-Apache2的SAPI

我们知道定义SAPI之前，首先要定义sapi_module_struct这个结构，相看源码：/soft/php-5.2.9/sapi/apache2handler/sapi_apache2.c，可以看到定义该结构，我直接复制过来：

[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的关闭函数。
3，PHP会在每个request的时候，处理一些初始化，资源分配的事务。这部分就是activate字段要定义的。

4，与activate的函数，就是deactiveate，它会提供一个handler, 用来处理收尾工作。

5，php_apache_sapi_ub_write：提供一个向Response数据写的接口。

[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：提供给zend刷新缓存的句柄。

[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 = '\0'; 
 
        do { 
                val++; 
        } while (*val == ' '); 
        if (!strcasecmp(sapi_header->header, "content-type")) { 
                if (ctx->content_type) { 
                        efree(ctx->content_type); 
                } 
                ctx->content_type = estrdup(val); 
        } else if (sapi_header->replace) { 
                apr_table_set(ctx->r->headers_out, sapi_header->header, val); 
        } else { 
                apr_table_add(ctx->r->headers_out, sapi_header->header, val); 
        } 
        *ptr = ':'; 
 
        return SAPI_HEADER_ADD; 
} 
11，php_apache_sapi_send_headers：当要真正发送header的时候，这个函数会被调用。
[cpp] 
static int 
php_apache_sapi_send_headers(sapi_headers_struct *sapi_headers TSRMLS_DC) 
{ 
        php_struct *ctx = SG(server_context); 
        const char *sline = SG(sapi_headers).http_status_line; 
 
        ctx->r->status = SG(sapi_headers).http_response_code; 
 
        /* httpd requires that r->status_line is set to the first digit of
         * the status-code: */ 
        if (sline && strlen(sline) > 12 && strncmp(sline, "HTTP/1.", 7) == 0 && sline[8] == ' ') { 
                ctx->r->status_line = apr_pstrdup(ctx->r->pool, sline + 9); 
                ctx->r->proto_num = 1000 + (sline[7]-'0'); 
                if ((sline[7]-'0') == 0) { 
                        apr_table_set(ctx->r->subprocess_env, "force-response-1.0", "true"); 
                } 
        } 
 
        /*      call ap_set_content_type only once, else each time we call it,
                configured output filters for that content type will be added */ 
        if (!ctx->content_type) { 
                ctx->content_type = sapi_get_default_content_type(TSRMLS_C); 
        } 
        ap_set_content_type(ctx->r, apr_pstrdup(ctx->r->pool, ctx->content_type)); 
        efree(ctx->content_type); 
        ctx->content_type = NULL; 
 
        return SAPI_HEADER_SENT_SUCCESSFULLY; 
} 

12，在php_apache_sapi_send_headers指针下面有一个域，用来指明发送每一个单独的header时调用。
13，php_apache_sapi_read_post：表示如何读取POST数据。

[cpp]
static int  
php_apache_sapi_read_post(char *buf, uint count_bytes TSRMLS_DC) 
{ 
        apr_size_t len, tlen=0; 
        php_struct *ctx = SG(server_context); 
        request_rec *r; 
        apr_bucket_brigade *brigade; 
 
        r = ctx->r; 
        brigade = ctx->brigade; 
        len = count_bytes; 
 
        /*
         * This loop is needed because ap_get_brigade() can return us partial data
         * which would cause premature termination of request read. Therefor we
         * need to make sure that if data is available we fill the buffer completely.
         */ 
 
        while (ap_get_brigade(r->input_filters, brigade, AP_MODE_READBYTES, APR_BLOCK_READ, len) == APR_SUCCESS) { 
                apr_brigade_flatten(brigade, buf, &len); 
                apr_brigade_cleanup(brigade); 
                tlen += len; 
                if (tlen == count_bytes || !len) { 
                        break; 
                } 
                buf += len; 
                len = count_bytes - tlen; 
        } 
 
        return tlen; 
} 

14，php_apache_sapi_read_cookie：如何读取cookie。

[cpp]
static char * 
php_apache_sapi_read_cookies(TSRMLS_D) 
{ 
        php_struct *ctx = SG(server_context); 
        const char *http_cookie; 
 
        http_cookie = apr_table_get(ctx->r->headers_in, "cookie"); 
 
        /* The SAPI interface should use 'const char *' */ 
        return (char *) http_cookie; 
} 

15，php_apache_sapi_register_variables：提供接口，用于给$_SERVER[]数组提供变量。
[cpp]
static void 
php_apache_sapi_register_variables(zval *track_vars_array TSRMLS_DC) 
{ 
        php_struct *ctx = SG(server_context); 
        const apr_array_header_t *arr = apr_table_elts(ctx->r->subprocess_env); 
        char *key, *val; 
        int new_val_len; 
 
        APR_ARRAY_FOREACH_OPEN(arr, key, val) 
                if (!val) { 
                        val = ""; 
                } 
                if (sapi_module.input_filter(PARSE_SERVER, key, &val, strlen(val), &new_val_len TSRMLS_CC)) { 
                        php_register_variable_safe(key, val, new_val_len, track_vars_array TSRMLS_CC); 
                } 
        APR_ARRAY_FOREACH_CLOSE() 
 
        if (sapi_module.input_filter(PARSE_SERVER, "PHP_SELF", &ctx->r->uri, strlen(ctx->r->uri), &new_val_len TSRMLS_CC)) { 
                php_register_variable_safe("PHP_SELF", ctx->r->uri, new_val_len, track_vars_array TSRMLS_CC); 
        } 
} 

16，php_apache_sapi_log_message：输出错误信息。
[cpp]
static void php_apache_sapi_log_message(char *msg) 
{ 
        php_struct *ctx; 
        TSRMLS_FETCH(); 
 
        ctx = SG(server_context); 
 
        if (ctx == NULL) { /* we haven't initialized our ctx yet, oh well */ 
                ap_log_error(APLOG_MARK, APLOG_ERR | APLOG_STARTUP, 0, NULL, "%s", msg); 
        } else { 
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, ctx->r, "%s", msg); 
        } 
} 

17，php_apache_sapi_get_request_time：获取请求时间。

[cpp] 
static time_t php_apache_sapi_get_request_time(TSRMLS_D) { 
        php_struct *ctx = SG(server_context); 
        return apr_time_sec(ctx->r->request_time); 
} 

这就完成了apache的SAPI定义。之后，就是当用户用URL请求apache服务，这些函数指针就会在适当的时候，发挥作用了（被调用）。