前面说过一次通信的数据包分两次发送，第一个存储实际数据的大小，第二个存储实际的数据。

事实上，为了方便服务端客户端更好地对收到的数据进行处理，发送的实际的数据本身也有一定的格式。

请求

static char *
request_to_json (const char *service, const char *fcall_str, size_t fcall_len)
{
    json_t *object = json_object ();

    char *temp_request = g_malloc0(fcall_len + 1);
    memcpy(temp_request, fcall_str, fcall_len);

    json_object_set_string_member (object, "service", service);
    json_object_set_string_member (object, "request", temp_request);

    g_free (temp_request);

    char *str = json_dumps (object, 0);
    json_decref (object);
    return str;
}

static int
request_from_json (const char *content, size_t len, char **service, char **fcall_str)
{
    json_error_t jerror;
    json_t *object = json_loadb(content, len, 0, &jerror);
    if (!object) {
        g_warning ("Failed to parse request body: %s.\n", strlen(jerror.text) > 0 ? jerror.text : "");
        return -1;
    }

    *service = g_strdup(json_object_get_string_member (object, "service"));
    *fcall_str = g_strdup(json_object_get_string_member(object, "request"));

    json_decref (object);

    if (!*service || !*fcall_str) {
        g_free (*service);
        g_free (*fcall_str);
        return -1;
    }

    return 0;
}

可以看到请求本身的结构为

{
    "service": ***,
    "request": ***,
}

再将请求转化json格式进行发送。

回复

seafile对服务返回的结果也做了统一的格式处理。

/*
 * Returns -1 if error happens in parsing data or data contains error
 * message. In this case, the calling function should simply return
 * to up layer.
 *
 * Returns 0 otherwise, and root is set to the root node, object set
 * to the root node's containing object.
 */
static int
handle_ret_common (char *data, size_t len, json_t **object, GError **error)
{
    int err_code;
    const char *err_msg;
    json_error_t jerror;

    g_return_val_if_fail (object != 0, -1);

    *object=json_loadb(data,len,0,&jerror);
    if (*object == NULL) {
        setjetoge(&jerror,error);
        json_decref (*object);
        return -1;
    }

    if (json_object_get (*object, "err_code")) {
        err_code = json_integer_value(json_object_get (*object, "err_code"));
        err_msg = json_string_value(json_object_get (*object, "err_msg"));
        g_set_error (error, DFT_DOMAIN,
                     err_code, "%s", err_msg);
        json_decref (*object);
        return -1;
    }

    return 0;
}

结构为:

{
    "ret": ***,
    "err_code": ***,
    "err_msg": ***
}

总结

到这里，searpc-named-pipe-trans.h/c文件和named_pipe.py文件中涉及到的代码基本也全部覆盖到了，通信的部分也就基本介绍完毕了。