ubus-scriptd 代码分析

ubus-scriptd

來源：ubus-scriptd

ubus-scriptd主要自動帶起ubus service
因此只要停止ubus-scriptd，將會停止自動被帶起的ubus service

• ubus-scriptd有下例程序:

• app_load_services
  由/usr/lib/ubus-services目錄加入ubus service
  目前只提供使用lua寫的程式

• app_load_scripts
  由/usr/lib/ubus目錄加入ubus service
  此目前可以存放binary及script，需要依據使用方式

• app_load_script程序

• 讀取/usr/lib/ubus檔案，並且執行檔案帶參數(.methods)
  此時程式需要回應ubus mehtod的json檔案，並將此method加入obj

• 檔有人通過ubus call會將參數帶入執行檔
  ex. /usr/lib/ubus cmd-json

ubus-scriptd flow

• ubus-scriptd
  使用fork各別帶起lua(此lua內部使用ubus.so建立)
  各別執行/usr/lib/ubus，並且帶參數(.methods)來取得obj method json格式

  

  [ubus-scriptd]

  
  

• rpc_shell_script
  將ubus call的參數帶給/usr/lib/ubus/xxx cmd
  並將回傳值給client

  

  [rpc_shell_script]

  
  

ubus-scriptd

• 目前使用ubus source的test.lua

# ls -l /usr/lib/ubus-services/
-rwxr-xr-x    1 root     root           987 Feb  9  2017 test.lua

• ubus-scriptd

/opt/dvr_board/bin # ./ubus-scriptd 
parsing {"test":{"id":"int","msg":"string"}}
_parse_methods_json: allocating 48 bytes for methods
 - found test
 - blobattr: test id int
 - blobattr: test msg string
_parse_methods_json: method test with 2 params
 - 1 methods for /usr/lib/ubus/test-script
Registering ubus object /test-script (-test-script)

• 目前提供service

/usr/lib/ubus # ubus list -v
'/test-script' @19631336
        "test":{"id":"Integer","msg":"String"}
'broken' @64312369
        "hello1":{}
'test' @103e8e78
        "hello":{"id":"Integer","msg":"String"}
        "hello1":{"id":"Integer","msg":"String"}

Example

• /usr/lib/ubus-services/test.lua

• /usr/lib/ubus/test-script

• ubus-scriptd
  目前提供service

Call to function 'hello'
key=id value=123
key=msg value=tt123
Call to test event
key=id value=123
key=msg value=send test

• ubus call
  test-script直接回應帶入參數

/usr/lib/ubus # ubus call /test-script test '{"id":123,"msg":"str123"}'
{
        "id": 123,
        "msg": "str123"
}

• ubus call
  test.lua的hello

/usr/lib/ubus # ubus call test hello '{"id":123,"msg":"tt123"}'
{
        "message": "foo"
}

• ubus send

ubus send test '{"id":123,"msg":"send test"}

JUCI

github : juci

• JUCI JavaScript Webgui for embedded devices running OpenWRT

• JUCI scripts and services are handled entirely by a small C program called ubus-scriptd

creating-backend-scripts

• it creates ubus objects for all the scripts that are published into /usr/lib/ubus/ directory tree

• creates a ubus object and then listens for incoming ubus calls

• Writing a ubus script

• Writing a ubus service
  Services are different from scripts in that they register their own ubus methods directly and always maintain a running instance of the service in the background
  /usr/lib/ubus-services/
  All ubus-scriptd services are written in lua