Linux下hp打印机驱动hplip分析

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最新推荐文章于 2024-10-28 12:48:18 发布

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本文链接：https://blog.youkuaiyun.com/qq_44925290/article/details/89486806

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本文详细分析了Linux下HP打印机驱动hplip的工作流程，包括D-Bus初始化、服务器端hp-systray启动、客户端与服务器端交互、LEDM通信协议以及hpmud的使用。通过hplip，程序能够与打印机进行通信，获取状态信息，并通过D-Bus进行事件处理。

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Hplip分析

版本是2.14,源码位置:http://hplipopensource.com。图的来源：http://hplipopensource.com/node/128。实践中使用的打印机型号:Deskjet 1010.分析的目的就是搞清楚一个灰色地带---打印机通信.

1.D-Bus初始化流程

D-Bus的初始化同样是在ui4/devmgr5.py开始的。

ui4/devmgr5.py

01 class DevMgr5(QMainWindow, Ui_MainWindow):

02 ......

03 # TODO: Make sbus init mandatory success, else exit

04 def initDBus(self):

05 self.dbus_loop = DBusQtMainLoop(set_as_default=True)

06 self.dbus_avail, self.service, self.session_bus = device.init_dbus(self.dbus_loop)

07 ......

08 # Receive events from the session bus

09 self.session_bus.add_signal_receiver(self.handleSessionSignal, sender_keyword='sender',

10 destination_keyword='dest', interface_keyword='interface',

11 member_keyword='member', path_keyword='path')

12 ......

这里调用了base/device.py中的init_dbus()。从第9行可以看出handleSessionSignal是D-Bus服务器端回调函数。

base/device.py

01 #

02 # DBus Support

03 #

05 def init_dbus(dbus_loop=None):

06 ......

07 try:

08 if dbus_loop is None:

09 session_bus = dbus.SessionBus()

10 else:

11 session_bus = dbus.SessionBus(dbus_loop)

12 ......

13 try:

14 log.debug("Connecting to com.hplip.StatusService (try #1)...")

15 service = session_bus.get_object('com.hplip.StatusService', "/com/hplip/StatusService")

16 dbus_avail = True

17 except dbus.exceptions.DBusException, e:

18 try:

19 os.waitpid(-1, os.WNOHANG)

20 except OSError:

21 pass

23 path = utils.which('hp-systray')

24 ......

25 log.debug("Running hp-systray: %s --force-startup" % path)

27 os.spawnlp(os.P_NOWAIT, path, 'hp-systray', '--force-startup')

29 log.debug("Waiting for hp-systray to start...")

30 time.sleep(1)

32 t = 2

33 while True:

34 try:

35 log.debug("Connecting to com.hplip.StatusService (try #%d)..." % t)

36 service = session_bus.get_object('com.hplip.StatusService', "/com/hplip/StatusService")

37 ......

39 return dbus_avail, service, session_bus

41 ......

第27行启动了hp-systray作为d-bus的服务器端。D-bus服务器端启动完毕。

2.D-bus服务器hp-systray端启动

启动命令如下：

$ hp-systray --force-startup -g

说明:-g是调试模式启动

if __name__ == '__main__':    ......    if child_pid1:        # parent (UI)        os.close(w1)        ......                        else: # qt4            try:                import ui4.systemtray as systray            except ImportError:                log.error("Unable to load Qt4 support. Is it installed?")                mod.unlockInstance()                sys.exit(1)                 try:            systray.run(r1)        finally:            mod.unlockInstance()     else:        # child (dbus & device i/o [qt4] or dbus [qt3])        os.close(r1)                if ui_toolkit == 'qt4':            r2, w2 = os.pipe()            r3, w3 = os.pipe()              child_pid2 = os.fork()            if child_pid2:                # parent (dbus)                os.close(r2)                                import hpssd                hpssd.run(w1, w2, r3)                                    else:                # child (device i/o)                os.close(w2)                                import hpdio                hpdio.run(r2, w3)    ......

启动了hpssd和hpdio。hpssd前者会从w3管道从读取hpdio写入的打印机状态信息。下面单说hpdio如何获取打印机状态当hpdio run起来的时候会做以下调用run(hpdio.py)->queryDevice(device.py)->status.StatusType10(status.py)->StatusType10Status(status.py)来获取打印机状态。

在queryDevice这个函数中出现了6种与打印机通信方式,分别是:

Type 1/2 (s: or VSTATUS:) status
Type 3/9 LaserJet PML
Type 6: LJ XML
Type 8: LJ PJL
Type 10: LEDM
Type 11: LEDM_FF_CC_0

而我目前分析的这款打印机使用是第5种Type 10: LEDM通信协议 HPMUD_S_EWS_LEDM_CHANNEL。每种通信通信都有关于打印机状态值的定义,另外从这款打印机的DeviceId可以看出应该同时也是支持PJL的,这里先只说第5种LEDM通信方式.LEDM的大体通信方式是基于HTTP,通信USB传输一个HTTP的GET指令,然后再通过USB读取打印机返回的HTTP超文本,一个是XML.

StatusType10Status调用流程：

StatusType10FetchUrl 从打印机获取状态数据
# Parse the product status XML 解析xml，提取状态值

StatusType10FetchUrl调用流程：

getUrl_LEDM
LocalOpenerEWS_LEDM().openhp()

openhp调用流程：（进入LEDM处理流程）

writeEWS_LEDM
readEWS_LEDM
readLEDMData

3.刷新状态的流程

toolbox.py

01 else: # qt4

02 ......

03 from ui4.devmgr5 import DevMgr5

04 ......

第三行可以看出启动了ui4目录下的devmgr5这个python。

ui4/devmgr5.py

01 class DevMgr5(QMainWindow, Ui_MainWindow):

02 ......

03 def initUI(self):

04 ......

05 self.DeviceRefreshAction.setIcon(QIcon(load_pixmap("refresh1", "16x16")))

06 self.connect(self.DeviceRefreshAction, SIGNAL("triggered()"), self.DeviceRefreshAction_activated)

07 ......

08 def DeviceRefreshAction_activated(self):

09 self.DeviceRefreshAction.setEnabled(False)

10 self.requestDeviceUpdate()

11 self.DeviceRefreshAction.setEnabled(True)

12 ......

13 def requestDeviceUpdate(self, dev=None, item=None):

14 """ Submit device update request to update thread. """

16 if dev is None:

17 dev = self.cur_device

19 if dev is not None:

20 dev.error_state = ERROR_STATE_REFRESHING

21 self.updateDevice(dev, update_tab=False)

23 self.sendMessage(dev.device_uri, '', EVENT_DEVICE_UPDATE_REQUESTED)

24 ......

25 def sendMessage(self, device_uri, printer_name, event_code, username=prop.username,

26 job_id=0, title=''):

28 device.Event(device_uri, printer_name, event_code, username,

29 job_id, title).send_via_dbus(self.session_bus)

30 .....

从第06行可以看出DeviceRefreshAction的槽是DeviceRefreshAction_activated在行8行，接着调用了requestDeviceUpdate，然后调用了sendMessage，然后调用了device.Event。这个在device.py中。在

base/device.py

01 class Event(object):

02 ......

03 def send_via_dbus(self, session_bus, interface='com.hplip.StatusService'):

04 if session_bus is not None and dbus_avail:

05 log.debug("Sending event %d to %s (via dbus)..." % (self.event_code, interface))

06 msg = lowlevel.SignalMessage('/', interface, 'Event')

07 msg.append(signature=self.dbus_fmt, *self.as_tuple())

08 session_bus.send_message(msg)

09 ......

这里调用的send_message是获取的d-bus实例的send_message,它在hpdio.py中。

hpdio.py

01 def send_message(device_uri, event_code, bytes_written=0):

02 args = [device_uri, '', event_code, prop.username, 0, '', '', bytes_written]

03 msg = lowlevel.SignalMessage('/', 'com.hplip.StatusService', 'Event')

04 msg.append(signature='ssisissi', *args)

05 SessionBus().send_message(msg)

这里是标准的d-bus通信。D-bus在收到这个消息后，会怎么处理，且看以后分析。以上是向服务器端请求事件，服务器端收到事件后会调用handleSessionSignal回调。

handleSessionSignal -> handleStatusReply -> updateDevice。

4.客户端与服务器端交互

客户端hp-toolbox,服务器端hp-systray.他们分别启动后,如何进行交互是一个重点,基于服务器端是有自己的消息通知和界面显示的,不过只是一般的事件信息。hp-toolbox可以主动获取打印机信息。

服务器端会主动向打印机设备获取状态信息，客户端获取的要是服务器保存好的状态信息，这个基本属于生产者-消费者之间的关系。

5.LEDM通信协议

全称： Low End Data Model（在hplib的status.py中有介绍：def StatusType10(func): # Low End Data Model）。目前已经是HP一个专利：专利EP2556480A1.

打开channel调用流程：

openEWS_LEDM -> __openChannel -> hpmudext.open_channel -> hpmud处理

读数据流程：

readEWS_LEDM -> __readChannel -> hpmudext.read_channel -> hpmud处理

写命令流程：

writeEWS_LEDM -> __writeChannel -> hpmudext.write_channel -> hpmud处理

以获取ProductStatusDyn记录一下收发数据的情况。

发送命令（报文）：

GET /DevMgmt/ProductStatusDyn.xml HTTP/1.1#015#012Accept: text/plain#015#012Host:localhost#015#012User-Agent:hplip#015#012#015#012

接收数据：

<?xml version="1.0" encoding="UTF-8"?><!-- THIS DATA SUBJECT TO DISCLAIMER(S) INCLUDED WITH THE PRODUCT OF ORIGIN. --><psdyn:ProductStatusDyn xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:dd="http://www.hp.com/schemas/imaging/con/dictionaries/1.0/" xmlns:ad="http://www.hp.com/schemas/imaging/con/ledm/alertdetails/2007/10/31" xmlns:pscat="http://www.hp.com/schemas/imaging/con/ledm/productstatuscategories/2007/10/31" xmlns:locid="http://www.hp.com/schemas/imaging/con/ledm/localizationids/2007/10/31" xmlns:psdyn="http://www.hp.com/schemas/imaging/con/ledm/productstatusdyn/2007/10/31" xsi:schemaLocation="http://www.hp.com/schemas/imaging/con/dictionaries/1.0/ ../schemas/dd/DataDictionaryMasterLEDM.xsd http://www.hp.com/schemas/imaging/con/ledm/alertdetails/2007/10/31 ../schemas/AlertDetails.xsd http://www.hp.com/schemas/imaging/con/ledm/productstatuscategories/2007/10/31 ../schemas/ProductStatusCategories.xsd http://www.hp.com/schemas/imaging/con/ledm/localizationids/2007/10/31 ../schemas/LocalizationIds.xsd http://www.hp.com/schemas/imaging/con/ledm/productstatusdyn/2007/10/31 ../schemas/ProductStatusDyn.xsd"> <dd:Version>  <dd:Revision>SVN-IPG-LEDM.216</dd:Revision>  <dd:Date>2011-02-08</dd:Date> </dd:Version> <psdyn:Status>  <pscat:StatusCategory>closeDoorOrCover</pscat:StatusCategory>  <locid:StringId>65568</locid:StringId> </psdyn:Status> <psdyn:AlertTable>  <dd:ModificationNumber>6</dd:ModificationNumber>  <psdyn:Alert>   <ad:ProductStatusAlertID>closeDoorOrCover</ad:ProductStatusAlertID>   <locid:StringId>65568</locid:StringId>   <dd:SequenceNumber>5</dd:SequenceNumber>   <ad:Severity>Error</ad:Severity>   <ad:AlertPriority>1</ad:AlertPriority>   <ad:AlertDetails>    <ad:AlertDet

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