Hidd

Intro

This is a research page on hidd -- how to examine what it does, how it works, etc.

Files

Hidd is started from upstart (/etc/event.d/hidd) with a -f option to load a given configuration file. On the emulator, this is /etc/hidd/HidPluginsVbox.xml. On a pre, this is /etc/hidd/HidPlugins.xml. There's also something called casper there, not sure what that is as of yet

Architecture

Hidd seems to use a modular plugin-style architecture where each plugin is a shared library.

Default files are:

libhid.so libhidavrcp.so libhidlight.so libhidqemukeypad.so libhidtouchpanel.so libhidaccelerometer.so libhidkeypad.so libhidproximity.so libhidqemutouchpanel.so

Plugin definition in config file

<source lang=xml>

   <plugin>
       <name>HidKeypad</name>
       <eventsDeferIdle>true</eventsDeferIdle>
       <eventSocketAddress>/var/tmp/hidd/KeypadEventSocket</eventSocketAddress>
       <cmdSocketAddress>/var/tmp/hidd/KeypadCmdSocket</cmdSocketAddress>
       <path>/usr/lib/libhidkeypad.so</path>
   </plugin>

</source>

Starting the daemon

A lot of debug information can be obtained by starting the daemon like so (on a pre, on an emulator add Vbox before .xml)

/usr/bin/hidd -vvv -f /etc/hidd/HidPlugins.xml

Example trace

/usr/bin/hidd -vvv -f /etc/hidd/HidPlugins-keypadonly.xml

Verbosity level set to 7

root@castle:/etc/hidd# hidd -vvvv -f /etc/hidd/HidPlugins-test.xml Verbosity level set to 7 Plugin: 0

 Name: HidKeypad
 Path: /usr/lib/libhidkeypad.so
 Event Socket Address: /var/tmp/hidd/KeypadEventSocket
 Cmd Socket Address: /var/tmp/hidd/KeypadCmdSocket

_SetupPluginTransport:

 Socket created successfully

_SetupPluginTransport:

 --> Event socket address: /var/tmp/hidd/KeypadEventSocket

_SetupPluginTransport:

 --> Command socket address: /var/tmp/hidd/KeypadCmdSocket

Init:

 HidKeypad: init function called!

HidKeypadIpc.c:104 : GetSwitchStates: Bad file descriptor ReportEvent:

 kInputEvent received 1 events, fd: 7

_ReportStandardEvent:

 Event: 0.0, type=EV_SYN, code=8, value=0

HidPluginStartReaderThread:

 HidKeypad: starting reader thread

main:

 Setting up power management...

ReportEvent:

 kInputEvent received 2 events, fd: 7

_ReportStandardEvent:

 Event: 85906.791100, type=EV_KEY, code=19, value=1

_ReportStandardEvent:

 Event: 85906.791130, type=EV_SYN, code=0, value=0

ReportEvent:

 kInputEvent received 2 events, fd: 7

_ReportStandardEvent:

 Event: 85906.999809, type=EV_KEY, code=19, value=0

_ReportStandardEvent:

 Event: 85906.999840, type=EV_SYN, code=0, value=0