You are making this device world readable and writeable to all
applications... this is probably not what you want. Generally we define a
group id for access to a device, and allow apps to get access to it with a
permission that is associated with the group id. (Or actually more often
have a system service that opens and manages the device, and can return an
fd to the client if appropriate.)
On Mon, Jul 13, 2009 at 10:57 AM, Puneet <puneetjindal.1...@gmail.com>wrote:
>
> Hi everybody,
>
> I have solved the above problem as follows :
>
> I edited the file : <android-workspace>/system/core/init/devices.c
> and, added the line : { "/dev/ttyUSB0", 0666, AID_ROOT, AID_ROOT,
> 0 },
> to the data structure : static struct perms_ devperms[].
>
> Now, whenever /dev/ttyUSB0 is created, it has the permissions :
> crw-rw-rw- root root
>
>
> Any comments, whether this is a good solution ?
>
> And, does anyone know whether it is possible to do it with "udev
> scripts" ?
>
>
> Thanks,
> Puneet Jindal
>
>
> On Jul 4, 2:49 pm, Puneet <puneetjindal.1...@gmail.com> wrote:
> > Hi everybody,
> >
> > I am trying to run Android on my prototype phone. The phone has a
> > sensor (a device that reports its orientation to the phone) attached
> > to it through the USB interface.
> >
> > I have developed a hardware module for that sensor, the name of the
> > shared library for the module being "sensors.default.so". The module
> > communicates with the sensor through the device file /dev/ttyUSB0.
> >
> > The problem I am facing is that the device file /dev/ttyUSB0 has
> > permissions as:
> > crw------- root root 188, 0
> > 1980-01-10 18:47 ttyUSB0
> >
> > So, when I test the module's functionality by running a test android
> > application, the application doesn't have enough privileges to read/
> > write from/to the device file. So, the results are negative.
> >
> > And, if I test the same functionality by running a native test
> > application (via the adb shell, so it runs as root), the results are
> > positive.
> >
> > I tried to solve this issue by modifying the startup scripts (these
> > run as root) to change the device file permissions at startup, but it
> > seems that the device file is created after the scripts have completed
> > their execution.
> >
> > Any suggestions on what should be done, to make the android
> > application able to read/write from/to the device file ?
> > How to change the device file permissions at the time of creation ?
> >
> > Thanks,
> > Puneet Jindal
> >
>
--
Dianne Hackborn
Android framework engineer
hack...@android.com
Note: please don't send private questions to me, as I don't have time to
provide private support, and so won't reply to such e-mails. All such
questions should be posted on public forums, where I and others can see and
answer them.
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