Screensaver & Platform Security

[storsjo]

Hello,

I'm trying to build a screensaver for S60 3rd edition. I've managed to get the code running (as far as I've been able to test), but I run into problems with platform security.

As we all know, a DLL must have at least the same capabilities as the loading process.

In order to be able to select the screensaver plugin, the themes application has to be able to load it. On the emulator I've found out that this in practice means that the screensaver needs the following capabilities: ReadDeviceData WriteDeviceData DRM NetworkControl SwEvent NetworkServices LocalServices ReadUserData WriteUserData Location UserEnvironment

If I grant these capabilities, the screensaver shows up in the list in the themes application. But as far as I know, the emulator doesn't actually start the screensaver, so I haven't been able to see which capabilities the screensaver server(?) requires.

The problem is that this list of capabilities is insane, it's more than the end user can grant, and it's even more than what can be granted with a simple developer certificate. Thus I haven't been able to test it at all on a real device.

Is this really the case, or is there some workaround I don't know about? Does a simple screensaver really need manufacturer approved capabilities?

Platform Security in principle is ok, but in cases like this one it really creates unnecessary hurdles.

A suggestion for future versions would be to have a separate loader process with very low capabilities, which the themes application (and perhaps the screensaver server, too) communicates with using some sort of IPC. Cumbersome and clumsy, yes, but that would solve this problem at least.

// Martin

[dcrocha]

Hello storsjo,

I created an example screensaver for 3rd. edition, complete source code + article:

s60 3rd. edition: writing a screensaver

It's also published at NewLC.com.

Perhaps it can help you with your doubts.

[]s
Daniel

[navjotsingh1979]

hi dcrocha

i have also used this screen saver application as suggested at rawsocket.org ,

can u tell me one thing ,

is there any way to make this screen saver (ecom dll ) as default screen saver , i mean after installing the .sis , we dont need to go to themes settings to set our installed screen saver as the current screens aver.

one more thing pertaing to storsjo's querry , cant we place this screen saver plugin code inside some .exe application !

Thanks In advance !

Regards
NEO'

[rihoe]

Hi!

Has anyone found a solution how to set installed screensaver as default? Or how to set it from inside another application?

[symbianyucca]

actually its not public, but its most likely handled by the central repository, so maybe you could do a bit of research and check it out..

yucca

[rihoe]

Thanks for a tip.

It's so strange how in Symbian very often the answers are "I can tell you, but then I have to kill you". I wonder how the Windows would have looked if you had to get permission from Gates before attempting something more trivial than "Hello World".

[symbianyucca]

just noticed that the capability list in the first post is incorrect, mine works fine with "NetworkServices LocalServices Location ReadUserData WriteUserData ReadDeviceData WriteDeviceData SwEvent UserEnvironment PowerMgmt", so with current symbian signing thingi, it can be made with normal developer certificate, so no need to get any permissions... Anyway, it is a bit mre difficult than doing "Hello world", and what comes to the changing user settings, its often better to let user to do it.

yucca

[rihoe]

I agree. I just want to offer user the possibility to set my Screensaver in my application (for stupid users who otherwise wouldn't figure out how to do it)

[Paul.Todd]

Most things in Symbian require opening your wallet more than anything else..

There is an official example of a screen saver at
http://wiki.forum.nokia.com/index.ph...dition_devices

There is probably some central repository key to set the default saver, though it is broken on some releases

http://wiki.forum.nokia.com/index.ph...the_active_one