How to update a desktop app

http://bvckup2.com/wip/#14022013

by latitude • 13 years ago

30 9 13 years ago

Osiris• 13 years ago

I have an application that has an update process, but it's complicated by the fact that the application is really just a COM DLL that's loaded by explorer.exe to run as a toolbar next to the clock. I'd have to shutdown and restart explorer.exe, which closes the user's desktop and start menu. Dropbox seems to have found a way around this but I have no idea how they did it.

latitude3• 13 years ago

They probably use a proxy/stub process that uses the .exe that doesn't change often.

boduh• 13 years ago

AFAIK they also shutdown and restart explorer.exe.

fredsted• 13 years ago

Awesome post. There's some real talent behind those UI designs.

latitude3• 13 years ago

Took me a couple of days to figure this out, so I thought I'd share.

I also looked at the option of launching the program in a way that doesn't lock the .exe. For one, it's complicated. It requires creating a process in a Suspended state using a different executable, then basically gutting the memory of that process and replacing it with your own process copy, which needs to be fully preped with all imports and relocations taken care of, etc. In other words, it's pretty complicated.

But what's more important, the only type of software that employs this sort of process launching is the malware. In fact, the above method is derived straight from one of the viruses that made rounds a couple of years ago [1], and it was used by the virus to masquerade as a legit Windows process. So, in other words, you employ this sort of hackery in your program - you will quickly end up talking to anti-virus vendors about taking your software off their blacklists. It's a cool stuff, too bad it's off limits.

[1] http://blogs.avg.com/news-threats/puppet-process

nicholassmith• 13 years ago

I did this a while back, and everything I tried was a series of horrible hacks to get it sorted. With Windows whilst it maintains a lock on the process so you can't do anything nice like replace it, but you can actually just rename it to 'someapplication.old' then deal with it on relaunch. Made me miss Sparkle very much.

TheAnimus2• 13 years ago

Does your re-starter program which listens on the named event have any sig checking or similar?

First thing I thought when reading it was Hmmm ability to run something as another user.

latitude3• 13 years ago

There's no point in checking it. If another user is running an executable that you have full control over, then you can make him run anything you want anyways.

TheAnimus2• 13 years ago

But its not control over the binary executable file, its the control over the event?

Or am I really missing something here, and you set up the object with the security token used on the binary file?

My question (sorry if it's super dumb and I'm missing something) is what permissions are needed to communicate via the event?

How to update a desktop app

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