How do I make a file self-update (Native C++)

Question

I'm using Microsoft Visual Studio 2008 with a Windows target deployment. How would I make a file "update itself"? I've already got the "transmitting over a network" part down, but how do I make an executable write over itself?

Basically, I want to write an auto-updater for a directory that also includes the auto-updater, and the updater needs to update EVERYTHING in the directory.

Maybe a ways to pend the changes to the file for until the file lock is released would work. If I were to do that though, I'd probably follow it up with a hot-patch.

Answer 1

Write a new executable and delete or save a copy of the old one -- you could send a diff over the network and have a third program, the update monitor or whatever, to apply it. It would be just a small script that could be started from the remote app when it realizes an update is available. The updater could rename itself to $UPDATER_OLD_VERSION or whatever, write an updated copy of itself with the appropriate name, and then when the new updater is run you check if there is a file named $UPDATER_OLD_VERSION in the app directory and delete it. All other files could just be updated/overwritten.

Answer 2

I do this using an InnoSetup setup.exe that is launched silently and shuts my app down before it starts installing the new files. I had to add custom Pascal [Code] sections to ensure everything shuts down but it does the job.

Answer 3

You cannot generally modify an app while it is running. You will need to close down the original program and modify it from another location.

Answer 4

You can't overwrite a file while it's executing, but you CAN rename it. In my updater, I rename the existing exe to something meaningful (oldname_dateandtime), then write the new copy in. Then auto-shut our system down and restart it from a service. When the app starts, it's the new version running.

Answer 5

When I made a updater, I should separate the program several. The main reason was just same as what you want to do. Simply say, B updates target application plus A and A updates B. I tried to find another way but what I did was made extra small and simple updater. :(

Answer 6

I think you are talking about file versions and updaters. As you said you need autoupdater.So you need to create a service which monitors your install directory and compares the file version on your disk with server.

Once mismatch happens you can ask latest data from server . If the files going to be replaced are in use you have to mark them for deletion / unregistration during next reboot and you can mention these using registry.

You can copy all files in cache and later during reboot copy them to install directory.