ipfs-update should update itself

[jbenet]

ipfs-update should update itself, too. it's annoying to have to go download it.

[techtonik]

And ipfs update should update it too.

[victorb]

And ipfs update should update it too.

The ipfs update command in go-ipfs simply calls ipfs-update if you have it installed, so as long as ipfs-update itself can update, ipfs update will seamlessly work.

[Kubuxu]

This is a bit problematic on Windows as you can't replace the binary your are currently running.

What you have to do is have two binaries (ipfs-update.exe, ipfs-upate.new.exe) and during self update:

1. download update as ipfs-update.new.exe
2. run it and make it replace ipfs-update.exe with itself (but it can't remove itself as it is running.
3. run ipfs-update.exe with some flag for it to remove ipfs-update.new.exe.

[victorb]

@Kubuxu there is a library for doing self-updates in golang that I've had success with using in the past, https://github.com/inconshreveable/go-update

We could use that (and maybe even be able to provide the self-updates via IPFS)

[techtonik]

This is a bit problematic on Windows as you can't replace the binary your are currently running.

On Windows you can rename that binary and write new one with the old name while the process is still running. After process exits, the old renamed binary can be safely deleted.

[techtonik]

So the algorithm:

1. download update to ipfs.new.ex_
2. check update is ok
3. rename itself to ipfs.old.exe
4. rename ipfs.new.ex_ to ipfs.exe
5. run new process with some update --finish flag and exit
6. new process tries to clean ipfs.old.exe three times with 3 sec intervals

[godcong]

When we run ipfs update, if ipfs-update does not exist.
Maybe we should download ipfs to the specified directory instead of just prompting that it is not installed then let the user find ipfs-update, download it again, and run ipfs update.