Re:Ubuntu Snap update spoiled my World Cup Final
by iggldiggl on Monday December 19, 2022 @07:07AM
(#34051155)
Due to the way multi-process browsing works, Firefox at any time still needs to be able to launch new processes in order to accommodate new tabs, or thanks to site-isolation possibly even browsing to a different origin within the same tab. Once the old binaries have been unlinked, I assume there is no longer a sane way of launching a new process using the old binaries?
Re:Ubuntu Snap update spoiled my World Cup Final
by toast0 on Monday December 19, 2022 @11:35AM
(#34054073)
At start, you could start a new seed process, map all the libraries and what not, but don't do any browsing work... When it's time to launch an isolated process, fork the seed process and use the child.
This doesn't seem insane to me, but might not be an easy thing to fit in to the large body of code that's already there.
You still have issues if you're starting up during an upgrade, but that's a problem with anything dynamically linked.
Re:Ubuntu Snap update spoiled my World Cup Final
by iggldiggl on Tuesday December 20, 2022 @04:53AM
(#34063800)
Doesn't using fork make it more difficult to cleanly separate the various child processes from each other? It also makes address space layout randomisation less effective, because every forked process starts out with the same base memory layout, doesn't it?
Re:Ubuntu Snap update spoiled my World Cup Final
by toast0 on Wednesday December 21, 2022 @09:05PM
(#34088839)
> Doesn't using fork make it more difficult to cleanly separate the various child processes from each other?
I don't think so? As long as the main process is separate from the seed process, and the seed process is forked before specialization.
> It also makes address space layout randomisation less effective, because every forked process starts out with the same base memory layout, doesn't it?
Yeah, I think you're right. Not sure if you could maybe do some randomization post fork, but you're probably right.
Most software does fine, as long as it has already mapped in all of its libraries, those files can be unlinked in the filesystem, but will remain on disk in their current form. You do run into trouble if the software is part way through starting up and hasn't mapped all the libraries, or if you update the files rather than unlinking and copying new ones (at least, FreeBSD lets you update mmaped files and all processes will see the updates, which is usually not what you actually want when the files are code).
Windows makes it very hard to update program files while programs are running, so it's not surprising Firefox endeavors to do updates while it's not running.