[webkit-dev] Obtaining backtraces

[Michael Orlitzky]

On Fri, 2024-09-06 at 17:28 -0500, Michael Catanzaro wrote:
> Hey, sorry you had a bad time. Unfortunately everything on 
> https://trac.webkit.org is obsolete. All documentation is on 
> https://docs.webkit.org/ nowadays. But we don't yet have any warning 
> banner to tell you of this. I have created an issue report: 
> https://github.com/WebKit/Documentation/issues/99
> 
> Anyway, that documentation has not actually been migrated to the new 
> docs website, so there is no newer documentation to point you to. :(
> 

I figured. It's OK, that's why I brought it up.


> > * Core dumps don't happen any more because of bubblewrap
> 
> Hm, I guess the "without systemd" instructions from that wiki page will 
> not work anymore, since the core dump is probably created inside the 
> sandbox now instead of on your host system? I had never considered this.

Right. I was pretty close to editing bubblewrap.c and doing a sudo mv
bwrap /usr/bin.


> I strongly recommend using systemd-coredump. Manual handling of core 
> dumps is primitive and, as you've discovered, a waste of your time. I 
> wrote a blog post on how to enable this if you haven't already:

I too am primitive. None of these systems have systemd :)


> Use the environment variable 
> WEBKIT_DISABLE_SANDBOX_THIS_IS_DANGEROUS=1. (But certainly don't use 
> this just to take a backtrace!)

I left the problem machine at the office overnight, but this sounds
like exactly what I needed. I'm familiar enough with getting core dumps
the old-fashioned way outside of bwrap.

Is it dangerous in some new and exciting way, or is it simply that the
sandbox is not in effect? If it's the latter, capturing the dump as a
new unprivileged user would make it "safe" once again (so long as your
filesystem permissions aren't messed up).