Re: abort() fails to terminate PID 1 process

[Igmar Palsenberg <igmar@palsenberg.com>]

> > First, processes kan install handlers, which might 
> > instruct the kernel to ignore the signal. SIGABORT can be ignored. I don't 
> 
> abort() should terminate the process even if SIGABRT is ignored.

That rule doesn't apply to pid 1 by default. Pid 1 should be a proper init 
system, not a full blows application that makes the system blow up on 
every error.
 
> > expect my process to be SIGILL'ed next because of this (which, can also be 
> > ignored).
> > Libc should NOT mess with these kind of things, that's up to the 
> > application.
> 
> the glibc fallbacks are
> 
> change signal mask and set default handling for SIGABRT
> raise(SIGABRT);
> "abort instruction" (segfault, sigtrap or sigill depending on target)
> _exit(127);
> infinite loop

Pid 1 is an exception to all of this. 

> http://sourceware.org/git/?p=glibc.git;a=blob;f=stdlib/abort.c;h=155d70b0647e848f1d40fc0e3b15a2914d7145c0;hb=HEAD
> 
> on x86 glibc, pid 1 would terminate with SIGSEGV
> (unless there is a segfault handler).
> 
> the musl logic is explained in
> 
> http://git.musl-libc.org/cgit/musl/commit/?id=2557d0ba47286ed3e868f8ddc9dbed0942fe99dc
> 
> neither of them is correct because it is not possible to
> exit with the right status in general.
> 
> SIGKILL can only be ignored by pid 1 whose exit status is
> not supposed to be observable so musl may want to have a
> fallback after it since the pid namespace thing is nowadays
> widely abused on linux.

Well, normally abort() does some signal magic, and then raises again. 
Which is what POSIX mandates I think.

If you're pid 1 however, you should behave like one.



Igmar