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Re: Problem with atexit and _dl_fini
On 11.06.19 20:39, Adhemerval Zanella wrote:
It seems that this requirement seems to come from LSB, although I am not
sure which one came first (the specification or the implementation).
It also states that __cxa_atexit should register a function to be called
by exit or when a shared library is unloaded.
I don't really have much further to add to this topic, so this is just
some commentary and speculation... and I am probably repeating myself.
https://pubs.opengroup.org/onlinepubs/009695399/functions/atexit.htmlstates:
The /atexit/() function shall register the function pointed to by
/func/, to be called without arguments at normal program termination.
That's "normal program termination" not anytime before. dlclose is
anytime before. What is happening is a violation of `atexit`.
When I read
http://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic.html#BASELIB---CXA-FINALIZE
I see that it's *Intels* version of C++ that originally dictated this
violation of the C standard. Possibly Intel was writing this with
Windows in mind ?
And __cxa_finalize requires to call atexit registers functions as well. It
also states __cxa_finalize should be called on dlclose.
In my opinion the__cxa_finalize requirement is wrong. It's further my
opinion, that a vendors requirement for its C++ ABI, does not "trump"
open standards. :)
I think it might due the fact old gcc version uses atexit to register C++
destructors for local static and global objects. However it seems to be
enabled as default for GLIBC (since it support __cxa_atexit since initial
versions).
So I think there is no impeding reason to make atexit not be called from
__cxa_finalize, although I am not sure how we would handle the LSB deviation.
I will write down a libc-alpha to check what other developer think.
I think the proper solution is to rewrite __cxa__finalize and remove
atexit functionality completely from it.
Alas I am not hopeful, that this will be resolved to my taste :)
[1] http://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic.pdf
Ciao
Nat!