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Subject: Re: program exit code, "at exit" handler and explicit close of shared objects
To: cygwin AT cygwin DOT com
References: <a24efbf6-872e-1e5b-017a-b14c59d84550 AT roumenpetrov DOT info> <20754eea-2b5e-dbbb-6027-2643be062e41 AT cornell DOT edu> <1805e95e-6733-7a73-56fe-8493389ae367 AT cornell DOT edu>
From: Roumen Petrov <bugtrack AT roumenpetrov DOT info>
Message-ID: <10986264-df7a-8dcc-4a3a-e8a7cc32b693@roumenpetrov.info>
Date: Tue, 5 Nov 2019 21:32:41 +0200
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Hello,

As non-regular user I did tests when I have access to environment.


Ken Brown wrote:

> On 10/29/2019 10:53 AM, Ken Brown wrote:
>> On 10/26/2019 11:07 AM, Roumen Petrov wrote:
>>> First test is as is:
>>> [SNIP]

>>> I ran this second version of test-dlclose (with DLCLOSE_ATEXIT defined) under
>>> strace and got the following:
>>>
>>> $ strace -o trace.out ./test-dlclose.exe
>>> exit with code 33
>>> Segmentation fault
>>>
>>> The strace output ends with
>>>
>>>       30   30143 [main] test-dlclose 847 write: 18 = write(1, 0x600061E20, 18)
>>> --- Process 33456 (pid: 847) unloaded DLL at 00000003e7930000
>>> --- Process 33456 (pid: 847), exception c0000005 at 00000003e7931080
>>> --- Process 33456 (pid: 847) thread 26088 exited with status 0xc0000005
>>> --- Process 33456 (pid: 847) thread 33544 exited with status 0xc0000005
>>> --- Process 33456 (pid: 847) thread 36020 exited with status 0xc0000005
>>> --- Process 33456 exited with status 0xc0000005
>>>
>>> The address 00000003e7930000 seems to be in /usr/bin/cygz.dll, which is the DLL
> Sorry, I meant to say 00000003e7931080; 00000003e7930000 is the start of cygz.dll.
>
>> that got unloaded.  After installing zlib-debuginfo, I ran addr2line to see
>> where the crash occurred, and this too crashed:
>>
>> $ addr2line -C -f -i -p -e /usr/bin/cygz.dll 0x3e7931080
>> Segmentation fault (core dumped)

The test was with compression library because this is default OpenSSL 
configuration - dynamic loading of compression library.

It seems to me issue could be reproduced with other libraries as well.
For instance I get the same with ssh ("libssh-4.so") or bz2 ("libbz2-1.so").



>> That's as far as I've gotten.
>>
>> Ken

Regards,
Roumen Petrov

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