[Python-Dev] Strange umask(?)/st_mode issue

[Steve Dower]

On 29Mar.2019 1944, Steve Dower wrote:
> On 29Mar.2019 1939, Cameron Simpson wrote:
>> Can you get a branch into your pipeline? Then you could just hack the
>> tarfile test with something quick and dirty like:
>>
>>    pid = os.getpid()
>>    system("strace -p %d 2>/path/to/strace.out &" % pid)
>>    time.sleep(2)   # get strace heaps of time to start
>>
>> just before the tarfile open. A ghastly hack but it would get you
>> debugging info. You could even decide to remove the strace.out file if
>> the umask issue doesn't show, if it is erratic (can't see why it would
>> be though).
> 
> Perfect, I'll give this a go. Thanks!

I set up a PR to collect this trace and the results are at:
https://github.com/python/cpython/pull/12625

However, I suspect it's a non-result:

umask(022)                              = 022
open("/home/vsts/work/1/s/build/test_python_5154/@test_5154_tmp-tardir/tmp.tar",
O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666) = 3
write(3, "BZh91AY&SYY{\270\344\0\0\24P\0\300\0\4\0\0\10
\0000\314\5)\246"..., 46) = 46
close(3)                                = 0
stat("/home/vsts/work/1/s/build/test_python_5154/@test_5154_tmp-tardir/tmp.tar",
{st_mode=S_IFREG|0666, st_size=46, ...}) = 0

Happy to take more suggestions if anyone has them.

Thanks,
Steve