Re: [gentoo-portage-dev] [PATCH] config.environ: delay export of A and AA (bug 720180)

[Zac Medico <zmedico@gentoo.org>]

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On 5/26/20 10:32 AM, Ulrich Mueller wrote:
>>>>>> On Tue, 26 May 2020, Zac Medico wrote:
> 
>> On 5/26/20 12:48 AM, Michał Górny wrote:
>>> On Mon, 2020-05-25 at 21:31 -0700, Zac Medico wrote:
>>>> Since variables like A and AA can contain extremely large values which
>>>> may trigger E2BIG errors during attempts to execute subprocesses, delay
>>>> export until the last moment, and unexport when appropriate.
>>>
>>> Please don't.  This will only hide the problem from developers who will
>>> unknowingly commit broken ebuilds and cause users of alternative package
>>> managers to suffer.
> 
>> We've seen in https://bugs.gentoo.org/719202 that developers can already
>> do that with existing versions of portage, since the failure can be
>> dependent on USE configuration.
> 
> We have seen in bug 719202 that A has exceeded _SC_ARG_MAX which is
> 128 KiB.
> 
> However, your commit message mentions E2BIG which will trigger at a much
> larger value, namely 2 MiB. We are far away from reaching that limit in
> any ebuild.
> 
> These are separate issues (although related), so I think we should make
> it very clear about which one we're talking.
> 
> Ulrich
> 
If we want to differentiate between these things then that's fine with me,
however, I have not seen an error other than errno 7 which I thought
corresponded to E2BIG. Test case:

$ python -c "import os, subprocess; os.environ['A'] = 131072 * ' '; subprocess.check_call(['echo', 'hello world'])"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib64/python3.6/subprocess.py", line 306, in check_call
    retcode = call(*popenargs, **kwargs)
  File "/usr/lib64/python3.6/subprocess.py", line 287, in call
    with Popen(*popenargs, **kwargs) as p:
  File "/usr/lib64/python3.6/subprocess.py", line 729, in __init__
    restore_signals, start_new_session)
  File "/usr/lib64/python3.6/subprocess.py", line 1364, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
OSError: [Errno 7] Argument list too long: 'echo'
-- 
Thanks,
Zac


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