[issue43431] Subprocess timeout causes output to be returned as bytes in text mode

[Eryk Sun]

Change by Eryk Sun :


--
versions:  -Python 3.7

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue43431] Subprocess timeout causes output to be returned as bytes in text mode

[Jordan Macdonald]

Jordan Macdonald  added the comment:

Eryk Sun: Well, I think step 1 should be to update the documentation for Python 
3.7 through 3.10 on `subprocess.run()` and `subprocess.TimeoutExpired` to 
clearly state that `TimeoutExpired.stdout` and `TimeoutExpired.stderr` will be 
in bytes format even if text mode is set.

If we went with the model of having `stdout_bytes` and attempting to decode 
into `stdout`, we'd want an option to ignore a trailing decoding error.

--
versions: +Python 3.7

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue43431] Subprocess timeout causes output to be returned as bytes in text mode

[Eryk Sun]

Eryk Sun  added the comment:

communicate() is incomplete, so decoding the output may fail. For example, say 
the encoding is UTF-8, and the last multibyte character sequence (2-4 bytes) is 
incomplete. Maybe communicate() should always set `stdout_bytes` and 
`stderr_bytes` attributes on the timeout exception, and, in text mode, try to 
decode the output as `stdout` and/or `stderr`. If decoding fails, set the 
decoded value to None.

In Windows, run() tries to complete communication, which is dysfunctional in 
cases. I created bpo-43346 to propose changing the design in Windows, in order 
to address 3 cases that can cause subprocess.run() to ignore the given timeout. 
The proposed change also sets an incomplete read of stdout and stderr as bytes 
objects, regardless of text mode, because I was simply matching what POSIX does 
in this case.

--
nosy: +eryksun, giampaolo.rodola
versions: +Python 3.10, Python 3.8, Python 3.9 -Python 3.7

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com

[issue43431] Subprocess timeout causes output to be returned as bytes in text mode

[Jordan Macdonald]

New submission from Jordan Macdonald :

Passing the argument `text=True` to `subprocess.run()` is supposed to mean that 
any captured output of the called process is automatically decoded and retuned 
to the user as test instead of bytes.

However, if you give a timeout and that timeout expires, the raised 
`subprocess.TimeoutExpired` exception will have the captured output as as bytes 
even if text mode is enabled.

Test output:
bash-5.0$ python3 test_subprocess.py
Version and interpreter information: namespace(_multiarch='x86_64-linux-gnu', 
cache_tag='cpython-37', hexversion=50792432, name='cpython', 
version=sys.version_info(major=3, minor=7, micro=7, releaselevel='final', 
serial=0))
Completed STDOUT Type: 
Completed STDOUT Content: 'Start\nDone\n'
Timeout STDOUT Type: 
Timeout STDOUT Content: b'Start\n'

--
components: Library (Lib)
files: test_subprocess.py
messages: 388257
nosy: macdjord
priority: normal
severity: normal
status: open
title: Subprocess timeout causes output to be returned as bytes in text mode
type: behavior
versions: Python 3.7
Added file: https://bugs.python.org/file49856/test_subprocess.py

___
Python tracker 

___
___
Python-bugs-list mailing list
Unsubscribe: 
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com