internal error on write while reading

[dsm001]

BPO	5844
Nosy	@pitrou, @benjaminp
Files	write_while_reading_test.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2009-05-14.22:02:14.074>
created_at = <Date 2009-04-25.22:45:24.018>
labels = ['interpreter-core', 'type-bug']
title = 'internal error on write while reading'
updated_at = <Date 2009-05-14.22:02:14.072>
user = 'https://bugs.python.org/dsm001'

bugs.python.org fields:

activity = <Date 2009-05-14.22:02:14.072>
actor = 'benjamin.peterson'
assignee = 'none'
closed = True
closed_date = <Date 2009-05-14.22:02:14.074>
closer = 'benjamin.peterson'
components = ['Interpreter Core']
creation = <Date 2009-04-25.22:45:24.018>
creator = 'dsm001'
dependencies = []
files = ['13785']
hgrepos = []
issue_num = 5844
keywords = ['patch']
message_count = 3.0
messages = ['86562', '86567', '87773']
nosy_count = 3.0
nosy_names = ['pitrou', 'dsm001', 'benjamin.peterson']
pr_nums = []
priority = 'critical'
resolution = 'fixed'
stage = 'needs patch'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue5844'
versions = ['Python 3.1']

[dsm001]

Inspired by http://bugs.python.org/issue1653416 , I tried writing to a
file opened for reading in 3.1 trunk, and found:

Python 3.1a2+ (py3k:71900M, Apr 25 2009, 16:12:31) 
[GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> fp = open('/etc/passwd')
>>> fp.write('test')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
SystemError: null argument to internal routine
>>> print('test',file=fp)        
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
SystemError: null argument to internal routine

but binary mode gives:

>>> fp = open('/etc/passwd','rb')
>>> fp.write(b'test')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
io.UnsupportedOperation: write
>>> print(b'test',file=fp)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
io.UnsupportedOperation: write

[dsm001]

Added tests to py3k/Lib/test/test_file.py. Patch against py3k trunk @
r71904.

[benjaminp]

Fixed in r72649.