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codecs.StreamReader doesn't work with nonblocking streams: TypeError: can't concat bytes to NoneType #68748

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yac mannequin opened this issue Jul 3, 2015 · 4 comments
Closed

codecs.StreamReader doesn't work with nonblocking streams: TypeError: can't concat bytes to NoneType #68748

yac mannequin opened this issue Jul 3, 2015 · 4 comments
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3.7 (EOL) end of life topic-unicode

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@yac
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yac mannequin commented Jul 3, 2015

BPO 24560
Nosy @vstinner, @ezio-melotti
Superseder
  • bpo-13322: The io module doesn't support non-blocking files
    		•

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

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    GitHub fields:

    assignee = None
closed_at = <Date 2019-10-10.08:29:35.445>
created_at = <Date 2015-07-03.15:12:04.370>
labels = ['3.7', 'expert-unicode']
title = "codecs.StreamReader doesn't work with nonblocking streams: TypeError: can't concat bytes to NoneType"
updated_at = <Date 2019-10-10.08:29:35.441>
user = 'https://bugs.python.org/yac'

    bugs.python.org fields:

    activity = <Date 2019-10-10.08:29:35.441>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2019-10-10.08:29:35.445>
closer = 'vstinner'
components = ['Unicode']
creation = <Date 2015-07-03.15:12:04.370>
creator = 'yac'
dependencies = []
files = []
hgrepos = []
issue_num = 24560
keywords = []
message_count = 4.0
messages = ['246186', '246261', '354298', '354340']
nosy_count = 4.0
nosy_names = ['vstinner', 'ezio.melotti', 'yac', 'Fritz Reese']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '13322'
type = None
url = 'https://bugs.python.org/issue24560'
versions = ['Python 3.4', 'Python 3.7']
    @yac
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    yac mannequin commented Jul 3, 2015

    File "/usr/lib64/python3.4/codecs.py", line 490, in read
    data = self.bytebuffer + newdata
    TypeError: can't concat bytes to NoneType

                if size < 0:
                newdata = self.stream.read()
            else:
                newdata = self.stream.read(size)
            # decode bytes (those remaining from the last call included)
            data = self.bytebuffer + newdata

    if self.stream is nonblocking, it's read will return None (py3, py2 raises IOError(EGAIN)).

    Simple if newdata is None: return None should fix that I guess

    @yac yac mannequin added the topic-unicode label Jul 3, 2015
    @vstinner
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    vstinner commented Jul 4, 2015

    Use the io module instead using the open() function.

    @FritzReese
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    FritzReese mannequin commented Oct 9, 2019

    This is still an issue on Linux in both 3.4 and 3.7 even when using io.open() as suggested by @vstinner:

    >>> import io, os, fcntl
>>> r, w = os.pipe()
>>> fcntl(r, fcntl.F_SETFL, os.O_NONBLOCK)
0
>>> stream = io.open(r, 'rt')
>>> stream
<_io.TextIOWrapper name=X mode='rt' encoding='UTF-8'>
>>> stream.buffer
<_io.BufferedReader name=X>
>>> print(repr(stream.buffer.read()))
None
>>> stream.read()
Traceback (most recent call last):
  ...
  File ".../python3.7/codecs.py"..., in decode
    data = self.buffer + input
TypeError: can't concat NoneType to bytes

    The error is present in at least 3.4 up to 3.7 where the underlying buffer.read() returns None which is not handled by the TextIOStream.

    @FritzReese FritzReese mannequin added the 3.7 (EOL) end of life label Oct 9, 2019
    @vstinner
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    I close this issue as a duplicate of bpo-13322.

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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