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FileIO.seekable() can return False #49266

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pitrou opened this issue Jan 20, 2009 · 9 comments
Closed

FileIO.seekable() can return False #49266

pitrou opened this issue Jan 20, 2009 · 9 comments
Labels
extension-modules C modules in the Modules dir type-bug An unexpected behavior, bug, or error

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@pitrou
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pitrou commented Jan 20, 2009

BPO 5016
Nosy @pitrou, @vstinner
Files
  • fileio_seekable-trunk-2.patch
    		•

    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 2010-09-10.23:22:08.660>
created_at = <Date 2009-01-20.23:38:37.542>
labels = ['extension-modules', 'type-bug']
title = 'FileIO.seekable() can return False'
updated_at = <Date 2010-09-10.23:22:08.659>
user = 'https://github.com/pitrou'

    bugs.python.org fields:

    activity = <Date 2010-09-10.23:22:08.659>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2010-09-10.23:22:08.660>
closer = 'vstinner'
components = ['Extension Modules']
creation = <Date 2009-01-20.23:38:37.542>
creator = 'pitrou'
dependencies = []
files = ['13433']
hgrepos = []
issue_num = 5016
keywords = ['patch']
message_count = 9.0
messages = ['80295', '80301', '80302', '80474', '83545', '84238', '84241', '84246', '116059']
nosy_count = 2.0
nosy_names = ['pitrou', 'vstinner']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue5016'
versions = ['Python 2.7']
    @pitrou
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    pitrou commented Jan 20, 2009

    FileIO.seekable() can return False if we first seek to a position such
    that, when truncated to a signed int, it becomes negative:

    >>> f = open('largefile', 'wb', buffering=0)
>>> f.seek(2**31, 0)
2147483648
>>> f.write(b'x')
1
>>> f.close()
>>> f = open('largefile', 'rb', buffering=0)
>>> f.seek(0, 2)
2147483649
>>> f.seekable()
False

    @pitrou pitrou added extension-modules C modules in the Modules dir type-bug An unexpected behavior, bug, or error labels Jan 20, 2009
    @vstinner
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    Patch with regression test in test_largefile: test 2**31-1, 2**31,
    2**31+1.

    @vstinner
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    See also issue bpo-5008.

    @vstinner
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    Woops, I attached the wrong patch!

    @pitrou
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    pitrou commented Mar 13, 2009

    Committed in r70352 (py3k), r70353 (3.0). Needs backport to trunk and
    2.6, if someone is interested.

    @vstinner
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    Needs backport to trunk and 2.6, if someone is interested.

    I'm interrested by a backport at least in trunk. I updated the patch
    to trunk:

    • test directly _file._FileIO() instead of using open() because in
      Python trunk, a file has no seekable() method :-/
    • use contextlib.closing() because _FileIO doesn't implement context
      API (not __exit__() method)

    @pitrou
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    pitrou commented Mar 27, 2009

    You can use io.open() instead of open()...

    @vstinner
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    You can use io.open() instead of open()...

    Alright, it's much easier with io.open() :-)

    @vstinner
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    It is fixed in 2.7 with the backport of the Python3's io library (r73394).

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