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test_time test_strptime fails on windows #54862
Description
| BPO | 10653 |
|---|---|
| Nosy | @abalkin, @pitrou, @vstinner, @jkloth, @briancurtin, @eryksun |
| 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 = 'https://github.com/vstinner'
closed_at = <Date 2011-10-16.20:07:05.917>
created_at = <Date 2010-12-08.15:01:27.776>
labels = ['OS-windows']
title = 'test_time test_strptime fails on windows'
updated_at = <Date 2021-03-08.19:52:06.863>
user = 'https://bugs.python.org/ocean-city'bugs.python.org fields:
activity = <Date 2021-03-08.19:52:06.863>
actor = 'eryksun'
assignee = 'vstinner'
closed = True
closed_date = <Date 2011-10-16.20:07:05.917>
closer = 'vstinner'
components = ['Windows']
creation = <Date 2010-12-08.15:01:27.776>
creator = 'ocean-city'
dependencies = []
files = ['19978', '19986']
hgrepos = []
issue_num = 10653
keywords = ['patch']
message_count = 22.0
messages = ['123612', '123618', '123623', '123624', '123625', '123626', '123628', '123631', '123639', '123676', '144419', '145490', '145492', '145596', '145628', '145629', '145647', '243660', '388237', '388238', '388279', '388292']
nosy_count = 8.0
nosy_names = ['belopolsky', 'pitrou', 'vstinner', 'ocean-city', 'jkloth', 'brian.curtin', 'python-dev', 'eryksun']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue10653'
versions = ['Python 3.2', 'Python 3.3', 'Python 3.4', 'Python 3.5']
Activity
ocean-city commentedon Dec 8, 2010
Following tests fails on official Python3.2 Windows binary.
I cannot reproduce this on VC6.
/////////////////////////////////////////////////////
C:\Python32>.\python -m test.regrtest -v test_time test_strptime
[1/2] test_time
test_asctime (test.test_time.TimeTestCase) ... ok
test_asctime_bounding_check (test.test_time.TimeTestCase) ... ok
test_clock (test.test_time.TimeTestCase) ... ok
test_conversions (test.test_time.TimeTestCase) ... ok
test_ctime_without_arg (test.test_time.TimeTestCase) ... ok
test_data_attributes (test.test_time.TimeTestCase) ... ok
test_default_values_for_zero (test.test_time.TimeTestCase) ... ok
test_gmtime_without_arg (test.test_time.TimeTestCase) ... ok
test_insane_timestamps (test.test_time.TimeTestCase) ... ok
test_localtime_without_arg (test.test_time.TimeTestCase) ... ok
test_sleep (test.test_time.TimeTestCase) ... ok
test_strftime (test.test_time.TimeTestCase) ... ok
test_strftime_bounding_check (test.test_time.TimeTestCase) ... ok
test_strptime (test.test_time.TimeTestCase) ... FAIL
test_strptime_bytes (test.test_time.TimeTestCase) ... ok
test_tzset (test.test_time.TimeTestCase) ... ok
test_bug_3061 (test.test_time.TestLocale) ... ok
======================================================================
FAIL: test_strptime (test.test_time.TimeTestCase)
----------------------------------------------------------------------
======================================================================
ERROR: test_timezone (test.test_strptime.StrptimeTests)
----------------------------------------------------------------------
======================================================================
ERROR: test_day_of_week_calculation (test.test_strptime.CalculationTests)
----------------------------------------------------------------------
======================================================================
ERROR: test_gregorian_calculation (test.test_strptime.CalculationTests)
----------------------------------------------------------------------
======================================================================
ERROR: test_julian_calculation (test.test_strptime.CalculationTests)
----------------------------------------------------------------------
======================================================================
FAIL: test_timezone (test.test_strptime.LocaleTime_Tests)
----------------------------------------------------------------------
briancurtin commentedon Dec 8, 2010
I don't see this on a US/English version of Windows 7 with 3.2b1 installed. cp932 is the default on a Japanese version, correct?
(I'm not very good with all of this encoding stuff so I don't know how much help I can be)
ocean-city commentedon Dec 8, 2010
I think this is locale problem. With "C" locale on windows,
wcsftime doesn't return UTF16. (when non ascii characters
are contained)
It is just like ....
char cbuf[] = "...."; /* contains non ascii chars in MBCS */
wchar_t wbuf[sizeof(cbuf)];
for (size_t i = 0; i < sizeof(cbuf); ++i)
wbuf[i] = cbuf[i];
/* just copy it. non ascii chars in MBCS uses two bytes,
but should use 1 char space in UTF16. But this case,
it uses 2 chars space! (something strange encoding) */
In japanese, wcsftime returns non ascii characters for
timezone in this strange encoding. Python converts this
with
so Unicode object will contain data in this strange encoding.
This is cause of problem.
I investigated a little about locale, and I learned C
standard does not guarantee wchar_t is always UTF16.
ocean-city commentedon Dec 8, 2010
I'll attach workaround. I used to confirm this works on
VS8, but I don't have VS8 now. I hope this still works.
abalkin commentedon Dec 8, 2010
Please help me with Japanese, but I think the above means Tokyo timezone. However, strftime should have produced decoded unicode strings, not raw cp932 in a str. What does time.strftime('%Z') return on your system?
ocean-city commentedon Dec 8, 2010
Here you are.
abalkin commentedon Dec 8, 2010
On Wed, Dec 8, 2010 at 1:12 PM, Hirokazu Yamamoto <report@bugs.python.org> wrote: .. >>>> import time >>>> time.strftime('%Z') > '\x93\x8c\x8b\x9e (\x95W\x8f\x80\x8e\x9e)'Thanks. Please bear with me for one more question: what is
?
ocean-city commentedon Dec 8, 2010
I got readable result. ;-)
>>> import time >>> time.tzname ('東京 (標準時)', '東京 (標準時)')abalkin commentedon Dec 8, 2010
On Wed, Dec 8, 2010 at 1:50 PM, Hirokazu Yamamoto
<report@bugs.python.org> wrote:
..
You mean readable to *you*. :-)
This makes sense now. There are two issues here:
Decoding the output of wcsftime(). Python expects mbcs (which I
believe is an UTF16-like wide char encoding) while Windows apparently
puts cp932 there in your locale. I don't have expertise to address
this issue.
strptime() cannot parse strftime() output when strftime('%Z') is
different from time.tzname[dst]. This issue we can address. Note
that for most of the locale information such as day of the week or
month names, strptime() relies on strftime() output, so the
round-tripping should work even when strftime() results are
nonsensical. On the other hand, tz spellings are taken from
time.tzname. I think we can make strptime() more robust by adding
[time.strftime('%Z', (2000,1,1,0,0,0,0,0,dst) for dst in (0,1)] to the
list of recognized tz names if they differ from time.tzname.
ocean-city commentedon Dec 9, 2010
No, mbcs is not wide character sets (wchar_t*) but ANSI character sets
(char*). In my environment, mbcs == cp932. And python expects UTF-16.
I attached test program to test behavior of strftime and wcsftime
on locale. On VC6, strftime doesn't depend on locale, wheres
wcsftime changed the value depends on locale. (I tested only "C"
locale and "System" locale because I could not find other
locales working on my environment, so )
If strftime doesn't depend on locale and equals to tzname
for every locale, maybe strftime is preferred on windows.
# Can somebody test this on VS9? And other locales?
vstinner commentedon Sep 22, 2011
See also issue bpo-13029.
python-dev commentedon Oct 14, 2011
New changeset e3d9c5e690fc by Victor Stinner in branch '3.2':
Issue bpo-10653: On Windows, use strftime() instead of wcsftime() because
http://hg.python.org/cpython/rev/e3d9c5e690fc
New changeset 79e60977fc04 by Victor Stinner in branch 'default':
(Merge 3.2) Issue bpo-10653: On Windows, use strftime() instead of wcsftime()
http://hg.python.org/cpython/rev/79e60977fc04
vstinner commentedon Oct 14, 2011
It's a bug in the Windows API: I used the workaround suggested by Hirokazu Yamamoto. Thanks Hirokazu!
Python 2.7 doesn't use wcsftime() and so it is not affected by this issue.
pitrou commentedon Oct 15, 2011
Crashes on the Windows buildbots:
f:\dd\vctools\crt_bld\self_x86\crt\src\strftime.c(832) : Assertion failed: ( "Invalid format directive" , 0 )
f:\dd\vctools\crt_bld\self_x86\crt\src\strftime.c(484) : Assertion failed: FALSE
python-dev commentedon Oct 16, 2011
New changeset e3c13a1d2595 by Victor Stinner in branch 'default':
Issue bpo-10653: Fix time.strftime() on Windows, check for invalid format strings
http://hg.python.org/cpython/rev/e3c13a1d2595
vstinner commentedon Oct 16, 2011
Oops, it should be fixed by my last commits.
python-dev commentedon Oct 16, 2011
New changeset 977c5753ca32 by Victor Stinner in branch '3.2':
Issue bpo-10653: Fix time.strftime() on Windows, check for invalid format strings
http://hg.python.org/cpython/rev/977c5753ca32
eryksun commentedon May 20, 2015
This solution no longer works. If the system is configured to use the Japanese system locale and language pack, then 3.4.3 returns codepage 932 mojibake for the "%Z" time zone name. Originally this approach worked because it called PyUnicode_Decode using the 'mbcs' encoding.
Currently it calls PyUnicode_DecodeLocaleAndSize, which just ends up calling mbstowcs. That's pretty much what wcsftime does. In the default C locale, mbstowcs casts the byte values to wchar_t:
>>> time.strftime('%Z') '\x91\xbe\x95\xbd\x97m\x89\xc4\x8e\x9e\x8a\xd4' >>> time.strftime('%Z').encode('latin-1').decode('932') '太平洋夏時間'The problem is worse for 3.5 built with VC++ 14. In the new CRT strftime decodes the format string via MultiByteToWideChar, calls _Wcsftime_l, and encodes the result back via WideCharToMultiByte. The outer conversions use the default LC_TIME codepage, which is ANSI (ACP), so they're not the problem. The problem is the internal _mbstowcs_s_l conversion of the ANSI time zone name, which creates the above-shown mojibake 'unicode' string. This is then compounded by calling WideCharToMultiByte on the result:
>>> time.strftime('%Z') '?????m?A???O'There's no way to fix this by transcoding. The result is just garbage.
eryksun commentedon Mar 7, 2021
Update since msg243660:
Python 3.8+ now calls setlocale(LC_CTYPE, "") at startup in Windows, as it has always done in POSIX, so decoding the output of strftime("%Z") with PyUnicode_DecodeLocaleAndSize() works again since both agree on using the process active code page.
In 3.7+, per bpo-36779, time.tzname is set when the module is first loaded by directly querying GetTimeZoneInformation(). time.tzset() is still not supported, despite the fact that it was always supported by ucrt, so this value can become stale relative to strftime("%Z").
Starting with Windows 10 v2004 (build 19041), ucrt uses an internal wide-character version of the time-zone name that gets returned by an internal __wide_tzname() call and used for "%Z" in wcsftime(). The wide-character value gets updated by _tzset() and kept in sync with _tzname.
eryksun commentedon Mar 7, 2021
At least it works as much as it ever did. It depends on the process active code page being compatible with the preferred UI language of the current process or thread. For example if the UI language is Japanese ('ja-JP') for the current user, but the process active code page is Latin 1252 (based on the system locale), then the result will be garbage. In that case, given the time-zone name is in Japanese, both LC_TIME and LC_CTYPE have to be changed to "ja-JP" in order to correctly encode (as tzname in ucrt), decode-encode (for strftime in ucrt) and finally decode again via PyUnicode_DecodeLocaleAndSize(). If Python switched back to using wcsftime() in Windows 10 2004+, then the current locale encoding would no longer be a problem for any UI language.
vstinner commentedon Mar 8, 2021
Eryk Sun: This issue is now closed. If you want to enhance the time module, please open a new issue.
eryksun commentedon Mar 8, 2021
I was aware of that at the time, Victor. The problem can be worked on in a new issue, or in the older issue bpo-8304, which remains open. The two messages that I added are purely informative, to update my original comment in msg243660.