[ python-Bugs-1729170 ] os.stat producing incorrect / invalid results

Thu May 31 23:24:13 CEST 2007

Bugs item #1729170, was opened at 2007-05-31 17:24
Message generated for change (Tracker Item Submitted) made by Item Submitter
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Category: Python Library
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Joe (joesalmeri)
Assigned to: Nobody/Anonymous (nobody)
Summary: os.stat producing incorrect / invalid results

Initial Comment:
Python 2.51
Windows XP SP2 + all updates
*** NOTE all code has worked on previous python versions

I just upgraded from Python 2.4.2 to Python 2.5.1 and have found some 
unexpected behavior that appears to be a bug in the os.stat module.

My OS is Windows XP SP2 + all updates.

I have several programs that have worked flawlessly on all previous Python 
versions for years and they are now producing incorrect results in the code 
that uses os.stat.

Searching through the 2.5.1 release notes I found the following:

    Use Win32 API to implement os.stat/fstat. As a result, subsecond 
timestamps
    are reported, the limit on path name lengths is removed, and stat 
reports
    WindowsError now (instead of OSError).

*********************
* Overview of the problem:
*********************

Reviewing my code it seems that it should still work with the 2.5.1 os.stat 
changes however that does not appear to be the case.

Timestamps reported by os.stat() are no longer correct and the results are 
not even consistent.

In my first test case ALL 3 timestamps reported by Python are 1 hour less 
than the actual timestamp on the file.

In my second test case the created and last accessed timestamps reported by 
Python are correct but the last write timestamp is 1 hour less than the 
actual timestamp on the file.

As a third test I looked at the last write timestamps on approximately 
21,000 files.
Python determined wrong last write timestamp on approximately 1581 files.

Assuming there is no error in the following code that prints out the 
timestamps using the new return value from os.stat() then it would appear 
that the 2.5.1 os.stat changes have a bug.

print 'Creation    Time: %s' % time.strftime('%m/%d/%Y %H:%M:%S', 
time.localtime(file_stats[stat.ST_CTIME]))
print 'Last Access Time: %s' % time.strftime('%m/%d/%Y %H:%M:%S', 
time.localtime(file_stats[stat.ST_ATIME]))
print 'Last Write  Time: %s' % time.strftime('%m/%d/%Y %H:%M:%S', 
time.localtime(file_stats[stat.ST_MTIME]))

*********************
* Detailed test results
*********************

To demonstrate the problem I have created the following test.

Here are the files that will be used in my test and their associated 
timestamps as reported the the dir command.

01/02/2003  12:34 PM                       0 broke_test
03/06/2007  05:24 PM         3,497,177 broke_test2
05/31/2007  04:35 PM                   254 runtest.cmd
05/31/2007  04:31 PM                   513 broke.py

The file named broke_test has a timestamp of 01/02/2003 12:34:56 (dir does 
not show seconds).

The runtest.cmd script shows the created, last accessed, and last write 
timestamps as reported by the dir command (and also verified via right 
clicking on the file and selecting properties in Explorer.

------ >>> START runtest.cmd script <<<<
@Echo Off

echo Create TimeStamp reported by dir command
dir /tc %1

echo Last Access TimeStamp reported by dir command
dir /ta %1

echo Last Write TimeStamp reported by dir command
dir /tw %1

echo Python 2.5.1 timestamp info
broke.py %1

------ >>> END runtest.cmd script <<<<

The broke.py script prints out the created, last accessed, last write 
timestamps as Python sees them.

------ >>> START broke.py script <<<<
import sys
import os
import stat
import time

file_name  = sys.argv[1]

file_stats = os.stat(file_name)

print
print 'File Name       : %s' % (file_name)
print
print 'Creation    Time: %s' % time.strftime('%m/%d/%Y %H:%M:%S', 
time.localtime(file_stats[stat.ST_CTIME]))
print 'Last Access Time: %s' % time.strftime('%m/%d/%Y %H:%M:%S', 
time.localtime(file_stats[stat.ST_ATIME]))
print 'Last Write  Time: %s' % time.strftime('%m/%d/%Y %H:%M:%S', 
time.localtime(file_stats[stat.ST_MTIME]))
print

------ >>> END broke.py script <<<<

#
# Test 1 on file broke_test
#

runtest broke_test

Create TimeStamp reported by dir command

01/02/2003  12:34 PM                 0 broke_test

Last Access TimeStamp reported by dir command

01/02/2003  12:34 PM                 0 broke_test

Last Write TimeStamp reported by dir command

01/02/2003  12:34 PM                 0 broke_test

Python 2.5.1 timestamp info

File Name       : broke_test

Creation    Time: 01/02/2003 11:34:56   -- Python results are WRONG hours 
reported are 1 hour short
Last Access Time: 01/02/2003 11:34:56   -- Python results are WRONG hours 
reported are 1 hour short
Last Write  Time: 01/02/2003 11:34:56   -- Python results are WRONG hours 
reported are 1 hour short

#
# Test 2 on file broke_test2
#

runtest broke_test2

Create TimeStamp reported by dir command

05/31/2007  04:26 PM         3,497,177 broke_test2

Last Access TimeStamp reported by dir command

05/31/2007  04:26 PM         3,497,177 broke_test2

Last Write TimeStamp reported by dir command

03/06/2007  05:24 PM         3,497,177 broke_test2

Python 2.5.1 timestamp info

File Name       : broke_test2

Creation    Time: 05/31/2007 16:26:36   -- Python results are correct
Last Access Time: 05/31/2007 16:26:38   -- Python results are correct
Last Write  Time: 03/06/2007 16:24:21   -- Python results are WRONG hours 
reported are 1 hour short

----------------------------------------------------------------------

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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1729170&group_id=5470