Problems wth os.stat().st_mtime on Mac

Michael Glassford glassfordm at hotmail.com
Fri Sep 29 16:28:05 CEST 2006


The Python 2.5 News at 
http://www.python.org/download/releases/2.5/NEWS.txt states that Python 
2.5 was changed to "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)."

Although not mentioned in the Python 2.5 News, apparently there was a 
similar change on Mac that I'm having some problems with. On the Mac, 
just as on Windows, os.stat().st_mtime now returns a float instead of an 
integer. My problem is that the decimal part of the float is 
inconsistent in two ways.

1) The more serious problem (for me), is that on two machines (PowerPC 
Mac Mini running Tiger and Intel Mac Mini running Tiger), the decimal 
part of the returned float always appears to be ".0". On an iBook 
running Panther, however, the decimal part appears to be ".0" for many 
files, but for other files it contains actual significant digits. For 
example:

     import os
     f = open("/tmp/tmp.tmp", "w")
     f.close()
     print os.stat("/tmp/tmp.tmp").st_mtime

     #Both Mac Minis: 1159536137.0
     #iBook: 1159536233.08

a) Why the difference between machines?

Also, on the iBook, I created this listing:

     >>> for x in os.listdir("/tmp"): os.stat(os.path.join("/tmp", 
x)).st_mtime, x
     (1159466888.0, '502')
     (1159469259.0, '505')
     (1159472677.0, 'hsperfdata_build')
     (1159466868.0, 'mcx_compositor')
     (1159466908.0, 'SoftwareUpdateCheck.pkgcatalog')
     (1159532547.2405169, 'test.xxx')
     (1159536233.0794201, 'tmp.tmp')

b) Why do most files on this machine have ".0", while some (generally 
those I created myself using Python 2.5, I think) don't?


2) Even on the same machine, the results are different depending on how 
I access them. For example, after setting up as follows:

     strPath = "/tmp/test.xxx"
     f = open(strPath, "w")
     f.close()

I get the following output:

     >>> os.stat(strPath)
     (33188, 1822331L, 234881030L, 1, 505, 0, 0L, 1159532547, 
1159532547, 1159533628)
     #Note that the results are all integers, including mtime

     >>> os.stat(strPath).st_mtime
     1159532547.2405169
     #The result has 7 decimal places

I understand how the results can be different: the os.stat() function 
returns a posix.stat_result object, which gives back an integer value 
for the mtime if you call __str__ or __repr__, or if you iterate on it; 
and a float if you get the st_mtime attribute. But I would consider it a 
bug that the results are different: a float should be returned in either 
case.


Mike




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