File size error in os.stat with large files.

[Tim Peters]

[Joe Woodward]
> Does anyone know the file size limit that os.stat will handle
> correctly?

It depends on OS, Python version, and whether Python was compiled with
"large file" support.

> I have a 4.2GB file that os.stat is reporting to be 164MB. Smaller
> files seem to work just fine, but I have not played with it to find
> out where the cut-off point is.
>
> I am using Python 2.1 on Windows 2000.

Microsoft's implementations of the standard C functions for doing this stuff
are limited to 32-bit results, and there's no indication of overflow when
they're applied to files that are "too large" for that; information is just
lost.  Python 2.1 uses these MS C functions in 2.1.

Substantial work was done for Python 2.2 to use better large-file functions
on Windows.

C:\Python21>dir \junk\big.file2
07/09/2002  03:57p       5,847,842,817 big.file2

C:\Python21>python
Python 2.1.3 (#35, Apr  8 2002, 17:47:50) [MSC 32 bit (Intel)] on win32
Type "copyright", "credits" or "license" for more information.
>>> import os
>>> os.path.getsize('/junk/big.file2') # Nonsense result
1552875521
>>>

C:\Python22>python
Python 2.2.1 (#34, Apr  9 2002, 19:34:33) [MSC 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> os.path.getsize('/junk/big.file2') # Correct result, as unbounded long
5847842817L
>>>

(Note that getsize() calls a stat()-like routine under the covers; the same
kinds of concerns apply to other calls, like stat() and tell()).  If you
need to do real work with large files on Windows, upgrade to 2.2.1.