file.seek misbehaving?

[David Broadwell]

Run a virus scan?

Note:files on unix and NT are stored in differnt native formats.

What is the differential i their seeks?
ther is a 2 character difference in the line lengths of the sustems as
on unix, a new line is a CR/lf (carriage return/line feed) and on nt and
windows platforms is just a CR.

cheesecake wrote:
> 
> I've run into a problem that is perhaps not a Python-specific
> bug. I was processing some log files using Python, when I
> noticed some mysterious bugs in certain files. I tracked down
> the problem to the seek method misbehaving.
> 
> Some of the files I worked with were files created in NT or
> saved in NT using a text editor. The problem files were copied
> over ftp from a unix machine to the NT machine on which I work.
> None of the files that were saved in NT (ie, NT native files)
> had any problems.
> 
> It seems that seek doesn't work correctly because it's not clear
> how large the file really is. I copied all the contents of one
> bad file into a new file, and the new file was over 5KB bigger
> according to NT. The new file works just fine with the seek
> operations. But when I read() both files into memory, they're
> identical strings and have the content-length of the original
> file.
> 
> Could the problem be that the differences between the NT file
> system and the unix file system of the other computer are not
> properly handled because I'm running on NT, so the Python
> interpreter figures it should assume everything is NT?
> 
> Let me summarize the problem with some code:
> fd1 = open("somefile.txt", "r")  # somefile.txt is a unix file
> fd2 = open("someother.txt", "r") # someother.txt is NT
> lines1 = []
> lines2 = []
> lines1[0] = fd1.readline()
> lines2[0] = fd2.readline() # lines1[0] == lines2[0]
> pos1 = fd1.tell()
> pos2 = fd2.tell() # at this point pos1 == pos2, like it should be
> lines1[1] = fd1.readline()
> lines2[1] = fd2.readline() # lines1[1] == lines2[1]
> fd1.seek(pos1)
> fd2.seek(pos2) # pos1 == pos2 (still)
> lines1[2] = fd1.readline()
> lines2[2] = fd2.readline() # lines1[2] != lines2[2] !!!!?
> 
> What gives here? That's like having file.seek(file.tell())
> moving you somewhere else.
> 
> Anyway, I'd like to find out if anyone else has had such
> problems or knows what the solution is. I don't read this ng, so
> please send replies to my email address at townsend at beehive.de.
> 
> TD
> 
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