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why does CopyFile choke on transparently encrypted files?

• To: mathgroup at smc.vnet.net
• Subject: [mg110265] why does CopyFile choke on transparently encrypted files?
• From: Michael <michael2718 at gmail.com>
• Date: Thu, 10 Jun 2010 08:11:32 -0400 (EDT)

Last night I ran into a puzzling error message when trying to run a
bunch of CopyFile[] calls intended to sync files on different
machines:


CopyFile::ioarg: Argument in CopyFile[...] is not valid for I/O operation. >>

Most of the calls were succeeding, so I was puzzled as to why this one
failed.  The permissions of the file and destination looked fine.
Then I noticed that the filenames were tinted green in Explorer (I'm
running Windows Vista Ultimate) - I had copied the files from an
external drive, and since I don't have BitLocker on the external drive
I had manually set the encrypt bit, but for some reason at some point
in copying them to my local drive it decided to retain the encryption.

After I manually removed the encryption CopyFile worked fine.   As an
experiment I also tried changing the file to "compressed" and CopyFile
still worked fine.

Anyway, I am puzzled as to why Mathematica can't CopyFile a file with
encryption on it.  Shouldn't the OS be transparently doing the
encryption?  I can copy the file just fine from Explorer, or even from
a cygwin prompt, and when I look at the destination the file is NOT
encrypted, just like I would expect.  What's Mathematica doing here
and what can I do to work around this problem?


Thanks,

Michael