Date: Wed, 06 Sep 1995 15:37:20 +0900 From: yuhara@flab.fujitsu.co.jp To: freebsd-bugs@freebsd.org Subject: mv truncates files Message-ID: <199509060637.PAA04767@cindy.avalon.flab.fujitsu.co.jp>
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Bug Report: cross device "mv" corrupts files
FreeBSD version: 2.1.0-SNAP-950726
File: /usr/src/bin/mv/mv.c
Symptom: If a owner of a file is not a member of the group ID of the
source file, cross device "mv" by the owner sometimes TRUNCATES
the file, especially when the destination is in a NFS mounted
directory.
The source file is deleted so there is no way to retrieve the lost
data!!
Detail:
For cross device "mv", "mv" opens the source and the
destination, copies data, closes the source, changes uid/gid/mode
of the destination (fchown(), fchmod()), and then closes the destination.
Problem occurs when fchown() fails.
My guess: When an error occurs during fchown(), the written data that
is in the buffer cache but not yet transferred to a disk
is regarded as erronous and is abandoned in the kernel.
Either the filesystem or "mv" is wrong.
Since I don't know the intended semantics of the
filesystem of FreeBSD, I can't say which is wrong.
If "mv" is the culprit, the fix seems to be simple.
Close the destination just after the copy.
Use chown(), chmod() instead of fchown(), fchmod().
(I'm not on the mailing lists. Please include my address in your reply.)
------
Masanobu Yuhara yuhara@flab.fujitsu.co.jp
Fujitsu Laboratories Ltd.
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