On 01/12/2011 03:47 AM, Corinna Vinschen wrote: > > On second thought, let's take a step back. > > Actually, directories can change all the time. Why on earth is tar > checking the st_size member of a directory at all? That's a bug IMO. > No application should do that. I understand that a change in the inode > number points to the fact that the directory has been replaced > underfoot, but why should tar be concerned that a directory has changed > its size while it's reading files from it? I mean, even during a tar > backup, there's no reason to expect that files are *not* added or > deleted to a directory by other applications, and these actions may > naturally change the size of the directory.
When tar is trying to capture the entire contents of the directory, any modification to that directory (including adding a file to the directory which changes the st_size of the directory) means that tar missed something, so tar emits a warning to tell you about that fact. > > Having said that, I don't think it's correct to change Cygwin here. > It's just a bug in tar. I'm not sure we've established that point yet, but I'll raise the question upstream. But, assuming tar is doing the right thing... > The fact that the directory size changes even > if the content hasn't changed is just a side effect of the OS MO. It > doesn't matter if the directory has actually changed or not. It's not > in the hand of a single application. then cygwin's behavior DOES matter to tar - no other system changes the st_size of a directory without ALSO adding or deleting files within that directory and also updating the st_mtim of the directory; at which point tar is entirely within its rights to complain (the directory changed while trying to read it, so the tar file may be incomplete). Locking st_size at 0 avoids the issue entirely, whether or not upstream tar agrees that checking changes in st_mtim but ignoring changes in st_size would be a more appropriate behavior. -- Eric Blake ebl...@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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