bug#6953: 24.0.50; serious security bug in create backup files

[Glenn Morris]

Stefan Monnier wrote:

>> Do you mean changing Fcopy_file to optionally not copy the source file
>> permission bits to the output file?
>
> Something like that.

Just had a thought that this kind of approach is not going to work for
securing ~/%backup%~ files for people who have AFS home directories.
Which probably is not many in % terms, but is more than zero. In AFS,
the _only_ way to make files private to the owner is to put them in a
private directory.

On the other hand, simply creating a mode 700 directory does not
necessarily make it private, you have to use AFS commands to set ACLs.
But the approach of having backup files in a special directory would
be closer to how AFS normally works.