Re: [bug #46481] install-info can "corrupt" dir file if interrupted.

[Assaf Gordon]

Hello,

Regarding a 'safer' way to replace files during installation:

On 11/20/2015 06:22 PM, Gavin Smith wrote:
> On 20 November 2015 at 22:53, Karl Berry <address@hidden> wrote:
> > 3) all that said, writing to a temp file and renaming is at least
> > viable, although rather a pain and susceptible to many hard-to-pin-down
> > bugs
>
> That's my worry too. How do we know that there's not some other way to
> make it fail by abusing the program? What if you turn the power off to
> your computer as the operating system is renaming the file? And so on.

Eric Blake (CC'd) recently mentioned on the GNU coreutils mailing list the 
'renameat2' syscall
and was looking for possible use-cases of its new atomic file-swap ability:
  http://lists.gnu.org/archive/html/coreutils/2015-11/msg00068.html

This could be such a case: install everything to a temp location,
then atomically swap the temp/real files, then (if the swap succeeded), delete 
the (now old) temp files.

just a thought...
 - assaf