Re: chmod/chown -R - maybe an ITP
On Tue, 14 Dec 1999, Craig Sanders wrote:
>On Mon, Dec 13, 1999 at 11:37:09PM +0000, Jules Bean wrote:
>> On Tue, 14 Dec 1999, Craig Sanders wrote:
>> > you could write a safe-chown program, but even that would be vulnerable
>> > to races, since there is no atomic test-and-chown operation...it would
>> > just reduce the window of opportunity.
>> You're wrong, of course, as was pointed out earlier in the thread.
>yeah, i noticed that...read the rest of the thread after sending my
>messages. should have read first, written later.
>> Once you open a file, you can check it's the right one with fstat(), and
>> chown it with fchown(), and it can't be replaced in between (since you
>> have an fd open to it, and it will stay open to the original file).
>yep. so a safe-chown program is possible.
>probably the best way to implement would be to add an '-a' or '--atomic'
>(alternatively, '-s' or '--safe') option to the chown in GNU fileutils,
>and contribute it back upstream.
I've already downloaded the source to fileutils for that purpose.
The ultimate result is that some innovations that would truly benefit
consumers never occur for the sole reason that they do not coincide with
-- Judge Thomas Penfield Jackson, U.S. District Judge