On 8/24/21 8:40 AM, Lars Ingebrigtsen wrote:

> I'm surprised that the `M' command even tries to do the chmod on the
> symlink.

Unfortunately the M command doesn't know in advance whether chmod will 
work on the symlink, as that is platform and filesystem dependent (this 
is in addition to the usual race-condition problem). So as a practical 
matter the M command must try the chmod and report the failure somehow. 
(Perhaps the reporting could be improved; I expect that's low priority.)

A few things:

* I neglected to document this behavior change, so I just now installed 
the attached to fix that oversight.

* Because of this behavior change, the example Eli gives at the start of 
Bug#11912 is now obsolete, as the bug has been fixed in a different way. 
However, as Eli mentioned, there are other commands (like 'O') where the 
bug is still present.

* And this suggests that some longstanding security and other bugs 
remain in this area. I plan to file more bug reports that will cite 
Bug#11912. If the other bugs are fixed, then Bug#11912 should be 
completely obsolete and can be closed.