On 01/03/2013 10:11 PM, Glenn Morris wrote:

Chong Yidong wrote:

Can someone summarize again a *correct* recipe to see the bug?

mkdir foo
cd foo
mkdir RCS
echo initial > file
ci -u -t-foo file
emacs-24.2 -Q file

M-x toggle-read-only

Enter some text in the buffer, eg now it looks like:

-----
initial
foobar
-----

Press C-x v v, and "foobar" is deleted with no prompting and no way to
get it back.

I changed vc-mistrust-permissions to t for 24.3 because of this.
But now that I check, it doesn't seem to help...

The problem described above may indeed be a problem, but it's not the problem I reported.

The problem I reported is:

mkdir foo
cd foo
mkdir RCS
echo initial > file
ci -u -t-foo file
chmod +w file
echo second >> file
chmod -w file
emacs -Q file
C-x v v - the changes are overwritten without prompting

I think the step missing from Chong Yidong's recipe was making sure the file is read-only before trying to edit it in emacs.

If vc-mistrust-permissions is true by default then this issue doesn't occur.

jik