Re: creating backups in temporary directories

[Richard Stallman]

    But in a directory with mode 1777 when you open a file that *you* own,
    nobody else can remove it or rename it, so normally nobody can replace it
    with a symlink.  Emacs creates the problem when it moves /tmp/foo to
    /tmp/foo~ at which point /tmp/foo is free for an attacker to take.

This suggests that Emacs should always do backup by copying
in such directories.  Would that solve the problem?