And that virtio-beep existed.
I wonder what would happen if I pushed to get the support into KVM and the kernel. Best case scenario, the videos accompanying the too-bemused-to-really-be-angry bug reports would be legendary.
> there's only one file opening, and while there is a potential race condition there, it's with /dev/console. If someone can exploit this race by replacing /dev/console, you've got bigger problems. :)
However, by reading the source one can see that you can now tell beep where it should direct its output (-e, which is not documented anywhere), so the note above is no longer accurate.
I would guess that this is the crux of the problem – the patch that fixes the security issue basically changes "open the output device once for each beep" to "open the output device on startup", greatly reducing the number of races. (It also zeroes out the buffer that's being written to certain output devices, but I have no idea if that is also to patch this security hole or to proactively prevent uninitialized bytes from leaking.)
#include <curses.h>
main() { beep(); }
sudo echo -e "\07" echo -e "\07"I think some terminal emulators (eg Konsole) will just read char 7 and play a system defined WAV or other workaround but your more classic terminals (eg xterm) would potentially have difficulties calling the system bell.
[1] for reference: Xorg terminals are also classed as remote terminals (eg check the TTY column in `w` to see how Linux assigns pseudo-tty's to terminal emulators inside X).
To be honest that was my assumption as well but I didn't test that theory so was only reporting on the rationale of the GPs post
> X11 also has beep functionality built in, which is what I'd expect xterm to use
X11 runs as root though (that said Xorg may not anymore now as there were talks about patching Linux so it didn't have to be) so Xorg could easily still use the standard ioctl bell (that's possibly all Xorg is doing behind the scenes in fact?)
But as I said earlier, some GUI terminal emulators avoid ioctl entirely and play a WAV tone instead.
The portable way to print ASCII BEL is:
printf '\a'