Possibility to turn off the phone while the screen is locked

[GTriderXC]

I think it is a bug that a locked device, especially a phone, is able to switch off when the power button is longer pressed.

How to:
Lock your phone with the power button or wait till the phone locks by itself after time You set in settings. When the screen goes black, press and hold a power button.

What happens now:
We are able to switch off the phone by mistake/by chance

Expected behaviour(of any other phone device in the world):

Never mind what happens to Your phone in a pocket or a bag, never mind if You sit on it or crush and squeeze: by the stroke of luck You will turn on a silent mode, wifi, hotspot etc. BUT the device itself should NEVER be able to turn off by chance by itself!!!

—---------------------------
Ubuntu UX:

This is a reliability issue. In smartphone devices we have a very unreliable alarm clock. I call it unreliable cause if the battery of my phone will die (or the phone will turn off by chance) while I sleep, I'm gonna die as well the very next day if the alarm clock will not wake me up (my boss will kill me).
 If we want to have a reliable device, we must have as much control over it as possible and not let serious things happen.
I often recall in my bug reports a solutions we used to have in Nokia phones. I do not want to copy Nokia solutions but I expect at least the same reliability. We should go forward, not move back.

It happened to me already three times that my phone became silent so that I couldn't hear the incoming calls and messages. I walk a lot and keep the phone in a pocket of my jeans. I'd say the volume control of the phone should also be disabled as long as user will not answer the phone, the phone will not start to ring or the user will not unlock the screen for example with a code or password.

[Nathan Haines (nhaines)]

This is a requirement for devices that have neither discrete power switches nor removable batteries. Without this feature, if the phone locks up, it cannot be turned off and is completely non-functional until the battery dies, which also damages the battery.

The volume issue is non-orthogonal, but do note that changing the volume outside of phone calls is important. As described, you would have to call a friend and keep them on the online while you adjusted your ringtone volume. You'd also have to pause music and call someone and keep them on the line if you wanted to turn up the music volume a little. Or call someone and keep them on the line if you wanted to turn off alarms or raise their volume.

Better to file a different bug to deal with volume, and keep this one for the power issue.

[Michael Zanetti (mzanetti)]

As Nathan says, the power button is really required. Also it is a hardware feature and afaik cannot be disabled by software.

For the volume buttons, there is bug 1291458 already.

For the alarm not waking up the device when it is off, there is bug 1420169.

Closing this as invalid.

[GTriderXC (gtriderxc)]

Actually You're right. I didn't think about it. That's how I somehow recovered from this loop two days ago:
https://youtu.be/GZLGdf8rZSs
When it happened I woke up that there was no battery which I could remove :-/
I hardly managed to reboot the phone but the system still heard the power button so somehow I finally succeded