problem with composer on magento 2

Go to Setings > General > Restrictions and enable it.

Do nothing and re-enable it, the app should be back. On iOS 10 and later, you might also need to go to the App Store and reinstall system apps so be sure to try that as well.

Last - look for any profiles in settings in case someone managing your device has prevented use of that app systematically. You can generally remove the profile or ask them to reassign your device if you should have access to the health app and store health data on your device.

Then sounds like permissions on /tmp are messed up..

chmod 1777 /tmp

Then try to restart mysql

You will have to add a server side controller to your component and use the UserInfo Class to obtain this information.