Add some safety checks when sourcing files in /etc/profile.d/, in particular:
- source only *.sh files, not every file. This is the practice in use in both
Fedora and Debian/Ubuntu (see
https://help.ubuntu.com/community/EnvironmentVariables#A.2Fetc.2Fprofile.d.2F.2A.sh);
- check the input is actually a file and is readable. This check is especially
important if profile.d is empty, as "*.sh" will get expanded only if
profile.d is not empty. Previously if profile.d was present but empty,
"/etc/profile.d/*" was sourced causing errors on login and breaking stuff, for
example X startup.
Signed-off-by: Diego Rondini <diego.ml@zoho.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
