string, always apply the C-style unescaping fist, followed by the specifier
expansion. When doing the reverse, make sure to escape '%' in specifier-style
first (i.e. '%' → '%%'), and then do C-style escaping where necessary.
+
+- It's a good idea to use O_NONBLOCK when opening 'foreign' regular files, i.e
+ file system objects that are supposed to be regular files whose paths where
+ specified by the user and hence might actually refer to other types of file
+ system objects. This is a good idea so that we don't end up blocking on
+ 'strange' file nodes, for example if the user pointed us to a FIFO or device
+ node which may block when opening. Moreover even for actual regular files
+ O_NONBLOCK has a benefit: it bypasses any mandatory lock that might be in
+ effect on the regular file. If in doubt consider turning off O_NONBLOCK again
+ after opening.