Modifying The System Calls Dispatch Table (Cont.)

Finally, 'versioned_string' used earlier by our code could be implemented as a macro, such as this:

 /* BEGINNING OF TRICKY PART */
 /* DON'T mess with these - they are required to   */
 /* allow proper expansion of (possibly) versioned */
 /* symbols into strings.                          */

 /* this macro turns its argument into a quoted string */
 /* (adding double quotation marks to its front and    */
 /* back. This is standard C.                          */
 #define do_turn_into_versioned_string(x) #x
 /* the reason for using this second macro, is so the C */
 /* pre-processor would process the parameter (which is */
 /* a kernel symbol name), and turn it into a versioned */
 /* string, without quotes. This works since the kernel */
 /* defines all its symbols as macros translating into  */
 /* versioned symbol names.                             */
 #define versioned_string(x) do_turn_into_versioned_string(x)
 /* END OF TRICKY PART */