Thanks to google code watch I see that an open source real-time Linux project has reached new heights of originality – changing the magic number that they copied from RTLinux 10 years ago to a new number. The constant definition
#define RT_TASK_MAGIC 0x754d2774
which was in very early versions of RTLinux and appeared every previous version of the claimed “completely original” RTAI releases has been replaced by
#define RT_TASK_MAGIC 0x9ad25f6f
And people say there is no originality in open source software! For the non-programmers, a “magic number” is a elementary way of identifying a data structure to help in debugging – chosen to be unusual but not bound by any functional requirement at all. It’s just an arbitrary marker. The appearance of 2 identical magic numbers, with identical symbolic names, used in the identical way, in similar data structures, in code that essentially does the same thing can only be due to copying. Of course, this is a well known example, we’ve been pointing it out to people for years.