Dear All,

Notes from today's class are in the course directory, as follows:

   Signals:      signals.txt, signals/sig.c

   Kmem/DTrace:  kmem/  (scripts and their output with comments, compressed)

------

Also, I think I misspoke about the handler's function-pointer type in the
signal(2) example. More carefully, looking at the signal(2) manpage
(or Linux's http://man7.org/linux/man-pages/man2/signal.2.html for reference):

   "signal()  returns the previous value of the signal handler, or SIG_ERR on error."

The type of the handler is  void (*handler)(int) ---a function that takes a single
int argument and doesn't have a return value. So the type of signal() is "a function
that returns a function pointer to a function that takes an int and returns void, 
and takes an int and a void (*handler)(int) as arguments". So it is written as:

   void ( *signal(int signum, void (*handler)(int)) ) (int);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~    ^^^^^

where the ^^^-underlined specifies the arguments of the _returned_ function pointer type,
and ~~~-underlined specifies the argument types of the signal function itself.

As usual, stackoverflow has all kind of fun examples:
http://stackoverflow.com/questions/840501/how-do-function-pointers-in-c-work
including the answer called "The guide to getting fired". One answer explains
how to read the function pointer expressions "top down" and "bottom up".
I thought that one useful.

Another useful example is http://c.learncodethehardway.org/book/ex18.html

Thanks,

--Sergey