Trapping system calls

[Scott Bronson]

Is there any way to break into GDB when a particular system call
is made?  I want to trap every ioctl of a certain type.  Short
of scattering thousands of breakpoints throughout the code, I could
find no way of doing this.

In other words, I'm looking for the equivalent of "atb WaitNextEvent"
(if there are any other ex-Mac hackers out there :).

Am I missing the truly obvious?  Thanks,

	- Scott