lkaplan@bbn.com (Larry Kaplan) (09/07/89)
I'm looking for information regarding the 4.x routine called spgrp. It is only called from exit with a comment to the effect of protecting the exiting process from future tty signals. It claims to clear TSTP/TTIN/TTOU if pending in the exiting process and all its descendents. This routine has been causing us some problems and so we are trying what its true purpose is. I have noted that elsewhere in the signal code that delivering a terminal stop signal to a process whose parent is init causes that process to be killed. So the only explanation I can come up with for spgrp() is that it catches the case where a process is about to be inherited by init and gets a terminal stop. Before it processes it, its parent exits causing the process to be inherited. spgrp() then clears the signal to prevent it from being killed. Note that this doesn't work if the process was asleep when the signal arrived since it will end up stopped right away and the signal will no longer be in the process's signal list. This doesn't appear too useful so I am probably missing something. Any clues?? By the way, our source are derived from CMU MACH release 1.0 which is derived 4.3 BSD, I believe. Please respond directly to me as I do not normally read this group. _______________________________________________________________________________ ____ \ / ____ Laurence S. Kaplan | \ 0 / | BBN Advanced Computers lkaplan@bbn.com \____|||____/ 10 Fawcett St. (617) 873-2431 /__/ | \__\ Cambridge, MA 02238