PATCH: loop killing

[Sven Wischnowsky <wischnow@informatik.hu-berlin.de>]

This is the solution which executes commands in a loop in the same
process group as the parent shell. I.e. ^C'ing loops such as

  while true; do zcat ...; done

works now, even with ill-behaved progrms such as zcat. But of course I 
could think of a case where we still have problems with such programs:

  zcat ... | while true; do zcat ...; done

Here we need two ^C's to interrupt the whole thing. The first one
interrupts both zcats currently running, but since none of them tells
us that it was interrupted the loop happily continues running. But
every zcat started in it after the first ^C finds out that the group
leader is finished and puts itself in the process group of the shell
and thus the shell sees the second ^C.
Again, two possible ways to solve this are: 1) do all job control by
hand -- merely thinking about this causes me pain, 2) these dummy
processes I was talking about. I half-heartedly had a look at 2) and
couldn't get it to work immediatly and then stopped trying. Especially 
since Bart and I don't like this anyway and, after all, this is a
different case because we *can* stop such a loop -- we only need two
^C's. And what the heck... at least we are much better than bash.

This also fixes another problem with loops, namely:

  foo | while true; do bar; done

...where bar was finishing very quickly. In that case the code didn't
find out that it had to suspend because it never looked at the state
of the super-job (foo).


Bye
 Sven

diff -u oos/exec.c Src/exec.c
--- oos/exec.c	Thu Jun 24 08:55:15 1999
+++ Src/exec.c	Thu Jun 24 10:47:16 1999
@@ -933,7 +933,10 @@
 		    lastval2 & 0200)
 		    killpg(mypgrp, lastval2 & ~0200);
 		if ((list_pipe || last1 || pline_level) &&
-		    !list_pipe_child && jn->stat & STAT_STOPPED) {
+		    !list_pipe_child && 
+		    ((jn->stat & STAT_STOPPED) ||
+		     (list_pipe_job && pline_level &&
+		      (jobtab[list_pipe_job].stat & STAT_STOPPED)))) {
 		    pid_t pid;
 		    int synch[2];
 
@@ -959,10 +962,14 @@
 			close(synch[1]);
 			read(synch[0], &dummy, 1);
 			close(synch[0]);
-			jobtab[list_pipe_job].other = newjob;
-			jobtab[list_pipe_job].stat |= STAT_SUPERJOB;
-			jn->stat |= STAT_SUBJOB | STAT_NOPRINT;
-			jn->other = pid;
+			/* If this job has finished, we turn this into a
+			 * normal (non-super-) job. */
+			if (!(jn->stat & STAT_DONE)) {
+			    jobtab[list_pipe_job].other = newjob;
+			    jobtab[list_pipe_job].stat |= STAT_SUPERJOB;
+			    jn->stat |= STAT_SUBJOB | STAT_NOPRINT;
+			    jn->other = pid;
+			}
 			if (list_pipe || last1)
 			    killpg(jobtab[list_pipe_job].gleader, SIGSTOP);
 			break;
@@ -2196,8 +2203,9 @@
 		    attachtty(jobtab[thisjob].gleader);
 	    }
 	}
-	else if (!jobtab[thisjob].gleader ||
-		 (setpgrp(0L, jobtab[thisjob].gleader) == -1)) {
+	else if (!(list_pipe || list_pipe_child || pline_level > 1) &&
+		 (!jobtab[thisjob].gleader ||
+		  setpgrp(0L, jobtab[thisjob].gleader) == -1)) {
 	    jobtab[thisjob].gleader = getpid();
 	    if (list_pipe_job != thisjob &&
 		!jobtab[list_pipe_job].gleader)
diff -u oos/jobs.c Src/jobs.c
--- oos/jobs.c	Thu Jun 24 08:55:16 1999
+++ Src/jobs.c	Thu Jun 24 10:56:48 1999
@@ -185,8 +185,9 @@
 
 		for (i = 1; i < MAXJOB; i++)
 		    if ((jobtab[i].stat & STAT_SUPERJOB) &&
-			jobtab[i].other == job) {
-			killpg(jobtab[i].gleader, SIGSTOP);
+			jobtab[i].other == job &&
+			jobtab[i].gleader) {
+			killpg(jobtab[i].gleader, SIGTSTP);
 			break;
 		    }
 	    }
diff -u oos/signals.c Src/signals.c
--- oos/signals.c	Thu Jun 24 08:55:18 1999
+++ Src/signals.c	Thu Jun 24 10:57:16 1999
@@ -584,7 +584,7 @@
                 for (pn = jobtab[jn->other].procs; pn; pn = pn->next)
                     kill(pn->pid, sig);
  
-                for (pn = jn->procs; pn->next; pn = pn->next)
+                for (pn = jn->procs; pn; pn = pn->next)
                     err = kill(pn->pid, sig);
  
                 return err;

--
Sven Wischnowsky                         wischnow@informatik.hu-berlin.de