From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Sun, 24 Apr 2011 23:36:17 -0400
To: 9fans@9fans.net
Message-ID: <84c61fe2a739f0786622f2e27e7a1b82@ladd.quanstro.net>
In-Reply-To: <2afb8aa9b8f443793d7bf20463b78c1c@ladd.quanstro.net>
References: <ip0bb0$59m$1@dough.gmane.org> <86wrijennb.fsf@cmarib.ramside>
	<ip1l97$naq$1@dough.gmane.org>
	<20110424171741.D5865B827@mail.bitblocks.com>
	<ip2egi$83e$1@dough.gmane.org> <20110425020029.GA29551@dinah>
	<2afb8aa9b8f443793d7bf20463b78c1c@ladd.quanstro.net>
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Subject: Re: [9fans] Different results for the same rc script when using
	listen1
Topicbox-Message-UUID: d48686e4-ead6-11e9-9d60-3106f5b1d025

; hg diff rfork.c
> hmm.  is that right?  it's wait3/wait4 that's failing.  it shouldn't
> be necesary to catch SIGCHLD for wait to work.  but maybe
> it is

i take it back.  i'd forgotten how quirky unix is these days.
here's the solution.  not rc's fault.  recompile lib9 and listen1:

diff -r 5caa04977471 src/lib9/rfork.c
--- a/src/lib9/rfork.c	Sun Dec 27 09:22:43 2009 -0800
+++ b/src/lib9/rfork.c	Sun Apr 24 23:33:52 2011 -0400
@@ -18,7 +18,9 @@
 	int n;
 	char buf[128], *q;
 	extern char **environ;
+	void *oldchild;

+	oldchild = nil;
 	if((flags&(RFPROC|RFFDG|RFMEM)) == (RFPROC|RFFDG)){
 		/* check other flags before we commit */
 		flags &= ~(RFPROC|RFFDG|RFENVG);
@@ -34,7 +36,7 @@
 			 * NOWAIT once, they're not likely to want child notes
 			 * after that.
 			 */
-			signal(SIGCHLD, nop);
+			oldchild = signal(SIGCHLD, nop);
 			if(pipe(p) < 0)
 				return -1;
 		}
@@ -81,7 +83,10 @@
 				 * Child - fork a new child whose wait message can't
 				 * get back to the parent because we're going to exit!
 				 */
-				signal(SIGCHLD, SIG_IGN);
+				if(oldchild == nil)
+					oldchild = signal(SIGCHLD, SIG_IGN);
+				else
+					signal(SIGCHLD, SIG_IGN);
 				close(p[0]);
 				pid = fork();
 				if(pid){
@@ -95,6 +100,8 @@
 				}else{
 					/* Child child - close pipe. */
 					close(p[1]);
+					if(oldchild)
+						signal(SIGCHLD, oldchild);
 				}
 			}
 		}


- erik