Fix for sigwait problem.

Submitted by: Daniel M. Eischen <eischen@vigrid.com>
PR:           misc/7039

3 files changed, 99 insertions, 17 deletions

diff --git a/lib/libc_r/uthread/uthread_kill.c b/lib/libc_r/uthread/uthread_kill.c
index f6e684b..98b3a2d 100644
--- a/lib/libc_r/uthread/uthread_kill.c
+++ b/lib/libc_r/uthread/uthread_kill.c
@@ -47,9 +47,18 @@ pthread_kill(pthread_t pthread, int sig)
 		ret = EINVAL;
 
 	/* Find the thread in the list of active threads: */
-	else if ((ret = _find_thread(pthread)) == 0)
-		/* Increment the pending signal count: */
-		sigaddset(&pthread->sigpend,sig);
+	else if ((ret = _find_thread(pthread)) == 0) {
+		if ((pthread->state == PS_SIGWAIT) &&
+		    sigismember(&pthread->sigmask, sig)) {
+			/* Change the state of the thread to run: */
+			PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+			/* Return the signal number: */
+			pthread->signo = sig;
+		} else
+			/* Increment the pending signal count: */
+			sigaddset(&pthread->sigpend,sig);
+	}
 
 	/* Return the completion status: */
 	return (ret);
diff --git a/lib/libc_r/uthread/uthread_sig.c b/lib/libc_r/uthread/uthread_sig.c
index 316b78e..073b1ba 100644
--- a/lib/libc_r/uthread/uthread_sig.c
+++ b/lib/libc_r/uthread/uthread_sig.c
@@ -212,6 +212,31 @@ _thread_sig_handler(int sig, int code, struct sigcontext * scp)
 				sigdelset(&pthread->sigpend,SIGCONT);
 		}
 
+		/*
+		 * Enter a loop to process each thread in the linked
+		 * list that is sigwait-ing on a signal.  Since POSIX
+		 * doesn't specify which thread will get the signal
+		 * if there are multiple waiters, we'll give it to the
+		 * first one we find.
+		 */
+		for (pthread = _thread_link_list; pthread != NULL;
+		    pthread = pthread->nxt) {
+			if ((pthread->state == PS_SIGWAIT) &&
+			    sigismember(&pthread->sigmask, sig)) {
+				/* Change the state of the thread to run: */
+				PTHREAD_NEW_STATE(pthread,PS_RUNNING);
+
+				/* Return the signal number: */
+				pthread->signo = sig;
+
+				/*
+				 * Do not attempt to deliver this signal
+				 * to other threads.
+				 */
+				return;
+			}
+		}
+
 		/* Check if the signal is not being ignored: */
 		if (_thread_sigact[sig - 1].sa_handler != SIG_IGN)
 			/*
@@ -259,6 +284,7 @@ _thread_signal(pthread_t pthread, int sig)
 	case PS_RUNNING:
 	case PS_STATE_MAX:
 	case PS_SIGTHREAD:
+	case PS_SIGWAIT:
 	case PS_SUSPENDED:
 		/* Nothing to do here. */
 		break;
@@ -290,7 +316,6 @@ _thread_signal(pthread_t pthread, int sig)
 	case PS_FDR_WAIT:
 	case PS_FDW_WAIT:
 	case PS_SLEEP_WAIT:
-	case PS_SIGWAIT:
 	case PS_SELECT_WAIT:
 		if (sig != SIGCHLD ||
 		    _thread_sigact[sig - 1].sa_handler != SIG_DFL) {
diff --git a/lib/libc_r/uthread/uthread_sigwait.c b/lib/libc_r/uthread/uthread_sigwait.c
index 63c7093..f441fa3 100644
--- a/lib/libc_r/uthread/uthread_sigwait.c
+++ b/lib/libc_r/uthread/uthread_sigwait.c
@@ -39,24 +39,72 @@
 int
 sigwait(const sigset_t * set, int *sig)
 {
-	int ret;
-	int status;
-	sigset_t oset;
+	int		ret = 0;
+	int		i;
+	sigset_t	oset;
+	struct sigaction act;
+	
+	/*
+	 * Specify the thread kernel signal handler.
+	 */
+	act.sa_handler = (void (*) ()) _thread_sig_handler;
+	act.sa_flags = SA_RESTART;
+	act.sa_mask = *set;
 
-	/* Save the current sigmal mask: */
-	oset = _thread_run->sigmask;
+	/*
+	 * These signals can't be waited on.
+	 */
+	sigdelset(&act.sa_mask, SIGKILL);
+	sigdelset(&act.sa_mask, SIGSTOP);
+	sigdelset(&act.sa_mask, SIGVTALRM);
+	sigdelset(&act.sa_mask, SIGCHLD);
+	sigdelset(&act.sa_mask, SIGINFO);
 
-	/* Combine the caller's mask with the current one: */
-	_thread_run->sigmask |= *set;
+	/*
+	 * Enter a loop to find the signals that are SIG_DFL.  For
+	 * these signals we must install a dummy signal handler in
+	 * order for the kernel to pass them in to us.  POSIX says
+	 * that the application must explicitly install a dummy
+	 * handler for signals that are SIG_IGN in order to sigwait
+	 * on them, so we ignore SIG_IGN signals.
+	 */
+	for (i = 1; i < NSIG; i++) {
+		if (sigismember(&act.sa_mask, i)) {
+			if (_thread_sigact[i - 1].sa_handler == SIG_DFL) {
+				if (_thread_sys_sigaction(i,&act,NULL) != 0)
+					ret = -1;
+			}
+			else if (_thread_sigact[i - 1].sa_handler == SIG_IGN)
+				sigdelset(&act.sa_mask, i);
+		}
+	}
+	if (ret == 0) {
 
-	/* Wait for a signal: */
-	_thread_kern_sched_state(PS_SIGWAIT, __FILE__, __LINE__);
+		/* Save the current signal mask: */
+		oset = _thread_run->sigmask;
 
-	/* Return the signal number to the caller: */
-	*sig = _thread_run->signo;
+		/* Combine the caller's mask with the current one: */
+		_thread_run->sigmask |= act.sa_mask;
 
-	/* Restore the signal mask: */
-	_thread_run->sigmask = oset;
+		/* Wait for a signal: */
+		_thread_kern_sched_state(PS_SIGWAIT, __FILE__, __LINE__);
+
+		/* Return the signal number to the caller: */
+		*sig = _thread_run->signo;
+
+		/* Restore the signal mask: */
+		_thread_run->sigmask = oset;
+	}
+
+	/* Restore the sigactions: */
+	act.sa_handler = SIG_DFL;
+	for (i = 1; i < NSIG; i++) {
+		if (sigismember(&act.sa_mask, i) &&
+		    (_thread_sigact[i - 1].sa_handler == SIG_DFL)) {
+			if (_thread_sys_sigaction(i,&act,NULL) != 0)
+				ret = -1;
+		}
+	}
 
 	/* Return the completion status: */
 	return (ret);