diff --git a/CHANGES b/CHANGES
index db5845d556..cdcdd0b35a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,4 +1,8 @@
 
+ 417.	[func]		Add isc_app_block() and isc_app_unblock(), which
+			allow an application to handle signals while
+			blocking.		
+
  416.	[bug]		Slave zones with no master file tried to use a
 			NULL pointer for a journal file name when they
 			received an IXFR. [RT #273]
diff --git a/lib/isc/unix/app.c b/lib/isc/unix/app.c
index 6a00319dcc..47374b8639 100644
--- a/lib/isc/unix/app.c
+++ b/lib/isc/unix/app.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: app.c,v 1.28 2000/08/30 23:47:16 bwelling Exp $ */
+/* $Id: app.c,v 1.29 2000/09/01 21:31:51 bwelling Exp $ */
 
 #include <config.h>
 
@@ -58,6 +58,11 @@ static isc_boolean_t		want_shutdown = ISC_FALSE;
  */
 static isc_boolean_t		want_reload = ISC_FALSE;
 
+static isc_boolean_t		blocked  = ISC_FALSE;
+#ifdef ISC_PLATFORM_USETHREADS
+static pthread_t		blockedthread;
+#endif
+
 #ifdef HAVE_LINUXTHREADS
 /*
  * Linux has sigwait(), but it appears to prevent signal handlers from
@@ -521,3 +526,43 @@ isc_app_finish(void) {
 
 	DESTROYLOCK(&lock);
 }
+
+void
+isc_app_block(void) {
+#ifdef ISC_PLATFORM_USETHREADS
+	sigset_t sset;
+#endif
+	REQUIRE(running);
+	REQUIRE(!blocked);
+
+	blocked = ISC_TRUE;
+#ifdef ISC_PLATFORM_USETHREADS
+	blockedthread = pthread_self();
+	RUNTIME_CHECK(sigemptyset(&sset) == 0 &&
+		      sigaddset(&sset, SIGINT) == 0 &&
+		      sigaddset(&sset, SIGTERM) == 0);
+	RUNTIME_CHECK(pthread_sigmask(SIG_UNBLOCK, &sset, NULL) == 0);
+#endif
+}
+
+void
+isc_app_unblock(void) {
+#ifdef ISC_PLATFORM_USETHREADS
+	sigset_t sset;
+#endif
+
+	REQUIRE(running);
+	REQUIRE(blocked);
+
+	blocked = ISC_FALSE;
+
+#ifdef ISC_PLATFORM_USETHREADS
+	REQUIRE(blockedthread == pthread_self());
+
+	RUNTIME_CHECK(sigemptyset(&sset) == 0 &&
+		      sigaddset(&sset, SIGINT) == 0 && 
+		      sigaddset(&sset, SIGTERM) == 0);
+	RUNTIME_CHECK(pthread_sigmask(SIG_BLOCK, &sset, NULL) == 0);
+#endif
+}
+
diff --git a/lib/isc/unix/include/isc/app.h b/lib/isc/unix/include/isc/app.h
index 2e2955291a..4eb504c7c5 100644
--- a/lib/isc/unix/include/isc/app.h
+++ b/lib/isc/unix/include/isc/app.h
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: app.h,v 1.8 2000/08/01 01:31:34 tale Exp $ */
+/* $Id: app.h,v 1.9 2000/09/01 21:31:53 bwelling Exp $ */
 
 #ifndef ISC_APP_H
 #define ISC_APP_H 1
@@ -176,6 +176,37 @@ isc_app_finish(void);
  *	Any resources allocated by isc_app_start() have been released.
  */
 
+void
+isc_app_block(void);
+/*
+ * Indicate that a blocking operation will be performed.
+ *
+ * Notes:
+ *	If a blocking operation is in process, a call to isc_app_shutdown()
+ *	or an external signal will abort the program, rather than allowing
+ *	clean shutdown.  This is primarily useful for reading user input.
+ *
+ * Requires:
+ * 	isc_app_start() has been called.
+ * 	No other blocking operations are in progress.
+ */
+
+void
+isc_app_unblock(void);
+/*
+ * Indicate that a blocking operation is complete.
+ *
+ * Notes:
+ * 	When a blocking operation has completed, return the program to a
+ * 	state where a call to isc_app_shutdown() or an external signal will
+ * 	shutdown normally.
+ *
+ * Requires:
+ * 	isc_app_start() has been called.
+ * 	isc_app_block() has been called by the same thread.
+ */
+
+
 ISC_LANG_ENDDECLS
 
 #endif /* ISC_APP_H */