os/signal: add ability to ignore signals and restore initial signal handlers

There is currently no way to ignore signals using the os/signal package.
It is possible to catch a signal and do nothing but this is not the same
as ignoring it. The new function Ignore allows a set of signals to be
ignored. The new function Reset allows the initial handlers for a set of
signals to be restored.

Fixes #5572

Change-Id: I5c0f07956971e3a9ff9b9d9631e6e3a08c20df15
Reviewed-on: https://go-review.googlesource.com/3580
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/runtime/sigqueue_plan9.go b/src/runtime/sigqueue_plan9.go
index b029a300a8..38f0a57b90 100644
--- a/src/runtime/sigqueue_plan9.go
+++ b/src/runtime/sigqueue_plan9.go
@@ -113,3 +113,7 @@ func signal_enable(s uint32) {
 // Must only be called from a single goroutine at a time.
 func signal_disable(s uint32) {
 }
+
+// Must only be called from a single goroutine at a time.
+func signal_ignore(s uint32) {
+}