Runtime v2

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

sys/reaper.go

@@ -18,7 +18,9 @@
 
 package sys
 
-import "golang.org/x/sys/unix"
+import (
+	"golang.org/x/sys/unix"
+)
 
 // Exit is the wait4 information from an exited process
 type Exit struct {

sys/reaper_linux.go

@@ -0,0 +1,52 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package sys
+
+import (
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// If arg2 is nonzero, set the "child subreaper" attribute of the
+// calling process; if arg2 is zero, unset the attribute.  When a
+// process is marked as a child subreaper, all of the children
+// that it creates, and their descendants, will be marked as
+// having a subreaper.  In effect, a subreaper fulfills the role
+// of init(1) for its descendant processes.  Upon termination of
+// a process that is orphaned (i.e., its immediate parent has
+// already terminated) and marked as having a subreaper, the
+// nearest still living ancestor subreaper will receive a SIGCHLD
+// signal and be able to wait(2) on the process to discover its
+// termination status.
+const setChildSubreaper = 36
+
+// SetSubreaper sets the value i as the subreaper setting for the calling process
+func SetSubreaper(i int) error {
+	return unix.Prctl(setChildSubreaper, uintptr(i), 0, 0, 0)
+}
+
+// GetSubreaper returns the subreaper setting for the calling process
+func GetSubreaper() (int, error) {
+	var i uintptr
+
+	if err := unix.Prctl(unix.PR_GET_CHILD_SUBREAPER, uintptr(unsafe.Pointer(&i)), 0, 0, 0); err != nil {
+		return -1, err
+	}
+
+	return int(i), nil
+}