signals: move ParseSignal to containerd package

Signed-off-by: Samuel Karp <skarp@amazon.com>

cmd/ctr/commands/signals.go

@@ -18,11 +18,8 @@ package commands
 
 import (
 	gocontext "context"
-	"fmt"
 	"os"
 	"os/signal"
-	"strconv"
-	"strings"
 	"syscall"
 
 	"github.com/containerd/containerd"
@@ -53,23 +50,3 @@ func StopCatch(sigc chan os.Signal) {
 	signal.Stop(sigc)
 	close(sigc)
 }
-
-// ParseSignal parses a given string into a syscall.Signal
-// it checks that the signal exists in the platform-appropriate signalMap
-func ParseSignal(rawSignal string) (syscall.Signal, error) {
-	s, err := strconv.Atoi(rawSignal)
-	if err == nil {
-		sig := syscall.Signal(s)
-		for _, msig := range signalMap {
-			if sig == msig {
-				return sig, nil
-			}
-		}
-		return -1, fmt.Errorf("unknown signal %q", rawSignal)
-	}
-	signal, ok := signalMap[strings.TrimPrefix(strings.ToUpper(rawSignal), "SIG")]
-	if !ok {
-		return -1, fmt.Errorf("unknown signal %q", rawSignal)
-	}
-	return signal, nil
-}