Support all platform signal names

Author: bduffany

internal/godemon/signals.go

@@ -5,6 +5,8 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+
+	"golang.org/x/sys/unix"
 )
 
 const (
@@ -18,15 +20,13 @@ func parseSignal(name string) (syscall.Signal, error) {
 	if err == nil {
 		return syscall.Signal(n), nil
 	}
-	switch strings.TrimPrefix(strings.ToUpper(name), "SIG") {
-	case "INT":
-		return syscall.SIGINT, nil
-	case "TERM":
-		return syscall.SIGTERM, nil
-	case "QUIT":
-		return syscall.SIGQUIT, nil
-	case "KILL":
-		return syscall.SIGKILL, nil
+
+	signalName := strings.ToUpper(name)
+	if !strings.HasPrefix(signalName, "SIG") {
+		signalName = "SIG" + signalName
+	}
+	if signal := unix.SignalNum(signalName); signal != 0 {
+		return signal, nil
 	}
 	return 0, fmt.Errorf("unsupported signal %q", name)
 }

internal/godemon/signals_test.go

@@ -0,0 +1,75 @@
+package godemon
+
+import (
+	"strconv"
+	"strings"
+	"syscall"
+	"testing"
+
+	"golang.org/x/sys/unix"
+)
+
+func TestParseSignalNameVariants(t *testing.T) {
+	for _, testCase := range []struct {
+		name string
+		want syscall.Signal
+	}{
+		{name: "USR1", want: syscall.SIGUSR1},
+		{name: "usr1", want: syscall.SIGUSR1},
+		{name: "SIGUSR1", want: syscall.SIGUSR1},
+		{name: "sigusr1", want: syscall.SIGUSR1},
+	} {
+		t.Run(testCase.name, func(t *testing.T) {
+			got, err := parseSignal(testCase.name)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got != testCase.want {
+				t.Fatalf("parseSignal(%q) = %d, want %d", testCase.name, got, testCase.want)
+			}
+		})
+	}
+}
+
+func TestParseSignalAcceptsEveryPlatformSignalName(t *testing.T) {
+	for signal := syscall.Signal(1); signal < 256; signal++ {
+		name := unix.SignalName(signal)
+		if name == "" {
+			continue
+		}
+
+		for _, input := range []string{
+			name,
+			strings.ToLower(name),
+			strings.TrimPrefix(name, "SIG"),
+		} {
+			got, err := parseSignal(input)
+			if err != nil {
+				t.Errorf("parseSignal(%q): %s", input, err)
+				continue
+			}
+			if got != signal {
+				t.Errorf("parseSignal(%q) = %d, want %d", input, got, signal)
+			}
+		}
+	}
+}
+
+func TestParseSignalPreservesNumericSignals(t *testing.T) {
+	for _, signal := range []syscall.Signal{0, syscall.SIGUSR1, 255, -1} {
+		name := strconv.Itoa(int(signal))
+		got, err := parseSignal(name)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got != signal {
+			t.Fatalf("parseSignal(%q) = %d, want %d", name, got, signal)
+		}
+	}
+}
+
+func TestParseSignalRejectsUnknownName(t *testing.T) {
+	if _, err := parseSignal("definitely-not-a-signal"); err == nil {
+		t.Fatal("parseSignal accepted an unknown name")
+	}
+}