Fix errcheck warnings

Signed-off-by: z1cheng <imchench@gmail.com>

pkg/flags/flags.go

@@ -228,14 +228,19 @@ https://blog.maxmind.com/2019/12/18/significant-changes-to-accessing-and-using-g
 	flags.IntVar(&nginx.MaxmindRetriesCount, "maxmind-retries-count", 1, "Number of attempts to download the GeoIP DB.")
 	flags.DurationVar(&nginx.MaxmindRetriesTimeout, "maxmind-retries-timeout", time.Second*0, "Maxmind downloading delay between 1st and 2nd attempt, 0s - do not retry to download if something went wrong.")
 
-	flag.Set("logtostderr", "true")
-
+	if err := flag.Set("logtostderr", "true"); err != nil {
+		return false, nil, err
+	}
 	flags.AddGoFlagSet(flag.CommandLine)
-	flags.Parse(os.Args)
+	if err := flags.Parse(os.Args); err != nil {
+		return false, nil, err
+	}
 
 	// Workaround for this issue:
 	// https://github.com/kubernetes/kubernetes/issues/17162
-	flag.CommandLine.Parse([]string{})
+	if err := flag.CommandLine.Parse([]string{}); err != nil {
+		return false, nil, err
+	}
 
 	pflag.VisitAll(func(flag *pflag.Flag) {
 		klog.V(2).InfoS("FLAG", flag.Name, flag.Value)

pkg/tcpproxy/tcp.go

@@ -119,7 +119,9 @@ func (p *TCPProxy) Handle(conn net.Conn) {
 
 func pipe(client, server net.Conn) {
 	doCopy := func(s, c net.Conn, cancel chan<- bool) {
-		io.Copy(s, c)
+		if _, err := io.Copy(s, c); err != nil {
+			klog.Errorf("Error copying data: %v", err)
+		}
 		cancel <- true
 	}
 

pkg/util/file/file_test.go

@@ -35,8 +35,12 @@ func TestSHA1(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		f.Write(test.content)
-		f.Sync()
+		if _, err := f.Write(test.content); err != nil {
+			t.Error(err)
+		}
+		if err := f.Sync(); err != nil {
+			t.Error(err)
+		}
 
 		sha := SHA1(f.Name())
 		f.Close()

pkg/util/file/file_watcher_test.go

@@ -59,7 +59,9 @@ func TestFileWatcher(t *testing.T) {
 		t.Fatalf("expected no events before writing a file")
 	case <-timeoutChan:
 	}
-	os.WriteFile(f.Name(), []byte{}, ReadWriteByUser)
+	if err := os.WriteFile(f.Name(), []byte{}, ReadWriteByUser); err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
 	select {
 	case <-events:
 	case <-timeoutChan:

pkg/util/process/sigterm_test.go

@@ -42,9 +42,9 @@ func (f *FakeProcess) exiterFunc(code int) {
 	f.exitCode = code
 }
 
-func sendDelayedSignal(delay time.Duration) {
+func sendDelayedSignal(delay time.Duration) error {
 	time.Sleep(delay * time.Second)
-	syscall.Kill(syscall.Getpid(), syscall.SIGTERM)
+	return syscall.Kill(syscall.Getpid(), syscall.SIGTERM)
 }
 
 func TestHandleSigterm(t *testing.T) {
@@ -66,7 +66,12 @@ func TestHandleSigterm(t *testing.T) {
 	for _, tt := range tests {
 		process := &FakeProcess{shouldError: tt.shouldError}
 		t.Run(tt.name, func(t *testing.T) {
-			go sendDelayedSignal(2) // Send a signal after 2 seconds
+			go func() {
+				err := sendDelayedSignal(2) // Send a signal after 2 seconds
+				if err != nil {
+					t.Errorf("error sending delayed signal: %v", err)
+				}
+			}()
 			HandleSigterm(process, tt.delay, process.exiterFunc)
 		})
 		if tt.shouldError && process.exitCode != 1 {