fix go lint warnings

- handle errors where possible
- explicitly ignore errors where it makes sense to
- fix deprecations and unused var

cmd/imageproxy-sign/main.go

@@ -54,7 +54,9 @@ func sign(key string, s string, urlOnly bool) ([]byte, error) {
 	}
 
 	mac := hmac.New(sha256.New, []byte(k))
-	mac.Write([]byte(u.String()))
+	if _, err := mac.Write([]byte(u.String())); err != nil {
+		return nil, err
+	}
 	return mac.Sum(nil), nil
 }
 

cmd/imageproxy/main.go

@@ -54,7 +54,7 @@ var signatureKeys signatureKeyList
 var scaleUp = flag.Bool("scaleUp", false, "allow images to scale beyond their original dimensions")
 var timeout = flag.Duration("timeout", 0, "time limit for requests served by this proxy")
 var verbose = flag.Bool("verbose", false, "print verbose logging messages")
-var version = flag.Bool("version", false, "Deprecated: this flag does nothing")
+var _ = flag.Bool("version", false, "Deprecated: this flag does nothing")
 var contentTypes = flag.String("contentTypes", "image/*", "comma separated list of allowed content types")
 var userAgent = flag.String("userAgent", "willnorris/imageproxy", "specify the user-agent used by imageproxy when fetching images from origin website")
 

imageproxy.go

@@ -234,7 +234,9 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Access-Control-Allow-Origin", "*")
 
 	w.WriteHeader(resp.StatusCode)
-	io.Copy(w, resp.Body)
+	if _, err := io.Copy(w, resp.Body); err != nil {
+		p.logf("error copying response: %v", err)
+	}
 }
 
 // peekContentType peeks at the first 512 bytes of p, and attempts to detect
@@ -365,7 +367,7 @@ func validSignature(key []byte, r *Request) bool {
 
 	// check signature with URL only
 	mac := hmac.New(sha256.New, key)
-	mac.Write([]byte(r.URL.String()))
+	_, _ = mac.Write([]byte(r.URL.String()))
 	want := mac.Sum(nil)
 	if hmac.Equal(got, want) {
 		return true
@@ -377,7 +379,7 @@ func validSignature(key []byte, r *Request) bool {
 	u.Fragment = opt.String()
 
 	mac = hmac.New(sha256.New, key)
-	mac.Write([]byte(u.String()))
+	_, _ = mac.Write([]byte(u.String()))
 	want = mac.Sum(nil)
 	return hmac.Equal(got, want)
 }
@@ -482,11 +484,13 @@ func (t *TransformingTransport) RoundTrip(req *http.Request) (*http.Response, er
 	// replay response with transformed image and updated content length
 	buf := new(bytes.Buffer)
 	fmt.Fprintf(buf, "%s %s\n", resp.Proto, resp.Status)
-	resp.Header.WriteSubset(buf, map[string]bool{
+	if err := resp.Header.WriteSubset(buf, map[string]bool{
 		"Content-Length": true,
 		// exclude Content-Type header if the format may have changed during transformation
 		"Content-Type": opt.Format != "" || resp.Header.Get("Content-Type") == "image/webp" || resp.Header.Get("Content-Type") == "image/tiff",
-	})
+	}); err != nil {
+		t.log("error copying headers: %v", err)
+	}
 	fmt.Fprintf(buf, "Content-Length: %d\n\n", len(img))
 	buf.Write(img)
 

imageproxy_test.go

@@ -375,7 +375,7 @@ func (t testTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 	case "/png":
 		m := image.NewNRGBA(image.Rect(0, 0, 1, 1))
 		img := new(bytes.Buffer)
-		png.Encode(img, m)
+		_ = png.Encode(img, m)
 
 		raw = fmt.Sprintf("HTTP/1.1 200 OK\nContent-Length: %d\nContent-Type: image/png\n\n%s", len(img.Bytes()), img.Bytes())
 	default:

internal/gcscache/gcscache.go

@@ -63,7 +63,7 @@ func (c *cache) object(key string) *storage.ObjectHandle {
 
 func keyToFilename(key string) string {
 	h := md5.New()
-	io.WriteString(h, key)
+	_, _ = io.WriteString(h, key)
 	return hex.EncodeToString(h.Sum(nil))
 }
 

internal/s3cache/s3cache.go

@@ -75,7 +75,7 @@ func (c *cache) Delete(key string) {
 
 func keyToFilename(key string) string {
 	h := md5.New()
-	io.WriteString(h, key)
+	_, _ = io.WriteString(h, key)
 	return hex.EncodeToString(h.Sum(nil))
 }
 

transform_test.go

@@ -44,7 +44,7 @@ var (
 func newImage(w, h int, pixels ...color.Color) image.Image {
 	m := image.NewNRGBA(image.Rect(0, 0, w, h))
 	if len(pixels) == 1 {
-		draw.Draw(m, m.Bounds(), &image.Uniform{pixels[0]}, image.ZP, draw.Src)
+		draw.Draw(m, m.Bounds(), &image.Uniform{pixels[0]}, image.Point{}, draw.Src)
 	} else {
 		for i, p := range pixels {
 			m.Set(i%w, i/w, p)
@@ -106,22 +106,26 @@ func TestTransform(t *testing.T) {
 	src := newImage(2, 2, red, green, blue, yellow)
 
 	buf := new(bytes.Buffer)
-	png.Encode(buf, src)
+	if err := png.Encode(buf, src); err != nil {
+		t.Errorf("error encoding reference image: %v", err)
+	}
 
 	tests := []struct {
 		name        string
-		encode      func(io.Writer, image.Image)
+		encode      func(io.Writer, image.Image) error
 		exactOutput bool // whether input and output should match exactly
 	}{
-		{"bmp", func(w io.Writer, m image.Image) { bmp.Encode(w, m) }, true},
+		{"bmp", func(w io.Writer, m image.Image) error { return bmp.Encode(w, m) }, true},
-		{"gif", func(w io.Writer, m image.Image) { gif.Encode(w, m, nil) }, true},
+		{"gif", func(w io.Writer, m image.Image) error { return gif.Encode(w, m, nil) }, true},
-		{"jpeg", func(w io.Writer, m image.Image) { jpeg.Encode(w, m, nil) }, false},
+		{"jpeg", func(w io.Writer, m image.Image) error { return jpeg.Encode(w, m, nil) }, false},
-		{"png", func(w io.Writer, m image.Image) { png.Encode(w, m) }, true},
+		{"png", func(w io.Writer, m image.Image) error { return png.Encode(w, m) }, true},
 	}
 
 	for _, tt := range tests {
 		buf := new(bytes.Buffer)
-		tt.encode(buf, src)
+		if err := tt.encode(buf, src); err != nil {
+			t.Errorf("error encoding image: %v", err)
+		}
 		in := buf.Bytes()
 
 		out, err := Transform(in, emptyOptions)
@@ -152,7 +156,9 @@ func TestTransform(t *testing.T) {
 func TestTransform_InvalidFormat(t *testing.T) {
 	src := newImage(2, 2, red, green, blue, yellow)
 	buf := new(bytes.Buffer)
-	png.Encode(buf, src)
+	if err := png.Encode(buf, src); err != nil {
+		t.Errorf("error encoding reference image: %v", err)
+	}
 
 	_, err := Transform(buf.Bytes(), Options{Format: "invalid"})
 	if err == nil {