fix: blob race condition (#619)

* fix: blob race condition

* fix: blob race condition

Author: cshum

imagor.go

@@ -208,7 +208,7 @@ func (app *Imagor) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	app.setResponseHeaders(w, r, blob, p)
-	if checkStatNotModified(w, r, blob.Stat) {
+	if blob != nil && checkStatNotModified(w, r, blob.Stat) {
 		w.WriteHeader(http.StatusNotModified)
 		return
 	}
@@ -779,6 +779,10 @@ func (app *Imagor) suppress(
 
 // setResponseHeaders sets common response headers for blob responses
 func (app *Imagor) setResponseHeaders(w http.ResponseWriter, r *http.Request, blob *Blob, p imagorpath.Params) {
+	if blob == nil {
+		w.Header().Set("Content-Type", "application/octet-stream")
+		return
+	}
 	w.Header().Set("Content-Type", blob.ContentType())
 	w.Header().Set("Content-Disposition", getContentDisposition(p, blob))
 	setCacheHeaders(w, r, getTtl(p, app.CacheHeaderTTL), app.CacheHeaderSWR)
@@ -966,9 +970,11 @@ func getContentDisposition(p imagorpath.Params, blob *Blob) string {
 				_, filename = filepath.Split(p.Image)
 			}
 			filename = strings.ReplaceAll(filename, `"`, "%22")
-			if ext := getExtension(blob.BlobType()); ext != "" &&
-				!(ext == ".jpg" && strings.HasSuffix(filename, ".jpeg")) {
-				filename = strings.TrimSuffix(filename, ext) + ext
+			if blob != nil {
+				if ext := getExtension(blob.BlobType()); ext != "" &&
+					!(ext == ".jpg" && strings.HasSuffix(filename, ".jpeg")) {
+					filename = strings.TrimSuffix(filename, ext) + ext
+				}
 			}
 			return fmt.Sprintf(`attachment; filename="%s"`, filename)
 		}

storage/filestorage/filestorage.go

@@ -66,12 +66,13 @@ func (s *FileStorage) Get(_ *http.Request, image string) (*imagor.Blob, error) {
 	if !ok {
 		return nil, imagor.ErrInvalid
 	}
-	return imagor.NewBlobFromFile(image, func(stat os.FileInfo) error {
+	blob := imagor.NewBlobFromFile(image, func(stat os.FileInfo) error {
 		if s.Expiration > 0 && time.Now().Sub(stat.ModTime()) > s.Expiration {
 			return imagor.ErrExpired
 		}
 		return nil
-	}), nil
+	})
+	return blob, blob.Err()
 }
 
 // Put implements imagor.Storage interface

storage/filestorage/filestorage_test.go

@@ -198,7 +198,7 @@ func TestFileStorage_Load_Save(t *testing.T) {
 	})
 
 	t.Run("expiration", func(t *testing.T) {
-		s := New(dir, WithExpiration(time.Millisecond*10))
+		s := New(dir, WithExpiration(time.Millisecond*100))
 		var err error
 
 		_, err = checkBlob(s.Get(r, "/foo/bar/asdf"))

storage/gcloudstorage/gcloudstorage.go

@@ -75,7 +75,7 @@ func (s *GCloudStorage) Get(r *http.Request, image string) (imageData *imagor.Bl
 			ModifiedTime: attrs.Updated,
 		}
 	}
-	return blob, err
+	return blob, blob.Err()
 }
 
 // Put implements imagor.Storage interface

storage/gcloudstorage/gcloudstorage_test.go

@@ -201,8 +201,5 @@ func TestContextCancel(t *testing.T) {
 	assert.Equal(t, "bar", string(buf))
 	cancel()
 	b, err = s.Get(r, "/foo/bar/asdf")
-	require.NoError(t, err)
-	buf, err = b.ReadAll()
-	assert.Empty(t, buf)
 	require.ErrorIs(t, err, context.Canceled)
 }