fix(webdav): cache a file the built-in extractors find no image in, as for Tika

services/webdav/pkg/preprocessor/errors.go

@@ -2,10 +2,4 @@ package preprocessor
 
 import "errors"
 
-var (
-	ErrNoImageFromAudioFile                      = errors.New("preprocessor: could not extract image from audio file")
-	ErrNoConverterForExtractedImageFromGgsFile   = errors.New("preprocessor: could not find converter for image extracted from ggs file")
-	ErrNoConverterForExtractedImageFromAudioFile = errors.New("preprocessor: could not find converter for image extracted from audio file")
-	ErrNoConverterForExtractedImageFromGgpFile   = errors.New("preprocessor: could not find converter for image extracted from ggp file")
-	ErrNoThumbnail                               = errors.New("preprocessor: the document has no thumbnail")
-)
+var ErrNoThumbnail = errors.New("preprocessor: the document has no thumbnail")

services/webdav/pkg/preprocessor/preprocessor.go

@@ -86,7 +86,7 @@ func (g GgsDecoder) Convert(r io.Reader) (*Image, error) {
 			return &Image{ContentType: "image/png", Data: data}, nil
 		}
 	}
-	return nil, errors.Errorf("%s not found", g.thumbnailpath)
+	return nil, ErrNoThumbnail
 }
 
 // AudioDecoder is a converter for the audio file.
@@ -111,12 +111,8 @@ func (i AudioDecoder) Convert(r io.Reader) (*Image, error) {
 	}
 
 	picture := m.Picture()
-	if picture == nil {
-		return nil, ErrNoImageFromAudioFile
-	}
-
-	if !strings.HasPrefix(picture.MIMEType, "image/") {
-		return nil, ErrNoConverterForExtractedImageFromAudioFile
+	if picture == nil || !strings.HasPrefix(picture.MIMEType, "image/") {
+		return nil, ErrNoThumbnail
 	}
 
 	return &Image{ContentType: picture.MIMEType, Data: picture.Data}, nil
@@ -260,7 +256,7 @@ func (j GgpDecoder) Convert(r io.Reader) (*Image, error) {
 
 	contentType := http.DetectContentType(b)
 	if !strings.HasPrefix(contentType, "image/") {
-		return nil, ErrNoConverterForExtractedImageFromGgpFile
+		return nil, ErrNoThumbnail
 	}
 
 	return &Image{ContentType: contentType, Data: b}, nil
@@ -268,12 +264,12 @@ func (j GgpDecoder) Convert(r io.Reader) (*Image, error) {
 
 func extractBase64ImageFromGGP(ggp *GGPStruct) (string, error) {
 	if len(ggp.Sections) < 1 || len(ggp.Sections[0].Cards) < 1 {
-		return "", errors.New("cant find thumbnail in ggp file")
+		return "", ErrNoThumbnail
 	}
 
 	raw := strings.Split(ggp.Sections[0].Cards[0].Element.Image.Base64Image, "base64,")
 	if len(raw) < 2 {
-		return "", errors.New("cant decode ggp thumbnail")
+		return "", ErrNoThumbnail
 	}
 
 	return raw[1], nil

services/webdav/pkg/preprocessor/preprocessor_test.go

@@ -3,15 +3,17 @@ package preprocessor
 import (
 	"archive/zip"
 	"bytes"
+	"encoding/base64"
 	"encoding/binary"
 	"io"
 	"os"
+	"strings"
 	"testing"
 
 	"golang.org/x/image/font"
 	"golang.org/x/image/font/opentype"
 
-	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 )
 
@@ -77,6 +79,19 @@ var _ = Describe("preprocessor", func() {
 			Expect(img).To(BeNil())
 		})
 
+		It("reports a ggs without a thumbnail as having none", func() {
+			var buf bytes.Buffer
+			w := zip.NewWriter(&buf)
+			_, err := w.Create("geogebra.xml")
+			Expect(err).ToNot(HaveOccurred())
+			Expect(w.Close()).To(Succeed())
+
+			decoder := GgsDecoder{thumbnailpath: ggsThumbnailPath, maxSize: defaultMaxExtractedSize}
+			img, err := decoder.Convert(bytes.NewReader(buf.Bytes()))
+			Expect(err).To(MatchError(ErrNoThumbnail))
+			Expect(img).To(BeNil())
+		})
+
 		It("refuses an entry that expands past the limit", func() {
 			decoder := GgsDecoder{thumbnailpath: ggsThumbnailPath, maxSize: 1 << 20}
 
@@ -109,7 +124,7 @@ var _ = Describe("preprocessor", func() {
 			Expect(img.ContentType).To(HavePrefix("image/"))
 			Expect(img.Data).ToNot(BeEmpty())
 		})
-		It("should decode an audio", func() {
+		It("reports an audio without cover art as having none", func() {
 			fileContent, err := os.ReadFile("test_assets/empty_no_image.mp3")
 			if err != nil {
 				panic(err)
@@ -117,13 +132,46 @@ var _ = Describe("preprocessor", func() {
 			fileReader = bytes.NewReader(fileContent)
 			decoder := AudioDecoder{}
 			img, err := decoder.Convert(fileReader)
-			Expect(err).To(HaveOccurred())
+			Expect(err).To(MatchError(ErrNoThumbnail))
 			Expect(img).To(BeNil())
 		})
 		It("should return an error if the audio is invalid", func() {
 			decoder := AudioDecoder{}
 			img, err := decoder.Convert(bytes.NewReader([]byte("not an audio")))
 			Expect(err).To(HaveOccurred())
+			Expect(err).ToNot(MatchError(ErrNoThumbnail))
+			Expect(img).To(BeNil())
+		})
+	})
+
+	Describe("GgpDecoder", func() {
+		It("hands on the embedded thumbnail", func() {
+			data, err := os.ReadFile("test_assets/noise.png")
+			Expect(err).ToNot(HaveOccurred())
+			ggp := `{"sections":[{"cards":[{"element":{"image":{"base64Image":"data:image/png;base64,` + base64.StdEncoding.EncodeToString(data) + `"}}}]}]}`
+
+			img, err := GgpDecoder{}.Convert(strings.NewReader(ggp))
+			Expect(err).ToNot(HaveOccurred())
+			Expect(img.ContentType).To(Equal("image/png"))
+			Expect(img.Data).To(Equal(data))
+		})
+
+		DescribeTable("reports a ggp without a thumbnail as having none",
+			func(ggp string) {
+				img, err := GgpDecoder{}.Convert(strings.NewReader(ggp))
+				Expect(err).To(MatchError(ErrNoThumbnail))
+				Expect(img).To(BeNil())
+			},
+			Entry("no sections", `{}`),
+			Entry("no cards", `{"sections":[{"cards":[]}]}`),
+			Entry("no base64 image", `{"sections":[{"cards":[{"element":{"image":{"base64Image":""}}}]}]}`),
+			Entry("not an image", `{"sections":[{"cards":[{"element":{"image":{"base64Image":"data:text/plain;base64,aGVsbG8="}}}]}]}`),
+		)
+
+		It("should return an error if the ggp is invalid", func() {
+			img, err := GgpDecoder{}.Convert(strings.NewReader("not a ggp"))
+			Expect(err).To(HaveOccurred())
+			Expect(err).ToNot(MatchError(ErrNoThumbnail))
 			Expect(img).To(BeNil())
 		})
 	})

services/webdav/pkg/preprocessor/tika_test.go

@@ -9,7 +9,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 
-	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 	"github.com/onsi/gomega/types"