[MM-29241] Image logic refactor (#17702)

* Image logic refactor

* Add missing translations

* Improve prepareImage

* Use iota

* Limit image encoder concurrency

* Unexport validation methods

* Avoid shortening on exported names

* Remove unnecessary complexity

app/bot.go

@@ -11,6 +11,7 @@ import (
 	"mime/multipart"
 	"net/http"
 
+	"github.com/mattermost/mattermost-server/v5/app/imaging"
 	"github.com/mattermost/mattermost-server/v5/app/request"
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/shared/i18n"
@@ -526,7 +527,7 @@ func (a *App) SetBotIconImage(botUserId string, file io.ReadSeeker) *model.AppEr
 		return err
 	}
 
-	if _, err := parseSVG(file); err != nil {
+	if _, err := imaging.ParseSVG(file); err != nil {
 		return model.NewAppError("SetBotIconImage", "api.bot.set_bot_icon_image.parse.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
 

app/brand.go

@@ -5,10 +5,6 @@ package app
 
 import (
 	"bytes"
-	"image"
-	_ "image/gif"
-	_ "image/jpeg"
-	"image/png"
 	"mime/multipart"
 	"net/http"
 	"time"
@@ -32,28 +28,17 @@ func (a *App) SaveBrandImage(imageData *multipart.FileHeader) *model.AppError {
 	}
 	defer file.Close()
 
-	// Decode image config first to check dimensions before loading the whole thing into memory later on
-	config, _, err := image.DecodeConfig(file)
-	if err != nil {
-		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.decode_config.app_error", nil, err.Error(), http.StatusBadRequest)
+	if err = checkImageLimits(file); err != nil {
+		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.check_image_limits.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
 
-	// This casting is done to prevent overflow on 32 bit systems (not needed
-	// in 64 bits systems because images can't have more than 32 bits height or
-	// width)
-	if int64(config.Width)*int64(config.Height) > model.MaxImageSize {
-		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.too_large.app_error", nil, "", http.StatusBadRequest)
-	}
-
-	file.Seek(0, 0)
-
-	img, _, err := image.Decode(file)
+	img, _, err := a.srv.imgDecoder.Decode(file)
 	if err != nil {
 		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.decode.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
 
 	buf := new(bytes.Buffer)
-	err = png.Encode(buf, img)
+	err = a.srv.imgEncoder.EncodePNG(buf, img)
 	if err != nil {
 		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.encode.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}

app/file.go

@@ -11,10 +11,7 @@ import (
 	"encoding/base64"
 	"fmt"
 	"image"
-	"image/color"
-	"image/draw"
 	"image/gif"
-	"image/jpeg"
 	"io"
 	"mime/multipart"
 	"net/http"
@@ -27,13 +24,7 @@ import (
 	"sync"
 	"time"
 
-	"github.com/disintegration/imaging"
-	_ "github.com/oov/psd"
-	"github.com/pkg/errors"
-	"github.com/rwcarlsen/goexif/exif"
-	_ "golang.org/x/image/bmp"
-	_ "golang.org/x/image/tiff"
-
+	"github.com/mattermost/mattermost-server/v5/app/imaging"
 	"github.com/mattermost/mattermost-server/v5/app/request"
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/plugin"
@@ -42,41 +33,20 @@ import (
 	"github.com/mattermost/mattermost-server/v5/shared/mlog"
 	"github.com/mattermost/mattermost-server/v5/store"
 	"github.com/mattermost/mattermost-server/v5/utils"
+
+	"github.com/pkg/errors"
 )
 
 const (
-	/*
-	  EXIF Image Orientations
-	  1        2       3      4         5            6           7          8
-
-	  888888  888888      88  88      8888888888  88                  88  8888888888
-	  88          88      88  88      88  88      88  88          88  88      88  88
-	  8888      8888    8888  8888    88          8888888888  8888888888          88
-	  88          88      88  88
-	  88          88  888888  888888
-	*/
-	Upright            = 1
-	UprightMirrored    = 2
-	UpsideDown         = 3
-	UpsideDownMirrored = 4
-	RotatedCWMirrored  = 5
-	RotatedCCW         = 6
-	RotatedCCWMirrored = 7
-	RotatedCW          = 8
-
-	MaxImageSize         = int64(6048 * 4032) // 24 megapixels, roughly 36MB as a raw image
-	ImageThumbnailWidth  = 120
-	ImageThumbnailHeight = 100
-	ImageThumbnailRatio  = float64(ImageThumbnailHeight) / float64(ImageThumbnailWidth)
-	ImagePreviewWidth    = 1920
-
-	maxUploadInitialBufferSize = 1024 * 1024 // 1Mb
-
-	// Deprecated
-	ImageThumbnailPixelWidth  = 120
-	ImageThumbnailPixelHeight = 100
-	ImagePreviewPixelWidth    = 1920
-	MaxContentExtractionSize  = 1024 * 1024 // 1Mb
+	maxImageRes                = int64(6048 * 4032) // 24 megapixels, up to ~196MB as a raw image
+	imageThumbnailWidth        = 120
+	imageThumbnailHeight       = 100
+	imagePreviewWidth          = 1920
+	miniPreviewImageWidth      = 16
+	miniPreviewImageHeight     = 16
+	jpegEncQuality             = 90
+	maxUploadInitialBufferSize = 1024 * 1024 // 1MB
+	maxContentExtractionSize   = 1024 * 1024 // 1MB
 )
 
 func (a *App) FileBackend() (filestore.FileBackend, *model.AppError) {
@@ -683,6 +653,9 @@ type UploadFileTask struct {
 	pluginsEnvironment *plugin.Environment
 	writeFile          func(io.Reader, string) (int64, *model.AppError)
 	saveToDatabase     func(*model.FileInfo) (*model.FileInfo, error)
+
+	imgDecoder *imaging.Decoder
+	imgEncoder *imaging.Encoder
 }
 
 func (t *UploadFileTask) init(a *App) {
@@ -729,6 +702,8 @@ func (a *App) UploadFileX(c *request.Context, channelID, name string, input io.R
 		Name:        filepath.Base(name),
 		Input:       input,
 		maxFileSize: *a.Config().FileSettings.MaxFileSize,
+		imgDecoder:  a.srv.imgDecoder,
+		imgEncoder:  a.srv.imgEncoder,
 	}
 	for _, o := range opts {
 		o(t)
@@ -811,7 +786,7 @@ func (a *App) UploadFileX(c *request.Context, channelID, name string, input io.R
 func (t *UploadFileTask) preprocessImage() *model.AppError {
 	// If SVG, attempt to extract dimensions and then return
 	if t.fileinfo.MimeType == "image/svg+xml" {
-		svgInfo, err := parseSVG(t.teeInput)
+		svgInfo, err := imaging.ParseSVG(t.teeInput)
 		if err != nil {
 			mlog.Warn("Failed to parse SVG", mlog.Err(err))
 		}
@@ -824,21 +799,17 @@ func (t *UploadFileTask) preprocessImage() *model.AppError {
 	}
 
 	// If we fail to decode, return "as is".
-	config, _, err := image.DecodeConfig(t.teeInput)
+	w, h, err := imaging.GetDimensions(t.teeInput)
 	if err != nil {
 		return nil
 	}
+	t.fileinfo.Width = w
+	t.fileinfo.Height = h
 
-	t.fileinfo.Width = config.Width
-	t.fileinfo.Height = config.Height
-
-	// Check dimensions before loading the whole thing into memory later on.
-	// This casting is done to prevent overflow on 32 bit systems (not needed
-	// in 64 bits systems because images can't have more than 32 bits height or
-	// width)
-	if int64(t.fileinfo.Width)*int64(t.fileinfo.Height) > MaxImageSize {
+	if err = checkImageResolutionLimit(w, h); err != nil {
 		return t.newAppError("api.file.upload_file.large_image_detailed.app_error", http.StatusBadRequest)
 	}
+
 	t.fileinfo.HasPreviewImage = true
 	nameWithoutExtension := t.Name[:strings.LastIndex(t.Name, ".")]
 	t.fileinfo.PreviewPath = t.pathPrefix() + nameWithoutExtension + "_preview.jpg"
@@ -847,11 +818,11 @@ func (t *UploadFileTask) preprocessImage() *model.AppError {
 	// check the image orientation with goexif; consume the bytes we
 	// already have first, then keep Tee-ing from input.
 	// TODO: try to reuse exif's .Raw buffer rather than Tee-ing
-	if t.imageOrientation, err = getImageOrientation(io.MultiReader(bytes.NewReader(t.buf.Bytes()), t.teeInput)); err == nil &&
-		(t.imageOrientation == RotatedCWMirrored ||
-			t.imageOrientation == RotatedCCW ||
-			t.imageOrientation == RotatedCCWMirrored ||
-			t.imageOrientation == RotatedCW) {
+	if t.imageOrientation, err = imaging.GetImageOrientation(io.MultiReader(bytes.NewReader(t.buf.Bytes()), t.teeInput)); err == nil &&
+		(t.imageOrientation == imaging.RotatedCWMirrored ||
+			t.imageOrientation == imaging.RotatedCCW ||
+			t.imageOrientation == imaging.RotatedCCWMirrored ||
+			t.imageOrientation == imaging.RotatedCW) {
 		t.fileinfo.Width, t.fileinfo.Height = t.fileinfo.Height, t.fileinfo.Width
 	}
 
@@ -877,35 +848,32 @@ func (t *UploadFileTask) postprocessImage(file io.Reader) {
 		return
 	}
 
-	decoded, typ := t.decoded, t.imageType
+	decoded, imgType := t.decoded, t.imageType
 	if decoded == nil {
 		var err error
-		decoded, typ, err = image.Decode(file)
+		var release func()
+		decoded, imgType, release, err = t.imgDecoder.DecodeMemBounded(file)
 		if err != nil {
 			mlog.Error("Unable to decode image", mlog.Err(err))
 			return
 		}
+		defer release()
 	}
 
-	// Fill in the background of a potentially-transparent png file as
-	// white.
-	if typ == "png" {
-		dst := image.NewRGBA(decoded.Bounds())
-		draw.Draw(dst, dst.Bounds(), image.NewUniform(color.White), image.Point{}, draw.Src)
-		draw.Draw(dst, dst.Bounds(), decoded, decoded.Bounds().Min, draw.Over)
-		decoded = dst
+	// Fill in the background of a potentially-transparent png file as white
+	if imgType == "png" {
+		imaging.FillImageTransparency(decoded, image.White)
 	}
 
-	decoded = makeImageUpright(decoded, t.imageOrientation)
+	decoded = imaging.MakeImageUpright(decoded, t.imageOrientation)
 	if decoded == nil {
 		return
 	}
 
-	const jpegQuality = 90
 	writeJPEG := func(img image.Image, path string) {
 		r, w := io.Pipe()
 		go func() {
-			err := jpeg.Encode(w, img, &jpeg.Options{Quality: jpegQuality})
+			err := t.imgEncoder.EncodeJPEG(w, img, jpegEncQuality)
 			if err != nil {
 				mlog.Error("Unable to encode image as jpeg", mlog.String("path", path), mlog.Err(err))
 				w.CloseWithError(err)
@@ -926,18 +894,23 @@ func (t *UploadFileTask) postprocessImage(file io.Reader) {
 	// This is needed on mobile in case of animated GIFs.
 	go func() {
 		defer wg.Done()
-		writeJPEG(genThumbnail(decoded), t.fileinfo.ThumbnailPath)
+		writeJPEG(imaging.GenerateThumbnail(decoded, imageThumbnailWidth, imageThumbnailHeight), t.fileinfo.ThumbnailPath)
 	}()
 
 	go func() {
 		defer wg.Done()
-		writeJPEG(genPreview(decoded), t.fileinfo.PreviewPath)
+		writeJPEG(imaging.GeneratePreview(decoded, imagePreviewWidth), t.fileinfo.PreviewPath)
 	}()
 
 	go func() {
 		defer wg.Done()
 		if t.fileinfo.MiniPreview == nil {
-			t.fileinfo.MiniPreview = model.GenerateMiniPreviewImage(decoded)
+			if miniPreview, err := imaging.GenerateMiniPreviewImage(decoded,
+				miniPreviewImageWidth, miniPreviewImageHeight, jpegEncQuality); err != nil {
+				mlog.Info("Unable to generate mini preview image", mlog.Err(err))
+			} else {
+				t.fileinfo.MiniPreview = &miniPreview
+			}
 		}
 	}()
 	wg.Wait()
@@ -984,11 +957,11 @@ func (a *App) DoUploadFileExpectModification(c *request.Context, now time.Time,
 		return nil, data, err
 	}
 
-	if orientation, err := getImageOrientation(bytes.NewReader(data)); err == nil &&
-		(orientation == RotatedCWMirrored ||
-			orientation == RotatedCCW ||
-			orientation == RotatedCCWMirrored ||
-			orientation == RotatedCW) {
+	if orientation, err := imaging.GetImageOrientation(bytes.NewReader(data)); err == nil &&
+		(orientation == imaging.RotatedCWMirrored ||
+			orientation == imaging.RotatedCCW ||
+			orientation == imaging.RotatedCCWMirrored ||
+			orientation == imaging.RotatedCW) {
 		info.Width, info.Height = info.Height, info.Width
 	}
 
@@ -1000,12 +973,8 @@ func (a *App) DoUploadFileExpectModification(c *request.Context, now time.Time,
 	info.Path = pathPrefix + filename
 
 	if info.IsImage() {
-		// Check dimensions before loading the whole thing into memory later on
-		// This casting is done to prevent overflow on 32 bit systems (not needed
-		// in 64 bits systems because images can't have more than 32 bits height or
-		// width)
-		if int64(info.Width)*int64(info.Height) > MaxImageSize {
-			err := model.NewAppError("uploadFile", "api.file.upload_file.large_image.app_error", map[string]interface{}{"Filename": filename}, "", http.StatusBadRequest)
+		if limitErr := checkImageResolutionLimit(info.Width, info.Height); limitErr != nil {
+			err := model.NewAppError("uploadFile", "api.file.upload_file.large_image.app_error", map[string]interface{}{"Filename": filename}, limitErr.Error(), http.StatusBadRequest)
 			return nil, data, err
 		}
 
@@ -1070,113 +1039,75 @@ func (a *App) HandleImages(previewPathList []string, thumbnailPathList []string,
 	wg := new(sync.WaitGroup)
 
 	for i := range fileData {
-		img, _, _ := prepareImage(fileData[i])
-		if img != nil {
-			wg.Add(2)
-			go func(img image.Image, path string) {
-				defer wg.Done()
-				a.generateThumbnailImage(img, path)
-			}(img, thumbnailPathList[i])
-
-			go func(img image.Image, path string) {
-				defer wg.Done()
-				a.generatePreviewImage(img, path)
-			}(img, previewPathList[i])
+		img, release, err := prepareImage(a.srv.imgDecoder, bytes.NewReader(fileData[i]))
+		if err != nil {
+			mlog.Debug("Failed to prepare image", mlog.Err(err))
+			continue
 		}
+		wg.Add(2)
+		go func(img image.Image, path string) {
+			defer wg.Done()
+			a.generateThumbnailImage(img, path)
+		}(img, thumbnailPathList[i])
+
+		go func(img image.Image, path string) {
+			defer wg.Done()
+			a.generatePreviewImage(img, path)
+		}(img, previewPathList[i])
+
+		wg.Wait()
+		release()
 	}
-	wg.Wait()
 }
 
-func prepareImage(fileData []byte) (image.Image, int, int) {
+func prepareImage(imgDecoder *imaging.Decoder, imgData io.ReadSeeker) (img image.Image, release func(), err error) {
 	// Decode image bytes into Image object
-	img, imgType, err := image.Decode(bytes.NewReader(fileData))
+	var imgType string
+	img, imgType, release, err = imgDecoder.DecodeMemBounded(imgData)
 	if err != nil {
-		mlog.Error("Unable to decode image", mlog.Err(err))
-		return nil, 0, 0
+		return nil, nil, fmt.Errorf("prepareImage: failed to decode image: %w", err)
 	}
 
-	width := img.Bounds().Dx()
-	height := img.Bounds().Dy()
-
 	// Fill in the background of a potentially-transparent png file as white
 	if imgType == "png" {
-		dst := image.NewRGBA(img.Bounds())
-		draw.Draw(dst, dst.Bounds(), image.NewUniform(color.White), image.Point{}, draw.Src)
-		draw.Draw(dst, dst.Bounds(), img, img.Bounds().Min, draw.Over)
-		img = dst
+		imaging.FillImageTransparency(img, image.White)
 	}
 
+	imgData.Seek(0, io.SeekStart)
+
 	// Flip the image to be upright
-	orientation, _ := getImageOrientation(bytes.NewReader(fileData))
-	img = makeImageUpright(img, orientation)
-
-	return img, width, height
-}
-
-func makeImageUpright(img image.Image, orientation int) image.Image {
-	switch orientation {
-	case UprightMirrored:
-		return imaging.FlipH(img)
-	case UpsideDown:
-		return imaging.Rotate180(img)
-	case UpsideDownMirrored:
-		return imaging.FlipV(img)
-	case RotatedCWMirrored:
-		return imaging.Transpose(img)
-	case RotatedCCW:
-		return imaging.Rotate270(img)
-	case RotatedCCWMirrored:
-		return imaging.Transverse(img)
-	case RotatedCW:
-		return imaging.Rotate90(img)
-	default:
-		return img
-	}
-}
-
-func getImageOrientation(input io.Reader) (int, error) {
-	exifData, err := exif.Decode(input)
+	orientation, err := imaging.GetImageOrientation(imgData)
 	if err != nil {
-		return Upright, err
+		mlog.Debug("GetImageOrientation failed", mlog.Err(err))
 	}
+	img = imaging.MakeImageUpright(img, orientation)
 
-	tag, err := exifData.Get("Orientation")
-	if err != nil {
-		return Upright, err
-	}
-
-	orientation, err := tag.Int(0)
-	if err != nil {
-		return Upright, err
-	}
-
-	return orientation, nil
+	return img, release, nil
 }
 
 func (a *App) generateThumbnailImage(img image.Image, thumbnailPath string) {
-	buf := new(bytes.Buffer)
-	if err := jpeg.Encode(buf, genThumbnail(img), &jpeg.Options{Quality: 90}); err != nil {
+	var buf bytes.Buffer
+	if err := a.srv.imgEncoder.EncodeJPEG(&buf, imaging.GenerateThumbnail(img, imageThumbnailWidth, imageThumbnailHeight), jpegEncQuality); err != nil {
 		mlog.Error("Unable to encode image as jpeg", mlog.String("path", thumbnailPath), mlog.Err(err))
 		return
 	}
 
-	if _, err := a.WriteFile(buf, thumbnailPath); err != nil {
+	if _, err := a.WriteFile(&buf, thumbnailPath); err != nil {
 		mlog.Error("Unable to upload thumbnail", mlog.String("path", thumbnailPath), mlog.Err(err))
 		return
 	}
 }
 
 func (a *App) generatePreviewImage(img image.Image, previewPath string) {
-	preview := genPreview(img)
+	var buf bytes.Buffer
+	preview := imaging.GeneratePreview(img, imagePreviewWidth)
 
-	buf := new(bytes.Buffer)
-
-	if err := jpeg.Encode(buf, preview, &jpeg.Options{Quality: 90}); err != nil {
+	if err := a.srv.imgEncoder.EncodeJPEG(&buf, preview, jpegEncQuality); err != nil {
 		mlog.Error("Unable to encode image as preview jpg", mlog.Err(err), mlog.String("path", previewPath))
 		return
 	}
 
-	if _, err := a.WriteFile(buf, previewPath); err != nil {
+	if _, err := a.WriteFile(&buf, previewPath); err != nil {
 		mlog.Error("Unable to upload preview", mlog.Err(err), mlog.String("path", previewPath))
 		return
 	}
@@ -1186,18 +1117,26 @@ func (a *App) generatePreviewImage(img image.Image, previewPath string) {
 // will save fileinfo with the preview added
 func (a *App) generateMiniPreview(fi *model.FileInfo) {
 	if fi.IsImage() && fi.MiniPreview == nil {
-		data, err := a.ReadFile(fi.Path)
+		file, err := a.FileReader(fi.Path)
 		if err != nil {
-			mlog.Error("error reading image file", mlog.Err(err))
+			mlog.Debug("error reading image file", mlog.Err(err))
 			return
 		}
-		img, _, _ := prepareImage(data)
-		if img == nil {
+		defer file.Close()
+		img, release, imgErr := prepareImage(a.srv.imgDecoder, file)
+		if imgErr != nil {
+			mlog.Debug("generateMiniPreview: prepareImage failed", mlog.Err(imgErr))
 			return
 		}
-		fi.MiniPreview = model.GenerateMiniPreviewImage(img)
+		defer release()
+		if miniPreview, err := imaging.GenerateMiniPreviewImage(img,
+			miniPreviewImageWidth, miniPreviewImageHeight, jpegEncQuality); err != nil {
+			mlog.Info("Unable to generate mini preview image", mlog.Err(err))
+		} else {
+			fi.MiniPreview = &miniPreview
+		}
 		if _, appErr := a.Srv().Store.FileInfo().Upsert(fi); appErr != nil {
-			mlog.Error("creating mini preview failed", mlog.Err(appErr))
+			mlog.Debug("creating mini preview failed", mlog.Err(appErr))
 		} else {
 			a.Srv().Store.FileInfo().InvalidateFileInfosForPostCache(fi.PostId, false)
 		}
@@ -1411,8 +1350,8 @@ func (a *App) ExtractContentFromFileInfo(fileInfo *model.FileInfo) error {
 		return errors.Wrap(err, "failed to extract file content")
 	}
 	if text != "" {
-		if len(text) > MaxContentExtractionSize {
-			text = text[0:MaxContentExtractionSize]
+		if len(text) > maxContentExtractionSize {
+			text = text[0:maxContentExtractionSize]
 		}
 		if storeErr := a.Srv().Store.FileInfo().SetContent(fileInfo.Id, text); storeErr != nil {
 			return errors.Wrap(storeErr, "failed to save the extracted file content")

app/image.go

@@ -4,47 +4,29 @@
 package app
 
 import (
-	"image"
+	"fmt"
+	"io"
 
-	"github.com/disintegration/imaging"
+	"github.com/mattermost/mattermost-server/v5/app/imaging"
 )
 
-func genThumbnail(img image.Image) image.Image {
-	thumb := img
-	w := img.Bounds().Dx()
-	h := img.Bounds().Dy()
-
-	if h > ImageThumbnailHeight || w > ImageThumbnailWidth {
-		ratio := float64(h) / float64(w)
-		if ratio < ImageThumbnailRatio {
-			// we pre-calculate the thumbnail's width to make sure we are not upscaling.
-			targetWidth := int(float64(ImageThumbnailHeight) * float64(w) / float64(h))
-			if targetWidth <= w {
-				thumb = imaging.Resize(img, 0, ImageThumbnailHeight, imaging.Lanczos)
-			} else {
-				thumb = imaging.Resize(img, ImageThumbnailWidth, 0, imaging.Lanczos)
-			}
-		} else {
-			// we pre-calculate the thumbnail's height to make sure we are not upscaling.
-			targetHeight := int(float64(ImageThumbnailWidth) * float64(h) / float64(w))
-			if targetHeight <= h {
-				thumb = imaging.Resize(img, ImageThumbnailWidth, 0, imaging.Lanczos)
-			} else {
-				thumb = imaging.Resize(img, 0, ImageThumbnailHeight, imaging.Lanczos)
-			}
-		}
+func checkImageResolutionLimit(w, h int) error {
+	// This casting is done to prevent overflow on 32 bit systems (not needed
+	// in 64 bits systems because images can't have more than 32 bits height or
+	// width)
+	imageRes := int64(w) * int64(h)
+	if imageRes > maxImageRes {
+		return fmt.Errorf("image resolution is too high: %d, max allowed is %d", imageRes, maxImageRes)
 	}
 
-	return thumb
+	return nil
 }
 
-func genPreview(img image.Image) image.Image {
-	preview := img
-	w := img.Bounds().Dx()
-
-	if w > ImagePreviewWidth {
-		preview = imaging.Resize(img, ImagePreviewWidth, 0, imaging.Lanczos)
+func checkImageLimits(imageData io.Reader) error {
+	w, h, err := imaging.GetDimensions(imageData)
+	if err != nil {
+		return fmt.Errorf("failed to get image dimensions: %w", err)
 	}
 
-	return preview
+	return checkImageResolutionLimit(w, h)
 }

app/imaging/decode.go

@@ -0,0 +1,146 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	_ "image/gif"
+	_ "image/jpeg"
+	_ "image/png"
+	"io"
+	"sync"
+
+	_ "github.com/oov/psd"
+	_ "golang.org/x/image/bmp"
+	_ "golang.org/x/image/tiff"
+)
+
+// DecoderOptions holds configuration options for an image decoder.
+type DecoderOptions struct {
+	// The level of concurrency for the decoder. This defines a limit on the
+	// number of concurrently running encoding goroutines.
+	ConcurrencyLevel int
+}
+
+func (o *DecoderOptions) validate() error {
+	if o.ConcurrencyLevel < 0 {
+		return errors.New("ConcurrencyLevel must be non-negative")
+	}
+	return nil
+}
+
+// Decoder holds the necessary state to decode images.
+// This is safe to be used from multiple goroutines.
+type Decoder struct {
+	sem  chan struct{}
+	opts DecoderOptions
+}
+
+// NewDecoder creates and returns a new image decoder with the given options.
+func NewDecoder(opts DecoderOptions) (*Decoder, error) {
+	var d Decoder
+	if err := opts.validate(); err != nil {
+		return nil, fmt.Errorf("imaging: error validating decoder options: %w", err)
+	}
+	if opts.ConcurrencyLevel > 0 {
+		d.sem = make(chan struct{}, opts.ConcurrencyLevel)
+	}
+	d.opts = opts
+	return &d, nil
+}
+
+// Decode decodes the given encoded data and returns the decoded image.
+func (d *Decoder) Decode(rd io.Reader) (img image.Image, format string, err error) {
+	if d.opts.ConcurrencyLevel != 0 {
+		d.sem <- struct{}{}
+		defer func() { <-d.sem }()
+	}
+
+	img, format, err = image.Decode(rd)
+	if err != nil {
+		return nil, "", fmt.Errorf("imaging: failed to decode image: %w", err)
+	}
+
+	return img, format, nil
+}
+
+// DecodeMemBounded works similarly to Decode but also returns a release function that
+// must be called when access to the raw image is not needed anymore.
+// This sets the raw image data pointer to nil in an attempt to help the GC to re-use the underlying data as soon as possible.
+func (d *Decoder) DecodeMemBounded(rd io.Reader) (img image.Image, format string, releaseFunc func(), err error) {
+	if d.opts.ConcurrencyLevel != 0 {
+		d.sem <- struct{}{}
+		defer func() {
+			if err != nil {
+				<-d.sem
+			}
+		}()
+	}
+
+	img, format, err = image.Decode(rd)
+	if err != nil {
+		return nil, "", nil, fmt.Errorf("imaging: failed to decode image: %w", err)
+	}
+
+	var once sync.Once
+	releaseFunc = func() {
+		if d.opts.ConcurrencyLevel == 0 {
+			return
+		}
+		once.Do(func() {
+			if img != nil {
+				releaseImageData(img)
+			}
+			<-d.sem
+		})
+	}
+
+	return img, format, releaseFunc, nil
+}
+
+// DecodeConfig returns the image config for the given data.
+func (d *Decoder) DecodeConfig(rd io.Reader) (image.Config, string, error) {
+	img, format, err := image.DecodeConfig(rd)
+	if err != nil {
+		return image.Config{}, "", fmt.Errorf("imaging: failed to decode image config: %w", err)
+	}
+	return img, format, nil
+}
+
+// GetDimensions returns the dimensions for the given encoded image data.
+func GetDimensions(imageData io.Reader) (int, int, error) {
+	cfg, _, err := image.DecodeConfig(imageData)
+	if seeker, ok := imageData.(io.ReadSeeker); ok {
+		defer seeker.Seek(0, 0)
+	}
+	return cfg.Width, cfg.Height, err
+}
+
+// This is only needed to try and simplify GC work.
+func releaseImageData(img image.Image) {
+	switch raw := img.(type) {
+	case *image.Alpha:
+		raw.Pix = nil
+	case *image.Alpha16:
+		raw.Pix = nil
+	case *image.Gray:
+		raw.Pix = nil
+	case *image.Gray16:
+		raw.Pix = nil
+	case *image.NRGBA:
+		raw.Pix = nil
+	case *image.NRGBA64:
+		raw.Pix = nil
+	case *image.Paletted:
+		raw.Pix = nil
+	case *image.RGBA:
+		raw.Pix = nil
+	case *image.RGBA64:
+		raw.Pix = nil
+	default:
+		return
+	}
+}

app/imaging/decode_bench_test.go

@@ -0,0 +1,89 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"sync"
+	"testing"
+
+	"github.com/mattermost/mattermost-server/v5/utils/fileutils"
+
+	"github.com/stretchr/testify/require"
+)
+
+func BenchmarkDecoderDecode(b *testing.B) {
+	n := runtime.NumCPU()
+	for k := 1; k <= n; k++ {
+		b.Run(fmt.Sprintf("%d concurrency", k), func(b *testing.B) {
+			d, err := NewDecoder(DecoderOptions{
+				ConcurrencyLevel: k,
+			})
+			require.NotNil(b, d)
+			require.NoError(b, err)
+
+			imgDir, ok := fileutils.FindDir("tests")
+			require.True(b, ok)
+
+			b.ResetTimer()
+
+			var wg sync.WaitGroup
+			for i := 0; i < b.N; i++ {
+				b.StopTimer()
+				wg.Add(1)
+				imgFile, err := os.Open(imgDir + "/fill_test_opaque.png")
+				require.NoError(b, err)
+				defer imgFile.Close()
+				b.StartTimer()
+				go func() {
+					defer wg.Done()
+					img, _, err := d.Decode(imgFile)
+					require.NoError(b, err)
+					require.NotNil(b, img)
+				}()
+			}
+
+			wg.Wait()
+		})
+	}
+}
+
+func BenchmarkDecoderDecodeMemBounded(b *testing.B) {
+	n := runtime.NumCPU()
+	for k := 1; k <= n; k++ {
+		b.Run(fmt.Sprintf("%d concurrency", k), func(b *testing.B) {
+			d, err := NewDecoder(DecoderOptions{
+				ConcurrencyLevel: k,
+			})
+			require.NotNil(b, d)
+			require.NoError(b, err)
+
+			imgDir, ok := fileutils.FindDir("tests")
+			require.True(b, ok)
+
+			b.ResetTimer()
+
+			var wg sync.WaitGroup
+			for i := 0; i < b.N; i++ {
+				b.StopTimer()
+				wg.Add(1)
+				imgFile, err := os.Open(imgDir + "/fill_test_opaque.png")
+				require.NoError(b, err)
+				defer imgFile.Close()
+				b.StartTimer()
+				go func() {
+					defer wg.Done()
+					img, _, release, err := d.DecodeMemBounded(imgFile)
+					require.NoError(b, err)
+					require.NotNil(b, img)
+					release()
+				}()
+			}
+
+			wg.Wait()
+		})
+	}
+}

app/imaging/decode_test.go

@@ -0,0 +1,225 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"bytes"
+	"os"
+	"sync"
+	"testing"
+
+	"github.com/mattermost/mattermost-server/v5/utils/fileutils"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewDecoder(t *testing.T) {
+	t.Run("invalid options", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{
+			ConcurrencyLevel: -1,
+		})
+		require.Nil(t, d)
+		require.Error(t, err)
+	})
+
+	t.Run("empty options", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{})
+		require.NotNil(t, d)
+		require.NoError(t, err)
+		require.Nil(t, d.sem)
+	})
+
+	t.Run("valid options", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{
+			ConcurrencyLevel: 4,
+		})
+		require.NotNil(t, d)
+		require.NoError(t, err)
+		require.NotNil(t, d.sem)
+		require.Equal(t, 4, cap(d.sem))
+	})
+}
+
+func TestDecoderDecode(t *testing.T) {
+	t.Run("default options", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{})
+		require.NotNil(t, d)
+		require.NoError(t, err)
+
+		imgDir, ok := fileutils.FindDir("tests")
+		require.True(t, ok)
+
+		imgFile, err := os.Open(imgDir + "/test.png")
+		require.NoError(t, err)
+		require.NotNil(t, imgFile)
+		defer imgFile.Close()
+
+		img, format, err := d.Decode(imgFile)
+		require.NoError(t, err)
+		require.NotNil(t, img)
+		require.Equal(t, "png", format)
+	})
+
+	t.Run("concurrency bounded", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{
+			ConcurrencyLevel: 1,
+		})
+		require.NotNil(t, d)
+		require.NoError(t, err)
+
+		imgDir, ok := fileutils.FindDir("tests")
+		require.True(t, ok)
+
+		var wg sync.WaitGroup
+		wg.Add(2)
+
+		go func() {
+			defer wg.Done()
+
+			imgFile, err := os.Open(imgDir + "/test.png")
+			require.NoError(t, err)
+			require.NotNil(t, imgFile)
+			defer imgFile.Close()
+
+			img, format, err := d.Decode(imgFile)
+			require.NoError(t, err)
+			require.NotNil(t, img)
+			require.Equal(t, "png", format)
+		}()
+
+		go func() {
+			defer wg.Done()
+
+			imgFile, err := os.Open(imgDir + "/test.png")
+			require.NoError(t, err)
+			require.NotNil(t, imgFile)
+			defer imgFile.Close()
+
+			img, format, err := d.Decode(imgFile)
+			require.NoError(t, err)
+			require.NotNil(t, img)
+			require.Equal(t, "png", format)
+		}()
+
+		wg.Wait()
+		require.Empty(t, d.sem)
+	})
+}
+
+func TestDecoderDecodeMemBounded(t *testing.T) {
+	t.Run("concurrency bounded", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{
+			ConcurrencyLevel: 1,
+		})
+		require.NotNil(t, d)
+		require.NoError(t, err)
+
+		imgDir, ok := fileutils.FindDir("tests")
+		require.True(t, ok)
+
+		imgFile, err := os.Open(imgDir + "/test.png")
+		require.NoError(t, err)
+		require.NotNil(t, imgFile)
+		defer imgFile.Close()
+
+		var wg sync.WaitGroup
+		wg.Add(2)
+
+		var lock sync.Mutex
+
+		go func() {
+			defer wg.Done()
+			img, format, release, err := d.DecodeMemBounded(imgFile)
+			lock.Lock()
+			imgFile.Seek(0, 0)
+			lock.Unlock()
+			require.NoError(t, err)
+			defer release()
+			require.NotNil(t, img)
+			require.Equal(t, "png", format)
+			require.NotNil(t, release)
+			require.NotEmpty(t, d.sem)
+		}()
+
+		go func() {
+			defer wg.Done()
+			img, format, release, err := d.DecodeMemBounded(imgFile)
+			lock.Lock()
+			imgFile.Seek(0, 0)
+			lock.Unlock()
+			require.NoError(t, err)
+			defer release()
+			require.NotNil(t, img)
+			require.Equal(t, "png", format)
+			require.NotNil(t, release)
+			require.NotEmpty(t, d.sem)
+		}()
+
+		wg.Wait()
+		require.Empty(t, d.sem)
+	})
+
+	t.Run("decode error", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{
+			ConcurrencyLevel: 1,
+		})
+		require.NotNil(t, d)
+		require.NoError(t, err)
+
+		var data bytes.Buffer
+
+		var wg sync.WaitGroup
+		wg.Add(2)
+
+		go func() {
+			defer wg.Done()
+			img, format, release, err := d.DecodeMemBounded(&data)
+			require.Error(t, err)
+			require.Nil(t, img)
+			require.Empty(t, format)
+			require.Nil(t, release)
+		}()
+
+		go func() {
+			defer wg.Done()
+			img, format, release, err := d.DecodeMemBounded(&data)
+			require.Error(t, err)
+			require.Nil(t, img)
+			require.Empty(t, format)
+			require.Nil(t, release)
+		}()
+
+		wg.Wait()
+		require.Empty(t, d.sem)
+	})
+
+	t.Run("multiple releases", func(t *testing.T) {
+		d, err := NewDecoder(DecoderOptions{
+			ConcurrencyLevel: 1,
+		})
+		require.NotNil(t, d)
+		require.NoError(t, err)
+
+		imgDir, ok := fileutils.FindDir("tests")
+		require.True(t, ok)
+
+		imgFile, err := os.Open(imgDir + "/test.png")
+		require.NoError(t, err)
+		require.NotNil(t, imgFile)
+		defer imgFile.Close()
+
+		img, format, release, err := d.DecodeMemBounded(imgFile)
+		require.NoError(t, err)
+		require.NotNil(t, img)
+		require.Equal(t, "png", format)
+		require.NotNil(t, release)
+		require.Len(t, d.sem, 1)
+		release()
+		require.Empty(t, d.sem)
+		release()
+		require.Empty(t, d.sem)
+		release()
+		require.Empty(t, d.sem)
+	})
+}

app/imaging/encode.go

@@ -0,0 +1,86 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"io"
+
+	"image/jpeg"
+	"image/png"
+)
+
+// EncoderOptions holds configuration options for an image encoder.
+type EncoderOptions struct {
+	// The level of concurrency for the encoder. This defines a limit on the
+	// number of concurrently running encoding goroutines.
+	ConcurrencyLevel int
+}
+
+func (o *EncoderOptions) validate() error {
+	if o.ConcurrencyLevel < 0 {
+		return errors.New("ConcurrencyLevel must be non-negative")
+	}
+	return nil
+}
+
+// Decoder holds the necessary state to encode images.
+// This is safe to be used from multiple goroutines.
+type Encoder struct {
+	sem        chan struct{}
+	opts       EncoderOptions
+	pngEncoder *png.Encoder
+}
+
+// NewEncoder creates and returns a new image encoder with the given options.
+func NewEncoder(opts EncoderOptions) (*Encoder, error) {
+	var e Encoder
+	if err := opts.validate(); err != nil {
+		return nil, fmt.Errorf("imaging: error validating encoder options: %w", err)
+	}
+	if opts.ConcurrencyLevel > 0 {
+		e.sem = make(chan struct{}, opts.ConcurrencyLevel)
+	}
+	e.opts = opts
+	e.pngEncoder = &png.Encoder{}
+	return &e, nil
+}
+
+// EncodeJPEG encodes the given image in JPEG format and writes the data to
+// the passed writer.
+func (e *Encoder) EncodeJPEG(wr io.Writer, img image.Image, quality int) error {
+	if e.opts.ConcurrencyLevel > 0 {
+		e.sem <- struct{}{}
+		defer func() {
+			<-e.sem
+		}()
+	}
+
+	var encOpts jpeg.Options
+	encOpts.Quality = quality
+	if err := jpeg.Encode(wr, img, &encOpts); err != nil {
+		return fmt.Errorf("imaging: failed to encode jpeg: %w", err)
+	}
+
+	return nil
+}
+
+// EncodePNG encodes the given image in PNG format and writes the data to
+// the passed writer.
+func (e *Encoder) EncodePNG(wr io.Writer, img image.Image) error {
+	if e.opts.ConcurrencyLevel > 0 {
+		e.sem <- struct{}{}
+		defer func() {
+			<-e.sem
+		}()
+	}
+
+	if err := e.pngEncoder.Encode(wr, img); err != nil {
+		return fmt.Errorf("imaging: failed to encode png: %w", err)
+	}
+
+	return nil
+}

app/imaging/encode_test.go

@@ -0,0 +1,90 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"bytes"
+	"image"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewEncoder(t *testing.T) {
+	t.Run("invalid options", func(t *testing.T) {
+		e, err := NewEncoder(EncoderOptions{
+			ConcurrencyLevel: -1,
+		})
+		require.Nil(t, e)
+		require.Error(t, err)
+	})
+
+	t.Run("empty options", func(t *testing.T) {
+		e, err := NewEncoder(EncoderOptions{})
+		require.NotNil(t, e)
+		require.NoError(t, err)
+		require.Nil(t, e.sem)
+	})
+
+	t.Run("valid options", func(t *testing.T) {
+		e, err := NewEncoder(EncoderOptions{
+			ConcurrencyLevel: 4,
+		})
+		require.NotNil(t, e)
+		require.NoError(t, err)
+		require.NotNil(t, e.sem)
+		require.Equal(t, 4, cap(e.sem))
+	})
+}
+
+func TestEncoderEncode(t *testing.T) {
+	t.Run("default options", func(t *testing.T) {
+		e, err := NewEncoder(EncoderOptions{})
+		require.NotNil(t, e)
+		require.NoError(t, err)
+
+		var buf bytes.Buffer
+		rawImg := image.NewRGBA(image.Rect(0, 0, 1280, 1024))
+		err = e.EncodePNG(&buf, rawImg)
+		require.NoError(t, err)
+		require.NotEmpty(t, buf)
+
+		err = e.EncodeJPEG(&buf, rawImg, 50)
+		require.NoError(t, err)
+		require.NotEmpty(t, buf)
+	})
+
+	t.Run("concurrency bounded", func(t *testing.T) {
+		e, err := NewEncoder(EncoderOptions{
+			ConcurrencyLevel: 1,
+		})
+		require.NotNil(t, e)
+		require.NoError(t, err)
+
+		rawImg := image.NewRGBA(image.Rect(0, 0, 1280, 1024))
+
+		var wg sync.WaitGroup
+		wg.Add(2)
+
+		go func() {
+			defer wg.Done()
+			var buf bytes.Buffer
+			err := e.EncodePNG(&buf, rawImg)
+			require.NoError(t, err)
+			require.NotEmpty(t, buf)
+		}()
+
+		go func() {
+			defer wg.Done()
+			var buf bytes.Buffer
+			err := e.EncodeJPEG(&buf, rawImg, 50)
+			require.NoError(t, err)
+			require.NotEmpty(t, buf)
+		}()
+
+		wg.Wait()
+		require.Empty(t, e.sem)
+	})
+}

app/imaging/orientation.go

@@ -0,0 +1,76 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"image"
+	"io"
+
+	"github.com/disintegration/imaging"
+	"github.com/rwcarlsen/goexif/exif"
+)
+
+const (
+	/*
+	  EXIF Image Orientations
+	  1        2       3      4         5            6           7          8
+
+	  888888  888888      88  88      8888888888  88                  88  8888888888
+	  88          88      88  88      88  88      88  88          88  88      88  88
+	  8888      8888    8888  8888    88          8888888888  8888888888          88
+	  88          88      88  88
+	  88          88  888888  888888
+	*/
+	Upright = iota + 1
+	UprightMirrored
+	UpsideDown
+	UpsideDownMirrored
+	RotatedCWMirrored
+	RotatedCCW
+	RotatedCCWMirrored
+	RotatedCW
+)
+
+// MakeImageUpright changes the orientation of the given image.
+func MakeImageUpright(img image.Image, orientation int) image.Image {
+	switch orientation {
+	case UprightMirrored:
+		return imaging.FlipH(img)
+	case UpsideDown:
+		return imaging.Rotate180(img)
+	case UpsideDownMirrored:
+		return imaging.FlipV(img)
+	case RotatedCWMirrored:
+		return imaging.Transpose(img)
+	case RotatedCCW:
+		return imaging.Rotate270(img)
+	case RotatedCCWMirrored:
+		return imaging.Transverse(img)
+	case RotatedCW:
+		return imaging.Rotate90(img)
+	default:
+		return img
+	}
+}
+
+// GetImageOrientation reads the input data and returns the EXIF encoded
+// image orientation.
+func GetImageOrientation(input io.Reader) (int, error) {
+	exifData, err := exif.Decode(input)
+	if err != nil {
+		return Upright, err
+	}
+
+	tag, err := exifData.Get("Orientation")
+	if err != nil {
+		return Upright, err
+	}
+
+	orientation, err := tag.Int(0)
+	if err != nil {
+		return Upright, err
+	}
+
+	return orientation, nil
+}

app/imaging/preview.go

@@ -0,0 +1,66 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"image/jpeg"
+
+	"github.com/disintegration/imaging"
+)
+
+// GeneratePreview generates the preview for the given image.
+func GeneratePreview(img image.Image, width int) image.Image {
+	preview := img
+	w := img.Bounds().Dx()
+
+	if w > width {
+		preview = imaging.Resize(img, width, 0, imaging.Lanczos)
+	}
+
+	return preview
+}
+
+// GenerateThumbnail generates the thumbnail for the given image.
+func GenerateThumbnail(img image.Image, width, height int) image.Image {
+	thumb := img
+	w := img.Bounds().Dx()
+	h := img.Bounds().Dy()
+	expectedRatio := float64(height) / float64(width)
+
+	if h > height || w > width {
+		ratio := float64(h) / float64(w)
+		if ratio < expectedRatio {
+			// we pre-calculate the thumbnail's width to make sure we are not upscaling.
+			targetWidth := int(float64(height) * float64(w) / float64(h))
+			if targetWidth <= w {
+				thumb = imaging.Resize(img, 0, height, imaging.Lanczos)
+			} else {
+				thumb = imaging.Resize(img, width, 0, imaging.Lanczos)
+			}
+		} else {
+			// we pre-calculate the thumbnail's height to make sure we are not upscaling.
+			targetHeight := int(float64(width) * float64(h) / float64(w))
+			if targetHeight <= h {
+				thumb = imaging.Resize(img, width, 0, imaging.Lanczos)
+			} else {
+				thumb = imaging.Resize(img, 0, height, imaging.Lanczos)
+			}
+		}
+	}
+
+	return thumb
+}
+
+// GenerateMiniPreviewImage generates the mini preview for the given image.
+func GenerateMiniPreviewImage(img image.Image, w, h, q int) ([]byte, error) {
+	var buf bytes.Buffer
+	preview := imaging.Resize(img, w, h, imaging.Lanczos)
+	if err := jpeg.Encode(&buf, preview, &jpeg.Options{Quality: q}); err != nil {
+		return nil, fmt.Errorf("failed to encode image to JPEG format: %w", err)
+	}
+	return buf.Bytes(), nil
+}

app/imaging/svg.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
 // See LICENSE.txt for license information.
 
-package app
+package imaging
 
 import (
 	"encoding/xml"
@@ -12,12 +12,14 @@ import (
 	"github.com/pkg/errors"
 )
 
+// SVGInfo holds information for a SVG image.
 type SVGInfo struct {
 	Width  int
 	Height int
 }
 
-func parseSVG(svgReader io.Reader) (SVGInfo, error) {
+// ParseSVG returns information for the given SVG input data.
+func ParseSVG(svgReader io.Reader) (SVGInfo, error) {
 	var parsedSVG struct {
 		Width   string `xml:"width,attr,omitempty"`
 		Height  string `xml:"height,attr,omitempty"`

app/imaging/svg_test.go

@@ -1,7 +1,7 @@
 // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
 // See LICENSE.txt for license information.
 
-package app
+package imaging
 
 import (
 	"fmt"
@@ -45,7 +45,7 @@ func TestParseValidSVGData(t *testing.T) {
 		generateSVGData(width, height, false, true, true),  // missing viewBox, properly formed width & height; alternate format
 	}
 	for index, svg := range validSVGs {
-		svgInfo, err := parseSVG(svg)
+		svgInfo, err := ParseSVG(svg)
 		if err != nil {
 			t.Errorf("Should be able to parse SVG attributes at index %d, but was not able to: err = %v", index, err)
 		} else {
@@ -68,7 +68,7 @@ func TestParseInvalidSVGData(t *testing.T) {
 		generateSVGData(width, 0, false, true, false),       // missing viewBox, malformed height, properly formed width
 	}
 	for index, svg := range invalidSVGs {
-		_, err := parseSVG(svg)
+		_, err := ParseSVG(svg)
 		if err == nil {
 			t.Errorf("Should not be able to parse SVG attributes at index %d, but was definitely able to!", index)
 		}

app/imaging/utils.go

@@ -0,0 +1,147 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"image"
+	"image/color"
+
+	"github.com/disintegration/imaging"
+)
+
+type rawImg interface {
+	Set(x, y int, c color.Color)
+	Opaque() bool
+}
+
+func isFullyTransparent(c color.Color) bool {
+	// TODO: This can be optimized by checking the color type and
+	// only extract the needed alpha value.
+	_, _, _, a := c.RGBA()
+	return a == 0
+}
+
+// FillImageTransparency fills in-place all the fully transparent pixels of the
+// input image with the given color.
+func FillImageTransparency(img image.Image, c color.Color) {
+	var i rawImg
+
+	bounds := img.Bounds()
+
+	fillFunc := func() {
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			for x := bounds.Min.X; x < bounds.Max.X; x++ {
+				if isFullyTransparent(img.At(x, y)) {
+					i.Set(x, y, c)
+				}
+			}
+		}
+	}
+
+	switch raw := img.(type) {
+	case *image.Alpha:
+		i = raw
+	case *image.Alpha16:
+		i = raw
+	case *image.Gray:
+		i = raw
+	case *image.Gray16:
+		i = raw
+	case *image.NRGBA:
+		i = raw
+		col := color.NRGBAModel.Convert(c).(color.NRGBA)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					if raw.Pix[i+3] == 0x00 {
+						raw.Pix[i] = col.R
+						raw.Pix[i+1] = col.G
+						raw.Pix[i+2] = col.B
+						raw.Pix[i+3] = col.A
+					}
+				}
+			}
+		}
+	case *image.NRGBA64:
+		i = raw
+		col := color.NRGBA64Model.Convert(c).(color.NRGBA64)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					a := uint16(raw.Pix[i+6])<<8 | uint16(raw.Pix[i+7])
+					if a == 0 {
+						raw.Pix[i] = uint8(col.R >> 8)
+						raw.Pix[i+1] = uint8(col.R)
+						raw.Pix[i+2] = uint8(col.G >> 8)
+						raw.Pix[i+3] = uint8(col.G)
+						raw.Pix[i+4] = uint8(col.B >> 8)
+						raw.Pix[i+5] = uint8(col.B)
+						raw.Pix[i+6] = uint8(col.A >> 8)
+						raw.Pix[i+7] = uint8(col.A)
+					}
+				}
+			}
+		}
+	case *image.Paletted:
+		i = raw
+		fillFunc = func() {
+			for i := range raw.Palette {
+				if isFullyTransparent(raw.Palette[i]) {
+					raw.Palette[i] = c
+				}
+			}
+		}
+	case *image.RGBA:
+		i = raw
+		col := color.RGBAModel.Convert(c).(color.RGBA)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					if raw.Pix[i+3] == 0x00 {
+						raw.Pix[i] = col.R
+						raw.Pix[i+1] = col.G
+						raw.Pix[i+2] = col.B
+						raw.Pix[i+3] = col.A
+					}
+				}
+			}
+		}
+	case *image.RGBA64:
+		i = raw
+		col := color.RGBA64Model.Convert(c).(color.RGBA64)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					a := uint16(raw.Pix[i+6])<<8 | uint16(raw.Pix[i+7])
+					if a == 0 {
+						raw.Pix[i] = uint8(col.R >> 8)
+						raw.Pix[i+1] = uint8(col.R)
+						raw.Pix[i+2] = uint8(col.G >> 8)
+						raw.Pix[i+3] = uint8(col.G)
+						raw.Pix[i+4] = uint8(col.B >> 8)
+						raw.Pix[i+5] = uint8(col.B)
+						raw.Pix[i+6] = uint8(col.A >> 8)
+						raw.Pix[i+7] = uint8(col.A)
+					}
+				}
+			}
+		}
+	default:
+		return
+	}
+
+	if !i.Opaque() {
+		fillFunc()
+	}
+}
+
+// FillCenter creates an image with the specified dimensions and fills it with
+// the centered and scaled source image.
+func FillCenter(img image.Image, w, h int) *image.NRGBA {
+	return imaging.Fill(img, w, h, imaging.Center, imaging.Lanczos)
+}

app/imaging/utils_bench_test.go

@@ -0,0 +1,103 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"testing"
+)
+
+func fillImageTransparencyOld(img image.Image, c color.Color) {
+	dst := image.NewRGBA(img.Bounds())
+	draw.Draw(dst, dst.Bounds(), image.NewUniform(color.White), image.Point{}, draw.Src)
+	draw.Draw(dst, dst.Bounds(), img, img.Bounds().Min, draw.Over)
+}
+
+func fullyOpaqueGen(w, h int) func() image.Image {
+	return func() image.Image {
+		dst := image.NewRGBA(image.Rect(0, 0, w, h))
+		draw.Draw(dst, dst.Bounds(), image.NewUniform(color.White), image.Point{}, draw.Src)
+		return dst
+	}
+}
+
+func partiallyOpaqueGen(w, h int) func() image.Image {
+	return func() image.Image {
+		dst := image.NewRGBA(image.Rect(0, 0, w, h))
+		draw.Draw(dst, image.Rect(0, 0, w/2, h/2), image.NewUniform(color.White), image.Point{}, draw.Src)
+		return dst
+	}
+}
+
+func fullyTransparentGen(w, h int) func() image.Image {
+	return func() image.Image {
+		return image.NewRGBA(image.Rect(0, 0, w, h))
+	}
+}
+
+func fullyOpaquePaletteGen(w, h int) func() image.Image {
+	return func() image.Image {
+		return image.NewPaletted(image.Rect(0, 0, w, h), []color.Color{image.White})
+	}
+}
+
+func fullyTransparentPaletteGen(w, h int) func() image.Image {
+	return func() image.Image {
+		return image.NewPaletted(image.Rect(0, 0, w, h), []color.Color{image.Transparent})
+	}
+}
+
+var tcs = []struct {
+	name   string
+	imgGen func() image.Image
+}{
+	{
+		"10MPx fully transparent RGBA",
+		fullyTransparentGen(1000, 1000),
+	},
+	{
+		"10MPx partially opaque RGBA",
+		partiallyOpaqueGen(1000, 1000),
+	},
+	{
+		"10MPx fully opaque RGBA",
+		fullyOpaqueGen(1000, 1000),
+	},
+	{
+		"10MPx fully opaque palette",
+		fullyOpaquePaletteGen(1000, 1000),
+	},
+	{
+		"10MPx fully transparent palette",
+		fullyTransparentPaletteGen(1000, 1000),
+	},
+}
+
+func BenchmarkFillImageTransparency(b *testing.B) {
+	for _, tc := range tcs {
+		b.Run(tc.name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				b.StopTimer()
+				img := tc.imgGen()
+				b.StartTimer()
+				FillImageTransparency(img, image.White)
+			}
+		})
+	}
+}
+
+func BenchmarkFillImageTransparencyOld(b *testing.B) {
+	for _, tc := range tcs {
+		b.Run(tc.name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				b.StopTimer()
+				img := tc.imgGen()
+				b.StartTimer()
+				fillImageTransparencyOld(img, image.White)
+			}
+		})
+	}
+}

app/imaging/utils_test.go

@@ -0,0 +1,115 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"bytes"
+	"image/color"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/mattermost/mattermost-server/v5/utils/fileutils"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFillImageTransparency(t *testing.T) {
+	tcs := []struct {
+		name       string
+		inputName  string
+		outputName string
+		fillColor  color.Color
+	}{
+		{
+			"8-bit Palette",
+			"fill_test_8bit_palette.png",
+			"fill_test_8bit_palette_out.png",
+			color.RGBA{0, 255, 0, 255},
+		},
+		{
+			"8-bit RGB",
+			"fill_test_8bit_rgb.png",
+			"fill_test_8bit_rgb_out.png",
+			color.RGBA{0, 255, 0, 255},
+		},
+		{
+			"8-bit RGBA",
+			"fill_test_8bit_rgba.png",
+			"fill_test_8bit_rgba_out.png",
+			color.RGBA{0, 255, 0, 255},
+		},
+		{
+			"16-bit RGB",
+			"fill_test_16bit_rgb.png",
+			"fill_test_16bit_rgb_out.png",
+			color.RGBA{0, 255, 0, 255},
+		},
+		{
+			"16-bit RGBA",
+			"fill_test_16bit_rgba.png",
+			"fill_test_16bit_rgba_out.png",
+			color.RGBA{0, 255, 0, 255},
+		},
+	}
+
+	imgDir, ok := fileutils.FindDir("tests")
+	require.True(t, ok)
+
+	e, err := NewEncoder(EncoderOptions{})
+	require.NotNil(t, e)
+	require.NoError(t, err)
+
+	d, err := NewDecoder(DecoderOptions{})
+	require.NotNil(t, d)
+	require.NoError(t, err)
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			inputFile, err := os.Open(imgDir + "/" + tc.inputName)
+			require.NoError(t, err)
+			require.NotNil(t, inputFile)
+			defer inputFile.Close()
+
+			inputImg, format, err := d.Decode(inputFile)
+			require.NoError(t, err)
+			require.NotNil(t, inputImg)
+			require.Equal(t, "png", format)
+
+			expectedBytes, err := ioutil.ReadFile(imgDir + "/" + tc.outputName)
+			require.NoError(t, err)
+
+			FillImageTransparency(inputImg, tc.fillColor)
+
+			var b bytes.Buffer
+			err = e.EncodePNG(&b, inputImg)
+			require.NoError(t, err)
+
+			require.Equal(t, expectedBytes, b.Bytes())
+		})
+	}
+
+	t.Run("Opaque image", func(t *testing.T) {
+		inputFile, err := os.Open(imgDir + "/fill_test_opaque.png")
+		require.NoError(t, err)
+		require.NotNil(t, inputFile)
+		defer inputFile.Close()
+
+		inputImg, format, err := d.Decode(inputFile)
+		require.NoError(t, err)
+		require.NotNil(t, inputImg)
+		require.Equal(t, "png", format)
+
+		inputFile.Seek(0, 0)
+
+		expectedImg, format, err := d.Decode(inputFile)
+		require.NoError(t, err)
+		require.NotNil(t, expectedImg)
+		require.Equal(t, "png", format)
+
+		FillImageTransparency(inputImg, color.RGBA{0, 255, 0, 255})
+
+		require.Equal(t, expectedImg, inputImg)
+	})
+}

app/server.go

@@ -38,6 +38,7 @@ import (
 	"golang.org/x/crypto/acme/autocert"
 
 	"github.com/mattermost/mattermost-server/v5/app/featureflag"
+	"github.com/mattermost/mattermost-server/v5/app/imaging"
 	"github.com/mattermost/mattermost-server/v5/app/request"
 	"github.com/mattermost/mattermost-server/v5/audit"
 	"github.com/mattermost/mattermost-server/v5/config"
@@ -207,6 +208,9 @@ type Server struct {
 	featureFlagStop              chan struct{}
 	featureFlagStopped           chan struct{}
 	featureFlagSynchronizerMutex sync.Mutex
+
+	imgDecoder *imaging.Decoder
+	imgEncoder *imaging.Encoder
 }
 
 func NewServer(options ...Option) (*Server, error) {
@@ -245,6 +249,20 @@ func NewServer(options ...Option) (*Server, error) {
 		mlog.Error("Could not initiate logging", mlog.Err(err))
 	}
 
+	var imgErr error
+	s.imgDecoder, imgErr = imaging.NewDecoder(imaging.DecoderOptions{
+		ConcurrencyLevel: runtime.NumCPU(),
+	})
+	if imgErr != nil {
+		return nil, errors.Wrap(imgErr, "failed to create image decoder")
+	}
+	s.imgEncoder, imgErr = imaging.NewEncoder(imaging.EncoderOptions{
+		ConcurrencyLevel: runtime.NumCPU(),
+	})
+	if imgErr != nil {
+		return nil, errors.Wrap(imgErr, "failed to create image encoder")
+	}
+
 	// This is called after initLogging() to avoid a race condition.
 	mlog.Info("Server is initializing...", mlog.String("go_version", runtime.Version()))
 

app/slack.go

@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"image"
 	"mime/multipart"
 	"regexp"
 	"strings"
@@ -39,7 +40,13 @@ func (a *App) SlackImport(c *request.Context, fileData multipart.File, fileSize
 		GeneratePreviewImage:   a.generatePreviewImage,
 		InvalidateAllCaches:    func() { a.srv.InvalidateAllCaches() },
 		MaxPostSize:            func() int { return a.srv.MaxPostSize() },
-		PrepareImage:           prepareImage,
+		PrepareImage: func(fileData []byte) (image.Image, func(), error) {
+			img, release, err := prepareImage(a.srv.imgDecoder, bytes.NewReader(fileData))
+			if err != nil {
+				return nil, nil, err
+			}
+			return img, release, err
+		},
 	}
 
 	importer := slackimport.New(a.srv.Store, actions, a.Config())

app/team.go

@@ -9,15 +9,13 @@ import (
 	"errors"
 	"fmt"
 	"image"
-	"image/png"
 	"io"
 	"mime/multipart"
 	"net/http"
 	"net/url"
 	"strings"
 
-	"github.com/disintegration/imaging"
-
+	"github.com/mattermost/mattermost-server/v5/app/imaging"
 	"github.com/mattermost/mattermost-server/v5/app/request"
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/plugin"
@@ -1898,21 +1896,11 @@ func (a *App) SetTeamIconFromMultiPartFile(teamID string, file multipart.File) *
 		return model.NewAppError("setTeamIcon", "api.team.set_team_icon.storage.app_error", nil, "", http.StatusNotImplemented)
 	}
 
-	// Decode image config first to check dimensions before loading the whole thing into memory later on
-	config, _, err := image.DecodeConfig(file)
-	if err != nil {
-		return model.NewAppError("SetTeamIcon", "api.team.set_team_icon.decode_config.app_error", nil, err.Error(), http.StatusBadRequest)
+	if limitErr := checkImageLimits(file); limitErr != nil {
+		return model.NewAppError("SetTeamIcon", "api.team.set_team_icon.check_image_limits.app_error",
+			nil, limitErr.Error(), http.StatusBadRequest)
 	}
 
-	// This casting is done to prevent overflow on 32 bit systems (not needed
-	// in 64 bits systems because images can't have more than 32 bits height or
-	// width)
-	if int64(config.Width)*int64(config.Height) > model.MaxImageSize {
-		return model.NewAppError("SetTeamIcon", "api.team.set_team_icon.too_large.app_error", nil, "", http.StatusBadRequest)
-	}
-
-	file.Seek(0, 0)
-
 	return a.SetTeamIconFromFile(team, file)
 }
 
@@ -1923,15 +1911,15 @@ func (a *App) SetTeamIconFromFile(team *model.Team, file io.Reader) *model.AppEr
 		return model.NewAppError("SetTeamIcon", "api.team.set_team_icon.decode.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
 
-	orientation, _ := getImageOrientation(file)
-	img = makeImageUpright(img, orientation)
+	orientation, _ := imaging.GetImageOrientation(file)
+	img = imaging.MakeImageUpright(img, orientation)
 
 	// Scale team icon
 	teamIconWidthAndHeight := 128
-	img = imaging.Fill(img, teamIconWidthAndHeight, teamIconWidthAndHeight, imaging.Center, imaging.Lanczos)
+	img = imaging.FillCenter(img, teamIconWidthAndHeight, teamIconWidthAndHeight)
 
 	buf := new(bytes.Buffer)
-	err = png.Encode(buf, img)
+	err = a.srv.imgEncoder.EncodePNG(buf, img)
 	if err != nil {
 		return model.NewAppError("SetTeamIcon", "api.team.set_team_icon.encode.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}

app/upload.go

@@ -265,14 +265,11 @@ func (a *App) UploadData(c *request.Context, us *model.UploadSession, rd io.Read
 
 	// image post-processing
 	if info.IsImage() {
-		// Check dimensions before loading the whole thing into memory later on
-		// This casting is done to prevent overflow on 32 bit systems (not needed
-		// in 64 bits systems because images can't have more than 32 bits height or
-		// width)
-		if int64(info.Width)*int64(info.Height) > MaxImageSize {
+		if limitErr := checkImageResolutionLimit(info.Width, info.Height); limitErr != nil {
 			return nil, model.NewAppError("uploadData", "app.upload.upload_data.large_image.app_error",
 				map[string]interface{}{"Filename": us.Filename, "Width": info.Width, "Height": info.Height}, "", http.StatusBadRequest)
 		}
+
 		nameWithoutExtension := info.Name[:strings.LastIndex(info.Name, ".")]
 		info.PreviewPath = filepath.Dir(info.Path) + "/" + nameWithoutExtension + "_preview.jpg"
 		info.ThumbnailPath = filepath.Dir(info.Path) + "/" + nameWithoutExtension + "_thumb.jpg"

app/user.go

@@ -14,8 +14,6 @@ import (
 	"image"
 	"image/color"
 	"image/draw"
-	_ "image/gif"
-	_ "image/jpeg"
 	"image/png"
 	"io"
 	"io/ioutil"
@@ -25,10 +23,10 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/disintegration/imaging"
 	"github.com/golang/freetype"
 	"github.com/golang/freetype/truetype"
 
+	"github.com/mattermost/mattermost-server/v5/app/imaging"
 	"github.com/mattermost/mattermost-server/v5/app/request"
 	"github.com/mattermost/mattermost-server/v5/einterfaces"
 	"github.com/mattermost/mattermost-server/v5/model"
@@ -894,39 +892,29 @@ func (a *App) SetProfileImage(userID string, imageData *multipart.FileHeader) *m
 }
 
 func (a *App) SetProfileImageFromMultiPartFile(userID string, file multipart.File) *model.AppError {
-	// Decode image config first to check dimensions before loading the whole thing into memory later on
-	config, _, err := image.DecodeConfig(file)
-	if err != nil {
-		return model.NewAppError("SetProfileImage", "api.user.upload_profile_user.decode_config.app_error", nil, err.Error(), http.StatusBadRequest)
+	if limitErr := checkImageLimits(file); limitErr != nil {
+		return model.NewAppError("SetProfileImage", "api.user.upload_profile_user.check_image_limits.app_error", nil, "", http.StatusBadRequest)
 	}
-	// This casting is done to prevent overflow on 32 bit systems (not needed
-	// in 64 bits systems because images can't have more than 32 bits height or
-	// width)
-	if int64(config.Width)*int64(config.Height) > model.MaxImageSize {
-		return model.NewAppError("SetProfileImage", "api.user.upload_profile_user.too_large.app_error", nil, "", http.StatusBadRequest)
-	}
-
-	file.Seek(0, 0)
 
 	return a.SetProfileImageFromFile(userID, file)
 }
 
 func (a *App) AdjustImage(file io.Reader) (*bytes.Buffer, *model.AppError) {
 	// Decode image into Image object
-	img, _, err := image.Decode(file)
+	img, _, err := a.srv.imgDecoder.Decode(file)
 	if err != nil {
 		return nil, model.NewAppError("SetProfileImage", "api.user.upload_profile_user.decode.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
 
-	orientation, _ := getImageOrientation(file)
-	img = makeImageUpright(img, orientation)
+	orientation, _ := imaging.GetImageOrientation(file)
+	img = imaging.MakeImageUpright(img, orientation)
 
 	// Scale profile image
 	profileWidthAndHeight := 128
-	img = imaging.Fill(img, profileWidthAndHeight, profileWidthAndHeight, imaging.Center, imaging.Lanczos)
+	img = imaging.FillCenter(img, profileWidthAndHeight, profileWidthAndHeight)
 
 	buf := new(bytes.Buffer)
-	err = png.Encode(buf, img)
+	err = a.srv.imgEncoder.EncodePNG(buf, img)
 	if err != nil {
 		return nil, model.NewAppError("SetProfileImage", "api.user.upload_profile_user.encode.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}

i18n/en.json

@@ -3011,12 +3011,12 @@
     "translation": "Empty array under 'image' in request."
   },
   {
-    "id": "api.team.set_team_icon.decode.app_error",
-    "translation": "Could not decode team icon."
+    "id": "api.team.set_team_icon.check_image_limits.app_error",
+    "translation": "Image limits check failed. Resolution is too high."
   },
   {
-    "id": "api.team.set_team_icon.decode_config.app_error",
-    "translation": "Could not decode team icon metadata."
+    "id": "api.team.set_team_icon.decode.app_error",
+    "translation": "Could not decode team icon."
   },
   {
     "id": "api.team.set_team_icon.encode.app_error",
@@ -4199,12 +4199,12 @@
     "translation": "Empty array under 'image' in request."
   },
   {
-    "id": "api.user.upload_profile_user.decode.app_error",
-    "translation": "Could not decode profile image."
+    "id": "api.user.upload_profile_user.check_image_limits.app_error",
+    "translation": "Image limits check failed. Resolution is too high."
   },
   {
-    "id": "api.user.upload_profile_user.decode_config.app_error",
-    "translation": "Could not save profile image. File does not appear to be a valid image."
+    "id": "api.user.upload_profile_user.decode.app_error",
+    "translation": "Could not decode profile image."
   },
   {
     "id": "api.user.upload_profile_user.encode.app_error",
@@ -6743,12 +6743,12 @@
     "translation": "Failed to close user index."
   },
   {
-    "id": "brand.save_brand_image.decode.app_error",
-    "translation": "Unable to decode the image data."
+    "id": "brand.save_brand_image.check_image_limits.app_error",
+    "translation": "Image limits check failed. Resolution is too high."
   },
   {
-    "id": "brand.save_brand_image.decode_config.app_error",
-    "translation": "Unable to get image metadata."
+    "id": "brand.save_brand_image.decode.app_error",
+    "translation": "Unable to decode the image data."
   },
   {
     "id": "brand.save_brand_image.encode.app_error",
@@ -6762,10 +6762,6 @@
     "id": "brand.save_brand_image.save_image.app_error",
     "translation": "Unable to write the image file to your file storage. Please check your connection and try again."
   },
-  {
-    "id": "brand.save_brand_image.too_large.app_error",
-    "translation": "Unable to read the image file. Make sure the image size is less than 2 MB and try again."
-  },
   {
     "id": "cli.license.critical",
     "translation": "Feature requires an upgrade to Enterprise Edition and the inclusion of a license key. Please contact your System Administrator."

model/file_info.go

@@ -4,20 +4,14 @@
 package model
 
 import (
-	"bytes"
 	"encoding/json"
 	"image"
 	"image/gif"
-	"image/jpeg"
 	"io"
 	"mime"
 	"net/http"
 	"path/filepath"
 	"strings"
-
-	"github.com/disintegration/imaging"
-
-	"github.com/mattermost/mattermost-server/v5/shared/mlog"
 )
 
 const (
@@ -162,19 +156,6 @@ func NewInfo(name string) *FileInfo {
 	return info
 }
 
-func GenerateMiniPreviewImage(img image.Image) *[]byte {
-	preview := imaging.Resize(img, 16, 16, imaging.Lanczos)
-
-	buf := new(bytes.Buffer)
-
-	if err := jpeg.Encode(buf, preview, &jpeg.Options{Quality: 90}); err != nil {
-		mlog.Info("Unable to encode image as mini preview jpg", mlog.Err(err))
-		return nil
-	}
-	data := buf.Bytes()
-	return &data
-}
-
 func GetInfoForBytes(name string, data io.ReadSeeker, size int) (*FileInfo, *AppError) {
 	info := &FileInfo{
 		Name: name,

services/slackimport/slackimport.go

@@ -93,7 +93,7 @@ type Actions struct {
 	GeneratePreviewImage   func(image.Image, string)
 	InvalidateAllCaches    func()
 	MaxPostSize            func() int
-	PrepareImage           func(fileData []byte) (image.Image, int, int)
+	PrepareImage           func(fileData []byte) (image.Image, func(), error)
 }
 
 // SlackImporter is a service that allows to import slack dumps into mattermost
@@ -772,11 +772,13 @@ func (si *SlackImporter) oldImportFile(timestamp time.Time, file io.Reader, team
 	}
 
 	if fileInfo.IsImage() && fileInfo.MimeType != "image/svg+xml" {
-		img, _, _ := si.actions.PrepareImage(data)
-		if img != nil {
-			si.actions.GenerateThumbnailImage(img, fileInfo.ThumbnailPath)
-			si.actions.GeneratePreviewImage(img, fileInfo.PreviewPath)
+		img, release, err := si.actions.PrepareImage(data)
+		if err != nil {
+			return nil, err
 		}
+		defer release()
+		si.actions.GenerateThumbnailImage(img, fileInfo.ThumbnailPath)
+		si.actions.GeneratePreviewImage(img, fileInfo.PreviewPath)
 	}
 
 	return fileInfo, nil