MM-15480: Add server support for Range on files (#10892)

api4/file.go

@@ -546,7 +546,7 @@ func getFile(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 	defer fileReader.Close()
 
-	err = writeFileResponse(info.Name, info.MimeType, info.Size, *c.App.Config().ServiceSettings.WebserverMode, fileReader, forceDownload, w, r)
+	err = writeFileResponse(info.Name, info.MimeType, info.Size, time.Unix(0, info.UpdateAt*int64(1000*1000)), *c.App.Config().ServiceSettings.WebserverMode, fileReader, forceDownload, w, r)
 	if err != nil {
 		c.Err = err
 		return
@@ -588,7 +588,7 @@ func getFileThumbnail(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 	defer fileReader.Close()
 
-	err = writeFileResponse(info.Name, THUMBNAIL_IMAGE_TYPE, 0, *c.App.Config().ServiceSettings.WebserverMode, fileReader, forceDownload, w, r)
+	err = writeFileResponse(info.Name, THUMBNAIL_IMAGE_TYPE, 0, time.Unix(0, info.UpdateAt*int64(1000*1000)), *c.App.Config().ServiceSettings.WebserverMode, fileReader, forceDownload, w, r)
 	if err != nil {
 		c.Err = err
 		return
@@ -663,7 +663,7 @@ func getFilePreview(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 	defer fileReader.Close()
 
-	err = writeFileResponse(info.Name, PREVIEW_IMAGE_TYPE, 0, *c.App.Config().ServiceSettings.WebserverMode, fileReader, forceDownload, w, r)
+	err = writeFileResponse(info.Name, PREVIEW_IMAGE_TYPE, 0, time.Unix(0, info.UpdateAt*int64(1000*1000)), *c.App.Config().ServiceSettings.WebserverMode, fileReader, forceDownload, w, r)
 	if err != nil {
 		c.Err = err
 		return
@@ -729,14 +729,14 @@ func getPublicFile(c *Context, w http.ResponseWriter, r *http.Request) {
 	}
 	defer fileReader.Close()
 
-	err = writeFileResponse(info.Name, info.MimeType, info.Size, *c.App.Config().ServiceSettings.WebserverMode, fileReader, false, w, r)
+	err = writeFileResponse(info.Name, info.MimeType, info.Size, time.Unix(0, info.UpdateAt*int64(1000*1000)), *c.App.Config().ServiceSettings.WebserverMode, fileReader, false, w, r)
 	if err != nil {
 		c.Err = err
 		return
 	}
 }
 
-func writeFileResponse(filename string, contentType string, contentSize int64, webserverMode string, fileReader io.Reader, forceDownload bool, w http.ResponseWriter, r *http.Request) *model.AppError {
+func writeFileResponse(filename string, contentType string, contentSize int64, lastModification time.Time, webserverMode string, fileReader io.ReadSeeker, forceDownload bool, w http.ResponseWriter, r *http.Request) *model.AppError {
 	w.Header().Set("Cache-Control", "private, no-cache")
 	w.Header().Set("X-Content-Type-Options", "nosniff")
 
@@ -790,7 +790,7 @@ func writeFileResponse(filename string, contentType string, contentSize int64, w
 	w.Header().Set("X-Frame-Options", "DENY")
 	w.Header().Set("Content-Security-Policy", "Frame-ancestors 'none'")
 
-	io.Copy(w, fileReader)
+	http.ServeContent(w, r, filename, lastModification, fileReader)
 
 	return nil
 }

app/file.go

@@ -81,7 +81,7 @@ func (a *App) ReadFile(path string) ([]byte, *model.AppError) {
 }
 
 // Caller must close the first return value
-func (a *App) FileReader(path string) (io.ReadCloser, *model.AppError) {
+func (a *App) FileReader(path string) (filesstore.ReadCloseSeeker, *model.AppError) {
 	backend, err := a.FileBackend()
 	if err != nil {
 		return nil, err

services/filesstore/filesstore.go

@@ -10,10 +10,15 @@ import (
 	"github.com/mattermost/mattermost-server/model"
 )
 
+type ReadCloseSeeker interface {
+	io.ReadCloser
+	io.Seeker
+}
+
 type FileBackend interface {
 	TestConnection() *model.AppError
 
-	Reader(path string) (io.ReadCloser, *model.AppError)
+	Reader(path string) (ReadCloseSeeker, *model.AppError)
 	ReadFile(path string) ([]byte, *model.AppError)
 	FileExists(path string) (bool, *model.AppError)
 	CopyFile(oldPath, newPath string) *model.AppError

services/filesstore/localstore.go

@@ -34,7 +34,7 @@ func (b *LocalFileBackend) TestConnection() *model.AppError {
 	return nil
 }
 
-func (b *LocalFileBackend) Reader(path string) (io.ReadCloser, *model.AppError) {
+func (b *LocalFileBackend) Reader(path string) (ReadCloseSeeker, *model.AppError) {
 	f, err := os.Open(filepath.Join(b.directory, path))
 	if err != nil {
 		return nil, model.NewAppError("Reader", "api.file.reader.reading_local.app_error", nil, err.Error(), http.StatusInternalServerError)

services/filesstore/s3store.go

@@ -84,7 +84,7 @@ func (b *S3FileBackend) TestConnection() *model.AppError {
 }
 
 // Caller must close the first return value
-func (b *S3FileBackend) Reader(path string) (io.ReadCloser, *model.AppError) {
+func (b *S3FileBackend) Reader(path string) (ReadCloseSeeker, *model.AppError) {
 	s3Clnt, err := b.s3New()
 	if err != nil {
 		return nil, model.NewAppError("Reader", "api.file.reader.s3.app_error", nil, err.Error(), http.StatusInternalServerError)