Errcheck phase 1 (#1715)

* Avoid redundant logging in migrations

Return the error and let the caller handle the logging of the error if
needed.

While here, defer m.Close() to the function boundary.

* Treat errors as values

Use %v rather than %s and pass the errors directly.

* Generate a wrapped error on stat-failure

* Log 3 unchecked errors

Rather than ignore errors, log them at
the WARNING log level.

The server has been functioning without these, so assume they are not at
the ERROR level.

* Propagate errors upward

Failure in path generation was ignored. Propagate the errors upward the
call stack, so it can be handled at the level of orchestration.

* Warn on errors

Log errors rather than quenching them.

Errors are logged at the Warn-level for now.

* Check error when creating test databases

Use the builtin log package and stop the program fatally on error.

* Add warnings to uncheck task errors

Focus on the task system in a single commit, logging unchecked
errors as warnings.

* Warn-on-error in API routes

Look through the API routes, and make sure errors are being logged if
they occur. Prefer the Warn-log-level because none of these has proven
to be fatal in the system up until now.

* Propagate error when adding Util API

* Propagate error on adding util API

* Return unhandled error

* JS log API: propagate and log errors

* JS Plugins: log GQL addition failures.

* Warn on failure to write to stdin

* Warn on failure to stop task

* Wrap viper.BindEnv

The current viper code only errors if no name is provided, so it should
never fail. Rewrite the code flow to factor through a panic-function.

This removes error warnings from this part of the code.

* Log errors in concurrency test

If we can't initialize the configuration, treat the test as a failure.

* Warn on errors in configuration code

* Plug an unchecked error in gallery zip walking

* Warn on screenshot serving failure

* Warn on encoder screenshot failure

* Warn on errors in path-handling code

* Undo the errcheck on configurations for now.

* Use one-line initializers where applicable

rather than using

  err := f()
  if err!= nil { ..

prefer the shorter

  if err := f(); err != nil { ..

If f() isn't too long of a name, or wraps a function with a body.

pkg/api/resolver_mutation_configure.go

@@ -289,7 +289,9 @@ func (r *mutationResolver) ConfigureDlna(ctx context.Context, input models.Confi
 		if !*input.Enabled && dlnaService.IsRunning() {
 			dlnaService.Stop(nil)
 		} else if *input.Enabled && !dlnaService.IsRunning() {
-			dlnaService.Start(nil)
+			if err := dlnaService.Start(nil); err != nil {
+				logger.Warnf("error starting DLNA service: %v", err)
+			}
 		}
 	}
 

pkg/api/resolver_mutation_plugin.go

@@ -17,7 +17,7 @@ func (r *mutationResolver) RunPluginTask(ctx context.Context, pluginID string, t
 func (r *mutationResolver) ReloadPlugins(ctx context.Context) (bool, error) {
 	err := manager.GetInstance().PluginCache.LoadPlugins()
 	if err != nil {
-		logger.Errorf("Error reading plugin configs: %s", err.Error())
+		logger.Errorf("Error reading plugin configs: %v", err)
 	}
 
 	return true, nil

pkg/api/routes_image.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/go-chi/chi"
 	"github.com/stashapp/stash/pkg/image"
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/manager"
 	"github.com/stashapp/stash/pkg/models"
 	"github.com/stashapp/stash/pkg/utils"
@@ -59,7 +60,7 @@ func ImageCtx(next http.Handler) http.Handler {
 		imageID, _ := strconv.Atoi(imageIdentifierQueryParam)
 
 		var image *models.Image
-		manager.GetInstance().TxnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		readTxnErr := manager.GetInstance().TxnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			qb := repo.Image()
 			if imageID == 0 {
 				image, _ = qb.FindByChecksum(imageIdentifierQueryParam)
@@ -69,6 +70,9 @@ func ImageCtx(next http.Handler) http.Handler {
 
 			return nil
 		})
+		if readTxnErr != nil {
+			logger.Warnf("read transaction failure while trying to read image by id: %v", readTxnErr)
+		}
 
 		if image == nil {
 			http.Error(w, http.StatusText(404), 404)

pkg/api/routes_movie.go

@@ -6,6 +6,7 @@ import (
 	"strconv"
 
 	"github.com/go-chi/chi"
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/manager"
 	"github.com/stashapp/stash/pkg/models"
 	"github.com/stashapp/stash/pkg/utils"
@@ -32,17 +33,22 @@ func (rs movieRoutes) FrontImage(w http.ResponseWriter, r *http.Request) {
 	defaultParam := r.URL.Query().Get("default")
 	var image []byte
 	if defaultParam != "true" {
-		rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		err := rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			image, _ = repo.Movie().GetFrontImage(movie.ID)
 			return nil
 		})
+		if err != nil {
+			logger.Warnf("read transaction error while getting front image: %v", err)
+		}
 	}
 
 	if len(image) == 0 {
 		_, image, _ = utils.ProcessBase64Image(models.DefaultMovieImage)
 	}
 
-	utils.ServeImage(image, w, r)
+	if err := utils.ServeImage(image, w, r); err != nil {
+		logger.Warnf("error serving front image: %v", err)
+	}
 }
 
 func (rs movieRoutes) BackImage(w http.ResponseWriter, r *http.Request) {
@@ -50,17 +56,22 @@ func (rs movieRoutes) BackImage(w http.ResponseWriter, r *http.Request) {
 	defaultParam := r.URL.Query().Get("default")
 	var image []byte
 	if defaultParam != "true" {
-		rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		err := rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			image, _ = repo.Movie().GetBackImage(movie.ID)
 			return nil
 		})
+		if err != nil {
+			logger.Warnf("read transaction error on fetch back image: %v", err)
+		}
 	}
 
 	if len(image) == 0 {
 		_, image, _ = utils.ProcessBase64Image(models.DefaultMovieImage)
 	}
 
-	utils.ServeImage(image, w, r)
+	if err := utils.ServeImage(image, w, r); err != nil {
+		logger.Warnf("error while serving image: %v", err)
+	}
 }
 
 func MovieCtx(next http.Handler) http.Handler {

pkg/api/routes_performer.go

@@ -6,6 +6,7 @@ import (
 	"strconv"
 
 	"github.com/go-chi/chi"
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/manager"
 	"github.com/stashapp/stash/pkg/manager/config"
 	"github.com/stashapp/stash/pkg/models"
@@ -33,17 +34,22 @@ func (rs performerRoutes) Image(w http.ResponseWriter, r *http.Request) {
 
 	var image []byte
 	if defaultParam != "true" {
-		rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		readTxnErr := rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			image, _ = repo.Performer().GetImage(performer.ID)
 			return nil
 		})
+		if readTxnErr != nil {
+			logger.Warnf("couldn't execute getting a performer image from read transaction: %v", readTxnErr)
+		}
 	}
 
 	if len(image) == 0 || defaultParam == "true" {
 		image, _ = getRandomPerformerImageUsingName(performer.Name.String, performer.Gender.String, config.GetInstance().GetCustomPerformerImageLocation())
 	}
 
-	utils.ServeImage(image, w, r)
+	if err := utils.ServeImage(image, w, r); err != nil {
+		logger.Warnf("error serving image: %v", err)
+	}
 }
 
 func PerformerCtx(next http.Handler) http.Handler {

pkg/api/routes_scene.go

@@ -59,7 +59,7 @@ func getSceneFileContainer(scene *models.Scene) ffmpeg.Container {
 		// shouldn't happen, fallback to ffprobe
 		tmpVideoFile, err := ffmpeg.NewVideoFile(manager.GetInstance().FFProbePath, scene.Path, false)
 		if err != nil {
-			logger.Errorf("[transcode] error reading video file: %s", err.Error())
+			logger.Errorf("[transcode] error reading video file: %v", err)
 			return ffmpeg.Container("")
 		}
 
@@ -85,7 +85,9 @@ func (rs sceneRoutes) StreamMKV(w http.ResponseWriter, r *http.Request) {
 	container := getSceneFileContainer(scene)
 	if container != ffmpeg.Matroska {
 		w.WriteHeader(http.StatusBadRequest)
-		w.Write([]byte("not an mkv file"))
+		if _, err := w.Write([]byte("not an mkv file")); err != nil {
+			logger.Warnf("[stream] error writing to stream: %v", err)
+		}
 		return
 	}
 
@@ -105,7 +107,7 @@ func (rs sceneRoutes) StreamHLS(w http.ResponseWriter, r *http.Request) {
 
 	videoFile, err := ffmpeg.NewVideoFile(manager.GetInstance().FFProbePath, scene.Path, false)
 	if err != nil {
-		logger.Errorf("[stream] error reading video file: %s", err.Error())
+		logger.Errorf("[stream] error reading video file: %v", err)
 		return
 	}
 
@@ -126,7 +128,9 @@ func (rs sceneRoutes) StreamHLS(w http.ResponseWriter, r *http.Request) {
 	rangeStr := requestByteRange.ToHeaderValue(int64(str.Len()))
 	w.Header().Set("Content-Range", rangeStr)
 
-	w.Write(ret)
+	if n, err := w.Write(ret); err != nil {
+		logger.Warnf("[stream] error writing stream (wrote %v bytes): %v", n, err)
+	}
 }
 
 func (rs sceneRoutes) StreamTS(w http.ResponseWriter, r *http.Request) {
@@ -141,12 +145,15 @@ func (rs sceneRoutes) streamTranscode(w http.ResponseWriter, r *http.Request, vi
 
 	videoFile, err := ffmpeg.NewVideoFile(manager.GetInstance().FFProbePath, scene.Path, false)
 	if err != nil {
-		logger.Errorf("[stream] error reading video file: %s", err.Error())
+		logger.Errorf("[stream] error reading video file: %v", err)
 		return
 	}
 
 	// start stream based on query param, if provided
-	r.ParseForm()
+	if err = r.ParseForm(); err != nil {
+		logger.Warnf("[stream] error parsing query form: %v", err)
+	}
+
 	startTime := r.Form.Get("start")
 	requestedSize := r.Form.Get("resolution")
 
@@ -168,9 +175,11 @@ func (rs sceneRoutes) streamTranscode(w http.ResponseWriter, r *http.Request, vi
 	stream, err = encoder.GetTranscodeStream(options)
 
 	if err != nil {
-		logger.Errorf("[stream] error transcoding video file: %s", err.Error())
+		logger.Errorf("[stream] error transcoding video file: %v", err)
 		w.WriteHeader(http.StatusBadRequest)
-		w.Write([]byte(err.Error()))
+		if _, err := w.Write([]byte(err.Error())); err != nil {
+			logger.Warnf("[stream] error writing response: %v", err)
+		}
 		return
 	}
 
@@ -355,7 +364,7 @@ func SceneCtx(next http.Handler) http.Handler {
 		sceneID, _ := strconv.Atoi(sceneIdentifierQueryParam)
 
 		var scene *models.Scene
-		manager.GetInstance().TxnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		readTxnErr := manager.GetInstance().TxnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			qb := repo.Scene()
 			if sceneID == 0 {
 				// determine checksum/os by the length of the query param
@@ -370,6 +379,9 @@ func SceneCtx(next http.Handler) http.Handler {
 
 			return nil
 		})
+		if readTxnErr != nil {
+			logger.Warnf("error executing SceneCtx transaction: %v", readTxnErr)
+		}
 
 		if scene == nil {
 			http.Error(w, http.StatusText(404), 404)

pkg/api/routes_studio.go

@@ -6,6 +6,7 @@ import (
 	"strconv"
 
 	"github.com/go-chi/chi"
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/manager"
 	"github.com/stashapp/stash/pkg/models"
 	"github.com/stashapp/stash/pkg/utils"
@@ -32,17 +33,22 @@ func (rs studioRoutes) Image(w http.ResponseWriter, r *http.Request) {
 
 	var image []byte
 	if defaultParam != "true" {
-		rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		err := rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			image, _ = repo.Studio().GetImage(studio.ID)
 			return nil
 		})
+		if err != nil {
+			logger.Warnf("read transaction error while fetching studio image: %v", err)
+		}
 	}
 
 	if len(image) == 0 {
 		_, image, _ = utils.ProcessBase64Image(models.DefaultStudioImage)
 	}
 
-	utils.ServeImage(image, w, r)
+	if err := utils.ServeImage(image, w, r); err != nil {
+		logger.Warnf("error serving studio image: %v", err)
+	}
 }
 
 func StudioCtx(next http.Handler) http.Handler {

pkg/api/routes_tag.go

@@ -6,6 +6,7 @@ import (
 	"strconv"
 
 	"github.com/go-chi/chi"
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/manager"
 	"github.com/stashapp/stash/pkg/models"
 	"github.com/stashapp/stash/pkg/utils"
@@ -32,17 +33,22 @@ func (rs tagRoutes) Image(w http.ResponseWriter, r *http.Request) {
 
 	var image []byte
 	if defaultParam != "true" {
-		rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		err := rs.txnManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			image, _ = repo.Tag().GetImage(tag.ID)
 			return nil
 		})
+		if err != nil {
+			logger.Warnf("read transaction error while getting tag image: %v", err)
+		}
 	}
 
 	if len(image) == 0 {
 		image = models.DefaultTagImage
 	}
 
-	utils.ServeImage(image, w, r)
+	if err := utils.ServeImage(image, w, r); err != nil {
+		logger.Warnf("error serving tag image: %v", err)
+	}
 }
 
 func TagCtx(next http.Handler) http.Handler {

pkg/database/database.go

@@ -232,6 +232,7 @@ func RunMigrations() error {
 	if err != nil {
 		panic(err.Error())
 	}
+	defer m.Close()
 
 	databaseSchemaVersion, _, _ = m.Version()
 	stepNumber := appSchemaVersion - databaseSchemaVersion
@@ -240,14 +241,10 @@ func RunMigrations() error {
 		err = m.Steps(int(stepNumber))
 		if err != nil {
 			// migration failed
-			logger.Errorf("Error migrating database: %s", err.Error())
-			m.Close()
 			return err
 		}
 	}
 
-	m.Close()
-
 	// re-initialise the database
 	Initialize(dbPath)
 
@@ -255,7 +252,7 @@ func RunMigrations() error {
 	logger.Info("Performing vacuum on database")
 	_, err = DB.Exec("VACUUM")
 	if err != nil {
-		logger.Warnf("error while performing post-migration vacuum: %s", err.Error())
+		logger.Warnf("error while performing post-migration vacuum: %v", err)
 	}
 
 	return nil

pkg/dlna/service.go

@@ -251,7 +251,9 @@ func (s *Service) Stop(duration *time.Duration) {
 
 		if s.startTimer == nil {
 			s.startTimer = time.AfterFunc(*duration, func() {
-				s.Start(nil)
+				if err := s.Start(nil); err != nil {
+					logger.Warnf("error restarting DLNA server: %v", err)
+				}
 			})
 			t := time.Now().Add(*duration)
 			s.startTime = &t

pkg/ffmpeg/ffprobe.go

@@ -273,8 +273,9 @@ func parse(filePath string, probeJSON *FFProbeJSON, stripExt bool) (*VideoFile,
 	result.Duration = math.Round(duration*100) / 100
 	fileStat, err := os.Stat(filePath)
 	if err != nil {
-		logger.Errorf("Error statting file <%s>: %s", filePath, err.Error())
+		statErr := fmt.Errorf("error statting file <%s>: %w", filePath, err)
-		return nil, err
+		logger.Errorf("%v", statErr)
+		return nil, statErr
 	}
 	result.Size = fileStat.Size()
 	result.StartTime, _ = strconv.ParseFloat(probeJSON.Format.StartTime, 64)

pkg/ffmpeg/stream.go

@@ -224,7 +224,11 @@ func (e *Encoder) stream(probeResult VideoFile, options TranscodeStreamOptions)
 	}
 
 	registerRunningEncoder(probeResult.Path, cmd.Process)
-	go waitAndDeregister(probeResult.Path, cmd)
+	go func() {
+		if err := waitAndDeregister(probeResult.Path, cmd); err != nil {
+			logger.Warnf("Error while deregistering ffmpeg stream: %v", err)
+		}
+	}()
 
 	// stderr must be consumed or the process deadlocks
 	go func() {

pkg/manager/config/config.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/spf13/viper"
 
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/manager/paths"
 	"github.com/stashapp/stash/pkg/models"
 	"github.com/stashapp/stash/pkg/utils"
@@ -453,7 +454,10 @@ func (i *Instance) GetStashBoxes() []*models.StashBox {
 	i.RLock()
 	defer i.RUnlock()
 	var boxes []*models.StashBox
-	viper.UnmarshalKey(StashBoxes, &boxes)
+	if err := viper.UnmarshalKey(StashBoxes, &boxes); err != nil {
+		logger.Warnf("error in unmarshalkey: %v", err)
+	}
+
 	return boxes
 }
 
@@ -801,7 +805,9 @@ func (i *Instance) SetCSS(css string) {
 
 	buf := []byte(css)
 
-	ioutil.WriteFile(fn, buf, 0777)
+	if err := ioutil.WriteFile(fn, buf, 0777); err != nil {
+		logger.Warnf("error while writing %v bytes to %v: %v", len(buf), fn, err)
+	}
 }
 
 func (i *Instance) GetCSSEnabled() bool {

pkg/manager/config/config_concurrency_test.go

@@ -13,9 +13,9 @@ func TestConcurrentConfigAccess(t *testing.T) {
 	//const loops = 1000
 	const loops = 200
 	var wg sync.WaitGroup
-	for t := 0; t < workers; t++ {
+	for k := 0; k < workers; k++ {
 		wg.Add(1)
-		go func() {
+		go func(wk int) {
 			for l := 0; l < loops; l++ {
 				i.SetInitialConfig()
 
@@ -93,7 +93,7 @@ func TestConcurrentConfigAccess(t *testing.T) {
 				i.Set(MaxUploadSize, i.GetMaxUploadSize())
 			}
 			wg.Done()
-		}()
+		}(k)
 	}
 
 	wg.Wait()

pkg/manager/config/init.go

@@ -113,15 +113,21 @@ func initFlags() flagStruct {
 
 func initEnvs() {
 	viper.SetEnvPrefix("stash") // will be uppercased automatically
-	viper.BindEnv("host")          // STASH_HOST
+	bindEnv("host")             // STASH_HOST
-	viper.BindEnv("port")          // STASH_PORT
+	bindEnv("port")             // STASH_PORT
-	viper.BindEnv("external_host") // STASH_EXTERNAL_HOST
+	bindEnv("external_host")    // STASH_EXTERNAL_HOST
-	viper.BindEnv("generated")     // STASH_GENERATED
+	bindEnv("generated")        // STASH_GENERATED
-	viper.BindEnv("metadata")      // STASH_METADATA
+	bindEnv("metadata")         // STASH_METADATA
-	viper.BindEnv("cache")         // STASH_CACHE
+	bindEnv("cache")            // STASH_CACHE
 
 	// only set stash config flag if not already set
 	if instance.GetStashPaths() == nil {
-		viper.BindEnv("stash") // STASH_STASH
+		bindEnv("stash") // STASH_STASH
+	}
+}
+
+func bindEnv(key string) {
+	if err := viper.BindEnv(key); err != nil {
+		panic(fmt.Sprintf("unable to set environment key (%v): %v", key, err))
 	}
 }

pkg/manager/image.go

@@ -61,10 +61,13 @@ func walkGalleryZip(path string, walkFunc func(file *zip.File) error) error {
 
 func countImagesInZip(path string) int {
 	ret := 0
-	walkGalleryZip(path, func(file *zip.File) error {
+	err := walkGalleryZip(path, func(file *zip.File) error {
 		ret++
 		return nil
 	})
+	if err != nil {
+		logger.Warnf("Error while walking gallery zip: %v", err)
+	}
 
 	return ret
 }

pkg/manager/manager_tasks.go

@@ -163,7 +163,9 @@ func (s *singleton) Generate(ctx context.Context, input models.GenerateMetadataI
 	if err := s.validateFFMPEG(); err != nil {
 		return 0, err
 	}
-	instance.Paths.Generated.EnsureTmpDir()
+	if err := instance.Paths.Generated.EnsureTmpDir(); err != nil {
+		logger.Warnf("could not generate temporary directory: %v", err)
+	}
 
 	sceneIDs, err := utils.StringSliceToIntSlice(input.SceneIDs)
 	if err != nil {
@@ -250,14 +252,18 @@ func (s *singleton) Generate(ctx context.Context, input models.GenerateMetadataI
 
 		// Start measuring how long the generate has taken. (consider moving this up)
 		start := time.Now()
-		instance.Paths.Generated.EnsureTmpDir()
+		if err = instance.Paths.Generated.EnsureTmpDir(); err != nil {
+			logger.Warnf("could not create temprary directory: %v", err)
+		}
 
 		for _, scene := range scenes {
 			progress.Increment()
 			if job.IsCancelled(ctx) {
 				logger.Info("Stopping due to user request")
 				wg.Wait()
-				instance.Paths.Generated.EmptyTmpDir()
+				if err := instance.Paths.Generated.EmptyTmpDir(); err != nil {
+					logger.Warnf("failure emptying temporary directory: %v", err)
+				}
 				return
 			}
 
@@ -340,7 +346,9 @@ func (s *singleton) Generate(ctx context.Context, input models.GenerateMetadataI
 			if job.IsCancelled(ctx) {
 				logger.Info("Stopping due to user request")
 				wg.Wait()
-				instance.Paths.Generated.EmptyTmpDir()
+				if err := instance.Paths.Generated.EmptyTmpDir(); err != nil {
+					logger.Warnf("failure emptying temporary directory: %v", err)
+				}
 				elapsed := time.Since(start)
 				logger.Info(fmt.Sprintf("Generate finished (%s)", elapsed))
 				return
@@ -365,7 +373,9 @@ func (s *singleton) Generate(ctx context.Context, input models.GenerateMetadataI
 
 		wg.Wait()
 
-		instance.Paths.Generated.EmptyTmpDir()
+		if err = instance.Paths.Generated.EmptyTmpDir(); err != nil {
+			logger.Warnf("failure emptying temporary directory: %v", err)
+		}
 		elapsed := time.Since(start)
 		logger.Info(fmt.Sprintf("Generate finished (%s)", elapsed))
 	})
@@ -383,7 +393,9 @@ func (s *singleton) GenerateScreenshot(ctx context.Context, sceneId string, at f
 
 // generate default screenshot if at is nil
 func (s *singleton) generateScreenshot(ctx context.Context, sceneId string, at *float64) int {
-	instance.Paths.Generated.EnsureTmpDir()
+	if err := instance.Paths.Generated.EnsureTmpDir(); err != nil {
+		logger.Warnf("failure generating screenshot: %v", err)
+	}
 
 	j := job.MakeJobExec(func(ctx context.Context, progress *job.Progress) {
 		sceneIdInt, err := strconv.Atoi(sceneId)

pkg/manager/paths/paths_generated.go

@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"path/filepath"
 
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/utils"
 )
 
@@ -37,26 +38,30 @@ func (gp *generatedPaths) GetTmpPath(fileName string) string {
 	return filepath.Join(gp.Tmp, fileName)
 }
 
-func (gp *generatedPaths) EnsureTmpDir() {
+func (gp *generatedPaths) EnsureTmpDir() error {
-	utils.EnsureDir(gp.Tmp)
+	return utils.EnsureDir(gp.Tmp)
 }
 
-func (gp *generatedPaths) EmptyTmpDir() {
+func (gp *generatedPaths) EmptyTmpDir() error {
-	utils.EmptyDir(gp.Tmp)
+	return utils.EmptyDir(gp.Tmp)
 }
 
-func (gp *generatedPaths) RemoveTmpDir() {
+func (gp *generatedPaths) RemoveTmpDir() error {
-	utils.RemoveDir(gp.Tmp)
+	return utils.RemoveDir(gp.Tmp)
 }
 
 func (gp *generatedPaths) TempDir(pattern string) (string, error) {
-	gp.EnsureTmpDir()
+	if err := gp.EnsureTmpDir(); err != nil {
+		logger.Warnf("Could not ensure existence of a temporary directory: %v", err)
+	}
 	ret, err := ioutil.TempDir(gp.Tmp, pattern)
 	if err != nil {
 		return "", err
 	}
 
-	utils.EmptyDir(ret)
+	if err = utils.EmptyDir(ret); err != nil {
+		logger.Warnf("could not recursively empty dir: %v", err)
+	}
 
 	return ret, nil
 }

pkg/manager/paths/paths_json.go

@@ -3,6 +3,7 @@ package paths
 import (
 	"path/filepath"
 
+	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/utils"
 )
 
@@ -43,14 +44,30 @@ func GetJSONPaths(baseDir string) *JSONPaths {
 
 func EnsureJSONDirs(baseDir string) {
 	jsonPaths := GetJSONPaths(baseDir)
-	utils.EnsureDir(jsonPaths.Metadata)
+	if err := utils.EnsureDir(jsonPaths.Metadata); err != nil {
-	utils.EnsureDir(jsonPaths.Scenes)
+		logger.Warnf("couldn't create directories for Metadata: %v", err)
-	utils.EnsureDir(jsonPaths.Images)
+	}
-	utils.EnsureDir(jsonPaths.Galleries)
+	if err := utils.EnsureDir(jsonPaths.Scenes); err != nil {
-	utils.EnsureDir(jsonPaths.Performers)
+		logger.Warnf("couldn't create directories for Scenes: %v", err)
-	utils.EnsureDir(jsonPaths.Studios)
+	}
-	utils.EnsureDir(jsonPaths.Movies)
+	if err := utils.EnsureDir(jsonPaths.Images); err != nil {
-	utils.EnsureDir(jsonPaths.Tags)
+		logger.Warnf("couldn't create directories for Images: %v", err)
+	}
+	if err := utils.EnsureDir(jsonPaths.Galleries); err != nil {
+		logger.Warnf("couldn't create directories for Galleries: %v", err)
+	}
+	if err := utils.EnsureDir(jsonPaths.Performers); err != nil {
+		logger.Warnf("couldn't create directories for Performers: %v", err)
+	}
+	if err := utils.EnsureDir(jsonPaths.Studios); err != nil {
+		logger.Warnf("couldn't create directories for Studios: %v", err)
+	}
+	if err := utils.EnsureDir(jsonPaths.Movies); err != nil {
+		logger.Warnf("couldn't create directories for Movies: %v", err)
+	}
+	if err := utils.EnsureDir(jsonPaths.Tags); err != nil {
+		logger.Warnf("couldn't create directories for Tags: %v", err)
+	}
 }
 
 func (jp *JSONPaths) PerformerJSONPath(checksum string) string {

pkg/manager/running_streams.go

@@ -91,10 +91,16 @@ func (s *SceneServer) ServeScreenshot(scene *models.Scene, w http.ResponseWriter
 		http.ServeFile(w, r, filepath)
 	} else {
 		var cover []byte
-		s.TXNManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
+		err := s.TXNManager.WithReadTxn(r.Context(), func(repo models.ReaderRepository) error {
 			cover, _ = repo.Scene().GetCover(scene.ID)
 			return nil
 		})
-		utils.ServeImage(cover, w, r)
+		if err != nil {
+			logger.Warnf("read transaction failed while serving screenshot: %v", err)
+		}
+
+		if err = utils.ServeImage(cover, w, r); err != nil {
+			logger.Warnf("unable to serve screenshot image: %v", err)
+		}
 	}
 }

pkg/manager/screenshot.go

@@ -2,6 +2,7 @@ package manager
 
 import (
 	"github.com/stashapp/stash/pkg/ffmpeg"
+	"github.com/stashapp/stash/pkg/logger"
 )
 
 func makeScreenshot(probeResult ffmpeg.VideoFile, outputPath string, quality int, width int, time float64) {
@@ -12,5 +13,8 @@ func makeScreenshot(probeResult ffmpeg.VideoFile, outputPath string, quality int
 		Time:       time,
 		Width:      width,
 	}
-	encoder.Screenshot(probeResult, options)
+
+	if err := encoder.Screenshot(probeResult, options); err != nil {
+		logger.Warnf("[encoder] failure to generate screenshot: %v", err)
+	}
 }

pkg/manager/task_export.go

@@ -126,7 +126,7 @@ func (t *ExportTask) Start(wg *sync.WaitGroup) {
 
 	paths.EnsureJSONDirs(t.baseDir)
 
-	t.txnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
+	txnErr := t.txnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
 		// include movie scenes and gallery images
 		if !t.full {
 			// only include movie scenes if includeDependencies is also set
@@ -154,6 +154,9 @@ func (t *ExportTask) Start(wg *sync.WaitGroup) {
 
 		return nil
 	})
+	if txnErr != nil {
+		logger.Warnf("error while running export transaction: %v", txnErr)
+	}
 
 	if err := t.json.saveMappings(t.Mappings); err != nil {
 		logger.Errorf("[mappings] failed to save json: %s", err.Error())
@@ -202,17 +205,24 @@ func (t *ExportTask) zipFiles(w io.Writer) error {
 		return err
 	}
 
-	filepath.Walk(t.json.json.Tags, t.zipWalkFunc(u.json.Tags, z))
+	walkWarn(t.json.json.Tags, t.zipWalkFunc(u.json.Tags, z))
-	filepath.Walk(t.json.json.Galleries, t.zipWalkFunc(u.json.Galleries, z))
+	walkWarn(t.json.json.Galleries, t.zipWalkFunc(u.json.Galleries, z))
-	filepath.Walk(t.json.json.Performers, t.zipWalkFunc(u.json.Performers, z))
+	walkWarn(t.json.json.Performers, t.zipWalkFunc(u.json.Performers, z))
-	filepath.Walk(t.json.json.Studios, t.zipWalkFunc(u.json.Studios, z))
+	walkWarn(t.json.json.Studios, t.zipWalkFunc(u.json.Studios, z))
-	filepath.Walk(t.json.json.Movies, t.zipWalkFunc(u.json.Movies, z))
+	walkWarn(t.json.json.Movies, t.zipWalkFunc(u.json.Movies, z))
-	filepath.Walk(t.json.json.Scenes, t.zipWalkFunc(u.json.Scenes, z))
+	walkWarn(t.json.json.Scenes, t.zipWalkFunc(u.json.Scenes, z))
-	filepath.Walk(t.json.json.Images, t.zipWalkFunc(u.json.Images, z))
+	walkWarn(t.json.json.Images, t.zipWalkFunc(u.json.Images, z))
 
 	return nil
 }
 
+// like filepath.Walk but issue a warning on error
+func walkWarn(root string, fn filepath.WalkFunc) {
+	if err := filepath.Walk(root, fn); err != nil {
+		logger.Warnf("error walking structure %v: %v", root, err)
+	}
+}
+
 func (t *ExportTask) zipWalkFunc(outDir string, z *zip.Writer) filepath.WalkFunc {
 	return func(path string, info os.FileInfo, err error) error {
 		if err != nil {

pkg/manager/task_import.go

@@ -160,7 +160,9 @@ func (t *ImportTask) unzipFile() error {
 		fn := filepath.Join(t.BaseDir, f.Name)
 
 		if f.FileInfo().IsDir() {
-			os.MkdirAll(fn, os.ModePerm)
+			if err := os.MkdirAll(fn, os.ModePerm); err != nil {
+				logger.Warnf("couldn't create directory %v while unzipping import file: %v", fn, err)
+			}
 			continue
 		}
 

pkg/manager/task_scan.go

@@ -87,7 +87,9 @@ func (j *ScanJob) Execute(ctx context.Context, progress *job.Progress) {
 				galleries = append(galleries, path)
 			}
 
-			instance.Paths.Generated.EnsureTmpDir()
+			if err := instance.Paths.Generated.EnsureTmpDir(); err != nil {
+				logger.Warnf("couldn't create temporary directory: %v", err)
+			}
 
 			wg.Add()
 			task := ScanTask{
@@ -126,7 +128,11 @@ func (j *ScanJob) Execute(ctx context.Context, progress *job.Progress) {
 	}
 
 	wg.Wait()
-	instance.Paths.Generated.EmptyTmpDir()
+
+	if err := instance.Paths.Generated.EmptyTmpDir(); err != nil {
+		logger.Warnf("couldn't empty temporary directory: %v", err)
+	}
+
 	elapsed := time.Since(start)
 	logger.Info(fmt.Sprintf("Scan finished (%s)", elapsed))
 
@@ -753,7 +759,7 @@ func (t *ScanTask) scanScene() *models.Scene {
 
 	// check for scene by checksum and oshash - MD5 should be
 	// redundant, but check both
-	t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
+	txnErr := t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
 		qb := r.Scene()
 		if checksum != "" {
 			s, _ = qb.FindByChecksum(checksum)
@@ -765,6 +771,9 @@ func (t *ScanTask) scanScene() *models.Scene {
 
 		return nil
 	})
+	if txnErr != nil {
+		logger.Warnf("error in read transaction: %v", txnErr)
+	}
 
 	sceneHash := oshash
 
@@ -1320,7 +1329,7 @@ func (t *ScanTask) doesPathExist() bool {
 	gExt := config.GetGalleryExtensions()
 
 	ret := false
-	t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
+	txnErr := t.TxnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
 		if matchExtension(t.FilePath, gExt) {
 			gallery, _ := r.Gallery().FindByPath(t.FilePath)
 			if gallery != nil {
@@ -1340,6 +1349,9 @@ func (t *ScanTask) doesPathExist() bool {
 
 		return nil
 	})
+	if txnErr != nil {
+		logger.Warnf("error while executing read transaction: %v", txnErr)
+	}
 
 	return ret
 }

pkg/manager/task_stash_box_tag.go

@@ -47,7 +47,7 @@ func (t *StashBoxPerformerTagTask) stashBoxPerformerTag() {
 
 	if t.refresh {
 		var performerID string
-		t.txnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
+		txnErr := t.txnManager.WithReadTxn(context.TODO(), func(r models.ReaderRepository) error {
 			stashids, _ := r.Performer().GetStashIDs(t.performer.ID)
 			for _, id := range stashids {
 				if id.Endpoint == t.box.Endpoint {
@@ -56,6 +56,9 @@ func (t *StashBoxPerformerTagTask) stashBoxPerformerTag() {
 			}
 			return nil
 		})
+		if txnErr != nil {
+			logger.Warnf("error while executing read transaction: %v", err)
+		}
 		if performerID != "" {
 			performer, err = client.FindStashBoxPerformerByID(performerID)
 		}

pkg/plugin/js.go

@@ -2,6 +2,7 @@ package plugin
 
 import (
 	"errors"
+	"fmt"
 	"path/filepath"
 	"sync"
 
@@ -71,10 +72,21 @@ func (t *jsPluginTask) Start() error {
 		return err
 	}
 
-	t.vm.Set("input", t.input)
+	if err := t.vm.Set("input", t.input); err != nil {
-	js.AddLogAPI(t.vm, t.progress)
+		return fmt.Errorf("error setting input: %w", err)
-	js.AddUtilAPI(t.vm)
+	}
-	js.AddGQLAPI(t.vm, t.input.ServerConnection.SessionCookie, t.gqlHandler)
+
+	if err := js.AddLogAPI(t.vm, t.progress); err != nil {
+		return fmt.Errorf("error adding log API: %w", err)
+	}
+
+	if err := js.AddUtilAPI(t.vm); err != nil {
+		return fmt.Errorf("error adding util API: %w", err)
+	}
+
+	if err := js.AddGQLAPI(t.vm, t.input.ServerConnection.SessionCookie, t.gqlHandler); err != nil {
+		return fmt.Errorf("error adding GraphQL API: %w", err)
+	}
 
 	t.vm.Interrupt = make(chan func(), 1)
 

pkg/plugin/js/gql.go

@@ -103,9 +103,15 @@ func gqlRequestFunc(vm *otto.Otto, cookie *http.Cookie, gqlHandler http.Handler)
 	}
 }
 
-func AddGQLAPI(vm *otto.Otto, cookie *http.Cookie, gqlHandler http.Handler) {
+func AddGQLAPI(vm *otto.Otto, cookie *http.Cookie, gqlHandler http.Handler) error {
 	gql, _ := vm.Object("({})")
-	gql.Set("Do", gqlRequestFunc(vm, cookie, gqlHandler))
+	if err := gql.Set("Do", gqlRequestFunc(vm, cookie, gqlHandler)); err != nil {
+		return fmt.Errorf("unable to set GraphQL Do function: %w", err)
+	}
 
-	vm.Set("gql", gql)
+	if err := vm.Set("gql", gql); err != nil {
+		return fmt.Errorf("unable to set gql: %w", err)
+	}
+
+	return nil
 }

pkg/plugin/js/log.go

@@ -2,6 +2,7 @@ package js
 
 import (
 	"encoding/json"
+	"fmt"
 	"math"
 
 	"github.com/robertkrimen/otto"
@@ -64,14 +65,29 @@ func logProgressFunc(c chan float64) func(call otto.FunctionCall) otto.Value {
 	}
 }
 
-func AddLogAPI(vm *otto.Otto, progress chan float64) {
+func AddLogAPI(vm *otto.Otto, progress chan float64) error {
 	log, _ := vm.Object("({})")
-	log.Set("Trace", logTrace)
+	if err := log.Set("Trace", logTrace); err != nil {
-	log.Set("Debug", logDebug)
+		return fmt.Errorf("error setting Trace: %w", err)
-	log.Set("Info", logInfo)
+	}
-	log.Set("Warn", logWarn)
+	if err := log.Set("Debug", logDebug); err != nil {
-	log.Set("Error", logError)
+		return fmt.Errorf("error setting Debug: %w", err)
-	log.Set("Progress", logProgressFunc(progress))
+	}
+	if err := log.Set("Info", logInfo); err != nil {
+		return fmt.Errorf("error setting Info: %w", err)
+	}
+	if err := log.Set("Warn", logWarn); err != nil {
+		return fmt.Errorf("error setting Warn: %w", err)
+	}
+	if err := log.Set("Error", logError); err != nil {
+		return fmt.Errorf("error setting Error: %w", err)
+	}
+	if err := log.Set("Progress", logProgressFunc(progress)); err != nil {
+		return fmt.Errorf("error setting Progress: %v", err)
+	}
+	if err := vm.Set("log", log); err != nil {
+		return fmt.Errorf("unable to set log: %w", err)
+	}
 
-	vm.Set("log", log)
+	return nil
 }

pkg/plugin/js/util.go

@@ -1,6 +1,7 @@
 package js
 
 import (
+	"fmt"
 	"time"
 
 	"github.com/robertkrimen/otto"
@@ -14,9 +15,15 @@ func sleepFunc(call otto.FunctionCall) otto.Value {
 	return otto.UndefinedValue()
 }
 
-func AddUtilAPI(vm *otto.Otto) {
+func AddUtilAPI(vm *otto.Otto) error {
 	util, _ := vm.Object("({})")
-	util.Set("Sleep", sleepFunc)
+	if err := util.Set("Sleep", sleepFunc); err != nil {
+		return fmt.Errorf("unable to set sleep func: %w", err)
+	}
 
-	vm.Set("util", util)
+	if err := vm.Set("util", util); err != nil {
+		return fmt.Errorf("unable to set util: %w", err)
+	}
+
+	return nil
 }

pkg/plugin/plugins.go

@@ -219,7 +219,9 @@ func (c Cache) executePostHooks(ctx context.Context, hookType HookTriggerEnum, h
 
 			select {
 			case <-ctx.Done():
-				task.Stop()
+				if err := task.Stop(); err != nil {
+					logger.Warnf("could not stop task: %v", err)
+				}
 				return fmt.Errorf("operation cancelled")
 			case <-c:
 				// task finished normally

pkg/plugin/raw.go

@@ -51,7 +51,9 @@ func (t *rawPluginTask) Start() error {
 		defer stdin.Close()
 
 		inBytes, _ := json.Marshal(t.input)
-		io.WriteString(stdin, string(inBytes))
+		if k, err := io.WriteString(stdin, string(inBytes)); err != nil {
+			logger.Warnf("error writing input to plugins stdin (wrote %v bytes out of %v): %v", k, len(string(inBytes)), err)
+		}
 	}()
 
 	stderr, err := cmd.StderrPipe()

pkg/utils/crypto.go

@@ -7,6 +7,8 @@ import (
 	"hash/fnv"
 	"io"
 	"os"
+
+	"github.com/stashapp/stash/pkg/logger"
 )
 
 func MD5FromBytes(data []byte) string {
@@ -40,7 +42,9 @@ func MD5FromReader(src io.Reader) (string, error) {
 
 func GenerateRandomKey(l int) string {
 	b := make([]byte, l)
-	rand.Read(b)
+	if n, err := rand.Read(b); err != nil {
+		logger.Warnf("failure generating random key: %v (only read %v bytes)", err, n)
+	}
 	return fmt.Sprintf("%x", b)
 }
 

scripts/test_db_generator/makeTestDB.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"log"
 	"math/rand"
 	"os"
 	"strconv"
@@ -43,12 +44,14 @@ func main() {
 	var err error
 	c, err = loadConfig()
 	if err != nil {
-		panic(err)
+		log.Fatalf("couldn't load configuration: %v", err)
 	}
 
 	initNaming(*c)
 
-	database.Initialize(c.Database)
+	if err = database.Initialize(c.Database); err != nil {
+		log.Fatalf("couldn't initialize database: %v", err)
+	}
 	populateDB()
 }