Fix error counter - fixes #3650

For few commands, RClone counts a error multiple times. This was fixed by
creating a new error type which keeps a flag to remember if the error has
already been counted or not. The CountError function now wraps the original
error eith the above new error type and returns it.

fs/walk/walk.go

@@ -159,7 +159,7 @@ func listRwalk(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLe
 		// Carry on listing but return the error at the end
 		if err != nil {
 			listErr = err
-			fs.CountError(err)
+			err = fs.CountError(err)
 			fs.Errorf(path, "error listing: %v", err)
 			return nil
 		}
@@ -404,7 +404,7 @@ func walk(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel i
 					// NB once we have passed entries to fn we mustn't touch it again
 					if err != nil && err != ErrorSkipDir {
 						traversing.Done()
-						fs.CountError(err)
+						err = fs.CountError(err)
 						fs.Errorf(job.remote, "error listing: %v", err)
 						closeQuit()
 						// Send error to error channel if space

fs/walk/walk_test.go

@@ -10,7 +10,9 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/rclone/rclone/fs"
+	_ "github.com/rclone/rclone/fs/accounting"
 	"github.com/rclone/rclone/fs/filter"
+	"github.com/rclone/rclone/fs/fserrors"
 	"github.com/rclone/rclone/fstest/mockdir"
 	"github.com/rclone/rclone/fstest/mockfs"
 	"github.com/rclone/rclone/fstest/mockobject"
@@ -18,6 +20,15 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+var errDirNotFound, errorBoom error
+
+func init() {
+	errDirNotFound = fserrors.FsError(fs.ErrorDirNotFound)
+	fserrors.Count(errDirNotFound)
+	errorBoom = fserrors.FsError(errors.New("boom"))
+	fserrors.Count(errorBoom)
+}
+
 type (
 	listResult struct {
 		entries fs.DirEntries
@@ -196,12 +207,12 @@ func TestWalkREmptySkip(t *testing.T) { testWalkEmptySkip(t).WalkR() }
 func testWalkNotFound(t *testing.T) *listDirs {
 	return newListDirs(t, nil, true,
 		listResults{
-			"": {err: fs.ErrorDirNotFound},
+			"": {err: errDirNotFound},
 		},
 		errorMap{
-			"": fs.ErrorDirNotFound,
+			"": errDirNotFound,
 		},
-		fs.ErrorDirNotFound,
+		errDirNotFound,
 	)
 }
 func TestWalkNotFound(t *testing.T)  { testWalkNotFound(t).Walk() }
@@ -211,7 +222,7 @@ func TestWalkNotFoundMaskError(t *testing.T) {
 	// this doesn't work for WalkR
 	newListDirs(t, nil, true,
 		listResults{
-			"": {err: fs.ErrorDirNotFound},
+			"": {err: errDirNotFound},
 		},
 		errorMap{
 			"": nil,
@@ -224,7 +235,7 @@ func TestWalkNotFoundSkipError(t *testing.T) {
 	// this doesn't work for WalkR
 	newListDirs(t, nil, true,
 		listResults{
-			"": {err: fs.ErrorDirNotFound},
+			"": {err: errDirNotFound},
 		},
 		errorMap{
 			"": ErrorSkipDir,
@@ -342,7 +353,7 @@ func testWalkSkip(t *testing.T) *listDirs {
 func TestWalkSkip(t *testing.T)  { testWalkSkip(t).Walk() }
 func TestWalkRSkip(t *testing.T) { testWalkSkip(t).WalkR() }
 
-func testWalkErrors(t *testing.T) *listDirs {
+func walkErrors(t *testing.T, expectedErr error) *listDirs {
 	lr := listResults{}
 	em := errorMap{}
 	de := make(fs.DirEntries, 10)
@@ -357,13 +368,20 @@ func testWalkErrors(t *testing.T) *listDirs {
 	return newListDirs(t, nil, true,
 		lr,
 		em,
-		fs.ErrorDirNotFound,
+		expectedErr,
 	).NoCheckMaps()
 }
-func TestWalkErrors(t *testing.T)  { testWalkErrors(t).Walk() }
-func TestWalkRErrors(t *testing.T) { testWalkErrors(t).WalkR() }
 
-var errorBoom = errors.New("boom")
+func testWalkErrors(t *testing.T) *listDirs {
+	return walkErrors(t, errDirNotFound)
+}
+
+func testWalkRErrors(t *testing.T) *listDirs {
+	return walkErrors(t, fs.ErrorDirNotFound)
+}
+
+func TestWalkErrors(t *testing.T)  { testWalkErrors(t).Walk() }
+func TestWalkRErrors(t *testing.T) { testWalkRErrors(t).WalkR() }
 
 func makeTree(level int, terminalErrors bool) (listResults, errorMap) {
 	lr := listResults{}