accounting: Correct exitcode on Transfer Limit Exceeded flag. Fixes #3203

Before this change the exit code for transfer limit exceeded was
incorrect. This was because the `resolveExitCode` function unwraps the
error thus reading the underlying error which is not the same as the
error it was comparing to (`ErrorMaxTransferLimitReached`).

This change fixes it by splitting the error definition in two so that
when the Fatal error is unwrapped we match against
`ErrorMaxTransferLimitReached` however when we return the error we
return `ErrorMaxTransferLimitReachedFatal`.

fs/accounting/accounting.go

@@ -16,9 +16,13 @@ import (
 	"github.com/rclone/rclone/fs/fserrors"
 )
 
-// ErrorMaxTransferLimitReached is returned from Read when the max
+// ErrorMaxTransferLimitReached defines error when transfer limit is reached.
+// Used for checking on exit and matching to correct exit code.
+var ErrorMaxTransferLimitReached = errors.New("Max transfer limit reached as set by --max-transfer")
+
+// ErrorMaxTransferLimitReachedFatal is returned from Read when the max
 // transfer limit is reached.
-var ErrorMaxTransferLimitReached = fserrors.FatalError(errors.New("Max transfer limit reached as set by --max-transfer"))
+var ErrorMaxTransferLimitReachedFatal = fserrors.FatalError(ErrorMaxTransferLimitReached)
 
 // Account limits and accounts for one transfer
 type Account struct {
@@ -172,7 +176,7 @@ func (acc *Account) checkRead() (err error) {
 	acc.statmu.Lock()
 	if acc.max >= 0 && acc.stats.GetBytes() >= acc.max {
 		acc.statmu.Unlock()
-		return ErrorMaxTransferLimitReached
+		return ErrorMaxTransferLimitReachedFatal
 	}
 	// Set start time.
 	if acc.start.IsZero() {

fs/accounting/accounting_test.go

@@ -219,7 +219,7 @@ func TestAccountMaxTransfer(t *testing.T) {
 	assert.NoError(t, err)
 	n, err = acc.Read(b)
 	assert.Equal(t, 0, n)
-	assert.Equal(t, ErrorMaxTransferLimitReached, err)
+	assert.Equal(t, ErrorMaxTransferLimitReachedFatal, err)
 	assert.True(t, fserrors.IsFatalError(err))
 
 	fs.Config.CutoffMode = fs.CutoffModeSoft

fs/operations/operations.go

@@ -364,7 +364,7 @@ func Copy(ctx context.Context, f fs.Fs, dst fs.Object, remote string, src fs.Obj
 		actionTaken = "Copied (server side copy)"
 		if fs.Config.MaxTransfer >= 0 && (accounting.Stats(ctx).GetBytes() >= int64(fs.Config.MaxTransfer) ||
 			(fs.Config.CutoffMode == fs.CutoffModeCautious && accounting.Stats(ctx).GetBytesWithPending()+src.Size() >= int64(fs.Config.MaxTransfer))) {
-			return nil, accounting.ErrorMaxTransferLimitReached
+			return nil, accounting.ErrorMaxTransferLimitReachedFatal
 		}
 		if doCopy := f.Features().Copy; doCopy != nil && (SameConfig(src.Fs(), f) || (SameRemoteType(src.Fs(), f) && f.Features().ServerSideAcrossConfigs)) {
 			in := tr.Account(nil) // account the transfer

fs/sync/sync_test.go

@@ -1811,7 +1811,7 @@ func TestAbort(t *testing.T) {
 	accounting.GlobalStats().ResetCounters()
 
 	err := Sync(context.Background(), r.Fremote, r.Flocal, false)
-	expectedErr := fserrors.FsError(accounting.ErrorMaxTransferLimitReached)
+	expectedErr := fserrors.FsError(accounting.ErrorMaxTransferLimitReachedFatal)
 	fserrors.Count(expectedErr)
 	assert.Equal(t, expectedErr, err)
 }