make readonly export remotes really be readonly

When a remote is configured to be readonly, don't allow changing what's
exported to it.

This was missed in the original export remote implementation, but it makes
sense for a readonly export remote to not be allowed to change.

Remote/Helper/ReadOnly.hs

@@ -1,6 +1,6 @@
 {- Adds readonly support to remotes.
  -
- - Copyright 2013, 2015 Joey Hess <id@joeyh.name>
+ - Copyright 2013-2019 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -28,6 +28,17 @@ adjustReadOnly r
 		{ storeKey = readonlyStoreKey
 		, removeKey = readonlyRemoveKey
 		, repairRepo = Nothing
+		, exportActions = exportActions r
+			{ storeExport = readonlyStoreExport
+			, removeExport = readonlyRemoveExport
+			, removeExportDirectory = Just readonlyRemoveExportDirectory
+			, renameExport = readonlyRenameExport
+			}
+		, importActions = importActions r
+			{ storeExportWithContentIdentifier = readonlyStoreExportWithContentIdentifiera
+			, removeExportWithContentIdentifier = readonlyRemoveExportWithContentIdentifier
+			, removeExportDirectoryWhenEmpty = Just readonlyRemoveExportDirectory
+			}
 		}
 	| otherwise = r
 
@@ -40,7 +51,30 @@ readonlyRemoveKey _ = readonlyFail
 readonlyStorer :: Storer
 readonlyStorer _ _ _ = readonlyFail
 
+readonlyStoreExport :: FilePath -> Key -> ExportLocation -> MeterUpdate -> Annex Bool
+readonlyStoreExport _ _ _ _ = readonlyFail
+
+readonlyRemoveExport :: Key -> ExportLocation -> Annex Bool
+readonlyRemoveExport _ _ = readonlyFail
+
+readonlyRemoveExportDirectory :: ExportDirectory -> Annex Bool
+readonlyRemoveExportDirectory _ = readonlyFail
+
+readonlyRenameExport :: Key -> ExportLocation -> ExportLocation -> Annex (Maybe Bool)
+readonlyRenameExport _ _ _ = return Nothing
+
+readonlyStoreExportWithContentIdentifier :: FilePath -> Key -> ExportLocation -> [ContentIdentifier] -> MeterUpdate -> Annex (Maybe ContentIdentifier)
+readonlyStoreExportWithContentIdentifier _ _ _ _ _ = do
+	readonlyWarning
+	return Nothing
+
+removeExportWithContentIdentifier :: Key -> ExportLocation -> [ContentIdentifier] -> Annex Bool
+removeExportWithContentIdentifier _ _ _ = readonlyFail
+
 readonlyFail :: Annex Bool
 readonlyFail = do
-	warning "this remote is readonly"
+	readonlyWarning
 	return False
+
+readonlyWarning :: Annex ()
+readonylWarning = warning "this remote is readonly"