defer write permissions checking in import until after copy to repo

This should complete the fix started in
6329997ac4, fixing the actual cause of the
test suite failure this time.

Sponsored-by: Dartmouth College's Datalad project

Command/Import.hs

@@ -1,6 +1,6 @@
 {- git-annex command
  -
- - Copyright 2012-2020 Joey Hess <id@joeyh.name>
+ - Copyright 2012-2021 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -200,13 +200,31 @@ startLocal o addunlockedmatcher largematcher mode (srcfile, destfile) =
 		-- Move or copy the src file to the dest file.
 		-- The dest file is what will be ingested.
 		createWorkTreeDirectory (parentDir destfile)
-		liftIO $ if mode == Duplicate || mode == SkipDuplicates
-			then void $ copyFileExternal CopyAllMetaData 
-				(fromRawFilePath srcfile)
-				(fromRawFilePath destfile)
-			else moveFile 
-				(fromRawFilePath srcfile)
-				(fromRawFilePath destfile)
+		unwind <- liftIO $ if mode == Duplicate || mode == SkipDuplicates
+			then do
+				void $ copyFileExternal CopyAllMetaData 
+					(fromRawFilePath srcfile)
+					(fromRawFilePath destfile)
+				return $ removeWhenExistsWith R.removeLink destfile
+			else do
+				moveFile 
+					(fromRawFilePath srcfile)
+					(fromRawFilePath destfile)
+				return $ moveFile
+					(fromRawFilePath destfile)
+					(fromRawFilePath srcfile)
+		-- Make sure that the dest file has its write permissions
+		-- removed; the src file normally already did, but may
+		-- have imported it from a filesystem that does not allow
+		-- removing write permissions, to a repo on a filesystem
+		-- that does.
+		when (lockingFile (lockDownConfig ld)) $ do
+			freezeContent destfile
+			checkLockedDownWritePerms destfile srcfile >>= \case
+				Just err -> do
+					liftIO unwind
+					giveup err
+				Nothing -> noop
 		-- Get the inode cache of the dest file. It should be
 		-- weakly the same as the originally locked down file's
 		-- inode cache. (Since the file may have been copied,
@@ -249,6 +267,12 @@ startLocal o addunlockedmatcher largematcher mode (srcfile, destfile) =
 		let cfg = LockDownConfig
 			{ lockingFile = lockingfile
 			, hardlinkFileTmpDir = Nothing
+			-- The write perms of the file may not be able to be
+			-- removed, if it's being imported from a crippled
+			-- filesystem. So lockDown is asked to not check
+			-- the write perms. They will be checked later, after
+			-- the file gets copied into the repository.
+			, checkWritePerms = False
 			}
 		v <- lockDown cfg (fromRawFilePath srcfile)
 		case v of