prevent relatedTemplate from truncating a filename to end in "."

Avoid a problem with temp file names ending in "." on certian filesystems
that have problems with such filenames.

relatedTemplate is quite an ugly hack really; since it doesn't know the max
filename length of the filesystem it can only assume that the filename is
max allowed length. When given the input "lh.aparc.DKTatlas.annot", it
wants to reserve 20 characters for tempfile so it truncates to "lh.". That
ending period is apparently a problem on some filesystem (FAT eats it, but
does not throw EINVAL; ntfs does not seem bothered by it, I don't know what
FUSE filesystem the bug reporter was really using).

Sponsored-by: Brett Eisenberg on Patreon

CHANGELOG

@@ -4,6 +4,8 @@ git-annex (10.20231130) UNRELEASED; urgency=medium
     remote.foo.annex-ignore, as documented.
   * Support git-annex copy/move --from-anywhere --to remote.
   * sync: Fix locking problems during merge when annex.pidlock is set.
+  * Avoid a problem with temp file names ending in "." on certian
+    filesystems that have problems with such filenames.
 
  -- Joey Hess <id@joeyh.name>  Thu, 30 Nov 2023 14:48:12 -0400
 

Utility/Tmp.hs

@@ -35,7 +35,9 @@ type Template = String
  - to help identify what call was responsible.
  -}
 openTmpFileIn :: FilePath -> String -> IO (FilePath, Handle)
-openTmpFileIn dir template = openTempFile dir template
+openTmpFileIn dir template = do
+	liftIO $ print ("openTmpFileIn", dir, template)
+	openTempFile dir template
 		`catchIO` decoraterrror
   where
 	decoraterrror e = throwM $
@@ -105,7 +107,12 @@ withTmpFileIn tmpdir template a = bracket create remove use
  -}
 relatedTemplate :: FilePath -> FilePath
 relatedTemplate f
-	| len > 20 = truncateFilePath (len - 20) f
+	| len > 20 = 
+		{- Some filesystems like FAT have issues with filenames
+		 - ending in ".", so avoid truncating a filename to end
+		 - that way. -}
+		reverse $ dropWhile (== '.') $ reverse $
+			truncateFilePath (len - 20) f
 	| otherwise = f
   where
 	len = length f

doc/bugs/Invalid_argument_saving_FreeSurfer_file_on_NTFS.mdwn

@@ -91,3 +91,5 @@ add: 1 failed
 ### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
 
 Yes! I use git annex and datalad all the time for personal and work projects. 
+
+> [[fixed|done]] --[[Joey]]

doc/bugs/Invalid_argument_saving_FreeSurfer_file_on_NTFS/comment_1_181a319138cc10742bc8676d77e8a614._comment

@@ -0,0 +1,16 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2023-12-05T16:16:35Z"
+ content="""
+This is EINVAL from probably open(2) or something like that.
+
+       EINVAL The  final  component ("basename") of pathname is invalid (e.g.,
+              it contains characters not permitted by the underlying  filesys‐
+              tem).
+
+The problem is likely the ending ".", since FAT and probably other Microsoft filesystems
+don't allow that, and/or have other strange behavior like silently removing that.
+
+Changed the code to avoid this.
+"""]]