addurl --preserve-filename: reject control characters

As well as escape sequences, control characters seem unlikely to be desired when
doing addurl, and likely to trip someone up. So disallow them as well.

I did consider going the other way and allowing filenames with control characters
and escape sequences, since git-annex is in the process of escaping display
of all filenames. Might still be a better idea?

Also display the illegal filename git quoted when it rejects it.

Sponsored-by: Nicholas Golder-Manning on Patreon

Annex/UntrustedFilePath.hs

@@ -52,8 +52,8 @@ sanitizeLeadingFilePathCharacter ('-':s) = '_':s
 sanitizeLeadingFilePathCharacter ('/':s) = '_':s
 sanitizeLeadingFilePathCharacter s = s
 
-escapeSequenceInFilePath :: FilePath -> Bool
-escapeSequenceInFilePath f = '\ESC' `elem` f
+controlCharacterInFilePath :: FilePath -> Bool
+controlCharacterInFilePath = any isControl
 
 {- ../ is a path traversal, no matter where it appears.
  -