Re: [Lynx-dev] Question marks in local source filenames

[David Woolley]

On 13/02/2022 04:00, Thorsten Glaser wrote:
> This is of course a bug, local filenames are unconstrained
> other than not containing NUL and slash of course.

That's not true.  They have the same constraints as the path part of any 
URI:

RFC 8089
      file-URI       = file-scheme ":" file-hier-part

      file-scheme    = "file"

      file-hier-part = ( "//" auth-path )
                     / local-path

      auth-path      = [ file-auth ] path-absolute

      local-path     = path-absolute

      file-auth      = "localhost"
                     / host

RFC 3986
      path-absolute = "/" [ segment-nz *( "/" segment ) ]

      segment       = *pchar
      segment-nz    = 1*pchar


      pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"

      unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"
        
      sub-delims    = "!" / "$" / "&" / "'" / "(" / ")"
                 / "*" / "+" / "," / ";" / "="


so ? is not permitted, unless % encoded. White space is also not 
permitted.  Individual filesystems may further restrict available 
characters, e.g. Windows won't allow backslash.