Int 21 Fn 4301  - DOS 2+ - "chmod" - Set File Attributes                   [D]

   AX = 4301h
   CX = new file attributes (see below)
   DS:DX -> ASCIZ filename

Return: CF clear if successful
       AX destroyed
   CF set on error
       AX = error code (01h,02h,03h,05h) (see AH=59h)

Notes: will not change volume label or directory attribute bits, but will
     change the other attribute bits of a directory (the directory
     bit must be cleared to successfully change the other attributes of a
     directory, but the directory will not be changed to a normal file as
     a result)
   MS-DOS 4.01 reportedly closes the file if it is currently open
   for security reasons, the Novell NetWare execute-only bit can never
     be cleared; the file must be deleted and recreated
   under the FlashTek X-32 DOS extender, the filename pointer is in DS:EDX
   DOS 5.0 SHARE will close the file if it is currently open in sharing-
     compatibility mode, otherwise a sharing violation critical error is
     generated if the file is currently open

See Also: AX=4300h,AX=4311h,INT 2F/AX=110Eh

Bitfields for file attributes:
 bit 7 shareable (Novell NetWare)
 bit 6 unused
 bit 5 archive
 bit 4 directory
 bit 3 volume label
   execute-only (Novell NetWare)
 bit 2 system
 bit 1 hidden
 bit 0 read-only