Category: <b>DOS kernel</b>
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<pre><b>INT 21 - DOS 3.0+ - "TRUENAME" - CANONICALIZE FILENAME OR PATH</b>

	AH = 60h
	DS:SI -&gt; ASCIZ filename or path
	ES:DI -&gt; 128-byte buffer for canonicalized name
Return: CF set on error
	    AX = error code
		02h invalid component in directory path or drive letter only
		03h malformed path or invalid drive letter
	    ES:DI buffer unchanged
	CF clear if successful
	    AH = 00h or 3Ah (DOS 6.1/6.2 for character device)
	    AL = destroyed (00h or 2Fh or 5Ch or last character of current
		  directory on drive)
	    buffer filled with qualified name of form D:\PATH\FILE.EXT or
	      \\MACHINE\PATH\FILE.EXT
Desc:	determine the canonical name of the specified filename or path,
	  corresponding to the undocumented TRUENAME command in COMMAND.COM
Notes:	the input path need not actually exist
	letters are uppercased, forward slashes converted to backslashes,
	  asterisks converted to appropriate number of question marks, and
	  file and directory names are truncated to 8.3 if necessary.  (DR DOS
	  3.41 and 5.0 do not expand asterisks)
	'.' and '..' in the path are resolved
	filespecs on local drives always start with "d:", those on network
	  drives always start with "\\"
	if path string is on a JOINed drive, the returned name is the one that
	  would be needed if the drive were not JOINed; similarly for a
	  SUBSTed, ASSIGNed, or network drive letter.	Because of this, it is
	  possible to get a qualified name that is not legal under the current
	  combination of SUBSTs, ASSIGNs, JOINs, and network redirections
	under DOS 3.3 through 6.00, a device name is translated differently if
	  the device name does not have an explicit directory or the directory
	  is \DEV (relative directory DEV from the root directory works
	  correctly).  In these cases, the returned string consists of the
	  unchanged device name and extension appended to the string X:/
	  (forward slash instead of backward slash as in all other cases) where
	  X is the default or explicit drive letter.
	under MS-DOS 7.0, this call returns the short name for any
	  long-filename portions of the provided pathname or filename
	functions which take pathnames require canonical paths if invoked via
	  INT 21/AX=5D00h
	supported by OS/2 v1.1 compatibility box
	NetWare 2.1x does not support characters with the high bit set; early
	  versions of NetWare 386 support such characters except in this call.
	  In addition, NetWare returns error code 3 for the path "X:\"; one
	  should use "X:\." instead.
	Novell DOS 7 reportedly has difficulty with non-MS-DOS filenames on
	  network drives, and can return "D:" instead of "SERVER/VOLUME"
	for DOS 3.3-6.0, the input and output buffers may be the same, as the
	  canonicalized name is built in an internal buffer and copied to the
	  specified output buffer as the very last step
	for DR DOS 6.0, this function is not automatically called when on a
	  network.  Device drivers reportedly cannot make this call from their
	  INIT function.  Using the same pointer for both input and output
	  buffers is not supported in the April 1992 and earlier versions of
	  DR DOS
	Windows for Workgroups 3.11, Windows95 and even MS-DOS 7.00 only
	  return the local drive path; to obtain network paths use
	  INT 21/AX=5F02h or INT 21/AX=5F46h instead
	Corel's CORELCDX and MSCDEX without the /S switch return canonical
	  names of the form "\\D.\A.\path", where "D" is the CD-ROM drive
	  letter and "A" appears to indicate the first physical CD-ROM drive;
	  MSCDEX with the /S switch returns a canonical name with embedded
	  blanks.  Novell DOS 7 NWCDEX as of the 11/16/94 update returns the
	  same canonical path as MSCDEX; earlier revisions returned
	  "Cdex.   D:\path", where "D" is the CD-ROM drive letter
	the Windows95 MSCDEX-replacement VxD returns "D:\path", even though the
	  MS-DOS 7.00 MSCDEX behaves identically to older versions (above)
BUG:	Windows95 incorrectly treats filenames where the first two characters
	  after the drive letter and colon are both slashes (either forward
	  or backward) as a UNC (network name) and requires several seconds
	  to attempt to resolve the name before returning an unchanged
	  string
SeeAlso: AX=5F02h,AX=5FB3h,AX=7160h/CL=00h,INT 2F/AX=1123h,INT 2F/AX=1221h
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