X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcode%2Ffd-stream.lisp;h=089b7597cd602ac131738831d8da05b54533c11a;hb=428b60fff4247e34ff601810f33976908f22bbc0;hp=d8a2d5799d90e36d7c54a022c9e796c0dd95d90d;hpb=96a1badea2523bf188f7ba023e2f69a6785847d6;p=sbcl.git

diff --git a/src/code/fd-stream.lisp b/src/code/fd-stream.lisp
index d8a2d57..089b759 100644
--- a/src/code/fd-stream.lisp
+++ b/src/code/fd-stream.lisp
@@ -31,16 +31,10 @@
       (pop *available-buffers*)
       (allocate-system-memory bytes-per-buffer)))
 
-;;;; the FILE-STREAM structure
+;;;; the FD-STREAM structure
 
-(defstruct (file-stream
+(defstruct (fd-stream
 	    (:constructor %make-fd-stream)
-	    ;; KLUDGE: in an ideal world, maybe we'd rewrite
-	    ;; everything to use FILE-STREAM rather than simply
-	    ;; providing this hack for compatibility with the old
-	    ;; code.  However, CVS doesn't deal terribly well with
-	    ;; file renaming, so for now we use this
-	    ;; backward-compatibility feature.
 	    (:conc-name fd-stream-)
 	    (:predicate fd-stream-p)
 	    (:include ansi-stream
@@ -86,8 +80,10 @@
   ;; timeout specified for this stream, or NIL if none
   (timeout nil :type (or index null))
   ;; pathname of the file this stream is opened to (returned by PATHNAME)
-  (pathname nil :type (or pathname null)))
-(def!method print-object ((fd-stream file-stream) stream)
+  (pathname nil :type (or pathname null))
+  (external-format :default)
+  (output-bytes #'ill-out :type function))
+(def!method print-object ((fd-stream fd-stream) stream)
   (declare (type stream stream))
   (print-unreadable-object (fd-stream stream :type t :identity t)
     (format stream "for ~S" (fd-stream-name fd-stream))))
@@ -113,6 +109,17 @@
 	 :format-arguments
 	 (list note-format (list pathname) (strerror errno))))
 
+(defun stream-decoding-error (stream octets)
+  (error 'stream-decoding-error
+	 :stream stream
+         ;; FIXME: dunno how to get at OCTETS currently, or even if
+         ;; that's the right thing to report.
+         :octets octets))
+(defun stream-encoding-error (stream code)
+  (error 'stream-encoding-error
+	 :stream stream
+         :code code))
+
 ;;; This is called by the server when we can write to the given file
 ;;; descriptor. Attempt to write the data again. If it worked, remove
 ;;; the data from the OUTPUT-LATER list. If it didn't work, something
@@ -169,7 +176,7 @@
 ;;; writes. If so, just queue this one. Otherwise, try to write it. If
 ;;; this would block, queue it.
 (defun frob-output (stream base start end reuse-sap)
-  (declare (type file-stream stream)
+  (declare (type fd-stream stream)
 	   (type (or system-area-pointer (simple-array * (*))) base)
 	   (type index start end))
   (if (not (null (fd-stream-output-later stream))) ; something buffered.
@@ -197,7 +204,39 @@
       (frob-output stream (fd-stream-obuf-sap stream) 0 length t)
       (setf (fd-stream-obuf-tail stream) 0))))
 
-(defmacro output-wrapper ((stream size buffering) &body body)
+(defmacro output-wrapper/variable-width ((stream size buffering restart)
+					 &body body)
+  (let ((stream-var (gensym)))
+    `(let ((,stream-var ,stream)
+	   (size ,size))
+      ,(unless (eq (car buffering) :none)
+	 `(when (< (fd-stream-obuf-length ,stream-var)
+	           (+ (fd-stream-obuf-tail ,stream-var)
+		       size))
+            (flush-output-buffer ,stream-var)))
+      ,(unless (eq (car buffering) :none)
+	 `(when (> (fd-stream-ibuf-tail ,stream-var)
+		   (fd-stream-ibuf-head ,stream-var))
+            (file-position ,stream-var (file-position ,stream-var))))
+      ,(if restart
+           
+           `(with-simple-restart (output-nothing
+                                  "~@<Skip output of this character.~@:>")
+             ,@body
+             (incf (fd-stream-obuf-tail ,stream-var) size))
+           `(progn
+             ,@body
+             (incf (fd-stream-obuf-tail ,stream-var) size)))
+      ,(ecase (car buffering)
+	 (:none
+	  `(flush-output-buffer ,stream-var))
+	 (:line
+	  `(when (eq (char-code byte) (char-code #\Newline))
+	     (flush-output-buffer ,stream-var)))
+	 (:full))
+    (values))))
+
+(defmacro output-wrapper ((stream size buffering restart) &body body)
   (let ((stream-var (gensym)))
     `(let ((,stream-var ,stream))
       ,(unless (eq (car buffering) :none)
@@ -209,9 +248,14 @@
 	 `(when (> (fd-stream-ibuf-tail ,stream-var)
 		   (fd-stream-ibuf-head ,stream-var))
             (file-position ,stream-var (file-position ,stream-var))))
-    
-      ,@body
-      (incf (fd-stream-obuf-tail ,stream-var) ,size)
+      ,(if restart
+           `(with-simple-restart (output-nothing
+                                  "~@<Skip output of this character.~@:>")
+             ,@body
+             (incf (fd-stream-obuf-tail ,stream-var) ,size))
+           `(progn
+             ,@body
+             (incf (fd-stream-obuf-tail ,stream-var) ,size)))
       ,(ecase (car buffering)
 	 (:none
 	  `(flush-output-buffer ,stream-var))
@@ -221,9 +265,36 @@
 	 (:full))
     (values))))
 
+(defmacro def-output-routines/variable-width
+    ((name-fmt size restart external-format &rest bufferings)
+     &body body)
+  (declare (optimize (speed 1)))
+  (cons 'progn
+	(mapcar
+	    (lambda (buffering)
+	      (let ((function
+		     (intern (let ((*print-case* :upcase))
+			       (format nil name-fmt (car buffering))))))
+		`(progn
+		   (defun ,function (stream byte)
+		     (output-wrapper/variable-width (stream ,size ,buffering ,restart)
+		       ,@body))
+		   (setf *output-routines*
+			 (nconc *output-routines*
+				',(mapcar
+				   (lambda (type)
+				     (list type
+					   (car buffering)
+					   function
+					   1
+					   external-format))
+				   (cdr buffering)))))))
+	    bufferings)))
+
 ;;; Define output routines that output numbers SIZE bytes long for the
 ;;; given bufferings. Use BODY to do the actual output.
-(defmacro def-output-routines ((name-fmt size &rest bufferings) &body body)
+(defmacro def-output-routines ((name-fmt size restart &rest bufferings)
+                               &body body)
   (declare (optimize (speed 1)))
   (cons 'progn
 	(mapcar
@@ -233,7 +304,7 @@
 			       (format nil name-fmt (car buffering))))))
 		`(progn
 		   (defun ,function (stream byte)
-		     (output-wrapper (stream ,size ,buffering)
+		     (output-wrapper (stream ,size ,buffering ,restart)
 		       ,@body))
 		   (setf *output-routines*
 			 (nconc *output-routines*
@@ -242,16 +313,19 @@
 				     (list type
 					   (car buffering)
 					   function
-					   size))
+					   size
+					   nil))
 				   (cdr buffering)))))))
 	    bufferings)))
 
+;;; FIXME: is this used anywhere any more?
 (def-output-routines ("OUTPUT-CHAR-~A-BUFFERED"
 		      1
+                      t
 		      (:none character)
 		      (:line character)
 		      (:full character))
-  (if (and (base-char-p byte) (char= byte #\Newline))
+  (if (char= byte #\Newline)
       (setf (fd-stream-char-pos stream) 0)
       (incf (fd-stream-char-pos stream)))
   (setf (sap-ref-8 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
@@ -259,6 +333,7 @@
 
 (def-output-routines ("OUTPUT-UNSIGNED-BYTE-~A-BUFFERED"
 		      1
+                      nil
 		      (:none (unsigned-byte 8))
 		      (:full (unsigned-byte 8)))
   (setf (sap-ref-8 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
@@ -266,6 +341,7 @@
 
 (def-output-routines ("OUTPUT-SIGNED-BYTE-~A-BUFFERED"
 		      1
+                      nil
 		      (:none (signed-byte 8))
 		      (:full (signed-byte 8)))
   (setf (signed-sap-ref-8 (fd-stream-obuf-sap stream)
@@ -274,6 +350,7 @@
 
 (def-output-routines ("OUTPUT-UNSIGNED-SHORT-~A-BUFFERED"
 		      2
+                      nil
 		      (:none (unsigned-byte 16))
 		      (:full (unsigned-byte 16)))
   (setf (sap-ref-16 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
@@ -281,6 +358,7 @@
 
 (def-output-routines ("OUTPUT-SIGNED-SHORT-~A-BUFFERED"
 		      2
+                      nil
 		      (:none (signed-byte 16))
 		      (:full (signed-byte 16)))
   (setf (signed-sap-ref-16 (fd-stream-obuf-sap stream)
@@ -289,6 +367,7 @@
 
 (def-output-routines ("OUTPUT-UNSIGNED-LONG-~A-BUFFERED"
 		      4
+                      nil
 		      (:none (unsigned-byte 32))
 		      (:full (unsigned-byte 32)))
   (setf (sap-ref-32 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
@@ -296,6 +375,7 @@
 
 (def-output-routines ("OUTPUT-SIGNED-LONG-~A-BUFFERED"
 		      4
+                      nil
 		      (:none (signed-byte 32))
 		      (:full (signed-byte 32)))
   (setf (signed-sap-ref-32 (fd-stream-obuf-sap stream)
@@ -389,6 +469,8 @@
 					   :from-end t
 					   :start start
 					   :end end))))
+	  (if (and (typep thing 'base-string)
+		   (eq (fd-stream-external-format stream) :latin-1))
 	  (ecase (fd-stream-buffering stream)
 	    (:full
 	     (output-raw-bytes stream thing start end))
@@ -398,6 +480,13 @@
 	       (flush-output-buffer stream)))
 	    (:none
 	     (frob-output stream thing start end nil)))
+	      (ecase (fd-stream-buffering stream)
+		(:full (funcall (fd-stream-output-bytes stream)
+				stream thing nil start end))
+		(:line (funcall (fd-stream-output-bytes stream)
+				stream thing last-newline start end))
+		(:none (funcall (fd-stream-output-bytes stream)
+				stream thing t start end))))
 	  (if last-newline
 	      (setf (fd-stream-char-pos stream)
 		    (- end last-newline 1))
@@ -409,17 +498,38 @@
 	  (:none
 	   (frob-output stream thing start end nil))))))
 
+(defvar *external-formats* ()
+  #!+sb-doc
+  "List of all available external formats. Each element is a list of the
+  element-type, string input function name, character input function name,
+  and string output function name.")
+
 ;;; Find an output routine to use given the type and buffering. Return
 ;;; as multiple values the routine, the real type transfered, and the
 ;;; number of bytes per element.
-(defun pick-output-routine (type buffering)
+(defun pick-output-routine (type buffering &optional external-format)
+  (when (subtypep type 'character)
+    (dolist (entry *external-formats*)
+      (when (member external-format (first entry))
+	(return-from pick-output-routine
+	  (values (symbol-function (nth (ecase buffering
+					  (:none 4)
+					  (:line 5)
+					  (:full 6))
+					entry))
+		  'character
+		  1
+		  (symbol-function (fourth entry))
+		  (first (first entry)))))))
   (dolist (entry *output-routines*)
-    (when (and (subtypep type (car entry))
-	       (eq buffering (cadr entry)))
+    (when (and (subtypep type (first entry))
+	       (eq buffering (second entry))
+	       (or (not (fifth entry))
+		   (eq external-format (fifth entry))))
       (return-from pick-output-routine
-	(values (symbol-function (caddr entry))
-		(car entry)
-		(cadddr entry)))))
+	(values (symbol-function (third entry))
+		(first entry)
+		(fourth entry)))))
   ;; KLUDGE: dealing with the buffering here leads to excessive code
   ;; explosion.
   ;;
@@ -431,7 +541,7 @@
 	      (ecase buffering
 		(:none
 		 (lambda (stream byte)
-		   (output-wrapper (stream (/ i 8) (:none))
+		   (output-wrapper (stream (/ i 8) (:none) nil)
 		     (loop for j from 0 below (/ i 8)
 			   do (setf (sap-ref-8 
 				     (fd-stream-obuf-sap stream)
@@ -439,7 +549,7 @@
 				    (ldb (byte 8 (- i 8 (* j 8))) byte))))))
 		(:full
 		 (lambda (stream byte)
-		   (output-wrapper (stream (/ i 8) (:full))
+		   (output-wrapper (stream (/ i 8) (:full) nil)
 		     (loop for j from 0 below (/ i 8)
 			   do (setf (sap-ref-8 
 				     (fd-stream-obuf-sap stream)
@@ -454,7 +564,7 @@
 	      (ecase buffering
 		(:none
 		 (lambda (stream byte)
-		   (output-wrapper (stream (/ i 8) (:none))
+		   (output-wrapper (stream (/ i 8) (:none) nil)
 		     (loop for j from 0 below (/ i 8)
 			   do (setf (sap-ref-8 
 				     (fd-stream-obuf-sap stream)
@@ -462,7 +572,7 @@
 				    (ldb (byte 8 (- i 8 (* j 8))) byte))))))
 		(:full
 		 (lambda (stream byte)
-		   (output-wrapper (stream (/ i 8) (:full))
+		   (output-wrapper (stream (/ i 8) (:full) nil)
 		     (loop for j from 0 below (/ i 8)
 			   do (setf (sap-ref-8 
 				     (fd-stream-obuf-sap stream)
@@ -561,6 +671,66 @@
 	   (return))
 	 (frob-input ,stream-var)))))
 
+(defmacro input-wrapper/variable-width ((stream bytes eof-error eof-value
+						resync-function)
+					&body read-forms)
+  (let ((stream-var (gensym))
+	(retry-var (gensym))
+	(element-var (gensym)))
+    `(let ((,stream-var ,stream)
+	   (size nil))
+       (if (fd-stream-unread ,stream-var)
+	   (prog1
+	       (fd-stream-unread ,stream-var)
+	     (setf (fd-stream-unread ,stream-var) nil)
+	     (setf (fd-stream-listen ,stream-var) nil))
+	   (let ((,element-var nil))
+	     (do ((,retry-var t))
+		 ((not ,retry-var))
+	       (setq ,retry-var nil)
+	       (restart-case
+		   (catch 'eof-input-catcher
+		     (unless
+			 (block character-decode
+			   (input-at-least ,stream-var 1)
+			   (let* ((byte (sap-ref-8 (fd-stream-ibuf-sap
+						    ,stream-var)
+						   (fd-stream-ibuf-head
+						    ,stream-var))))
+			     (setq size ,bytes)
+			     (input-at-least ,stream-var size)
+			     (setq ,element-var (locally ,@read-forms))))
+		       (stream-decoding-error
+			,stream-var
+			(if size
+			    (loop for i from 0 below size
+				  collect (sap-ref-8 (fd-stream-ibuf-sap
+						      ,stream-var)
+						     (+ (fd-stream-ibuf-head
+							 ,stream-var)
+							i)))
+			    (list (sap-ref-8 (fd-stream-ibuf-sap
+					      ,stream-var)
+					     (fd-stream-ibuf-head
+					      ,stream-var)))))))
+		 (attempt-resync ()
+		   :report (lambda (stream)
+			     (format stream
+				     "~@<Attempt to resync the stream at a ~
+                                     character boundary and continue.~@:>"))
+		   (,resync-function ,stream-var)
+		   (setq ,retry-var t))
+		 (force-end-of-file ()
+		   :report (lambda (stream)
+			     (format stream
+				     "~@<Force an end of file.~@:>"))
+		   nil)))
+	     (cond (,element-var
+		    (incf (fd-stream-ibuf-head ,stream-var) size)
+		    ,element-var)
+		   (t
+		    (eof-or-lose ,stream-var ,eof-error ,eof-value))))))))
+
 ;;; a macro to wrap around all input routines to handle EOF-ERROR noise
 (defmacro input-wrapper ((stream bytes eof-error eof-value) &body read-forms)
   (let ((stream-var (gensym))
@@ -581,6 +751,21 @@
 		   (t
 		    (eof-or-lose ,stream-var ,eof-error ,eof-value))))))))
 
+(defmacro def-input-routine/variable-width (name
+					    (type external-format size sap head
+						  resync-function)
+					    &rest body)
+  `(progn
+     (defun ,name (stream eof-error eof-value)
+       (input-wrapper/variable-width (stream ,size eof-error eof-value
+					     ,resync-function)
+	 (let ((,sap (fd-stream-ibuf-sap stream))
+	       (,head (fd-stream-ibuf-head stream)))
+	   ,@body)))
+     (setf *input-routines*
+	   (nconc *input-routines*
+		  (list (list ',type ',name 1 ',external-format))))))
+
 (defmacro def-input-routine (name
 			     (type size sap head)
 			     &rest body)
@@ -592,7 +777,7 @@
 	   ,@body)))
      (setf *input-routines*
 	   (nconc *input-routines*
-		  (list (list ',type ',name ',size))))))
+		  (list (list ',type ',name ',size nil))))))
 
 ;;; STREAM-IN routine for reading a string char
 (def-input-routine input-character
@@ -629,16 +814,29 @@
 		   ((signed-byte 32) 4 sap head)
   (signed-sap-ref-32 sap head))
 
+
+
 ;;; Find an input routine to use given the type. Return as multiple
 ;;; values the routine, the real type transfered, and the number of
-;;; bytes per element.
-(defun pick-input-routine (type)
+;;; bytes per element (and for character types string input routine).
+(defun pick-input-routine (type &optional external-format)
+  (when (subtypep type 'character)
+    (dolist (entry *external-formats*)
+      (when (member external-format (first entry))
+	(return-from pick-input-routine
+	  (values (symbol-function (third entry))
+		  'character
+		  1
+		  (symbol-function (second entry))
+		  (first (first entry)))))))
   (dolist (entry *input-routines*)
-    (when (subtypep type (car entry))
+    (when (and (subtypep type (first entry))
+	       (or (not (fourth entry))
+		   (eq external-format (fourth entry))))
       (return-from pick-input-routine
-	(values (symbol-function (cadr entry))
-		(car entry)
-		(caddr entry)))))
+	(values (symbol-function (second entry))
+		(first entry)
+		(third entry)))))
   ;; FIXME: let's do it the hard way, then (but ignore things like
   ;; endianness, efficiency, and the necessary coupling between these
   ;; and the output routines).  -- CSR, 2004-02-09
@@ -671,7 +869,9 @@
 			  do (setf result
 				   (+ (* 256 result)
 				      (sap-ref-8 sap (+ head j))))
-			  finally (return (dpb result (byte i 0) -1))))))
+			  finally (return (if (logbitp (1- i) result)
+                                              (dpb result (byte i 0) -1)
+                                              result))))))
 	      `(signed-byte ,i)
 	      (/ i 8)))))
 
@@ -693,7 +893,7 @@
 ;;; isn't too problematical.
 (defun fd-stream-read-n-bytes (stream buffer start requested eof-error-p
 			       &aux (total-copied 0))
-  (declare (type file-stream stream))
+  (declare (type fd-stream stream))
   (declare (type index start requested total-copied))
   (let ((unread (fd-stream-unread stream)))
     (when unread
@@ -745,18 +945,404 @@
 (defun refill-fd-stream-buffer (stream)
   ;; We don't have any logic to preserve leftover bytes in the buffer,
   ;; so we should only be called when the buffer is empty.
-  (aver (= (fd-stream-ibuf-head stream) (fd-stream-ibuf-tail stream)))
-  (multiple-value-bind (count err)
-      (sb!unix:unix-read (fd-stream-fd stream)
-			 (fd-stream-ibuf-sap stream)
-			 (fd-stream-ibuf-length stream))
-    (declare (type (or index null) count))
-    (when (null count)
-      (simple-stream-perror "couldn't read from ~S" stream err))
-    (setf (fd-stream-listen stream) nil
-	  (fd-stream-ibuf-head stream) 0
-	  (fd-stream-ibuf-tail stream) count)
-    count))
+  ;; FIXME: can have three bytes in buffer because of UTF-8
+  (let ((new-head 0)
+        (sap (fd-stream-ibuf-sap stream)))
+    (do ((head (fd-stream-ibuf-head stream) (1+ head))
+         (tail (fd-stream-ibuf-tail stream)))
+        ((= head tail))
+      (setf (sap-ref-8 sap new-head) (sap-ref-8 sap head))
+      (incf new-head))
+    (multiple-value-bind (count err)
+        (sb!unix:unix-read (fd-stream-fd stream)
+                           (sap+ sap new-head)
+                           (- (fd-stream-ibuf-length stream) new-head))
+      (declare (type (or index null) count))
+      (when (null count)
+        (simple-stream-perror "couldn't read from ~S" stream err))
+      (setf (fd-stream-listen stream) nil
+            (fd-stream-ibuf-head stream) 0
+            (fd-stream-ibuf-tail stream) (+ count new-head))
+      count)))
+
+(defmacro define-external-format (external-format size output-restart
+                                  out-expr in-expr)
+  (let* ((name (first external-format))
+         (out-function (intern (let ((*print-case* :upcase))
+                                 (format nil "OUTPUT-BYTES/~A" name))))
+         (format (format nil "OUTPUT-CHAR-~A-~~A-BUFFERED" name))
+         (in-function (intern (let ((*print-case* :upcase))
+                                (format nil "FD-STREAM-READ-N-CHARACTERS/~A"
+                                        name))))
+         (in-char-function (intern (let ((*print-case* :upcase))
+                                     (format nil "INPUT-CHAR/~A" name)))))
+    `(progn
+      (defun ,out-function (stream string flush-p start end)
+	(let ((start (or start 0))
+	      (end (or end (length string))))
+	  (declare (type index start end))
+	  (when (> (fd-stream-ibuf-tail stream)
+		   (fd-stream-ibuf-head stream))
+	    (file-position stream (file-position stream)))
+	  (when (< end start)
+	    (error ":END before :START!"))
+	  (do ()
+	      ((= end start))
+	    (setf (fd-stream-obuf-tail stream)
+		  (do* ((len (fd-stream-obuf-length stream))
+			(sap (fd-stream-obuf-sap stream))
+			(tail (fd-stream-obuf-tail stream)))
+		       ((or (= start end) (< (- len tail) 4)) tail)
+                    ,(if output-restart
+                         `(with-simple-restart (output-nothing
+                                                "~@<Skip output of this character.~@:>")
+                           (let* ((byte (aref string start))
+                                  (bits (char-code byte)))
+                             ,out-expr
+                             (incf tail ,size)))
+                         `(let* ((byte (aref string start))
+                                  (bits (char-code byte)))
+                             ,out-expr
+                             (incf tail ,size)))
+		    (incf start)))
+	    (when (< start end)
+	      (flush-output-buffer stream)))
+	  (when flush-p
+	    (flush-output-buffer stream))))
+      (def-output-routines (,format
+			    ,size
+                            ,output-restart
+			    (:none character)
+			    (:line character)
+			    (:full character))
+	  (if (char= byte #\Newline)
+	      (setf (fd-stream-char-pos stream) 0)
+	      (incf (fd-stream-char-pos stream)))
+	(let ((bits (char-code byte))
+	      (sap (fd-stream-obuf-sap stream))
+	      (tail (fd-stream-obuf-tail stream)))
+	  ,out-expr))
+      (defun ,in-function (stream buffer start requested eof-error-p
+			   &aux (total-copied 0))
+	(declare (type fd-stream stream))
+	(declare (type index start requested total-copied))
+	(let ((unread (fd-stream-unread stream)))
+	  (when unread
+	    (setf (aref buffer start) unread)
+	    (setf (fd-stream-unread stream) nil)
+	    (setf (fd-stream-listen stream) nil)
+	    (incf total-copied)))
+	(do ()
+	    (nil)
+	  (let* ((head (fd-stream-ibuf-head stream))
+		 (tail (fd-stream-ibuf-tail stream))
+		 (sap (fd-stream-ibuf-sap stream)))
+	    (declare (type index head tail))
+	    ;; Copy data from stream buffer into user's buffer.
+	    (do ()
+		((or (= tail head) (= requested total-copied)))
+	      (let* ((byte (sap-ref-8 sap head)))
+		(when (> ,size (- tail head))
+		  (return))
+		(setf (aref buffer (+ start total-copied)) ,in-expr)
+		(incf total-copied)
+		(incf head ,size)))
+	    (setf (fd-stream-ibuf-head stream) head)
+	    ;; Maybe we need to refill the stream buffer.
+	    (cond ( ;; If there were enough data in the stream buffer, we're done.
+		   (= total-copied requested)
+		   (return total-copied))
+		  ( ;; If EOF, we're done in another way.
+		   (zerop (refill-fd-stream-buffer stream))
+		   (if eof-error-p
+		       (error 'end-of-file :stream stream)
+		       (return total-copied)))
+		  ;; Otherwise we refilled the stream buffer, so fall
+		  ;; through into another pass of the loop.
+		  ))))
+      (def-input-routine ,in-char-function (character ,size sap head)
+	(let ((byte (sap-ref-8 sap head)))
+	  ,in-expr))
+      (setf *external-formats*
+       (cons '(,external-format ,in-function ,in-char-function ,out-function
+	       ,@(mapcar #'(lambda (buffering)
+			     (intern (let ((*print-case* :upcase))
+				       (format nil format buffering))))
+			 '(:none :line :full)))
+	*external-formats*)))))
+
+(defmacro define-external-format/variable-width
+    (external-format output-restart out-size-expr
+     out-expr in-size-expr in-expr)
+  (let* ((name (first external-format))
+	 (out-function (intern (let ((*print-case* :upcase))
+				 (format nil "OUTPUT-BYTES/~A" name))))
+	 (format (format nil "OUTPUT-CHAR-~A-~~A-BUFFERED" name))
+	 (in-function (intern (let ((*print-case* :upcase))
+				(format nil "FD-STREAM-READ-N-CHARACTERS/~A"
+					name))))
+	 (in-char-function (intern (let ((*print-case* :upcase))
+				     (format nil "INPUT-CHAR/~A" name))))
+	 (resync-function (intern (let ((*print-case* :upcase))
+				    (format nil "RESYNC/~A" name)))))
+    `(progn
+      (defun ,out-function (fd-stream string flush-p start end)
+	(let ((start (or start 0))
+	      (end (or end (length string))))
+	  (declare (type index start end))
+	  (when (> (fd-stream-ibuf-tail fd-stream)
+		   (fd-stream-ibuf-head fd-stream))
+	    (file-position fd-stream (file-position fd-stream)))
+	  (when (< end start)
+	    (error ":END before :START!"))
+	  (do ()
+	      ((= end start))
+	    (setf (fd-stream-obuf-tail fd-stream)
+		  (do* ((len (fd-stream-obuf-length fd-stream))
+			(sap (fd-stream-obuf-sap fd-stream))
+			(tail (fd-stream-obuf-tail fd-stream)))
+		       ((or (= start end) (< (- len tail) 4)) tail)
+		    (let* ((byte (aref string start))
+			   (bits (char-code byte))
+			   (size ,out-size-expr))
+		      ,out-expr
+		      (incf tail size)
+		      (incf start))))
+	    (when (< start end)
+	      (flush-output-buffer fd-stream)))
+	  (when flush-p
+	    (flush-output-buffer fd-stream))))
+      (def-output-routines/variable-width (,format
+					   ,out-size-expr
+                                           ,output-restart
+					   ,external-format
+					   (:none character)
+					   (:line character)
+					   (:full character))
+	  (if (char= byte #\Newline)
+	      (setf (fd-stream-char-pos stream) 0)
+	      (incf (fd-stream-char-pos stream)))
+	(let ((bits (char-code byte))
+	      (sap (fd-stream-obuf-sap stream))
+	      (tail (fd-stream-obuf-tail stream)))
+	  ,out-expr))
+      (defun ,in-function (stream buffer start requested eof-error-p
+			   &aux (total-copied 0))
+	(declare (type fd-stream stream))
+	(declare (type index start requested total-copied))
+	(let ((unread (fd-stream-unread stream)))
+	  (when unread
+	    (setf (aref buffer start) unread)
+	    (setf (fd-stream-unread stream) nil)
+	    (setf (fd-stream-listen stream) nil)
+	    (incf total-copied)))
+	(do ()
+	    (nil)
+	  (let* ((head (fd-stream-ibuf-head stream))
+		 (tail (fd-stream-ibuf-tail stream))
+		 (sap (fd-stream-ibuf-sap stream)))
+	    (declare (type index head tail))
+	    ;; Copy data from stream buffer into user's buffer.
+	    (do ((size nil nil))
+		((or (= tail head) (= requested total-copied)))
+	      (restart-case
+		  (unless (block character-decode
+			    (let ((byte (sap-ref-8 sap head)))
+			      (setq size ,in-size-expr)
+			      (when (> size (- tail head))
+				(return))
+			      (setf (aref buffer (+ start total-copied))
+				    ,in-expr)
+			      (incf total-copied)
+			      (incf head size)))
+		    (setf (fd-stream-ibuf-head stream) head)
+		    (if (plusp total-copied)
+			(return-from ,in-function total-copied)
+			(stream-decoding-error
+			 stream
+			 (if size
+			     (loop for i from 0 below size
+				   collect (sap-ref-8 (fd-stream-ibuf-sap
+						       stream)
+						      (+ (fd-stream-ibuf-head
+							  stream)
+							 i)))
+			     (list (sap-ref-8 (fd-stream-ibuf-sap stream)
+					      (fd-stream-ibuf-head stream)))))))
+		(attempt-resync ()
+		  :report (lambda (stream)
+			    (format stream
+				    "~@<Attempt to resync the stream at a ~
+                                    character boundary and continue.~@:>"))
+		  (,resync-function stream)
+		  (setf head (fd-stream-ibuf-head stream)))
+		(force-end-of-file ()
+		  :report (lambda (stream)
+			    (format stream "~@<Force an end of file.~@:>"))
+		  (if eof-error-p
+		      (error 'end-of-file :stream stream)
+		      (return-from ,in-function total-copied)))))
+	    (setf (fd-stream-ibuf-head stream) head)
+	    ;; Maybe we need to refill the stream buffer.
+	    (cond ( ;; If there were enough data in the stream buffer, we're done.
+		   (= total-copied requested)
+		   (return total-copied))
+		  ( ;; If EOF, we're done in another way.
+		   (zerop (refill-fd-stream-buffer stream))
+		   (if eof-error-p
+		       (error 'end-of-file :stream stream)
+		       (return total-copied)))
+		  ;; Otherwise we refilled the stream buffer, so fall
+		  ;; through into another pass of the loop.
+		  ))))
+      (def-input-routine/variable-width ,in-char-function (character
+							   ,external-format
+							   ,in-size-expr
+							   sap head
+							   ,resync-function)
+	(let ((byte (sap-ref-8 sap head)))
+	  ,in-expr))
+      (defun ,resync-function (stream)
+        (loop (input-at-least stream 1)
+              (incf (fd-stream-ibuf-head stream))
+              (when (block character-decode
+                      (let* ((sap (fd-stream-ibuf-sap stream))
+                             (head (fd-stream-ibuf-head stream))
+                             (byte (sap-ref-8 sap head))
+                             (size ,in-size-expr))
+                        ,in-expr))
+                (return))))
+      (setf *external-formats*
+       (cons '(,external-format ,in-function ,in-char-function ,out-function
+	       ,@(mapcar #'(lambda (buffering)
+			     (intern (let ((*print-case* :upcase))
+				       (format nil format buffering))))
+			 '(:none :line :full))
+	       ,resync-function)
+	*external-formats*)))))
+
+(define-external-format (:latin-1 :latin1 :iso-8859-1)
+    1 t
+  (if (>= bits 256)
+      (stream-encoding-error stream bits)
+      (setf (sap-ref-8 sap tail) bits))
+  (code-char byte))
+
+(define-external-format (:ascii :us-ascii :ansi_x3.4-1968)
+    1 t
+  (if (>= bits 128)
+      (stream-encoding-error stream bits)
+      (setf (sap-ref-8 sap tail) bits))
+  (code-char byte))
+
+(let* ((table (let ((s (make-string 256)))
+		(map-into s #'code-char
+			  '(#x00 #x01 #x02 #x03 #x9c #x09 #x86 #x7f #x97 #x8d #x8e #x0b #x0c #x0d #x0e #x0f
+			    #x10 #x11 #x12 #x13 #x9d #x85 #x08 #x87 #x18 #x19 #x92 #x8f #x1c #x1d #x1e #x1f
+			    #x80 #x81 #x82 #x83 #x84 #x0a #x17 #x1b #x88 #x89 #x8a #x8b #x8c #x05 #x06 #x07
+			    #x90 #x91 #x16 #x93 #x94 #x95 #x96 #x04 #x98 #x99 #x9a #x9b #x14 #x15 #x9e #x1a
+			    #x20 #xa0 #xe2 #xe4 #xe0 #xe1 #xe3 #xe5 #xe7 #xf1 #xa2 #x2e #x3c #x28 #x2b #x7c
+			    #x26 #xe9 #xea #xeb #xe8 #xed #xee #xef #xec #xdf #x21 #x24 #x2a #x29 #x3b #xac
+			    #x2d #x2f #xc2 #xc4 #xc0 #xc1 #xc3 #xc5 #xc7 #xd1 #xa6 #x2c #x25 #x5f #x3e #x3f
+			    #xf8 #xc9 #xca #xcb #xc8 #xcd #xce #xcf #xcc #x60 #x3a #x23 #x40 #x27 #x3d #x22
+			    #xd8 #x61 #x62 #x63 #x64 #x65 #x66 #x67 #x68 #x69 #xab #xbb #xf0 #xfd #xfe #xb1
+			    #xb0 #x6a #x6b #x6c #x6d #x6e #x6f #x70 #x71 #x72 #xaa #xba #xe6 #xb8 #xc6 #xa4
+			    #xb5 #x7e #x73 #x74 #x75 #x76 #x77 #x78 #x79 #x7a #xa1 #xbf #xd0 #xdd #xde #xae
+			    #x5e #xa3 #xa5 #xb7 #xa9 #xa7 #xb6 #xbc #xbd #xbe #x5b #x5d #xaf #xa8 #xb4 #xd7
+			    #x7b #x41 #x42 #x43 #x44 #x45 #x46 #x47 #x48 #x49 #xad #xf4 #xf6 #xf2 #xf3 #xf5
+			    #x7d #x4a #x4b #x4c #x4d #x4e #x4f #x50 #x51 #x52 #xb9 #xfb #xfc #xf9 #xfa #xff
+			    #x5c #xf7 #x53 #x54 #x55 #x56 #x57 #x58 #x59 #x5a #xb2 #xd4 #xd6 #xd2 #xd3 #xd5
+			    #x30 #x31 #x32 #x33 #x34 #x35 #x36 #x37 #x38 #x39 #xb3 #xdb #xdc #xd9 #xda #x9f))
+		s))
+       (reverse-table (let ((rt (make-array 256 :element-type '(unsigned-byte 8) :initial-element 0)))
+			  (loop for char across table for i from 0
+			       do (aver (= 0 (aref rt (char-code char))))
+			       do (setf (aref rt (char-code char)) i))
+			  rt)))
+  (define-external-format (:ebcdic-us :ibm-037 :ibm037)
+      1 t
+    (if (>= bits 256)
+	(stream-encoding-error stream bits)
+	(setf (sap-ref-8 sap tail) (aref reverse-table bits)))
+    (aref table byte)))
+    
+
+#!+sb-unicode
+(let ((latin-9-table (let ((table (make-string 256)))
+                       (do ((i 0 (1+ i)))
+                           ((= i 256))
+                         (setf (aref table i) (code-char i)))
+                       (setf (aref table #xa4) (code-char #x20ac))
+                       (setf (aref table #xa6) (code-char #x0160))
+                       (setf (aref table #xa8) (code-char #x0161))
+                       (setf (aref table #xb4) (code-char #x017d))
+                       (setf (aref table #xb8) (code-char #x017e))
+                       (setf (aref table #xbc) (code-char #x0152))
+                       (setf (aref table #xbd) (code-char #x0153))
+                       (setf (aref table #xbe) (code-char #x0178))
+                       table))
+      (latin-9-reverse-1 (make-array 16
+                                     :element-type '(unsigned-byte 21)
+                                     :initial-contents '(#x0160 #x0161 #x0152 #x0153 0 0 0 0 #x0178 0 0 0 #x20ac #x017d #x017e 0)))
+      (latin-9-reverse-2 (make-array 16
+                                     :element-type '(unsigned-byte 8)
+                                     :initial-contents '(#xa6 #xa8 #xbc #xbd 0 0 0 0 #xbe 0 0 0 #xa4 #xb4 #xb8 0))))
+  (define-external-format (:latin-9 :latin9 :iso-8859-15)
+      1 t
+    (setf (sap-ref-8 sap tail)
+          (if (< bits 256)
+              (if (= bits (char-code (aref latin-9-table bits)))
+                  bits
+                  (stream-encoding-error stream byte))
+              (if (= (aref latin-9-reverse-1 (logand bits 15)) bits)
+                  (aref latin-9-reverse-2 (logand bits 15))
+                  (stream-encoding-error stream byte))))
+    (aref latin-9-table byte)))
+
+(define-external-format/variable-width (:utf-8 :utf8) nil
+  (let ((bits (char-code byte)))
+    (cond ((< bits #x80) 1)
+	  ((< bits #x800) 2)
+	  ((< bits #x10000) 3)
+	  (t 4)))
+  (ecase size
+    (1 (setf (sap-ref-8 sap tail) bits))
+    (2 (setf (sap-ref-8 sap tail) (logior #xc0 (ldb (byte 5 6) bits))
+	     (sap-ref-8 sap (1+ tail)) (logior #x80 (ldb (byte 6 0) bits))))
+    (3 (setf (sap-ref-8 sap tail) (logior #xe0 (ldb (byte 4 12) bits))
+	     (sap-ref-8 sap (1+ tail)) (logior #x80 (ldb (byte 6 6) bits))
+	     (sap-ref-8 sap (+ 2 tail)) (logior #x80 (ldb (byte 6 0) bits))))
+    (4 (setf (sap-ref-8 sap tail) (logior #xf0 (ldb (byte 3 18) bits))
+	     (sap-ref-8 sap (1+ tail)) (logior #x80 (ldb (byte 6 12) bits))
+	     (sap-ref-8 sap (+ 2 tail)) (logior #x80 (ldb (byte 6 6) bits))
+	     (sap-ref-8 sap (+ 3 tail)) (logior #x80 (ldb (byte 6 0) bits)))))
+  (cond ((< byte #x80) 1)
+	((< byte #xc2) (return-from character-decode))
+	((< byte #xe0) 2)
+	((< byte #xf0) 3)
+	(t 4))
+  (code-char (ecase size
+	       (1 byte)
+	       (2 (let ((byte2 (sap-ref-8 sap (1+ head))))
+		    (unless (<= #x80 byte2 #xbf)
+		      (return-from character-decode))
+		    (dpb byte (byte 5 6) byte2)))
+	       (3 (let ((byte2 (sap-ref-8 sap (1+ head)))
+			(byte3 (sap-ref-8 sap (+ 2 head))))
+		    (unless (and (<= #x80 byte2 #xbf)
+				 (<= #x80 byte3 #xbf))
+		      (return-from character-decode))
+		    (dpb byte (byte 4 12) (dpb byte2 (byte 6 6) byte3))))
+	       (4 (let ((byte2 (sap-ref-8 sap (1+ head)))
+			(byte3 (sap-ref-8 sap (+ 2 head)))
+			(byte4 (sap-ref-8 sap (+ 3 head))))
+		    (unless (and (<= #x80 byte2 #xbf)
+				 (<= #x80 byte3 #xbf)
+				 (<= #x80 byte4 #xbf))
+		      (return-from character-decode))
+		    (dpb byte (byte 3 18)
+			 (dpb byte2 (byte 6 12)
+			      (dpb byte3 (byte 6 6) byte4))))))))
 
 ;;;; utility functions (misc routines, etc)
 
@@ -774,7 +1360,8 @@
 	(input-type nil)
 	(output-type nil)
 	(input-size nil)
-	(output-size nil))
+	(output-size nil)
+	(character-stream-p (subtypep type 'character)))
 
     (when (fd-stream-obuf-sap fd-stream)
       (push (fd-stream-obuf-sap fd-stream) *available-buffers*)
@@ -783,39 +1370,73 @@
       (push (fd-stream-ibuf-sap fd-stream) *available-buffers*)
       (setf (fd-stream-ibuf-sap fd-stream) nil))
 
+    (when (and character-stream-p
+	       (eq (fd-stream-external-format fd-stream) :default))
+      (setf (fd-stream-external-format fd-stream)
+	    (intern (or (alien-funcall
+			 (extern-alien "nl_langinfo"
+				       (function c-string int))
+			 sb!unix:codeset)
+			"LATIN-1")
+		    "KEYWORD")))
+    (dolist (entry *external-formats*
+	     (setf (fd-stream-external-format fd-stream) :latin-1))
+      (when (member (fd-stream-external-format fd-stream) (first entry))
+	(return)))
+
     (when input-p
-      (multiple-value-bind (routine type size)
-	  (pick-input-routine target-type)
+      (multiple-value-bind (routine type size read-n-characters
+                                    normalized-external-format)
+	  (pick-input-routine target-type
+                              (fd-stream-external-format fd-stream))
+        (when normalized-external-format
+          (setf (fd-stream-external-format fd-stream)
+                normalized-external-format))
 	(unless routine
 	  (error "could not find any input routine for ~S" target-type))
 	(setf (fd-stream-ibuf-sap fd-stream) (next-available-buffer))
 	(setf (fd-stream-ibuf-length fd-stream) bytes-per-buffer)
 	(setf (fd-stream-ibuf-tail fd-stream) 0)
-	(if (subtypep type 'character)
+	(if character-stream-p
 	    (setf (fd-stream-in fd-stream) routine
 		  (fd-stream-bin fd-stream) #'ill-bin)
 	    (setf (fd-stream-in fd-stream) #'ill-in
 		  (fd-stream-bin fd-stream) routine))
 	(when (eql size 1)
-	  (setf (fd-stream-n-bin fd-stream) #'fd-stream-read-n-bytes)
+	  (setf (fd-stream-n-bin fd-stream)
+                (if character-stream-p
+                    read-n-characters
+                    #'fd-stream-read-n-bytes))
 	  (when (and buffer-p
 		     ;; We only create this buffer for streams of type
 		     ;; (unsigned-byte 8).  Because there's no buffer, the
 		     ;; other element-types will dispatch to the appropriate
 		     ;; input (output) routine in fast-read-byte.
-		     (equal target-type '(unsigned-byte 8))
-		     #+nil
+		     (or character-stream-p
+			 (equal target-type '(unsigned-byte 8)))
+		     (not output-p) ; temporary disable on :io streams
+		     #+(or)
 		     (or (eq type 'unsigned-byte)
 			 (eq type :default)))
-	    (setf (ansi-stream-in-buffer fd-stream)
-		  (make-array +ansi-stream-in-buffer-length+
-			      :element-type '(unsigned-byte 8)))))
+            (if character-stream-p
+                (setf (ansi-stream-cin-buffer fd-stream)
+                      (make-array +ansi-stream-in-buffer-length+
+                                  :element-type 'character))
+                (setf (ansi-stream-in-buffer fd-stream)
+                      (make-array +ansi-stream-in-buffer-length+
+                                  :element-type '(unsigned-byte 8))))))
 	(setf input-size size)
 	(setf input-type type)))
 
     (when output-p
-      (multiple-value-bind (routine type size)
-	  (pick-output-routine target-type (fd-stream-buffering fd-stream))
+      (multiple-value-bind (routine type size output-bytes
+				    normalized-external-format)
+	  (pick-output-routine target-type
+			       (fd-stream-buffering fd-stream)
+			       (fd-stream-external-format fd-stream))
+	(when normalized-external-format
+	  (setf (fd-stream-external-format fd-stream)
+		normalized-external-format))
 	(unless routine
 	  (error "could not find any output routine for ~S buffered ~S"
 		 (fd-stream-buffering fd-stream)
@@ -823,13 +1444,15 @@
 	(setf (fd-stream-obuf-sap fd-stream) (next-available-buffer))
 	(setf (fd-stream-obuf-length fd-stream) bytes-per-buffer)
 	(setf (fd-stream-obuf-tail fd-stream) 0)
-	(if (subtypep type 'character)
+	(when character-stream-p
+	  (setf (fd-stream-output-bytes fd-stream) output-bytes))
+	(if character-stream-p
 	  (setf (fd-stream-out fd-stream) routine
 		(fd-stream-bout fd-stream) #'ill-bout)
 	  (setf (fd-stream-out fd-stream)
 		(or (if (eql size 1)
-		      (pick-output-routine 'base-char
-					   (fd-stream-buffering fd-stream)))
+			  (pick-output-routine
+			   'base-char (fd-stream-buffering fd-stream)))
 		    #'ill-out)
 		(fd-stream-bout fd-stream) routine))
 	(setf (fd-stream-sout fd-stream)
@@ -998,7 +1621,7 @@
        ;; appropriate value for the EXPECTED-TYPE slot..
        (error 'simple-type-error
               :datum fd-stream
-              :expected-type 'file-stream
+              :expected-type 'fd-stream
               :format-control "~S is not a stream associated with a file."
               :format-arguments (list fd-stream)))
      (multiple-value-bind (okay dev ino mode nlink uid gid rdev size
@@ -1015,7 +1638,7 @@
      (fd-stream-file-position fd-stream arg1))))
 
 (defun fd-stream-file-position (stream &optional newpos)
-  (declare (type file-stream stream)
+  (declare (type fd-stream stream)
 	   (type (or (alien sb!unix:off-t) (member nil :start :end)) newpos))
   (if (null newpos)
       (sb!sys:without-interrupts
@@ -1113,6 +1736,7 @@
 		       (output nil output-p)
 		       (element-type 'base-char)
 		       (buffering :full)
+		       (external-format :default)
 		       timeout
 		       file
 		       original
@@ -1136,6 +1760,7 @@
 				 :delete-original delete-original
 				 :pathname pathname
 				 :buffering buffering
+				 :external-format external-format
 				 :timeout timeout)))
     (set-fd-stream-routines stream element-type input output input-buffer-p)
     (when (and auto-close (fboundp 'finalize))
@@ -1195,12 +1820,10 @@
    :DIRECTION - one of :INPUT, :OUTPUT, :IO, or :PROBE
    :ELEMENT-TYPE - the type of object to read or write, default BASE-CHAR
    :IF-EXISTS - one of :ERROR, :NEW-VERSION, :RENAME, :RENAME-AND-DELETE,
-		       :OVERWRITE, :APPEND, :SUPERSEDE or NIL
+                       :OVERWRITE, :APPEND, :SUPERSEDE or NIL
    :IF-DOES-NOT-EXIST - one of :ERROR, :CREATE or NIL
   See the manual for details."
 
-  (declare (ignore external-format)) ; FIXME: CHECK-TYPE?  WARN-if-not?
-  
   ;; Calculate useful stuff.
   (multiple-value-bind (input output mask)
       (case direction
@@ -1325,6 +1948,7 @@
 				      :input input
 				      :output output
 				      :element-type element-type
+				      :external-format external-format
 				      :file namestring
 				      :original original
 				      :delete-original delete-original
@@ -1387,7 +2011,8 @@
 	(make-fd-stream 1 :name "standard output" :output t :buffering :line))
   (setf *stderr*
 	(make-fd-stream 2 :name "standard error" :output t :buffering :line))
-  (let ((tty (sb!unix:unix-open "/dev/tty" sb!unix:o_rdwr #o666)))
+  (let* ((ttyname #.(coerce "/dev/tty" 'simple-base-string))
+	 (tty (sb!unix:unix-open ttyname sb!unix:o_rdwr #o666)))
     (if tty
 	(setf *tty*
 	      (make-fd-stream tty
@@ -1411,7 +2036,7 @@
 ;;;
 ;;; FIXME: misleading name, screwy interface
 (defun file-name (stream &optional new-name)
-  (when (typep stream 'file-stream)
+  (when (typep stream 'fd-stream)
       (cond (new-name
 	     (setf (fd-stream-pathname stream) new-name)
 	     (setf (fd-stream-file stream)
@@ -1428,7 +2053,7 @@
 ;;;; COMMON-LISP.)
 
 (defun file-string-length (stream object)
-  (declare (type (or string character) object) (type file-stream stream))
+  (declare (type (or string character) object) (type fd-stream stream))
   #!+sb-doc
   "Return the delta in STREAM's FILE-POSITION that would be caused by writing
    OBJECT to STREAM. Non-trivial only in implementations that support
@@ -1439,7 +2064,9 @@
     (string (length object))))
 
 (defun stream-external-format (stream)
-  (declare (type file-stream stream) (ignore stream))
+  (declare (type fd-stream stream))
   #!+sb-doc
-  "Return :DEFAULT."
-  :default)
+  "Return the actual external format for fd-streams, otherwise :DEFAULT."
+  (if (typep stream 'fd-stream)
+      (fd-stream-external-format stream)
+      :default))