0.9.1.47
[sbcl.git] / src / code / fd-stream.lisp
index 152acf2..60aeadb 100644 (file)
   (fd -1 :type fixnum)       
   ;; controls when the output buffer is flushed
   (buffering :full :type (member :full :line :none))
+  ;; controls whether the input buffer must be cleared before output
+  ;; (must be done for files, not for sockets, pipes and other data
+  ;; sources where input and output aren't related).  non-NIL means
+  ;; don't clear input buffer.
+  (dual-channel-p nil)
   ;; character position (if known)
   (char-pos nil :type (or index null))
   ;; T if input is waiting on FD. :EOF if we hit EOF.
         :stream stream
          :code code))
 
+;;; Returning true goes into end of file handling, false will enter another
+;;; round of input buffer filling followed by re-entering character decode.
+(defun stream-decoding-error-and-handle (stream octet-count)
+  (restart-case
+      (stream-decoding-error stream
+                            (let ((sap (fd-stream-ibuf-sap stream))
+                                  (head (fd-stream-ibuf-head stream)))
+                              (loop for i from 0 below octet-count
+                                    collect (sap-ref-8 sap (+ head i)))))
+    (attempt-resync ()
+      :report (lambda (stream)
+               (format stream
+                       "~@<Attempt to resync the stream at a character ~
+                        character boundary and continue.~@:>"))
+      (fd-stream-resync stream)
+      nil)
+    (force-end-of-file ()
+      :report (lambda (stream)
+               (format stream "~@<Force an end of file.~@:>"))
+      t)))
+
+(defun stream-encoding-error-and-handle (stream code)
+  (restart-case
+      (stream-encoding-error stream code)
+    (output-nothing ()
+      :report (lambda (stream)
+               (format stream "~@<Skip output of this character.~@:>"))
+      (throw 'output-nothing nil))))
+
 ;;; 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
                       size))
             (flush-output-buffer ,stream-var)))
       ,(unless (eq (car buffering) :none)
-        `(when (> (fd-stream-ibuf-tail ,stream-var)
-                  (fd-stream-ibuf-head ,stream-var))
+        `(when (and (not (fd-stream-dual-channel-p ,stream-var))
+                    (> (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))
+           `(catch 'output-nothing
+             ,@body
+             (incf (fd-stream-obuf-tail ,stream-var) size))
            `(progn
              ,@body
              (incf (fd-stream-obuf-tail ,stream-var) size)))
                       ,size))
             (flush-output-buffer ,stream-var)))
       ,(unless (eq (car buffering) :none)
-        `(when (> (fd-stream-ibuf-tail ,stream-var)
-                  (fd-stream-ibuf-head ,stream-var))
+        `(when (and (not (fd-stream-dual-channel-p ,stream-var))
+                    (> (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))
+          `(catch 'output-nothing
+             ,@body
+             (incf (fd-stream-obuf-tail ,stream-var) ,size))
            `(progn
              ,@body
              (incf (fd-stream-obuf-tail ,stream-var) ,size)))
        (mapcar
            (lambda (buffering)
              (let ((function
-                    (intern (let ((*print-case* :upcase))
-                              (format nil name-fmt (car buffering))))))
+                    (intern (format nil name-fmt (string (car buffering))))))
                `(progn
                   (defun ,function (stream byte)
                     (output-wrapper/variable-width (stream ,size ,buffering ,restart)
        (mapcar
            (lambda (buffering)
              (let ((function
-                    (intern (let ((*print-case* :upcase))
-                              (format nil name-fmt (car buffering))))))
+                    (intern (format nil name-fmt (string (car buffering))))))
                `(progn
                   (defun ,function (stream byte)
                     (output-wrapper (stream ,size ,buffering ,restart)
   (let ((start (or start 0))
        (end (or end (length (the (simple-array * (*)) thing)))))
     (declare (type index start end))
-    (when (> (fd-stream-ibuf-tail fd-stream)
-            (fd-stream-ibuf-head fd-stream))
+    (when (and (not (fd-stream-dual-channel-p fd-stream))
+              (> (fd-stream-ibuf-tail fd-stream)
+                 (fd-stream-ibuf-head fd-stream)))
       (file-position fd-stream (file-position fd-stream)))
     (let* ((len (fd-stream-obuf-length fd-stream))
           (tail (fd-stream-obuf-tail fd-stream))
                                           :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))
-           (:line
-            (output-raw-bytes stream thing start end)
-            (when last-newline
-              (flush-output-buffer stream)))
-           (:none
-            (frob-output stream thing start end nil)))
+              (ecase (fd-stream-buffering stream)
+                (:full
+                 (output-raw-bytes stream thing start end))
+                (:line
+                 (output-raw-bytes stream thing start end)
+                 (when last-newline
+                   (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))
 ;;; per element.
 (defvar *input-routines* ())
 
-;;; Fill the input buffer, and return the first character. Throw to
-;;; EOF-INPUT-CATCHER if the eof was reached. Drop into SYSTEM:SERVER
-;;; if necessary.
-(defun frob-input (stream)
+;;; Fill the input buffer, and return the number of bytes read. Throw
+;;; to EOF-INPUT-CATCHER if the eof was reached. Drop into
+;;; SYSTEM:SERVER if necessary.
+(defun refill-buffer/fd (stream)
   (let ((fd (fd-stream-fd stream))
        (ibuf-sap (fd-stream-ibuf-sap stream))
        (buflen (fd-stream-ibuf-length stream))
                   (unless (sb!sys:wait-until-fd-usable
                            fd :input (fd-stream-timeout stream))
                     (error 'io-timeout :stream stream :direction :read))
-                  (frob-input stream))
+                  (refill-buffer/fd stream))
                 (simple-stream-perror "couldn't read from ~S" stream errno)))
            ((zerop count)
             (setf (fd-stream-listen stream) :eof)
             (/show0 "THROWing EOF-INPUT-CATCHER")
             (throw 'eof-input-catcher nil))
            (t
-            (incf (fd-stream-ibuf-tail stream) count))))))
+            (incf (fd-stream-ibuf-tail stream) count)
+             count)))))
                        
 ;;; Make sure there are at least BYTES number of bytes in the input
-;;; buffer. Keep calling FROB-INPUT until that condition is met.
+;;; buffer. Keep calling REFILL-BUFFER/FD until that condition is met.
 (defmacro input-at-least (stream bytes)
   (let ((stream-var (gensym))
        (bytes-var (gensym)))
                      (fd-stream-ibuf-head ,stream-var))
                   ,bytes-var)
           (return))
-        (frob-input ,stream-var)))))
+        (refill-buffer/fd ,stream-var)))))
 
-(defmacro input-wrapper/variable-width ((stream bytes eof-error eof-value
-                                               resync-function)
+(defmacro input-wrapper/variable-width ((stream bytes eof-error eof-value)
                                        &body read-forms)
   (let ((stream-var (gensym))
        (retry-var (gensym))
               (fd-stream-unread ,stream-var)
             (setf (fd-stream-unread ,stream-var) nil)
             (setf (fd-stream-listen ,stream-var) nil))
-          (let ((,element-var nil))
+          (let ((,element-var nil)
+                (decode-break-reason nil))
             (do ((,retry-var t))
                 ((not ,retry-var))
-              (setq ,retry-var nil)
-              (restart-case
+              (unless
                   (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
+                    (setf decode-break-reason
+                          (block decode-break-reason
+                            (input-at-least ,stream-var 1)
+                            (let* ((byte (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)))
+                                                    (fd-stream-ibuf-head
+                                                     ,stream-var))))
+                              (setq size ,bytes)
+                              (input-at-least ,stream-var size)
+                              (setq ,element-var (locally ,@read-forms))
+                              (setq ,retry-var nil))
+                            nil))
+                    (when decode-break-reason
+                      (stream-decoding-error-and-handle stream
+                                                        decode-break-reason))
+                    t)
+                (let ((octet-count (- (fd-stream-ibuf-tail ,stream-var)
+                                     (fd-stream-ibuf-head ,stream-var))))
+                  (when (or (zerop octet-count)
+                            (and (not ,element-var)
+                                 (not decode-break-reason)
+                                 (stream-decoding-error-and-handle
+                                  stream octet-count)))
+                    (setq ,retry-var nil)))))
             (cond (,element-var
                    (incf (fd-stream-ibuf-head ,stream-var) size)
                    ,element-var)
                    (eof-or-lose ,stream-var ,eof-error ,eof-value))))))))
 
 (defmacro def-input-routine/variable-width (name
-                                           (type external-format size sap head
-                                                 resync-function)
+                                           (type external-format size sap head)
                                            &rest body)
   `(progn
      (defun ,name (stream eof-error eof-value)
-       (input-wrapper/variable-width (stream ,size eof-error eof-value
-                                            ,resync-function)
+       (input-wrapper/variable-width (stream ,size eof-error eof-value)
         (let ((,sap (fd-stream-ibuf-sap stream))
               (,head (fd-stream-ibuf-head stream)))
           ,@body)))
             (= total-copied requested)
             (return total-copied))
            (;; If EOF, we're done in another way.
-            (zerop (refill-fd-stream-buffer stream))
+             (null (catch 'eof-input-catcher (refill-buffer/fd stream)))
             (if eof-error-p
                 (error 'end-of-file :stream stream)
                 (return total-copied)))
            ;; through into another pass of the loop.
            ))))
 
-;;; Try to refill the stream buffer. Return the number of bytes read.
-;;; (For EOF, the return value will be zero, otherwise positive.)
-(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.
-  ;; 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)))
+(defun fd-stream-resync (stream)
+  (dolist (entry *external-formats*)
+    (when (member (fd-stream-external-format stream) (first entry))
+      (return-from fd-stream-resync
+       (funcall (symbol-function (eighth entry)) stream)))))
 
+;;; FIXME: OAOOM here vrt. *EXTERNAL-FORMAT-FUNCTIONS* in fd-stream.lisp
 (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)))))
+         (out-function (symbolicate "OUTPUT-BYTES/" name))
+         (format (format nil "OUTPUT-CHAR-~A-~~A-BUFFERED" (string name)))
+         (in-function (symbolicate "FD-STREAM-READ-N-CHARACTERS/" name))
+         (in-char-function (symbolicate "INPUT-CHAR/" 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))
+         (when (and (not (fd-stream-dual-channel-p stream))
+                    (> (fd-stream-ibuf-tail stream)
+                       (fd-stream-ibuf-head stream)))
            (file-position stream (file-position stream)))
          (when (< end start)
            (error ":END before :START!"))
                        (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)))
+                        `(catch 'output-nothing
+                           (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
                   (= total-copied requested)
                   (return total-copied))
                  ( ;; If EOF, we're done in another way.
-                  (zerop (refill-fd-stream-buffer stream))
+                   (null (catch 'eof-input-catcher (refill-buffer/fd stream)))
                   (if eof-error-p
                       (error 'end-of-file :stream stream)
                       (return total-copied)))
       (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))))
+                            (intern (format nil format (string buffering))))
                         '(:none :line :full)))
        *external-formats*)))))
 
     (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)))))
+        (out-function (symbolicate "OUTPUT-BYTES/" name))
+        (format (format nil "OUTPUT-CHAR-~A-~~A-BUFFERED" (string name)))
+        (in-function (symbolicate "FD-STREAM-READ-N-CHARACTERS/" name))
+        (in-char-function (symbolicate "INPUT-CHAR/" name))
+        (resync-function (symbolicate "RESYNC/" name)))
     `(progn
-      (defun ,out-function (fd-stream string flush-p start end)
+      (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 fd-stream)
-                  (fd-stream-ibuf-head fd-stream))
-           (file-position fd-stream (file-position fd-stream)))
+         (when (and (not (fd-stream-dual-channel-p stream))
+                    (> (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 fd-stream)
-                 (do* ((len (fd-stream-obuf-length fd-stream))
-                       (sap (fd-stream-obuf-sap fd-stream))
-                       (tail (fd-stream-obuf-tail fd-stream)))
+           (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)
-                   (let* ((byte (aref string start))
-                          (bits (char-code byte))
-                          (size ,out-size-expr))
-                     ,out-expr
-                     (incf tail size)
-                     (incf start))))
+                   ,(if output-restart
+                        `(catch 'output-nothing
+                           (let* ((byte (aref string start))
+                                  (bits (char-code byte))
+                                  (size ,out-size-expr))
+                             ,out-expr
+                             (incf tail size)))
+                        `(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)))
+             (flush-output-buffer stream)))
          (when flush-p
-           (flush-output-buffer fd-stream))))
+           (flush-output-buffer stream))))
       (def-output-routines/variable-width (,format
                                           ,out-size-expr
                                            ,output-restart
            (nil)
          (let* ((head (fd-stream-ibuf-head stream))
                 (tail (fd-stream-ibuf-tail stream))
-                (sap (fd-stream-ibuf-sap stream)))
+                (sap (fd-stream-ibuf-sap stream))
+                (head-start head)
+                (decode-break-reason nil))
            (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.~@:>"))
+             (setf decode-break-reason
+                   (block decode-break-reason
+                     (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))
+                     nil))
+             (setf (fd-stream-ibuf-head stream) head)
+             (when (and decode-break-reason
+                        (= head head-start))
+               (when (stream-decoding-error-and-handle
+                      stream decode-break-reason)
                  (if eof-error-p
                      (error 'end-of-file :stream stream)
-                     (return-from ,in-function total-copied)))))
+                     (return-from ,in-function total-copied)))
+               (setf head (fd-stream-ibuf-head stream))
+               (setf tail (fd-stream-ibuf-tail stream)))
+             (when (plusp total-copied)
+               (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))
+                  (or (eq decode-break-reason 'eof)
+                       (null (catch 'eof-input-catcher 
+                               (refill-buffer/fd stream))))
                   (if eof-error-p
                       (error 'end-of-file :stream stream)
                       (return total-copied)))
       (def-input-routine/variable-width ,in-char-function (character
                                                           ,external-format
                                                           ,in-size-expr
-                                                          sap head
-                                                          ,resync-function)
+                                                          sap head)
        (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))
+              (unless (block decode-break-reason
+                       (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)
+                       nil)
                 (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))))
+                            (intern (format nil format (string 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)
+      (stream-encoding-error-and-handle stream bits)
       (setf (sap-ref-8 sap tail) bits))
   (code-char byte))
 
-(define-external-format (:ascii :us-ascii :ansi_x3.4-1968)
+(define-external-format (:ascii :us-ascii :ansi_x3.4-1968 
+                         :iso-646 :iso-646-us :|646|)
     1 t
   (if (>= bits 128)
-      (stream-encoding-error stream bits)
+      (stream-encoding-error-and-handle stream bits)
       (setf (sap-ref-8 sap tail) bits))
   (code-char byte))
 
   (define-external-format (:ebcdic-us :ibm-037 :ibm037)
       1 t
     (if (>= bits 256)
-       (stream-encoding-error stream bits)
+       (stream-encoding-error-and-handle stream bits)
        (setf (sap-ref-8 sap tail) (aref reverse-table bits)))
     (aref table byte)))
     
           (if (< bits 256)
               (if (= bits (char-code (aref latin-9-table bits)))
                   bits
-                  (stream-encoding-error stream byte))
+                  (stream-encoding-error-and-handle 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))))
+                  (stream-encoding-error-and-handle stream byte))))
     (aref latin-9-table byte)))
 
 (define-external-format/variable-width (:utf-8 :utf8) nil
             (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 #xc2) (return-from decode-break-reason 1))
        ((< byte #xe0) 2)
        ((< byte #xf0) 3)
        (t 4))
               (1 byte)
               (2 (let ((byte2 (sap-ref-8 sap (1+ head))))
                    (unless (<= #x80 byte2 #xbf)
-                     (return-from character-decode))
+                     (return-from decode-break-reason 2))
                    (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))
+                     (return-from decode-break-reason 3))
                    (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)))
                    (unless (and (<= #x80 byte2 #xbf)
                                 (<= #x80 byte3 #xbf)
                                 (<= #x80 byte4 #xbf))
-                     (return-from character-decode))
+                     (return-from decode-break-reason 4))
                    (dpb byte (byte 3 18)
                         (dpb byte2 (byte 6 12)
                              (dpb byte3 (byte 6 6) byte4))))))))
        (output-size nil)
        (character-stream-p (subtypep type 'character)))
 
-    (when (fd-stream-obuf-sap fd-stream)
+    ;; drop buffers when direction changes
+    (when (and (fd-stream-obuf-sap fd-stream) (not output-p))
       (push (fd-stream-obuf-sap fd-stream) *available-buffers*)
       (setf (fd-stream-obuf-sap fd-stream) nil))
-    (when (fd-stream-ibuf-sap fd-stream)
+    (when (and (fd-stream-ibuf-sap fd-stream) (not input-p))
       (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))
+      (/show0 "/getting default external format")
       (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)))
-
+            (default-external-format))
+      (/show0 "cold-printing defaulted external-format:")
+      #!+sb-show
+      (cold-print (fd-stream-external-format fd-stream))
+      (/show0 "matching to known aliases")
+      (dolist (entry *external-formats*
+                    (restart-case
+                         (error "Invalid external-format ~A" 
+                                (fd-stream-external-format fd-stream))
+                     (use-default ()
+                        :report "Set external format to LATIN-1"
+                        (setf (fd-stream-external-format fd-stream) :latin-1))))
+        (/show0 "cold printing known aliases:")
+        #!+sb-show
+        (dolist (alias (first entry)) (cold-print alias))
+        (/show0 "done cold-printing known aliases")
+       (when (member (fd-stream-external-format fd-stream) (first entry))
+          (/show0 "matched")
+         (return)))
+      (/show0 "/default external format ok"))
+    
     (when input-p
       (multiple-value-bind (routine type size read-n-characters
                                     normalized-external-format)
                 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 character-stream-p
            (setf (fd-stream-in fd-stream) routine
                  (fd-stream-bin fd-stream) #'ill-bin)
          (error "could not find any output routine for ~S buffered ~S"
                 (fd-stream-buffering fd-stream)
                 target-type))
-       (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)
        (when character-stream-p
          (setf (fd-stream-output-bytes fd-stream) output-bytes))
        (if character-stream-p
                (fd-stream-bout fd-stream) routine))
        (setf (fd-stream-sout fd-stream)
              (if (eql size 1) #'fd-sout #'ill-out))
-       (setf (fd-stream-char-pos fd-stream) 0)
        (setf output-size size)
        (setf output-type type)))
 
                                                 0
                                                 0))))
          (cond ((eql count 1)
-                (frob-input fd-stream)
+                (refill-buffer/fd fd-stream)
                 (setf (fd-stream-ibuf-head fd-stream) 0)
                 (setf (fd-stream-ibuf-tail fd-stream) 0))
                (t
        (sb!sys:serve-all-events)))
     (:element-type
      (fd-stream-element-type fd-stream))
+    (:external-format
+     (fd-stream-external-format fd-stream))
     (:interactive-p
      (= 1 (the (member 0 1)
             (sb!unix:unix-isatty (fd-stream-fd fd-stream)))))
        (if (zerop mode)
           nil
           (truncate size (fd-stream-element-size fd-stream)))))
+    ;; FIXME: I doubt this is correct in the presence of Unicode,
+    ;; since fd-stream FILE-POSITION is measured in bytes. 
+    (:file-string-length
+     (etypecase arg1
+       (character 1)
+       (string (length arg1))))
     (:file-position
      (fd-stream-file-position fd-stream arg1))))
 
                       delete-original
                       pathname
                       input-buffer-p
+                      dual-channel-p
                       (name (if file
                                 (format nil "file ~S" file)
                                 (format nil "descriptor ~W" fd)))
                                 :delete-original delete-original
                                 :pathname pathname
                                 :buffering buffering
+                                :dual-channel-p dual-channel-p
                                 :external-format external-format
                                 :timeout timeout)))
+    (when input
+      (setf (fd-stream-ibuf-sap stream) (next-available-buffer))
+      (setf (fd-stream-ibuf-length stream) bytes-per-buffer)
+      (setf (fd-stream-ibuf-tail stream) 0))
+    (when output
+      (setf (fd-stream-obuf-sap stream) (next-available-buffer))
+      (setf (fd-stream-obuf-length stream) bytes-per-buffer)
+      (setf (fd-stream-obuf-tail stream) 0)
+      (setf (fd-stream-char-pos stream) 0))
     (set-fd-stream-routines stream element-type input output input-buffer-p)
     (when (and auto-close (fboundp 'finalize))
       (finalize stream
       (let ((original (case if-exists
                        ((:rename :rename-and-delete)
                         (pick-backup-name namestring))
-                       ((:append)
+                       ((:append :overwrite)
                         ;; KLUDGE: Provent CLOSE from deleting
                         ;; appending streams when called with :ABORT T
                         namestring)))
                                      :original original
                                      :delete-original delete-original
                                      :pathname pathname
+                                     :dual-channel-p nil
                                      :input-buffer-p t
                                      :auto-close t))
                     (:probe
             t)
            (t
             (fd-stream-pathname stream)))))
-\f
-;;;; international character support (which is trivial for our simple
-;;;; character sets)
-
-;;;; (Those who do Lisp only in English might not remember that ANSI
-;;;; requires these functions to be exported from package
-;;;; COMMON-LISP.)
-
-(defun file-string-length (stream object)
-  (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
-   international character sets."
-  (declare (ignore stream))
-  (etypecase object
-    (character 1)
-    (string (length object))))
-
-(defun stream-external-format (stream)
-  (declare (type fd-stream stream))
-  #!+sb-doc
-  "Return the actual external format for fd-streams, otherwise :DEFAULT."
-  (if (typep stream 'fd-stream)
-      (fd-stream-external-format stream)
-      :default))