1.0.19.22: fix bug #425
[sbcl.git] / src / code / stream.lisp
index 609df65..eb40f58 100644 (file)
          :format-arguments (list stream)))
 (defun closed-flame (stream &rest ignore)
   (declare (ignore ignore))
-  (error "~S is closed." stream))
+  (error 'closed-stream-error :stream stream))
 (defun no-op-placeholder (&rest ignore)
   (declare (ignore ignore)))
 \f
 ;;; stream manipulation functions
 
-(declaim (inline ansi-stream-input-stream-p))
 (defun ansi-stream-input-stream-p (stream)
   (declare (type ansi-stream stream))
-
-  (when (synonym-stream-p stream)
-    (setf stream
-          (symbol-value (synonym-stream-symbol stream))))
-
-  (and (not (eq (ansi-stream-in stream) #'closed-flame))
+  (if (synonym-stream-p stream)
+      (input-stream-p (symbol-value (synonym-stream-symbol stream)))
+      (and (not (eq (ansi-stream-in stream) #'closed-flame))
        ;;; KLUDGE: It's probably not good to have EQ tests on function
        ;;; values like this. What if someone's redefined the function?
        ;;; Is there a better way? (Perhaps just VALID-FOR-INPUT and
        ;;; VALID-FOR-OUTPUT flags? -- WHN 19990902
-       (or (not (eq (ansi-stream-in stream) #'ill-in))
-           (not (eq (ansi-stream-bin stream) #'ill-bin)))))
+           (or (not (eq (ansi-stream-in stream) #'ill-in))
+               (not (eq (ansi-stream-bin stream) #'ill-bin))))))
 
 (defun input-stream-p (stream)
   (declare (type stream stream))
   (and (ansi-stream-p stream)
        (ansi-stream-input-stream-p stream)))
 
-(declaim (inline ansi-stream-output-stream-p))
 (defun ansi-stream-output-stream-p (stream)
   (declare (type ansi-stream stream))
-
-  (when (synonym-stream-p stream)
-    (setf stream (symbol-value
-                  (synonym-stream-symbol stream))))
-
-  (and (not (eq (ansi-stream-in stream) #'closed-flame))
-       (or (not (eq (ansi-stream-out stream) #'ill-out))
-           (not (eq (ansi-stream-bout stream) #'ill-bout)))))
+  (if (synonym-stream-p stream)
+      (output-stream-p (symbol-value (synonym-stream-symbol stream)))
+      (and (not (eq (ansi-stream-in stream) #'closed-flame))
+           (or (not (eq (ansi-stream-out stream) #'ill-out))
+               (not (eq (ansi-stream-bout stream) #'ill-bout))))))
 
 (defun output-stream-p (stream)
   (declare (type stream stream))
   (setf (ansi-stream-in stream) #'closed-flame)
   (setf (ansi-stream-bin stream) #'closed-flame)
   (setf (ansi-stream-n-bin stream) #'closed-flame)
-  (setf (ansi-stream-in stream) #'closed-flame)
   (setf (ansi-stream-out stream) #'closed-flame)
   (setf (ansi-stream-bout stream) #'closed-flame)
   (setf (ansi-stream-sout stream) #'closed-flame)
   (setf (ansi-stream-misc stream) #'closed-flame))
 \f
 ;;;; file position and file length
+(defun external-format-char-size (external-format)
+  (let ((ef-entry (find-external-format external-format)))
+    (if (variable-width-external-format-p ef-entry)
+        (bytes-for-char-fun ef-entry)
+        (funcall (bytes-for-char-fun ef-entry) #\x))))
 
 ;;; Call the MISC method with the :FILE-POSITION operation.
 #!-sb-fluid (declaim (inline ansi-stream-file-position))
   (declare (type stream stream))
   (declare (type (or index (alien sb!unix:off-t) (member nil :start :end))
                  position))
+  ;; FIXME: It woud be good to comment on the stuff that is done here...
+  ;; FIXME: This doesn't look interrupt safe.
   (cond
     (position
      (setf (ansi-stream-in-index stream) +ansi-stream-in-buffer-length+)
             (- +ansi-stream-in-buffer-length+
                (ansi-stream-in-index stream)))
          #!+sb-unicode
-         (let* ((external-format (stream-external-format stream))
-                (ef-entry (find-external-format external-format))
-                (variable-width-p (variable-width-external-format-p ef-entry))
-                (char-len (bytes-for-char-fun ef-entry)))
+         (let ((char-size (if (fd-stream-p stream)
+                              (fd-stream-char-size stream)
+                              (external-format-char-size (stream-external-format stream)))))
            (- res
-              (if variable-width-p
-                  (loop with buffer = (ansi-stream-cin-buffer stream)
-                        with start = (ansi-stream-in-index stream)
-                        for i from start below +ansi-stream-in-buffer-length+
-                        sum (funcall char-len (aref buffer i)))
-                  (* (funcall char-len #\x)  ; arbitrary argument
-                     (- +ansi-stream-in-buffer-length+
-                        (ansi-stream-in-index stream)))))))))))
-
+              (etypecase char-size
+                (function
+                 (loop with buffer = (ansi-stream-cin-buffer stream)
+                       with start = (ansi-stream-in-index stream)
+                       for i from start below +ansi-stream-in-buffer-length+
+                       sum (funcall char-size (aref buffer i))))
+                (fixnum
+                 (* char-size
+                    (- +ansi-stream-in-buffer-length+
+                       (ansi-stream-in-index stream))))))))))))
 
 (defun file-position (stream &optional position)
-  (ansi-stream-file-position stream position))
+  (if (ansi-stream-p stream)
+      (ansi-stream-file-position stream position)
+      (stream-file-position stream position)))
 
 ;;; This is a literal translation of the ANSI glossary entry "stream
 ;;; associated with a file".
 \f
 ;;;; input functions
 
+(defun ansi-stream-read-line-from-frc-buffer (stream eof-error-p eof-value)
+  (prepare-for-fast-read-char stream
+    (declare (ignore %frc-method%))
+    (let ((chunks-total-length 0)
+          (chunks nil))
+      (declare (type index chunks-total-length)
+               (list chunks))
+      (labels ((refill-buffer ()
+                 (prog1
+                     (fast-read-char-refill stream nil nil)
+                   (setf %frc-index% (ansi-stream-in-index %frc-stream%))))
+               (newline-position ()
+                 (position #\Newline (the (simple-array character (*))
+                                       %frc-buffer%)
+                           :test #'char=
+                           :start %frc-index%))
+               (make-and-return-result-string (pos)
+                 (let* ((len (+ (- (or pos %frc-index%)
+                                   %frc-index%)
+                                chunks-total-length))
+                        (res (make-string len))
+                        (start 0))
+                   (declare (type index start))
+                   (when chunks
+                     (dolist (chunk (nreverse chunks))
+                       (declare (type (simple-array character) chunk))
+                       (replace res chunk :start1 start)
+                       (incf start (length chunk))))
+                   (unless (null pos)
+                     (replace res %frc-buffer%
+                              :start1 start
+                              :start2 %frc-index% :end2 pos)
+                     (setf %frc-index% (1+ pos)))
+                   (done-with-fast-read-char)
+                   (return-from ansi-stream-read-line-from-frc-buffer (values res (null pos)))))
+               (add-chunk ()
+                 (let* ((end (length %frc-buffer%))
+                        (len (- end %frc-index%))
+                        (chunk (make-string len)))
+                   (replace chunk %frc-buffer% :start2 %frc-index% :end2 end)
+                   (push chunk chunks)
+                   (incf chunks-total-length len)
+                   (when (refill-buffer)
+                     (make-and-return-result-string nil)))))
+        (declare (inline make-and-return-result-string
+                         refill-buffer))
+        (when (and (= %frc-index% +ansi-stream-in-buffer-length+)
+                   (refill-buffer))
+          ;; EOF had been reached before we read anything
+          ;; at all. Return the EOF value or signal the error.
+          (done-with-fast-read-char)
+          (return-from ansi-stream-read-line-from-frc-buffer
+            (values (eof-or-lose stream eof-error-p eof-value) t)))
+        (loop
+           (let ((pos (newline-position)))
+             (if pos
+                 (make-and-return-result-string pos)
+                 (add-chunk))))))))
+
 #!-sb-fluid (declaim (inline ansi-stream-read-line))
 (defun ansi-stream-read-line (stream eof-error-p eof-value recursive-p)
   (declare (ignore recursive-p))
-  (prepare-for-fast-read-char stream
-    ;; Check whether the FAST-READ-CHAR buffer contains a newline. If it
-    ;; does, we can do things quickly by just copying the line from the
-    ;; buffer instead of doing repeated calls to FAST-READ-CHAR.
-    (when %frc-buffer%
-      (locally
-          ;; For %FIND-POSITION transform
-          (declare (optimize (speed 2)))
-        (let ((pos (position #\Newline %frc-buffer%
-                             :test #'char=
-                             :start %frc-index%)))
-          (when pos
-            (let* ((len (- pos %frc-index%))
-                   (res (make-string len)))
-              (replace res %frc-buffer% :start2 %frc-index% :end2 pos)
-              (setf %frc-index% (1+ pos))
-              (done-with-fast-read-char)
-              (return-from ansi-stream-read-line res))))))
-    (let ((res (make-string 80))
-          (len 80)
-          (index 0))
-      (loop
-         (let ((ch (fast-read-char nil nil)))
-           (cond (ch
-                  (when (char= ch #\newline)
-                    (done-with-fast-read-char)
-                    (return (values (%shrink-vector res index) nil)))
-                  (when (= index len)
-                    (setq len (* len 2))
-                    (let ((new (make-string len)))
-                      (replace new res)
-                      (setq res new)))
-                  (setf (schar res index) ch)
-                  (incf index))
-                 ((zerop index)
-                  (done-with-fast-read-char)
-                  (return (values (eof-or-lose stream
-                                               eof-error-p
-                                               eof-value)
-                                  t)))
-                 ;; Since FAST-READ-CHAR already hit the eof char, we
-                 ;; shouldn't do another READ-CHAR.
-                 (t
-                  (done-with-fast-read-char)
-                  (return (values (%shrink-vector res index) t)))))))))
+  (if (ansi-stream-cin-buffer stream)
+      ;; Stream has a fast-read-char buffer. Copy large chunks directly
+      ;; out of the buffer.
+      (ansi-stream-read-line-from-frc-buffer stream eof-error-p eof-value)
+      ;; Slow path, character by character.
+      (prepare-for-fast-read-char stream
+        (let ((res (make-string 80))
+              (len 80)
+              (index 0))
+          (loop
+             (let ((ch (fast-read-char nil nil)))
+               (cond (ch
+                      (when (char= ch #\newline)
+                        (done-with-fast-read-char)
+                        (return (values (%shrink-vector res index) nil)))
+                      (when (= index len)
+                        (setq len (* len 2))
+                        (let ((new (make-string len)))
+                          (replace new res)
+                          (setq res new)))
+                      (setf (schar res index) ch)
+                      (incf index))
+                     ((zerop index)
+                      (done-with-fast-read-char)
+                      (return (values (eof-or-lose stream
+                                                   eof-error-p
+                                                   eof-value)
+                                      t)))
+                     ;; Since FAST-READ-CHAR already hit the eof char, we
+                     ;; shouldn't do another READ-CHAR.
+                     (t
+                      (done-with-fast-read-char)
+                      (return (values (%shrink-vector res index) t))))))))))
 
 (defun read-line (&optional (stream *standard-input*) (eof-error-p t) eof-value
                             recursive-p)
 ;;; some cases, but it wasn't being used in SBCL, so it was dropped.
 ;;; If we ever need it, it could be added later as a new variant N-BIN
 ;;; method (perhaps N-BIN-ASAP?) or something.
+#!-sb-fluid (declaim (inline read-n-bytes))
 (defun read-n-bytes (stream buffer start numbytes &optional (eof-error-p t))
+  (if (ansi-stream-p stream)
+      (ansi-stream-read-n-bytes stream buffer start numbytes eof-error-p)
+      ;; We don't need to worry about element-type size here is that
+      ;; callers are supposed to have checked everything is kosher.
+      (let* ((end (+ start numbytes))
+             (read-end (stream-read-sequence stream buffer start end)))
+        (eof-or-lose stream (and eof-error-p (< read-end end)) (- read-end start)))))
+
+(defun ansi-stream-read-n-bytes (stream buffer start numbytes eof-error-p)
   (declare (type ansi-stream stream)
            (type index numbytes start)
            (type (or (simple-array * (*)) system-area-pointer) buffer))
 
 ;;; This function is called by the FAST-READ-CHAR expansion to refill
 ;;; the IN-BUFFER for text streams. There is definitely an IN-BUFFER,
-;;; and hence must be an N-BIN method.
+;;; and hence must be an N-BIN method. It's also called by other stream
+;;; functions which directly peek into the frc buffer.
 (defun fast-read-char-refill (stream eof-error-p eof-value)
   (let* ((ibuf (ansi-stream-cin-buffer stream))
          (count (funcall (ansi-stream-n-bin stream)
          (start (- +ansi-stream-in-buffer-length+ count)))
     (declare (type index start count))
     (cond ((zerop count)
-           (setf (ansi-stream-in-index stream)
-                 +ansi-stream-in-buffer-length+)
-           (funcall (ansi-stream-in stream) stream eof-error-p eof-value))
+           ;; An empty count does not necessarily mean that we reached
+           ;; the EOF, it's also possible that it's e.g. due to a
+           ;; invalid octet sequence in a multibyte stream. To handle
+           ;; the resyncing case correctly we need to call the
+           ;; single-character reading function and check whether an
+           ;; EOF was really reached. If not, we can just fill the
+           ;; buffer by one character, and hope that the next refill
+           ;; will not need to resync.
+           (let* ((value (funcall (ansi-stream-in stream) stream nil :eof))
+                  (index (1- +ansi-stream-in-buffer-length+)))
+             (case value
+               ((:eof)
+                ;; Mark buffer as empty.
+                (setf (ansi-stream-in-index stream)
+                      +ansi-stream-in-buffer-length+)
+                ;; EOF. Redo the read, this time with the real eof parameters.
+                (values t (funcall (ansi-stream-in stream)
+                                   stream eof-error-p eof-value)))
+               (otherwise
+                (setf (aref ibuf index) value)
+                (values nil (setf (ansi-stream-in-index stream) index))))))
           (t
            (when (/= start +ansi-stream-in-buffer-extra+)
              (#.(let* ((n-character-array-bits
                 ibuf +ansi-stream-in-buffer-extra+
                 ibuf start
                 count))
-           (setf (ansi-stream-in-index stream) (1+ start))
-           (aref ibuf start)))))
+           (values nil
+                   (setf (ansi-stream-in-index stream) start))))))
 
 ;;; This is similar to FAST-READ-CHAR-REFILL, but we don't have to
 ;;; leave room for unreading.
   (declare (type string string))
   (declare (type ansi-stream stream))
   (declare (type index start end))
-  (if (array-header-p string)
-      (with-array-data ((data string) (offset-start start)
-                        (offset-end end))
-        (funcall (ansi-stream-sout stream)
-                 stream data offset-start offset-end))
-      (funcall (ansi-stream-sout stream) stream string start end))
+  (with-array-data ((data string) (offset-start start)
+                    (offset-end end)
+                    :check-fill-pointer t)
+    (funcall (ansi-stream-sout stream)
+             stream data offset-start offset-end))
   string)
 
 (defun %write-string (string stream start end)
             (truly-the index (+ index copy)))
       ;; FIXME: why are we VECTOR-SAP'ing things here?  what's the point?
       ;; and are there SB-UNICODE issues here as well?  --njf, 2005-03-24
-      (sb!sys:without-gcing
-       (system-area-ub8-copy (vector-sap string)
-                             index
-                             (if (typep buffer 'system-area-pointer)
-                                 buffer
-                                 (vector-sap buffer))
-                             start
-                             copy)))
+      (with-pinned-objects (string buffer)
+        (system-area-ub8-copy (vector-sap string)
+                              index
+                              (if (typep buffer 'system-area-pointer)
+                                  buffer
+                                  (vector-sap buffer))
+                              start
+                              copy)))
     (if (and (> requested copy) eof-error-p)
         (error 'end-of-file :stream stream)
         copy)))
   (declare (type string string)
            (type index start)
            (type (or index null) end))
-  (let* ((string (coerce string '(simple-array character (*))))
-         (end (%check-vector-sequence-bounds string start end)))
+  (let* ((string (coerce string '(simple-array character (*)))))
+    ;; FIXME: Why WITH-ARRAY-DATA, since the array is already simple?
     (with-array-data ((string string) (start start) (end end))
       (internal-make-string-input-stream
        string ;; now simple
        end))))
 \f
 ;;;; STRING-OUTPUT-STREAM stuff
+;;;;
+;;;; FIXME: This, like almost none of the stream code is particularly
+;;;; interrupt or thread-safe. While it should not be possible to
+;;;; corrupt the heap here, it certainly is possible to end up with
+;;;; a string-output-stream whose internal state is messed up.
+;;;;
+;;;; FIXME: It would be nice to support space-efficient
+;;;; string-output-streams with element-type base-char. This would
+;;;; mean either a separate subclass, or typecases in functions.
+
+(defparameter *string-output-stream-buffer-initial-size* 64)
 
+#!-sb-fluid
+(declaim (inline string-output-string-stream-buffer
+                 string-output-string-stream-pointer
+                 string-output-string-stream-index))
 (defstruct (string-output-stream
             (:include ansi-stream
                       (out #'string-ouch)
                       (misc #'string-out-misc))
             (:constructor make-string-output-stream
                           (&key (element-type 'character)
-                           &aux (string (make-string 40))))
+                           &aux (buffer
+                                 (make-string
+                                  *string-output-stream-buffer-initial-size*))))
             (:copier nil))
   ;; The string we throw stuff in.
-  (string (missing-arg) :type (simple-array character (*)))
-  ;; Index of the next location to use.
-  (index 0 :type fixnum)
-  ;; Index cache for string-output-stream-last-index
-  (index-cache 0 :type fixnum)
+  (buffer (missing-arg) :type (simple-array character (*)))
+  ;; Chains of buffers to use
+  (prev nil)
+  (next nil)
+  ;; Index of the next location to use in the current string.
+  (pointer 0 :type index)
+  ;; Global location in the stream
+  (index 0 :type index)
+  ;; Index cache: when we move backwards we save the greater of this
+  ;; and index here, so the greater of index and this is always the
+  ;; end of the stream.
+  (index-cache 0 :type index)
   ;; Requested element type
   (element-type 'character))
 
 #!+sb-doc
 (setf (fdocumentation 'make-string-output-stream 'function)
-  "Return an output stream which will accumulate all output given it for
-   the benefit of the function GET-OUTPUT-STREAM-STRING.")
-
-(defun string-output-stream-last-index (stream)
-  (max (string-output-stream-index stream)
-       (string-output-stream-index-cache stream)))
+  "Return an output stream which will accumulate all output given it for the
+benefit of the function GET-OUTPUT-STREAM-STRING.")
+
+;;; Pushes the current segment onto the prev-list, and either pops
+;;; or allocates a new one.
+(defun string-output-stream-new-buffer (stream size)
+  (declare (index size))
+  (/show0 "/string-output-stream-new-buffer")
+  (push (string-output-stream-buffer stream)
+        (string-output-stream-prev stream))
+  (setf (string-output-stream-buffer stream)
+        (or (pop (string-output-stream-next stream))
+            ;; FIXME: This would be the correct place to detect that
+            ;; more then FIXNUM characters are being written to the
+            ;; stream, and do something about it.
+            (make-string size))))
+
+;;; Moves to the end of the next segment or the current one if there are
+;;; no more segments. Returns true as long as there are next segments.
+(defun string-output-stream-next-buffer (stream)
+  (/show0 "/string-output-stream-next-buffer")
+  (let* ((old (string-output-stream-buffer stream))
+         (new (pop (string-output-stream-next stream)))
+         (old-size (length old))
+         (skipped (- old-size (string-output-stream-pointer stream))))
+    (cond (new
+           (let ((new-size (length new)))
+             (push old (string-output-stream-prev stream))
+             (setf (string-output-stream-buffer stream) new
+                   (string-output-stream-pointer stream) new-size)
+             (incf (string-output-stream-index stream) (+ skipped new-size)))
+           t)
+          (t
+           (setf (string-output-stream-pointer stream) old-size)
+           (incf (string-output-stream-index stream) skipped)
+           nil))))
+
+;;; Moves to the start of the previous segment or the current one if there
+;;; are no more segments. Returns true as long as there are prev segments.
+(defun string-output-stream-prev-buffer (stream)
+  (/show0 "/string-output-stream-prev-buffer")
+  (let ((old (string-output-stream-buffer stream))
+        (new (pop (string-output-stream-prev stream)))
+        (skipped (string-output-stream-pointer stream)))
+    (cond (new
+           (push old (string-output-stream-next stream))
+           (setf (string-output-stream-buffer stream) new
+                 (string-output-stream-pointer stream) 0)
+           (decf (string-output-stream-index stream) (+ skipped (length new)))
+           t)
+          (t
+           (setf (string-output-stream-pointer stream) 0)
+           (decf (string-output-stream-index stream) skipped)
+           nil))))
 
 (defun string-ouch (stream character)
-  (let ((current (string-output-stream-index stream))
-        (workspace (string-output-stream-string stream)))
-    (declare (type (simple-array character (*)) workspace)
-             (type fixnum current))
-    (if (= current (the fixnum (length workspace)))
-        (let ((new-workspace (make-string (* current 2))))
-          (replace new-workspace workspace)
-          (setf (aref new-workspace current) character
-                (string-output-stream-string stream) new-workspace))
-        (setf (aref workspace current) character))
-    (setf (string-output-stream-index stream) (1+ current))))
+  (/show0 "/string-ouch")
+  (let ((pointer (string-output-stream-pointer stream))
+        (buffer (string-output-stream-buffer stream))
+        (index (string-output-stream-index stream)))
+    (cond ((= pointer (length buffer))
+           (setf buffer (string-output-stream-new-buffer stream index)
+                 (aref buffer 0) character
+                 (string-output-stream-pointer stream) 1))
+          (t
+           (setf (aref buffer pointer) character
+                 (string-output-stream-pointer stream) (1+ pointer))))
+    (setf (string-output-stream-index stream) (1+ index))))
 
 (defun string-sout (stream string start end)
   (declare (type simple-string string)
-           (type fixnum start end))
-  (let* ((string (if (typep string '(simple-array character (*)))
-                     string
-                     (coerce string '(simple-array character (*)))))
-         (current (string-output-stream-index stream))
-         (length (- end start))
-         (dst-end (+ length current))
-         (workspace (string-output-stream-string stream)))
-    (declare (type (simple-array character (*)) workspace string)
-             (type fixnum current length dst-end))
-    (if (> dst-end (the fixnum (length workspace)))
-        (let ((new-workspace (make-string (+ (* current 2) length))))
-          (replace new-workspace workspace :end2 current)
-          (replace new-workspace string
-                   :start1 current :end1 dst-end
-                   :start2 start :end2 end)
-          (setf (string-output-stream-string stream) new-workspace))
-        (replace workspace string
-                 :start1 current :end1 dst-end
-                 :start2 start :end2 end))
-    (setf (string-output-stream-index stream) dst-end)))
+           (type index start end))
+  (let* ((full-length (- end start))
+         (length full-length)
+         (buffer (string-output-stream-buffer stream))
+         (pointer (string-output-stream-pointer stream))
+         (space (- (length buffer) pointer))
+         (here (min space length))
+         (stop (+ start here))
+         (overflow (- length space)))
+    (declare (index length space here stop full-length)
+             (fixnum overflow)
+             (type (simple-array character (*)) buffer))
+    (tagbody
+     :more
+       (when (plusp here)
+         (etypecase string
+           ((simple-array character (*))
+            (replace buffer string :start1 pointer :start2 start :end2 stop))
+           (simple-base-string
+            (replace buffer string :start1 pointer :start2 start :end2 stop))
+           ((simple-array nil (*))
+            (replace buffer string :start1 pointer :start2 start :end2 stop)))
+         (setf (string-output-stream-pointer stream) (+ here pointer)))
+       (when (plusp overflow)
+         (setf start stop
+               length (- end start)
+               buffer (string-output-stream-new-buffer
+                       stream (max overflow (string-output-stream-index stream)))
+               pointer 0
+               space (length buffer)
+               here (min space length)
+               stop (+ start here)
+               ;; there may be more overflow if we used a buffer
+               ;; already allocated to the stream
+               overflow (- length space))
+         (go :more)))
+    (incf (string-output-stream-index stream) full-length)))
+
+;;; Factored out of the -misc method due to size.
+(defun set-string-output-stream-file-position (stream pos)
+  (let* ((index (string-output-stream-index stream))
+         (end (max index (string-output-stream-index-cache stream))))
+    (declare (index index end))
+    (setf (string-output-stream-index-cache stream) end)
+    (cond ((eq :start pos)
+           (loop while (string-output-stream-prev-buffer stream)))
+          ((eq :end pos)
+           (loop while (string-output-stream-next-buffer stream))
+           (let ((over (- (string-output-stream-index stream) end)))
+             (decf (string-output-stream-pointer stream) over))
+           (setf (string-output-stream-index stream) end))
+          ((< pos index)
+           (loop while (< pos index)
+                 do (string-output-stream-prev-buffer stream)
+                 (setf index (string-output-stream-index stream)))
+           (let ((step (- pos index)))
+             (incf (string-output-stream-pointer stream) step)
+             (setf (string-output-stream-index stream) pos)))
+          ((> pos index)
+           ;; We allow moving beyond the end of stream, implicitly
+           ;; extending the output stream.
+           (let ((next (string-output-stream-next-buffer stream)))
+             ;; Update after -next-buffer, INDEX is kept pointing at
+             ;; the end of the current buffer.
+             (setf index (string-output-stream-index stream))
+             (loop while (and next (> pos index))
+                   do (setf next (string-output-stream-next-buffer stream)
+                            index (string-output-stream-index stream))))
+           ;; Allocate new buffer if needed, or step back to
+           ;; the desired index and set pointer and index
+           ;; correctly.
+           (let ((diff (- pos index)))
+             (if (plusp diff)
+                 (let* ((new (string-output-stream-new-buffer stream diff))
+                        (size (length new)))
+                   (aver (= pos (+ index size)))
+                   (setf (string-output-stream-pointer stream) size
+                         (string-output-stream-index stream) pos))
+                 (let ((size (length (string-output-stream-buffer stream))))
+                   (setf (string-output-stream-pointer stream) (+ size diff)
+                         (string-output-stream-index stream) pos))))))))
 
 (defun string-out-misc (stream operation &optional arg1 arg2)
   (declare (ignore arg2))
   (case operation
-    (:file-position
-     (if arg1
-         (let ((end (string-output-stream-last-index stream)))
-           (setf (string-output-stream-index-cache stream) end
-                 (string-output-stream-index stream)
-                 (case arg1
-                   (:start 0)
-                   (:end end)
-                   (t
-                    ;; We allow moving beyond the end of stream,
-                    ;; implicitly extending the output stream.
-                    (let ((buffer (string-output-stream-string stream)))
-                      (when (> arg1 (length buffer))
-                        (setf (string-output-stream-string stream)
-                              (make-string
-                               arg1 :element-type (array-element-type buffer))
-                              (subseq (string-output-stream-string stream)
-                                      0 end)
-                              (subseq buffer 0 end))))
-                      arg1))))
-         (string-output-stream-index stream)))
-    (:close (set-closed-flame stream))
     (:charpos
-     (do ((index (1- (the fixnum (string-output-stream-index stream)))
-                 (1- index))
-          (count 0 (1+ count))
-          (string (string-output-stream-string stream)))
-         ((< index 0) count)
-       (declare (type (simple-array character (*)) string)
-                (type fixnum index count))
-       (if (char= (schar string index) #\newline)
-           (return count))))
-    (:element-type (array-element-type (string-output-stream-string stream)))))
+     ;; Keeping this first is a silly micro-optimization: FRESH-LINE
+     ;; makes this the most common one.
+     (/show0 "/string-out-misc charpos")
+     (prog ((pointer (string-output-stream-pointer stream))
+            (buffer (string-output-stream-buffer stream))
+            (prev (string-output-stream-prev stream))
+            (base 0))
+      :next
+      (let ((pos (position #\newline buffer :from-end t :end pointer)))
+        (when (or pos (not buffer))
+          ;; If newline is at index I, and pointer at index I+N, charpos
+          ;; is N-1. If there is no newline, and pointer is at index N,
+          ;; charpos is N.
+          (return (+ base (if pos (- pointer pos 1) pointer))))
+        (setf base (+ base pointer)
+              buffer (pop prev)
+              pointer (length buffer))
+        (/show0 "/string-out-misc charpos next")
+        (go :next))))
+    (:file-position
+     (/show0 "/string-out-misc file-position")
+     (when arg1
+       (set-string-output-stream-file-position stream arg1))
+     (string-output-stream-index stream))
+    (:close
+     (/show0 "/string-out-misc close")
+     (set-closed-flame stream))
+    (:element-type (string-output-stream-element-type stream))))
 
 ;;; Return a string of all the characters sent to a stream made by
 ;;; MAKE-STRING-OUTPUT-STREAM since the last call to this function.
 (defun get-output-stream-string (stream)
   (declare (type string-output-stream stream))
-  (let* ((length (string-output-stream-last-index stream))
+  (let* ((length (max (string-output-stream-index stream)
+                      (string-output-stream-index-cache stream)))
          (element-type (string-output-stream-element-type stream))
+         (prev (string-output-stream-prev stream))
+         (this (string-output-stream-buffer stream))
+         (next (string-output-stream-next stream))
          (result
           (case element-type
             ;; overwhelmingly common case: can be inlined
+            ;;
+            ;; FIXME: If we were willing to use %SHRINK-VECTOR here,
+            ;; and allocate new strings the size of 2 * index in
+            ;; STRING-SOUT, we would not need to allocate one here in
+            ;; the common case, but could just use the last one
+            ;; allocated, and chop it down to size..
+            ;;
             ((character) (make-string length))
             ;; slightly less common cases: inline it anyway
             ((base-char standard-char)
              (make-string length :element-type 'base-char))
-            (t (make-string length :element-type element-type)))))
-    ;; For the benefit of the REPLACE transform, let's do this, so
-    ;; that the common case isn't ludicrously expensive.
-    (etypecase result
-      ((simple-array character (*))
-       (replace result (string-output-stream-string stream)))
-      (simple-base-string
-       (replace result (string-output-stream-string stream)))
-      ((simple-array nil (*))
-       (replace result (string-output-stream-string stream))))
+            (t
+             (make-string length :element-type element-type)))))
+
     (setf (string-output-stream-index stream) 0
-          (string-output-stream-index-cache stream) 0)
-    result))
+          (string-output-stream-index-cache stream) 0
+          (string-output-stream-pointer stream) 0
+          ;; throw them away for simplicity's sake: this way the rest of the
+          ;; implementation can assume that the greater of INDEX and INDEX-CACHE
+          ;; is always within the last buffer.
+          (string-output-stream-prev stream) nil
+          (string-output-stream-next stream) nil)
+
+    (flet ((replace-all (fun)
+             (let ((start 0))
+               (declare (index start))
+               (setf prev (nreverse prev))
+               (dolist (buffer prev)
+                 (funcall fun buffer start)
+                 (incf start (length buffer)))
+               (funcall fun this start)
+               (incf start (length this))
+               (dolist (buffer next)
+                 (funcall fun buffer start)
+                 (incf start (length buffer)))
+               ;; Hack: erase the pointers to strings, to make it less
+               ;; likely that the conservative GC will accidentally
+               ;; retain the buffers.
+               (fill prev nil)
+               (fill next nil))))
+      (macrolet ((frob (type)
+                   `(replace-all (lambda (buffer from)
+                                   (declare (type ,type result)
+                                            (type (simple-array character (*))
+                                                  buffer))
+                                   (replace result buffer :start1 from)))))
+        (etypecase result
+          ((simple-array character (*))
+           (frob (simple-array character (*))))
+          (simple-base-string
+           (frob simple-base-string))
+          ((simple-array nil (*))
+           (frob (simple-array nil (*)))))))
 
-;;; Dump the characters buffer up in IN-STREAM to OUT-STREAM as
-;;; GET-OUTPUT-STREAM-STRING would return them.
-(defun dump-output-stream-string (in-stream out-stream)
-  (%write-string (string-output-stream-string in-stream)
-                 out-stream
-                 0
-                 (string-output-stream-last-index in-stream))
-  (setf (string-output-stream-index in-stream) 0
-        (string-output-stream-index-cache in-stream) 0))
+    result))
 \f
 ;;;; fill-pointer streams
 
                (return i))
              (setf (first rem) el)))))
       (vector
-       (with-array-data ((data seq) (offset-start start) (offset-end end))
-         (if (compatible-vector-and-stream-element-types-p data stream)
-             (let* ((numbytes (- end start))
-                    (bytes-read (read-n-bytes stream data offset-start
-                                              numbytes nil)))
-               (if (< bytes-read numbytes)
-                   (+ start bytes-read)
-                   end))
-             (let ((read-function
-                    (if (subtypep (array-element-type data) 'character)
-                        #'ansi-stream-read-char
-                        #'ansi-stream-read-byte)))
-               (do ((i offset-start (1+ i)))
-                   ((>= i offset-end) end)
-                 (declare (type index i))
-                 (let ((el (funcall read-function stream nil :eof nil)))
-                   (when (eq el :eof)
-                     (return (+ start (- i offset-start))))
-                   (setf (aref data i) el))))))))))
+       (with-array-data ((data seq) (offset-start start) (offset-end end)
+                         :check-fill-pointer t)
+         (cond ((compatible-vector-and-stream-element-types-p data stream)
+                (let* ((numbytes (- end start))
+                       (bytes-read (read-n-bytes stream data offset-start
+                                                 numbytes nil)))
+                  (if (< bytes-read numbytes)
+                      (+ start bytes-read)
+                      end)))
+               ((and (ansi-stream-cin-buffer stream)
+                     (typep seq 'simple-string))
+                (ansi-stream-read-string-from-frc-buffer seq stream
+                                                         start %end))
+               (t
+                (let ((read-function
+                       (if (subtypep (stream-element-type stream) 'character)
+                           ;; If the stream-element-type is CHARACTER,
+                           ;; this might be a bivalent stream. If the
+                           ;; sequence is a specialized unsigned-byte
+                           ;; vector, try to read use binary IO. It'll
+                           ;; signal an error if stream is an pure
+                           ;; character stream.
+                           (if (subtypep (array-element-type data)
+                                         'unsigned-byte)
+                               #'ansi-stream-read-byte
+                               #'ansi-stream-read-char)
+                           #'ansi-stream-read-byte)))
+                  (do ((i offset-start (1+ i)))
+                      ((>= i offset-end) end)
+                    (declare (type index i))
+                    (let ((el (funcall read-function stream nil :eof nil)))
+                      (when (eq el :eof)
+                        (return (+ start (- i offset-start))))
+                      (setf (aref data i) el)))))))))))
+
+(defun ansi-stream-read-string-from-frc-buffer (seq stream start %end)
+  (declare (type simple-string seq)
+           (type ansi-stream stream)
+           (type index start)
+           (type (or null index) %end))
+  (let ((needed (- (or %end (length seq))
+                   start))
+        (read 0))
+    (prepare-for-fast-read-char stream
+      (declare (ignore %frc-method%))
+      (unless %frc-buffer%
+        (return-from ansi-stream-read-string-from-frc-buffer nil))
+      (labels ((refill-buffer ()
+                 (prog1
+                     (fast-read-char-refill stream nil nil)
+                   (setf %frc-index% (ansi-stream-in-index %frc-stream%))))
+               (add-chunk ()
+                 (let* ((end (length %frc-buffer%))
+                        (len (min (- end %frc-index%)
+                                  (- needed read))))
+                   (declare (type index end len read needed))
+                   (string-dispatch (simple-base-string
+                                     (simple-array character (*)))
+                       seq
+                     (replace seq %frc-buffer%
+                              :start1 (+ start read)
+                              :end1 (+ start read len)
+                              :start2 %frc-index%
+                              :end2 (+ %frc-index% len)))
+                   (incf read len)
+                   (incf %frc-index% len)
+                   (when (or (eql needed read)
+                             (refill-buffer))
+                     (done-with-fast-read-char)
+                     (return-from ansi-stream-read-string-from-frc-buffer
+                       read)))))
+        (declare (inline refill-buffer))
+        (when (and (= %frc-index% +ansi-stream-in-buffer-length+)
+                   (refill-buffer))
+          ;; EOF had been reached before we read anything
+          ;; at all. Return the EOF value or signal the error.
+          (done-with-fast-read-char)
+          (return-from ansi-stream-read-string-from-frc-buffer 0))
+        (loop (add-chunk))))))
+
 \f
 ;;;; WRITE-SEQUENCE
 
       (string
        (%write-string seq stream start end))
       (vector
-       (with-array-data ((data seq) (offset-start start) (offset-end end))
+       (with-array-data ((data seq) (offset-start start) (offset-end end)
+                         :check-fill-pointer t)
          (labels
              ((output-seq-in-loop ()
                 (let ((write-function
-                       (if (subtypep (array-element-type data) 'character)
-                           (ansi-stream-out stream)
+                       (if (subtypep (stream-element-type stream) 'character)
+                           (lambda (stream object)
+                             ;; This might be a bivalent stream, so we need
+                             ;; to dispatch on a per-element basis, rather
+                             ;; than just based on the sequence or stream
+                             ;; element types.
+                             (if (characterp object)
+                                 (funcall (ansi-stream-out stream)
+                                          stream object)
+                                 (funcall (ansi-stream-bout stream)
+                                          stream object)))
                            (ansi-stream-bout stream))))
                   (do ((i offset-start (1+ i)))
                       ((>= i offset-end))
                     (funcall write-function stream (aref data i))))))
            (if (and (fd-stream-p stream)
                     (compatible-vector-and-stream-element-types-p data stream))
-               (output-raw-bytes stream data offset-start offset-end)
+               (buffer-output stream data offset-start offset-end)
                (output-seq-in-loop)))))))
   seq)
 \f