1.0.14.34: slightly less and slightly faster constraint propagation
[sbcl.git] / src / code / fd-stream.lisp
index 6c73160..f6eb756 100644 (file)
 
 (in-package "SB!IMPL")
 
-;;;; buffer manipulation routines
+;;;; BUFFER
+;;;;
+;;;; Streams hold BUFFER objects, which contain a SAP, size of the
+;;;; memory area the SAP stands for (LENGTH bytes), and HEAD and TAIL
+;;;; indexes which delimit the "valid", or "active" area of the
+;;;; memory. HEAD is inclusive, TAIL is exclusive.
+;;;;
+;;;; Buffers get allocated lazily, and are recycled by returning them
+;;;; to the *AVAILABLE-BUFFERS* list. Every buffer has it's own
+;;;; finalizer, to take care of releasing the SAP memory when a stream
+;;;; is not properly closed.
+;;;;
+;;;; The code aims to provide a limited form of thread and interrupt
+;;;; safety: parallel writes and reads may lose output or input, cause
+;;;; interleaved IO, etc -- but they should not corrupt memory. The
+;;;; key to doing this is to read buffer state once, and update the
+;;;; state based on the read state:
+;;;;
+;;;; (let ((tail (buffer-tail buffer)))
+;;;;   ...
+;;;;   (setf (buffer-tail buffer) (+ tail n)))
+;;;;
+;;;; NOT
+;;;;
+;;;; (let ((tail (buffer-tail buffer)))
+;;;;   ...
+;;;;  (incf (buffer-tail buffer) n))
+;;;;
+
+(declaim (inline buffer-sap buffer-length buffer-head buffer-tail
+                 (setf buffer-head) (setf buffer-tail)))
+(defstruct (buffer (:constructor %make-buffer (sap length)))
+  (sap (missing-arg) :type system-area-pointer :read-only t)
+  (length (missing-arg) :type index :read-only t)
+  (head 0 :type index)
+  (tail 0 :type index))
 
-;;; FIXME: Is it really good to maintain this pool separate from the
-;;; GC and the C malloc logic?
 (defvar *available-buffers* ()
   #!+sb-doc
-  "List of available buffers. Each buffer is an sap pointing to
-  bytes-per-buffer of memory.")
+  "List of available buffers.")
 
-#!+sb-thread
-(defvar *available-buffers-mutex* (sb!thread:make-mutex
-                                   :name "lock for *AVAILABLE-BUFFERS*")
+(defvar *available-buffers-spinlock* (sb!thread::make-spinlock
+                                      :name "lock for *AVAILABLE-BUFFERS*")
   #!+sb-doc
   "Mutex for access to *AVAILABLE-BUFFERS*.")
 
 (defmacro with-available-buffers-lock ((&optional) &body body)
-  ;; WITHOUT-INTERRUPTS because streams are low-level enough to be
-  ;; async signal safe, and in particular a C-c that brings up the
-  ;; debugger while holding the mutex would lose badly
-  `(without-interrupts
-    (sb!thread:with-mutex (*available-buffers-mutex*)
-      ,@body)))
-
-(defconstant bytes-per-buffer (* 4 1024)
+  ;; CALL-WITH-SYSTEM-SPINLOCK because
+  ;;
+  ;; 1. streams are low-level enough to be async signal safe, and in
+  ;;    particular a C-c that brings up the debugger while holding the
+  ;;    mutex would lose badly
+  ;;
+  ;; 2. this can potentially be a fairly busy (but also probably
+  ;;    uncontended) lock, so we don't want to pay the syscall per
+  ;;    release -- hence a spinlock.
+  ;;
+  ;; ...again, once we have smarted locks the spinlock here can become
+  ;; a mutex.
+  `(sb!thread::call-with-system-spinlock (lambda () ,@body)
+                                         *available-buffers-spinlock*))
+
+(defconstant +bytes-per-buffer+ (* 4 1024)
   #!+sb-doc
-  "Number of bytes per buffer.")
+  "Default number of bytes per buffer.")
 
-;;; Return the next available buffer, creating one if necessary.
-#!-sb-fluid (declaim (inline next-available-buffer))
-(defun next-available-buffer ()
+(defun alloc-buffer (&optional (size +bytes-per-buffer+))
+  ;; Don't want to allocate & unwind before the finalizer is in place.
+  (without-interrupts
+    (let* ((sap (allocate-system-memory size))
+           (buffer (%make-buffer sap size)))
+      (when (zerop (sap-int sap))
+        (error "Could not allocate ~D bytes for buffer." size))
+      (finalize buffer (lambda ()
+                         (deallocate-system-memory sap size))
+                :dont-save t)
+      buffer)))
+
+(defun get-buffer ()
+  ;; Don't go for the lock if there is nothing to be had -- sure,
+  ;; another thread might just release one before we get it, but that
+  ;; is not worth the cost of locking. Also release the lock before
+  ;; allocation, since it's going to take a while.
+  (if *available-buffers*
+      (or (with-available-buffers-lock ()
+            (pop *available-buffers*))
+          (alloc-buffer))
+      (alloc-buffer)))
+
+(declaim (inline reset-buffer))
+(defun reset-buffer (buffer)
+  (setf (buffer-head buffer) 0
+        (buffer-tail buffer) 0)
+  buffer)
+
+(defun release-buffer (buffer)
+  (reset-buffer buffer)
   (with-available-buffers-lock ()
-    (if *available-buffers*
-        (pop *available-buffers*)
-        (allocate-system-memory bytes-per-buffer))))
+    (push buffer *available-buffers*)))
+
+;;; This is a separate buffer management function, as it wants to be
+;;; clever about locking -- grabbing the lock just once.
+(defun release-fd-stream-buffers (fd-stream)
+  (let ((ibuf (fd-stream-ibuf fd-stream))
+        (obuf (fd-stream-obuf fd-stream))
+        (queue (loop for item in (fd-stream-output-queue fd-stream)
+                       when (buffer-p item)
+                       collect (reset-buffer item))))
+    (when ibuf
+      (push (reset-buffer ibuf) queue))
+    (when obuf
+      (push (reset-buffer obuf) queue))
+    ;; ...so, anything found?
+    (when queue
+      ;; detach from stream
+      (setf (fd-stream-ibuf fd-stream) nil
+            (fd-stream-obuf fd-stream) nil
+            (fd-stream-output-queue fd-stream) nil)
+      ;; splice to *available-buffers*
+      (with-available-buffers-lock ()
+        (setf *available-buffers* (nconc queue *available-buffers*))))))
 \f
 ;;;; the FD-STREAM structure
 
 
   ;; the input buffer
   (unread nil)
-  (ibuf-sap nil :type (or system-area-pointer null))
-  (ibuf-length nil :type (or index null))
-  (ibuf-head 0 :type index)
-  (ibuf-tail 0 :type index)
+  (ibuf nil :type (or buffer null))
 
   ;; the output buffer
-  (obuf-sap nil :type (or system-area-pointer null))
-  (obuf-length nil :type (or index null))
-  (obuf-tail 0 :type index)
+  (obuf nil :type (or buffer null))
 
   ;; output flushed, but not written due to non-blocking io?
-  (output-later nil)
+  (output-queue nil)
   (handler nil)
   ;; timeout specified for this stream as seconds or NIL if none
   (timeout nil :type (or single-float null))
   ;; pathname of the file this stream is opened to (returned by PATHNAME)
   (pathname nil :type (or pathname null))
   (external-format :default)
+  ;; fixed width, or function to call with a character
+  (char-size 1 :type (or fixnum function))
   (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))))
 \f
+;;;; CORE OUTPUT FUNCTIONS
+
+;;; Buffer the section of THING delimited by START and END by copying
+;;; to output buffer(s) of stream.
+(defun buffer-output (stream thing start end)
+  (declare (index start end))
+  (when (< end start)
+    (error ":END before :START!"))
+  (when (> end start)
+    ;; Copy bytes from THING to buffers.
+    (flet ((copy-to-buffer (buffer tail count)
+             (declare (buffer buffer) (index tail count))
+             (aver (plusp count))
+             (let ((sap (buffer-sap buffer)))
+               (etypecase thing
+                 (system-area-pointer
+                  (system-area-ub8-copy thing start sap tail count))
+                 ((simple-unboxed-array (*))
+                  (copy-ub8-to-system-area thing start sap tail count))))
+             ;; Not INCF! If another thread has moved tail from under
+             ;; us, we don't want to accidentally increment tail
+             ;; beyond buffer-length.
+             (setf (buffer-tail buffer) (+ count tail))
+             (incf start count)))
+      (tagbody
+         ;; First copy is special: the buffer may already contain
+         ;; something, or be even full.
+         (let* ((obuf (fd-stream-obuf stream))
+                (tail (buffer-tail obuf))
+                (space (- (buffer-length obuf) tail)))
+           (when (plusp space)
+             (copy-to-buffer obuf tail (min space (- end start)))
+             (go :more-output-p)))
+       :flush-and-fill
+         ;; Later copies should always have an empty buffer, since
+         ;; they are freshly flushed, but if another thread is
+         ;; stomping on the same buffer that might not be the case.
+         (let* ((obuf (flush-output-buffer stream))
+                (tail (buffer-tail obuf))
+                (space (- (buffer-length obuf) tail)))
+           (copy-to-buffer obuf tail (min space (- end start))))
+       :more-output-p
+         (when (> end start)
+           (go :flush-and-fill))))))
+
+;;; Flush the current output buffer of the stream, ensuring that the
+;;; new buffer is empty. Returns (for convenience) the new output
+;;; buffer -- which may or may not be EQ to the old one. If the is no
+;;; queued output we try to write the buffer immediately -- otherwise
+;;; we queue it for later.
+(defun flush-output-buffer (stream)
+  (let ((obuf (fd-stream-obuf stream)))
+    (when obuf
+      (let ((head (buffer-head obuf))
+            (tail (buffer-tail obuf)))
+        (cond ((eql head tail)
+               ;; Buffer is already empty -- just ensure that is is
+               ;; set to zero as well.
+               (reset-buffer obuf))
+              ((fd-stream-output-queue stream)
+               ;; There is already stuff on the queue -- go directly
+               ;; there.
+               (aver (< head tail))
+               (%queue-and-replace-output-buffer stream))
+              (t
+               ;; Try a non-blocking write, queue whatever is left over.
+               (aver (< head tail))
+               (synchronize-stream-output stream)
+               (let ((length (- tail head)))
+                 (multiple-value-bind (count errno)
+                     (sb!unix:unix-write (fd-stream-fd stream) (buffer-sap obuf)
+                                         head length)
+                   (cond ((eql count length)
+                          ;; Complete write -- we can use the same buffer.
+                          (reset-buffer obuf))
+                         (count
+                          ;; Partial write -- update buffer status and queue.
+                          ;; Do not use INCF! Another thread might have moved
+                          ;; head...
+                          (setf (buffer-head obuf) (+ count head))
+                          (%queue-and-replace-output-buffer stream))
+                         #!-win32
+                         ((eql errno sb!unix:ewouldblock)
+                          ;; Blocking, queue.
+                          (%queue-and-replace-output-buffer stream))
+                         (t
+                          (simple-stream-perror "Couldn't write to ~s"
+                                                stream errno)))))))))))
+
+;;; Helper for FLUSH-OUTPUT-BUFFER -- returns the new buffer.
+(defun %queue-and-replace-output-buffer (stream)
+  (let ((queue (fd-stream-output-queue stream))
+        (later (list (or (fd-stream-obuf stream) (bug "Missing obuf."))))
+        (new (get-buffer)))
+    ;; Important: before putting the buffer on queue, give the stream
+    ;; a new one. If we get an interrupt and unwind losing the buffer
+    ;; is relatively OK, but having the same buffer in two places
+    ;; would be bad.
+    (setf (fd-stream-obuf stream) new)
+    (cond (queue
+           (nconc queue later))
+          (t
+           (setf (fd-stream-output-queue stream) later)))
+    (unless (fd-stream-handler stream)
+      (setf (fd-stream-handler stream)
+            (add-fd-handler (fd-stream-fd stream)
+                            :output
+                            (lambda (fd)
+                              (declare (ignore fd))
+                              (write-output-from-queue stream)))))
+    new))
+
+;;; This is called by the FD-HANDLER for the stream when output is
+;;; possible.
+(defun write-output-from-queue (stream)
+  (synchronize-stream-output stream)
+  (let (not-first-p)
+    (tagbody
+     :pop-buffer
+       (let* ((buffer (pop (fd-stream-output-queue stream)))
+              (head (buffer-head buffer))
+              (length (- (buffer-tail buffer) head)))
+         (declare (index head length))
+         (aver (>= length 0))
+         (multiple-value-bind (count errno)
+             (sb!unix:unix-write (fd-stream-fd stream) (buffer-sap buffer)
+                                 head length)
+           (cond ((eql count length)
+                  ;; Complete write, see if we can do another right
+                  ;; away, or remove the handler if we're done.
+                  (release-buffer buffer)
+                  (cond ((fd-stream-output-queue stream)
+                         (setf not-first-p t)
+                         (go :pop-buffer))
+                        (t
+                         (let ((handler (fd-stream-handler stream)))
+                           (aver handler)
+                           (setf (fd-stream-handler stream) nil)
+                           (remove-fd-handler handler)))))
+                 (count
+                  ;; Partial write. Update buffer status and requeue.
+                  (aver (< count length))
+                  ;; Do not use INCF! Another thread might have moved head.
+                  (setf (buffer-head buffer) (+ head count))
+                  (push buffer (fd-stream-output-queue stream)))
+                 (not-first-p
+                  ;; We tried to do multiple writes, and finally our
+                  ;; luck ran out. Requeue.
+                  (push buffer (fd-stream-output-queue stream)))
+                 (t
+                  ;; Could not write on the first try at all!
+                  #!+win32
+                  (simple-stream-perror "Couldn't write to ~S." stream errno)
+                  #!-win32
+                  (if (= errno sb!unix:ewouldblock)
+                      (bug "Unexpected blocking in WRITE-OUTPUT-FROM-QUEUE.")
+                      (simple-stream-perror "Couldn't write to ~S"
+                                            stream errno))))))))
+  nil)
+
+;;; Try to write THING directly to STREAM without buffering, if
+;;; possible. If direct write doesn't happen, buffer.
+(defun write-or-buffer-output (stream thing start end)
+  (declare (index start end))
+  (cond ((fd-stream-output-queue stream)
+         (buffer-output stream thing start end))
+        ((< end start)
+         (error ":END before :START!"))
+        ((> end start)
+         (let ((length (- end start)))
+           (synchronize-stream-output stream)
+           (multiple-value-bind (count errno)
+               (sb!unix:unix-write (fd-stream-fd stream) thing start length)
+             (cond ((eql count length)
+                    ;; Complete write -- done!
+                    )
+                   (count
+                    (aver (< count length))
+                    ;; Partial write -- buffer the rest.
+                    (buffer-output stream thing (+ start count) end))
+                   (t
+                    ;; Could not write -- buffer or error.
+                    #!+win32
+                    (simple-stream-perror "couldn't write to ~s" stream errno)
+                    #!-win32
+                    (if (= errno sb!unix:ewouldblock)
+                        (buffer-output stream thing start end)
+                        (simple-stream-perror "couldn't write to ~s" stream errno)))))))))
+
+;;; Deprecated -- can go away after 1.1 or so. Deprecated because
+;;; this is not something we want to export. Nikodemus thinks the
+;;; right thing is to support a low-level non-stream like IO layer,
+;;; akin to java.nio.
+(defun output-raw-bytes (stream thing &optional start end)
+  (write-or-buffer-output stream thing (or start 0) (or end (length thing))))
+
+(define-compiler-macro output-raw-bytes (stream thing &optional start end)
+  (deprecation-warning 'output-raw-bytes)
+  (let ((x (gensym "THING")))
+    `(let ((,x ,thing))
+       (write-or-buffer-output ,stream ,x (or ,start 0) (or ,end (length ,x))))))
+\f
 ;;;; output routines and related noise
 
 (defvar *output-routines* ()
 (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)))
+                             (let* ((buffer (fd-stream-ibuf stream))
+                                    (sap (buffer-sap buffer))
+                                    (head (buffer-head buffer)))
                                (loop for i from 0 below octet-count
                                      collect (sap-ref-8 sap (+ head i)))))
     (attempt-resync ()
       (stream-decoding-error stream octet-count)
       (c-string-decoding-error stream octet-count)))
 
-;;; 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
-;;; is wrong.
-(defun frob-output-later (stream)
-  (let* ((stuff (pop (fd-stream-output-later stream)))
-         (base (car stuff))
-         (start (cadr stuff))
-         (end (caddr stuff))
-         (reuse-sap (cadddr stuff))
-         (length (- end start)))
-    (declare (type index start end length))
-    (multiple-value-bind (count errno)
-        (sb!unix:unix-write (fd-stream-fd stream)
-                            base
-                            start
-                            length)
-      (cond ((not count)
-             #!+win32
-             (simple-stream-perror "couldn't write to ~S" stream errno)
-             #!-win32
-             (if (= errno sb!unix:ewouldblock)
-                 (error "Write would have blocked, but SERVER told us to go.")
-                 (simple-stream-perror "couldn't write to ~S" stream errno)))
-            ((eql count length) ; Hot damn, it worked.
-             (when reuse-sap
-               (with-available-buffers-lock ()
-                 (push base *available-buffers*))))
-            ((not (null count)) ; sorta worked..
-             (push (list base
-                         (the index (+ start count))
-                         end)
-                   (fd-stream-output-later stream))))))
-  (unless (fd-stream-output-later stream)
-    (remove-fd-handler (fd-stream-handler stream))
-    (setf (fd-stream-handler stream) nil)))
-
-;;; Arange to output the string when we can write on the file descriptor.
-(defun output-later (stream base start end reuse-sap)
-  (cond ((null (fd-stream-output-later stream))
-         (setf (fd-stream-output-later stream)
-               (list (list base start end reuse-sap)))
-         (setf (fd-stream-handler stream)
-               (add-fd-handler (fd-stream-fd stream)
-                                      :output
-                                      (lambda (fd)
-                                        (declare (ignore fd))
-                                        (frob-output-later stream)))))
-        (t
-         (nconc (fd-stream-output-later stream)
-                (list (list base start end reuse-sap)))))
-  (when reuse-sap
-    (let ((new-buffer (next-available-buffer)))
-      (setf (fd-stream-obuf-sap stream) new-buffer)
-      (setf (fd-stream-obuf-length stream) bytes-per-buffer))))
-
-;;; Output the given noise. Check to see whether there are any pending
-;;; 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 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.
-      (output-later stream base start end reuse-sap)
-      ;; ### check to see whether any of this noise can be output
-      (let ((length (- end start)))
-        (multiple-value-bind (count errno)
-            (sb!unix:unix-write (fd-stream-fd stream) base start length)
-          (cond ((not count)
-                 #!+win32
-                 (simple-stream-perror "Couldn't write to ~S" stream errno)
-                 #!-win32
-                 (if (= errno sb!unix:ewouldblock)
-                     (output-later stream base start end reuse-sap)
-                     (simple-stream-perror "Couldn't write to ~S"
-                                           stream errno)))
-                ((not (eql count length))
-                 (output-later stream base (the index (+ start count))
-                               end reuse-sap)))))))
-
-;;; Flush any data in the output buffer.
-(defun flush-output-buffer (stream)
-  (let ((length (fd-stream-obuf-tail stream)))
-    (unless (= length 0)
-      (frob-output stream (fd-stream-obuf-sap stream) 0 length t)
-      (setf (fd-stream-obuf-tail stream) 0))))
+(defun synchronize-stream-output (stream)
+  ;; If we're reading and writing on the same file, flush buffered
+  ;; input and rewind file position accordingly.
+  (unless (fd-stream-dual-channel-p stream)
+    (let ((adjust (nth-value 1 (flush-input-buffer stream))))
+      (unless (eql 0 adjust)
+        (sb!unix:unix-lseek (fd-stream-fd stream) (- adjust) sb!unix:l_incr)))))
 
 (defun fd-stream-output-finished-p (stream)
-  (and (zerop (fd-stream-obuf-tail stream))
-       (not (fd-stream-output-later stream))))
+  (let ((obuf (fd-stream-obuf stream)))
+    (or (not obuf)
+        (and (zerop (buffer-tail obuf))
+             (not (fd-stream-output-queue stream))))))
 
 (defmacro output-wrapper/variable-width ((stream size buffering restart)
                                          &body body)
-  (let ((stream-var (gensym)))
-    `(let ((,stream-var ,stream)
-           (size ,size))
+  (let ((stream-var (gensym "STREAM")))
+    `(let* ((,stream-var ,stream)
+            (obuf (fd-stream-obuf ,stream-var))
+            (tail (buffer-tail obuf))
+            (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)))
+         `(when (<= (buffer-length obuf) (+ tail size))
+            (setf obuf (flush-output-buffer ,stream-var)
+                  tail (buffer-tail obuf))))
       ,(unless (eq (car buffering) :none)
-         `(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))))
+         ;; FIXME: Why this here? Doesn't seem necessary.
+         `(synchronize-stream-output ,stream-var))
       ,(if restart
            `(catch 'output-nothing
               ,@body
-              (incf (fd-stream-obuf-tail ,stream-var) size))
+              (setf (buffer-tail obuf) (+ tail size)))
            `(progn
              ,@body
-             (incf (fd-stream-obuf-tail ,stream-var) size)))
+             (setf (buffer-tail obuf) (+ tail size))))
       ,(ecase (car buffering)
          (:none
           `(flush-output-buffer ,stream-var))
          (:line
-          `(when (eq (char-code byte) (char-code #\Newline))
+          `(when (eql byte #\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))
+  (let ((stream-var (gensym "STREAM")))
+    `(let* ((,stream-var ,stream)
+            (obuf (fd-stream-obuf ,stream-var))
+            (tail (buffer-tail obuf)))
       ,(unless (eq (car buffering) :none)
-         `(when (< (fd-stream-obuf-length ,stream-var)
-                   (+ (fd-stream-obuf-tail ,stream-var)
-                       ,size))
-            (flush-output-buffer ,stream-var)))
+         `(when (<= (buffer-length obuf) (+ tail ,size))
+            (setf obuf (flush-output-buffer ,stream-var)
+                  tail (buffer-tail obuf))))
+      ;; FIXME: Why this here? Doesn't seem necessary.
       ,(unless (eq (car buffering) :none)
-         `(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))))
+         `(synchronize-stream-output ,stream-var))
       ,(if restart
            `(catch 'output-nothing
               ,@body
-              (incf (fd-stream-obuf-tail ,stream-var) ,size))
+              (setf (buffer-tail obuf) (+ tail ,size)))
            `(progn
              ,@body
-             (incf (fd-stream-obuf-tail ,stream-var) ,size)))
+             (setf (buffer-tail obuf) (+ tail ,size))))
       ,(ecase (car buffering)
          (:none
           `(flush-output-buffer ,stream-var))
          (:line
-          `(when (eq (char-code byte) (char-code #\Newline))
+          `(when (eql byte #\Newline)
              (flush-output-buffer ,stream-var)))
          (:full))
     (values))))
                       (:none character)
                       (:line character)
                       (:full character))
-  (if (char= byte #\Newline)
+  (if (eql 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))
+  (setf (sap-ref-8 (buffer-sap obuf) tail)
         (char-code byte)))
 
 (def-output-routines ("OUTPUT-UNSIGNED-BYTE-~A-BUFFERED"
                       nil
                       (:none (unsigned-byte 8))
                       (:full (unsigned-byte 8)))
-  (setf (sap-ref-8 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
+  (setf (sap-ref-8 (buffer-sap obuf) tail)
         byte))
 
 (def-output-routines ("OUTPUT-SIGNED-BYTE-~A-BUFFERED"
                       nil
                       (:none (signed-byte 8))
                       (:full (signed-byte 8)))
-  (setf (signed-sap-ref-8 (fd-stream-obuf-sap stream)
-                          (fd-stream-obuf-tail stream))
+  (setf (signed-sap-ref-8 (buffer-sap obuf) tail)
         byte))
 
 (def-output-routines ("OUTPUT-UNSIGNED-SHORT-~A-BUFFERED"
                       nil
                       (:none (unsigned-byte 16))
                       (:full (unsigned-byte 16)))
-  (setf (sap-ref-16 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
+  (setf (sap-ref-16 (buffer-sap obuf) tail)
         byte))
 
 (def-output-routines ("OUTPUT-SIGNED-SHORT-~A-BUFFERED"
                       nil
                       (:none (signed-byte 16))
                       (:full (signed-byte 16)))
-  (setf (signed-sap-ref-16 (fd-stream-obuf-sap stream)
-                           (fd-stream-obuf-tail stream))
+  (setf (signed-sap-ref-16 (buffer-sap obuf) tail)
         byte))
 
 (def-output-routines ("OUTPUT-UNSIGNED-LONG-~A-BUFFERED"
                       nil
                       (:none (unsigned-byte 32))
                       (:full (unsigned-byte 32)))
-  (setf (sap-ref-32 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
+  (setf (sap-ref-32 (buffer-sap obuf) tail)
         byte))
 
 (def-output-routines ("OUTPUT-SIGNED-LONG-~A-BUFFERED"
                       nil
                       (:none (signed-byte 32))
                       (:full (signed-byte 32)))
-  (setf (signed-sap-ref-32 (fd-stream-obuf-sap stream)
-                           (fd-stream-obuf-tail stream))
+  (setf (signed-sap-ref-32 (buffer-sap obuf) tail)
         byte))
 
 #+#.(cl:if (cl:= sb!vm:n-word-bits 64) '(and) '(or))
                         nil
                         (:none (unsigned-byte 64))
                         (:full (unsigned-byte 64)))
-    (setf (sap-ref-64 (fd-stream-obuf-sap stream) (fd-stream-obuf-tail stream))
+    (setf (sap-ref-64 (buffer-sap obuf) tail)
           byte))
   (def-output-routines ("OUTPUT-SIGNED-LONG-LONG-~A-BUFFERED"
                         8
                         nil
                         (:none (signed-byte 64))
                         (:full (signed-byte 64)))
-    (setf (signed-sap-ref-64 (fd-stream-obuf-sap stream)
-                             (fd-stream-obuf-tail stream))
+    (setf (signed-sap-ref-64 (buffer-sap obuf) tail)
           byte)))
 
-;;; Do the actual output. If there is space to buffer the string,
-;;; buffer it. If the string would normally fit in the buffer, but
-;;; doesn't because of other stuff in the buffer, flush the old noise
-;;; out of the buffer and put the string in it. Otherwise we have a
-;;; very long string, so just send it directly (after flushing the
-;;; buffer, of course).
-(defun output-raw-bytes (fd-stream thing &optional start end)
-  #!+sb-doc
-  "Output THING to FD-STREAM. THING can be any kind of vector or a SAP. If
-  THING is a SAP, END must be supplied (as length won't work)."
-  (let ((start (or start 0))
-        (end (or end (length (the (simple-array * (*)) thing)))))
-    (declare (type index start end))
-    (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))
-           (space (- len tail))
-           (bytes (- end start))
-           (newtail (+ tail bytes)))
-      (cond ((minusp bytes) ; error case
-             (error ":END before :START!"))
-            ((zerop bytes)) ; easy case
-            ((<= bytes space)
-             (if (system-area-pointer-p thing)
-                 (system-area-ub8-copy thing start
-                                       (fd-stream-obuf-sap fd-stream)
-                                       tail
-                                       bytes)
-                 ;; FIXME: There should be some type checking somewhere to
-                 ;; verify that THING here is a vector, not just <not a SAP>.
-                 (copy-ub8-to-system-area thing start
-                                          (fd-stream-obuf-sap fd-stream)
-                                          tail
-                                          bytes))
-             (setf (fd-stream-obuf-tail fd-stream) newtail))
-            ((<= bytes len)
-             (flush-output-buffer fd-stream)
-             (if (system-area-pointer-p thing)
-                 (system-area-ub8-copy thing
-                                       start
-                                       (fd-stream-obuf-sap fd-stream)
-                                       0
-                                       bytes)
-                 ;; FIXME: There should be some type checking somewhere to
-                 ;; verify that THING here is a vector, not just <not a SAP>.
-                 (copy-ub8-to-system-area thing
-                                          start
-                                          (fd-stream-obuf-sap fd-stream)
-                                          0
-                                          bytes))
-             (setf (fd-stream-obuf-tail fd-stream) bytes))
-            (t
-             (flush-output-buffer fd-stream)
-             (frob-output fd-stream thing start end nil))))))
-
 ;;; the routine to use to output a string. If the stream is
 ;;; unbuffered, slam the string down the file descriptor, otherwise
 ;;; use OUTPUT-RAW-BYTES to buffer the string. Update charpos by
                (eq (fd-stream-external-format stream) :latin-1))
           (ecase (fd-stream-buffering stream)
             (:full
-             (output-raw-bytes stream thing start end))
+             (buffer-output stream thing start end))
             (:line
-             (output-raw-bytes stream thing start end)
+             (buffer-output stream thing start end)
              (when last-newline
                (flush-output-buffer stream)))
             (:none
-             (frob-output stream thing start end nil)))
+             (write-or-buffer-output stream thing start end)))
           (ecase (fd-stream-buffering stream)
             (:full (funcall (fd-stream-output-bytes stream)
                             stream thing nil start end))
                  (lambda (stream byte)
                    (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)
-                                     (+ j (fd-stream-obuf-tail stream)))
+                           do (setf (sap-ref-8 (buffer-sap obuf)
+                                               (+ j tail))
                                     (ldb (byte 8 (- i 8 (* j 8))) byte))))))
                 (:full
                  (lambda (stream byte)
                    (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)
-                                     (+ j (fd-stream-obuf-tail stream)))
+                           do (setf (sap-ref-8 (buffer-sap obuf)
+                                               (+ j tail))
                                     (ldb (byte 8 (- i 8 (* j 8))) byte)))))))
               `(unsigned-byte ,i)
               (/ i 8))))
                  (lambda (stream byte)
                    (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)
-                                     (+ j (fd-stream-obuf-tail stream)))
+                           do (setf (sap-ref-8 (buffer-sap obuf)
+                                               (+ j tail))
                                     (ldb (byte 8 (- i 8 (* j 8))) byte))))))
                 (:full
                  (lambda (stream byte)
                    (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)
-                                     (+ j (fd-stream-obuf-tail stream)))
+                           do (setf (sap-ref-8 (buffer-sap obuf)
+                                               (+ j tail))
                                     (ldb (byte 8 (- i 8 (* j 8))) byte)))))))
               `(signed-byte ,i)
               (/ i 8)))))
 ;;; If the read would block wait (using SERVE-EVENT) till input is available,
 ;;; then fill the input buffer, and return the number of bytes read. Throws
 ;;; to EOF-INPUT-CATCHER if the eof was reached.
-(defun refill-buffer/fd (stream)
+(defun refill-input-buffer (stream)
   (let ((fd (fd-stream-fd stream))
         (errno 0)
         (count 0))
+    (declare (dynamic-extent fd errno count))
     (tagbody
        ;; Check for blocking input before touching the stream, as if
        ;; we happen to wait we are liable to be interrupted, and the
        ;; Since the read should not block, we'll disable the
        ;; interrupts here, so that we don't accidentally unwind and
        ;; leave the stream in an inconsistent state.
-       (without-interrupts
-         (let ((ibuf-sap (fd-stream-ibuf-sap stream))
-               (buflen (fd-stream-ibuf-length stream))
-               (head (fd-stream-ibuf-head stream))
-               (tail (fd-stream-ibuf-tail stream)))
-           (declare (type index head tail))
-           ;; Check the SAP: if it is null, then someone has closed
-           ;; the stream from underneath us. This is not ment to fix
-           ;; multithreaded races, but to deal with interrupt handlers
-           ;; closing the stream.
-           (unless ibuf-sap
-             (go :closed-flame))
-           (unless (zerop head)
-             (cond ((eql head tail)
-                    (setf head 0
-                          tail 0
-                          (fd-stream-ibuf-head stream) 0
-                          (fd-stream-ibuf-tail stream) 0))
-                   (t
-                    (decf tail head)
-                    (system-area-ub8-copy ibuf-sap head
-                                          ibuf-sap 0 tail)
-                    (setf head 0
-                          (fd-stream-ibuf-head stream) 0
-                          (fd-stream-ibuf-tail stream) tail))))
-           (setf (fd-stream-listen stream) nil)
-           (setf (values count errno)
-                 (sb!unix:unix-read fd (int-sap (+ (sap-int ibuf-sap) tail))
-                                    (- buflen tail)))
-           (cond ((null count)
-                  #!+win32
-                  (go :read-error)
-                  #!-win32
-                  (if (eql errno sb!unix:ewouldblock)
-                      (go :wait-for-input)
-                      (go :read-error)))
-                 ((zerop count)
-                  (setf (fd-stream-listen stream) :eof)
-                  (/show0 "THROWing EOF-INPUT-CATCHER")
-                  (throw 'eof-input-catcher nil))
-                 (t
-                  ;; Success!
-                  (incf (fd-stream-ibuf-tail stream) count))))))
+
+       ;; Execute the nlx outside without-interrupts to ensure the
+       ;; resulting thunk is stack-allocatable.
+       ((lambda (return-reason)
+          (ecase return-reason
+            ((nil))             ; fast path normal cases
+            ((:wait-for-input) (go :wait-for-input))
+            ((:closed-flame)   (go :closed-flame))
+            ((:read-error)     (go :read-error))))
+        (without-interrupts
+          ;; Check the buffer: if it is null, then someone has closed
+          ;; the stream from underneath us. This is not ment to fix
+          ;; multithreaded races, but to deal with interrupt handlers
+          ;; closing the stream.
+          (block nil
+            (prog1 nil
+              (let* ((ibuf (or (fd-stream-ibuf stream) (return :closed-flame)))
+                     (sap (buffer-sap ibuf))
+                     (length (buffer-length ibuf))
+                     (head (buffer-head ibuf))
+                     (tail (buffer-tail ibuf)))
+                (declare (index length head tail)
+                         (inline sb!unix:unix-read))
+                (unless (zerop head)
+                  (cond ((eql head tail)
+                         ;; Buffer is empty, but not at yet reset -- make it so.
+                         (setf head 0
+                               tail 0)
+                         (reset-buffer ibuf))
+                        (t
+                         ;; Buffer has things in it, but they are not at the
+                         ;; head -- move them there.
+                         (let ((n (- tail head)))
+                           (system-area-ub8-copy sap head sap 0 n)
+                           (setf head 0
+                                 (buffer-head ibuf) head
+                                 tail n
+                                 (buffer-tail ibuf) tail)))))
+                (setf (fd-stream-listen stream) nil)
+                (setf (values count errno)
+                      (sb!unix:unix-read fd (sap+ sap tail) (- length tail)))
+                (cond ((null count)
+                       #!+win32
+                       (return :read-error)
+                       #!-win32
+                       (if (eql errno sb!unix:ewouldblock)
+                           (return :wait-for-input)
+                           (return :read-error)))
+                      ((zerop count)
+                       (setf (fd-stream-listen stream) :eof)
+                       (/show0 "THROWing EOF-INPUT-CATCHER")
+                       (throw 'eof-input-catcher nil))
+                      (t
+                       ;; Success! (Do not use INCF, for sake of other threads.)
+                       (setf (buffer-tail ibuf) (+ count tail))))))))))
     count))
 
 ;;; Make sure there are at least BYTES number of bytes in the input
-;;; buffer. Keep calling REFILL-BUFFER/FD until that condition is met.
+;;; buffer. Keep calling REFILL-INPUT-BUFFER until that condition is met.
 (defmacro input-at-least (stream bytes)
-  (let ((stream-var (gensym))
-        (bytes-var (gensym)))
-    `(let ((,stream-var ,stream)
-           (,bytes-var ,bytes))
+  (let ((stream-var (gensym "STREAM"))
+        (bytes-var (gensym "BYTES"))
+        (buffer-var (gensym "IBUF")))
+    `(let* ((,stream-var ,stream)
+            (,bytes-var ,bytes)
+            (,buffer-var (fd-stream-ibuf ,stream-var)))
        (loop
-         (when (>= (- (fd-stream-ibuf-tail ,stream-var)
-                      (fd-stream-ibuf-head ,stream-var))
+         (when (>= (- (buffer-tail ,buffer-var)
+                      (buffer-head ,buffer-var))
                    ,bytes-var)
            (return))
-         (refill-buffer/fd ,stream-var)))))
+         (refill-input-buffer ,stream-var)))))
 
 (defmacro input-wrapper/variable-width ((stream bytes eof-error eof-value)
                                         &body read-forms)
-  (let ((stream-var (gensym))
-        (retry-var (gensym))
-        (element-var (gensym)))
-    `(let ((,stream-var ,stream)
-           (size nil))
+  (let ((stream-var (gensym "STREAM"))
+        (retry-var (gensym "RETRY"))
+        (element-var (gensym "ELT")))
+    `(let* ((,stream-var ,stream)
+            (ibuf (fd-stream-ibuf ,stream-var))
+            (size nil))
        (if (fd-stream-unread ,stream-var)
            (prog1
                (fd-stream-unread ,stream-var)
                      (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))))
+                             (let* ((byte (sap-ref-8 (buffer-sap ibuf)
+                                                     (buffer-head ibuf))))
                                (declare (ignorable byte))
                                (setq size ,bytes)
                                (input-at-least ,stream-var size)
                        (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))))
+                 (let ((octet-count (- (buffer-tail ibuf)
+                                       (buffer-head ibuf))))
                    (when (or (zerop octet-count)
                              (and (not ,element-var)
                                   (not decode-break-reason)
                                    stream octet-count)))
                      (setq ,retry-var nil)))))
              (cond (,element-var
-                    (incf (fd-stream-ibuf-head ,stream-var) size)
+                    (incf (buffer-head ibuf) 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))
-        (element-var (gensym)))
-    `(let ((,stream-var ,stream))
+  (let ((stream-var (gensym "STREAM"))
+        (element-var (gensym "ELT")))
+    `(let* ((,stream-var ,stream)
+            (ibuf (fd-stream-ibuf ,stream-var)))
        (if (fd-stream-unread ,stream-var)
            (prog1
                (fd-stream-unread ,stream-var)
                     (input-at-least ,stream-var ,bytes)
                     (locally ,@read-forms))))
              (cond (,element-var
-                    (incf (fd-stream-ibuf-head ,stream-var) ,bytes)
+                    (incf (buffer-head (fd-stream-ibuf ,stream-var)) ,bytes)
                     ,element-var)
                    (t
                     (eof-or-lose ,stream-var ,eof-error ,eof-value))))))))
   `(progn
      (defun ,name (stream eof-error eof-value)
        (input-wrapper/variable-width (stream ,size eof-error eof-value)
-         (let ((,sap (fd-stream-ibuf-sap stream))
-               (,head (fd-stream-ibuf-head stream)))
+         (let ((,sap (buffer-sap ibuf))
+               (,head (buffer-head ibuf)))
            ,@body)))
      (setf *input-routines*
            (nconc *input-routines*
   `(progn
      (defun ,name (stream eof-error eof-value)
        (input-wrapper (stream ,size eof-error eof-value)
-         (let ((,sap (fd-stream-ibuf-sap stream))
-               (,head (fd-stream-ibuf-head stream)))
+         (let ((,sap (buffer-sap ibuf))
+               (,head (buffer-head ibuf)))
            ,@body)))
      (setf *input-routines*
            (nconc *input-routines*
              (values
               (lambda (stream eof-error eof-value)
                 (input-wrapper (stream (/ i 8) eof-error eof-value)
-                  (let ((sap (fd-stream-ibuf-sap stream))
-                        (head (fd-stream-ibuf-head stream)))
+                  (let ((sap (buffer-sap ibuf))
+                        (head (buffer-head ibuf)))
                     (loop for j from 0 below (/ i 8)
                           with result = 0
                           do (setf result
              (values
               (lambda (stream eof-error eof-value)
                 (input-wrapper (stream (/ i 8) eof-error eof-value)
-                  (let ((sap (fd-stream-ibuf-sap stream))
-                        (head (fd-stream-ibuf-head stream)))
+                  (let ((sap (buffer-sap ibuf))
+                        (head (buffer-head ibuf)))
                     (loop for j from 0 below (/ i 8)
                           with result = 0
                           do (setf result
               `(signed-byte ,i)
               (/ i 8)))))
 
-;;; Return a string constructed from SAP, START, and END.
-(defun string-from-sap (sap start end)
-  (declare (type index start end))
-  (let* ((length (- end start))
-         (string (make-string length)))
-    (copy-ub8-from-system-area sap start
-                               string 0
-                               length)
-    string))
-
 ;;; the N-BIN method for FD-STREAMs
 ;;;
 ;;; Note that this blocks in UNIX-READ. It is generally used where
   (do ()
       (nil)
     (let* ((remaining-request (- requested total-copied))
-           (head (fd-stream-ibuf-head stream))
-           (tail (fd-stream-ibuf-tail stream))
+           (ibuf (fd-stream-ibuf stream))
+           (head (buffer-head ibuf))
+           (tail (buffer-tail ibuf))
            (available (- tail head))
            (n-this-copy (min remaining-request available))
            (this-start (+ start total-copied))
            (this-end (+ this-start n-this-copy))
-           (sap (fd-stream-ibuf-sap stream)))
+           (sap (buffer-sap ibuf)))
       (declare (type index remaining-request head tail available))
       (declare (type index n-this-copy))
       ;; Copy data from stream buffer into user's buffer.
       (%byte-blt sap head buffer this-start this-end)
-      (incf (fd-stream-ibuf-head stream) n-this-copy)
+      (incf (buffer-head ibuf) n-this-copy)
       (incf total-copied n-this-copy)
       ;; Maybe we need to refill the stream buffer.
       (cond (;; If there were enough data in the stream buffer, we're done.
-             (= total-copied requested)
+             (eql total-copied requested)
              (return total-copied))
             (;; If EOF, we're done in another way.
-             (null (catch 'eof-input-catcher (refill-buffer/fd stream)))
+             (null (catch 'eof-input-catcher (refill-input-buffer stream)))
              (if eof-error-p
                  (error 'end-of-file :stream stream)
                  (return total-copied)))
         (let ((start (or start 0))
               (end (or end (length string))))
           (declare (type index start end))
-          (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)))
+          (synchronize-stream-output stream)
           (unless (<= 0 start end (length string))
-            (signal-bounding-indices-bad-error string start end))
+            (sequence-bounding-indices-bad-error string start end))
           (do ()
               ((= end start))
-            (setf (fd-stream-obuf-tail stream)
-                  (string-dispatch (simple-base-string
-                                    #!+sb-unicode
-                                    (simple-array character)
-                                    string)
-                      string
-                    (let ((len (fd-stream-obuf-length stream))
-                          (sap (fd-stream-obuf-sap stream))
-                          (tail (fd-stream-obuf-tail stream)))
-                      (declare (type index tail)
-                               ;; STRING bounds have already been checked.
-                               (optimize (safety 0)))
-                      (loop
+            (let ((obuf (fd-stream-obuf stream)))
+              (setf (buffer-tail obuf)
+                    (string-dispatch (simple-base-string
+                                      #!+sb-unicode
+                                      (simple-array character (*))
+                                      string)
+                        string
+                      (let ((sap (buffer-sap obuf))
+                            (len (buffer-length obuf))
+                            ;; FIXME: rename
+                            (tail (buffer-tail obuf)))
+                       (declare (type index tail)
+                                ;; STRING bounds have already been checked.
+                                (optimize (safety 0)))
+                       (loop
                          (,@(if output-restart
                                 `(catch 'output-nothing)
                                 `(progn))
                             (return tail))
                          ;; Exited via CATCH. Skip the current character
                          ;; and try the inner loop again.
-                         (incf start)))))
+                         (incf start))))))
             (when (< start end)
               (flush-output-buffer stream)))
           (when flush-p
                             (:none character)
                             (:line character)
                             (:full character))
-          (if (char= byte #\Newline)
+          (if (eql 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))
+          (let* ((obuf (fd-stream-obuf stream))
+                 (bits (char-code byte))
+                 (sap (buffer-sap obuf))
+                 (tail (buffer-tail obuf)))
+            ,out-expr))
       (defun ,in-function (stream buffer start requested eof-error-p
                            &aux (index start) (end (+ start requested)))
         (declare (type fd-stream stream)
             (incf index)))
         (do ()
             (nil)
-          (let* ((head (fd-stream-ibuf-head stream))
-                 (tail (fd-stream-ibuf-tail stream))
-                 (sap (fd-stream-ibuf-sap stream)))
+          (let* ((ibuf (fd-stream-ibuf stream))
+                 (head (buffer-head ibuf))
+                 (tail (buffer-tail ibuf))
+                 (sap (buffer-sap ibuf)))
             (declare (type index head tail)
                      (type system-area-pointer sap))
             ;; Copy data from stream buffer into user's buffer.
                 (setf (aref buffer index) ,in-expr)
                 (incf index)
                 (incf head ,size)))
-            (setf (fd-stream-ibuf-head stream) head)
+            (setf (buffer-head ibuf) head)
             ;; Maybe we need to refill the stream buffer.
             (cond ( ;; If there was enough data in the stream buffer, we're done.
                    (= index end)
                    (return (- index start)))
                   ( ;; If EOF, we're done in another way.
-                   (null (catch 'eof-input-catcher (refill-buffer/fd stream)))
+                   (null (catch 'eof-input-catcher (refill-input-buffer stream)))
                    (if eof-error-p
                        (error 'end-of-file :stream stream)
                        (return (- index start))))
             (let* ((length (length string))
                    (,n-buffer (make-array (* (1+ length) ,size)
                                           :element-type '(unsigned-byte 8)))
-                   ;; This SAP-taking may seem unsafe without pinning,
-                   ;; but since the variable name is a gensym OUT-EXPR
-                   ;; cannot close over it even if it tried, so the buffer
-                   ;; will always be either in a register or on stack.
-                   ;; FIXME: But ...this is true on x86oids only!
-                   (sap (vector-sap ,n-buffer))
                    (tail 0)
                    (stream ,name))
-              (declare (type index length tail)
-                       (type system-area-pointer sap))
-              (dotimes (i length)
-                (let* ((byte (aref string i))
-                       (bits (char-code byte)))
-                  (declare (ignorable byte bits))
-                  ,out-expr)
-                (incf tail ,size))
-              (let* ((bits 0)
-                     (byte (code-char bits)))
-                (declare (ignorable bits byte))
-                ,out-expr)
+              (declare (type index length tail))
+              (with-pinned-objects (,n-buffer)
+                (let ((sap (vector-sap ,n-buffer)))
+                  (declare (system-area-pointer sap))
+                  (dotimes (i length)
+                    (let* ((byte (aref string i))
+                           (bits (char-code byte)))
+                      (declare (ignorable byte bits))
+                      ,out-expr)
+                    (incf tail ,size))
+                  (let* ((bits 0)
+                         (byte (code-char bits)))
+                    (declare (ignorable bits byte))
+                    ,out-expr)))
               ,n-buffer)))
       (setf *external-formats*
        (cons '(,external-format ,in-function ,in-char-function ,out-function
         (let ((start (or start 0))
               (end (or end (length string))))
           (declare (type index start end))
-          (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)))
+          (synchronize-stream-output stream)
           (unless (<= 0 start end (length string))
-            (signal-bounding-indices-bad-error string start end))
+            (sequence-bounding-indices-bad string start end))
           (do ()
               ((= end start))
-            (setf (fd-stream-obuf-tail stream)
-                  (string-dispatch (simple-base-string
-                                    #!+sb-unicode
-                                    (simple-array character)
-                                    string)
-                      string
-                    (let ((len (fd-stream-obuf-length stream))
-                          (sap (fd-stream-obuf-sap stream))
-                          (tail (fd-stream-obuf-tail stream)))
-                      (declare (type index tail)
-                               ;; STRING bounds have already been checked.
-                               (optimize (safety 0)))
-                      (loop
-                         (,@(if output-restart
-                                `(catch 'output-nothing)
-                                `(progn))
-                            (do* ()
-                                 ((or (= start end) (< (- len tail) 4)))
-                              (let* ((byte (aref string start))
-                                     (bits (char-code byte))
-                                     (size ,out-size-expr))
-                                ,out-expr
-                                (incf tail size)
-                                (incf start)))
-                            ;; Exited from the loop normally
-                            (return tail))
-                         ;; Exited via CATCH. Skip the current character
-                         ;; and try the inner loop again.
-                         (incf start)))))
+            (let ((obuf (fd-stream-obuf stream)))
+              (setf (buffer-tail obuf)
+                    (string-dispatch (simple-base-string
+                                      #!+sb-unicode
+                                      (simple-array character (*))
+                                      string)
+                        string
+                      (let ((len (buffer-length obuf))
+                            (sap (buffer-sap obuf))
+                            ;; FIXME: Rename
+                            (tail (buffer-tail obuf)))
+                        (declare (type index tail)
+                                 ;; STRING bounds have already been checked.
+                                 (optimize (safety 0)))
+                        (loop
+                          (,@(if output-restart
+                                 `(catch 'output-nothing)
+                                 `(progn))
+                             (do* ()
+                                  ((or (= start end) (< (- len tail) 4)))
+                               (let* ((byte (aref string start))
+                                      (bits (char-code byte))
+                                      (size ,out-size-expr))
+                                 ,out-expr
+                                 (incf tail size)
+                                 (incf start)))
+                             ;; Exited from the loop normally
+                             (return tail))
+                          ;; Exited via CATCH. Skip the current character
+                          ;; and try the inner loop again.
+                          (incf start))))))
             (when (< start end)
               (flush-output-buffer stream)))
           (when flush-p
                                            (:none character)
                                            (:line character)
                                            (:full character))
-          (if (char= byte #\Newline)
+          (if (eql 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)))
+              (sap (buffer-sap obuf))
+              (tail (buffer-tail obuf)))
           ,out-expr))
       (defun ,in-function (stream buffer start requested eof-error-p
                            &aux (total-copied 0))
             (incf total-copied)))
         (do ()
             (nil)
-          (let* ((head (fd-stream-ibuf-head stream))
-                 (tail (fd-stream-ibuf-tail stream))
-                 (sap (fd-stream-ibuf-sap stream))
+          (let* ((ibuf (fd-stream-ibuf stream))
+                 (head (buffer-head ibuf))
+                 (tail (buffer-tail ibuf))
+                 (sap (buffer-sap ibuf))
                  (decode-break-reason nil))
             (declare (type index head tail))
             ;; Copy data from stream buffer into user's buffer.
                         (incf total-copied)
                         (incf head size))
                       nil))
-              (setf (fd-stream-ibuf-head stream) head)
+              (setf (buffer-head ibuf) head)
               (when decode-break-reason
                 ;; If we've already read some characters on when the invalid
                 ;; code sequence is detected, we return immediately. The
                   (if eof-error-p
                       (error 'end-of-file :stream stream)
                       (return-from ,in-function total-copied)))
-                (setf head (fd-stream-ibuf-head stream))
-                (setf tail (fd-stream-ibuf-tail stream))))
-            (setf (fd-stream-ibuf-head stream) head)
+                (setf head (buffer-head ibuf))
+                (setf tail (buffer-tail ibuf))))
+            (setf (buffer-head ibuf) 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)
                   ( ;; If EOF, we're done in another way.
                    (or (eq decode-break-reason 'eof)
                        (null (catch 'eof-input-catcher
-                               (refill-buffer/fd stream))))
+                               (refill-input-buffer stream))))
                    (if eof-error-p
                        (error 'end-of-file :stream stream)
                        (return total-copied)))
           (declare (ignorable byte))
           ,in-expr))
       (defun ,resync-function (stream)
-        (loop (input-at-least stream 2)
-              (incf (fd-stream-ibuf-head stream))
-              (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))
-                          (declare (ignorable byte))
-                          (input-at-least stream size)
-                          (let ((sap (fd-stream-ibuf-sap stream))
-                                (head (fd-stream-ibuf-head stream)))
-                            ,in-expr))
-                        nil)
-                (return))))
+        (let ((ibuf (fd-stream-ibuf stream)))
+          (loop
+            (input-at-least stream 2)
+            (incf (buffer-head ibuf))
+            (unless (block decode-break-reason
+                      (let* ((sap (buffer-sap ibuf))
+                             (head (buffer-head ibuf))
+                             (byte (sap-ref-8 sap head))
+                             (size ,in-size-expr))
+                        (declare (ignorable byte))
+                        (input-at-least stream size)
+                        (setf head (buffer-head ibuf))
+                        ,in-expr)
+                     nil)
+             (return)))))
       (defun ,read-c-string-function (sap element-type)
         (declare (type system-area-pointer sap))
         (locally
                  (tail 0)
                  (,n-buffer (make-array buffer-length
                                         :element-type '(unsigned-byte 8)))
-                 ;; This SAP-taking may seem unsafe without pinning,
-                 ;; but since the variable name is a gensym OUT-EXPR
-                 ;; cannot close over it even if it tried, so the buffer
-                 ;; will always be either in a register or on stack.
-                 ;; FIXME: But ...this is true on x86oids only!
-                 (sap (vector-sap ,n-buffer))
                  stream)
             (declare (type index length buffer-length tail)
-                     (type system-area-pointer sap)
                      (type null stream)
                      (ignorable stream))
-            (loop for i of-type index below length
-                  for byte of-type character = (aref string i)
-                  for bits = (char-code byte)
-                  for size of-type index = (aref char-length i)
-                  do (prog1
-                         ,out-expr
-                       (incf tail size)))
-            (let* ((bits 0)
-                   (byte (code-char bits))
-                   (size (aref char-length length)))
-              (declare (ignorable bits byte size))
-              ,out-expr)
+            (with-pinned-objects (,n-buffer)
+              (let ((sap (vector-sap ,n-buffer)))
+                (declare (system-area-pointer sap))
+                (loop for i of-type index below length
+                      for byte of-type character = (aref string i)
+                      for bits = (char-code byte)
+                      for size of-type index = (aref char-length i)
+                      do (prog1
+                             ,out-expr
+                           (incf tail size)))
+                (let* ((bits 0)
+                       (byte (code-char bits))
+                       (size (aref char-length length)))
+                  (declare (ignorable bits byte size))
+                  ,out-expr)))
             ,n-buffer)))
 
       (setf *external-formats*
           (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))
+    (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))
+    (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)
          (output-size nil)
          (output-bytes #'ill-bout))
 
-    ;; drop buffers when direction changes
-    (when (and (fd-stream-obuf-sap fd-stream) (not output-p))
-      (with-available-buffers-lock ()
-        (push (fd-stream-obuf-sap fd-stream) *available-buffers*)
-        (setf (fd-stream-obuf-sap fd-stream) nil)))
-    (when (and (fd-stream-ibuf-sap fd-stream) (not input-p))
-      (with-available-buffers-lock ()
-        (push (fd-stream-ibuf-sap fd-stream) *available-buffers*)
-        (setf (fd-stream-ibuf-sap fd-stream) nil)))
-    (when input-p
-      (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))
+    ;; Ensure that we have buffers in the desired direction(s) only,
+    ;; getting new ones and dropping/resetting old ones as necessary.
+    (let ((obuf (fd-stream-obuf fd-stream)))
+      (if output-p
+          (if obuf
+              (reset-buffer obuf)
+              (setf (fd-stream-obuf fd-stream) (get-buffer)))
+          (when obuf
+            (setf (fd-stream-obuf fd-stream) nil)
+            (release-buffer obuf))))
+
+    (let ((ibuf (fd-stream-ibuf fd-stream)))
+      (if input-p
+          (if ibuf
+              (reset-buffer ibuf)
+              (setf (fd-stream-ibuf fd-stream) (get-buffer)))
+          (when ibuf
+            (setf (fd-stream-ibuf fd-stream) nil)
+            (release-buffer ibuf))))
+
+    ;; FIXME: Why only for output? Why unconditionally?
     (when output-p
-      (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)
       (setf (fd-stream-char-pos fd-stream) 0))
 
     (when (and character-stream-p
                         input-type
                         output-type))))))
 
+;;; Handles the resource-release aspects of stream closing, and marks
+;;; it as closed.
+(defun release-fd-stream-resources (fd-stream)
+  (handler-case
+      (without-interrupts
+        ;; Drop handlers first.
+        (when (fd-stream-handler fd-stream)
+          (remove-fd-handler (fd-stream-handler fd-stream))
+          (setf (fd-stream-handler fd-stream) nil))
+        ;; Disable interrupts so that a asynch unwind will not leave
+        ;; us with a dangling finalizer (that would close the same
+        ;; --possibly reassigned-- FD again), or a stream with a closed
+        ;; FD that appears open.
+        (sb!unix:unix-close (fd-stream-fd fd-stream))
+        (set-closed-flame fd-stream)
+        (when (fboundp 'cancel-finalization)
+          (cancel-finalization fd-stream)))
+    ;; On error unwind from WITHOUT-INTERRUPTS.
+    (serious-condition (e)
+      (error e)))
+  ;; Release all buffers. If this is undone, or interrupted,
+  ;; we're still safe: buffers have finalizers of their own.
+  (release-fd-stream-buffers fd-stream))
+
+;;; Flushes the current input buffer and unread chatacter, and returns
+;;; the input buffer, and the amount of of flushed input in bytes.
+(defun flush-input-buffer (stream)
+  (let ((unread (if (fd-stream-unread stream)
+                    1
+                    0)))
+    (setf (fd-stream-unread stream) nil)
+    (let ((ibuf (fd-stream-ibuf stream)))
+      (if ibuf
+          (let ((head (buffer-head ibuf))
+                (tail (buffer-tail ibuf)))
+            (values (reset-buffer ibuf) (- (+ unread tail) head)))
+          (values nil unread)))))
+
+(defun fd-stream-clear-input (stream)
+  (flush-input-buffer stream)
+  #!+win32
+  (progn
+    (sb!win32:fd-clear-input (fd-stream-fd stream))
+    (setf (fd-stream-listen stream) nil))
+  #!-win32
+  (catch 'eof-input-catcher
+    (loop until (sysread-may-block-p stream)
+          do
+          (refill-input-buffer stream)
+          (reset-buffer (fd-stream-ibuf stream)))
+    t))
+
 ;;; Handle miscellaneous operations on FD-STREAM.
 (defun fd-stream-misc-routine (fd-stream operation &optional arg1 arg2)
   (declare (ignore arg2))
   (case operation
     (:listen
      (labels ((do-listen ()
-                (or (not (eql (fd-stream-ibuf-head fd-stream)
-                              (fd-stream-ibuf-tail fd-stream)))
-                    (fd-stream-listen fd-stream)
-                    #!+win32
-                    (sb!win32:fd-listen (fd-stream-fd fd-stream))
-                    #!-win32
-                    ;; If the read can block, LISTEN will certainly return NIL.
-                    (if (sysread-may-block-p fd-stream)
-                        nil
-                        ;; Otherwise select(2) and CL:LISTEN have slightly
-                        ;; different semantics.  The former returns that an FD
-                        ;; is readable when a read operation wouldn't block.
-                        ;; That includes EOF.  However, LISTEN must return NIL
-                        ;; at EOF.
-                        (progn (catch 'eof-input-catcher
-                                 ;; r-b/f too calls select, but it shouldn't
-                                 ;; block as long as read can return once w/o
-                                 ;; blocking
-                                 (refill-buffer/fd fd-stream))
-                               ;; At this point either IBUF-HEAD != IBUF-TAIL
-                               ;; and FD-STREAM-LISTEN is NIL, in which case
-                               ;; we should return T, or IBUF-HEAD ==
-                               ;; IBUF-TAIL and FD-STREAM-LISTEN is :EOF, in
-                               ;; which case we should return :EOF for this
-                               ;; call and all future LISTEN call on this stream.
-                               ;; Call ourselves again to determine which case
-                               ;; applies.
-                               (do-listen))))))
+                (let ((ibuf (fd-stream-ibuf fd-stream)))
+                  (or (not (eql (buffer-head ibuf) (buffer-tail ibuf)))
+                      (fd-stream-listen fd-stream)
+                      #!+win32
+                      (sb!win32:fd-listen (fd-stream-fd fd-stream))
+                      #!-win32
+                      ;; If the read can block, LISTEN will certainly return NIL.
+                      (if (sysread-may-block-p fd-stream)
+                          nil
+                          ;; Otherwise select(2) and CL:LISTEN have slightly
+                          ;; different semantics.  The former returns that an FD
+                          ;; is readable when a read operation wouldn't block.
+                          ;; That includes EOF.  However, LISTEN must return NIL
+                          ;; at EOF.
+                          (progn (catch 'eof-input-catcher
+                                   ;; r-b/f too calls select, but it shouldn't
+                                   ;; block as long as read can return once w/o
+                                   ;; blocking
+                                   (refill-input-buffer fd-stream))
+                                 ;; At this point either IBUF-HEAD != IBUF-TAIL
+                                 ;; and FD-STREAM-LISTEN is NIL, in which case
+                                 ;; we should return T, or IBUF-HEAD ==
+                                 ;; IBUF-TAIL and FD-STREAM-LISTEN is :EOF, in
+                                 ;; which case we should return :EOF for this
+                                 ;; call and all future LISTEN call on this stream.
+                                 ;; Call ourselves again to determine which case
+                                 ;; applies.
+                                 (do-listen)))))))
        (do-listen)))
     (:unread
      (setf (fd-stream-unread fd-stream) arg1)
      (setf (fd-stream-listen fd-stream) t))
     (:close
      (cond (arg1                    ; We got us an abort on our hands.
-            (when (fd-stream-handler fd-stream)
-              (remove-fd-handler (fd-stream-handler fd-stream))
-              (setf (fd-stream-handler fd-stream) nil))
-            ;; We can't do anything unless we know what file were
-            ;; dealing with, and we don't want to do anything
-            ;; strange unless we were writing to the file.
-            (when (and (fd-stream-file fd-stream)
-                       (fd-stream-obuf-sap fd-stream))
-              (if (fd-stream-original fd-stream)
-                  ;; If the original is EQ to file we are appending
-                  ;; and can just close the file without renaming.
-                  (unless (eq (fd-stream-original fd-stream)
-                              (fd-stream-file fd-stream))
-                    ;; We have a handle on the original, just revert.
+            (let ((outputp (fd-stream-obuf fd-stream))
+                  (file (fd-stream-file fd-stream))
+                  (orig (fd-stream-original fd-stream)))
+              ;; This takes care of the important stuff -- everything
+              ;; rest is cleaning up the file-system, which we cannot
+              ;; do on some platforms as long as the file is open.
+              (release-fd-stream-resources fd-stream)
+              ;; We can't do anything unless we know what file were
+              ;; dealing with, and we don't want to do anything
+              ;; strange unless we were writing to the file.
+              (when (and outputp file)
+                (if orig
+                    ;; If the original is EQ to file we are appending to
+                    ;; and can just close the file without renaming.
+                    (unless (eq orig file)
+                      ;; We have a handle on the original, just revert.
+                      (multiple-value-bind (okay err)
+                          (sb!unix:unix-rename orig file)
+                        ;; FIXME: Why is this a SIMPLE-STREAM-ERROR, and the
+                        ;; others are SIMPLE-FILE-ERRORS? Surely they should
+                        ;; all be the same?
+                        (unless okay
+                          (error 'simple-stream-error
+                                 :format-control
+                                 "~@<Couldn't restore ~S to its original contents ~
+                                  from ~S while closing ~S: ~2I~_~A~:>"
+                                 :format-arguments
+                                 (list file orig fd-stream (strerror err))
+                                 :stream fd-stream))))
+                    ;; We can't restore the original, and aren't
+                    ;; appending, so nuke that puppy.
+                    ;;
+                    ;; FIXME: This is currently the fate of superseded
+                    ;; files, and according to the CLOSE spec this is
+                    ;; wrong. However, there seems to be no clean way to
+                    ;; do that that doesn't involve either copying the
+                    ;; data (bad if the :abort resulted from a full
+                    ;; disk), or renaming the old file temporarily
+                    ;; (probably bad because stream opening becomes more
+                    ;; racy).
                     (multiple-value-bind (okay err)
-                        (sb!unix:unix-rename (fd-stream-original fd-stream)
-                                             (fd-stream-file fd-stream))
+                        (sb!unix:unix-unlink file)
                       (unless okay
-                        (simple-stream-perror
-                         "couldn't restore ~S to its original contents"
-                         fd-stream
-                         err))))
-                  ;; We can't restore the original, and aren't
-                  ;; appending, so nuke that puppy.
-                  ;;
-                  ;; FIXME: This is currently the fate of superseded
-                  ;; files, and according to the CLOSE spec this is
-                  ;; wrong. However, there seems to be no clean way to
-                  ;; do that that doesn't involve either copying the
-                  ;; data (bad if the :abort resulted from a full
-                  ;; disk), or renaming the old file temporarily
-                  ;; (probably bad because stream opening becomes more
-                  ;; racy).
-                  (multiple-value-bind (okay err)
-                      (sb!unix:unix-unlink (fd-stream-file fd-stream))
-                    (unless okay
-                      (error 'simple-file-error
-                             :pathname (fd-stream-file fd-stream)
-                             :format-control
-                             "~@<couldn't remove ~S: ~2I~_~A~:>"
-                             :format-arguments (list (fd-stream-file fd-stream)
-                                                     (strerror err))))))))
+                        (error 'simple-file-error
+                               :pathname file
+                               :format-control
+                               "~@<Couldn't remove ~S while closing ~S: ~2I~_~A~:>"
+                               :format-arguments
+                               (list file fd-stream (strerror err)))))))))
            (t
-            (fd-stream-misc-routine fd-stream :finish-output)
-            (when (and (fd-stream-original fd-stream)
-                       (fd-stream-delete-original fd-stream))
-              (multiple-value-bind (okay err)
-                  (sb!unix:unix-unlink (fd-stream-original fd-stream))
-                (unless okay
-                  (error 'simple-file-error
-                         :pathname (fd-stream-original fd-stream)
-                         :format-control
-                         "~@<couldn't delete ~S during close of ~S: ~
-                          ~2I~_~A~:>"
-                         :format-arguments
-                         (list (fd-stream-original fd-stream)
-                               fd-stream
-                               (strerror err))))))))
-     (when (fboundp 'cancel-finalization)
-       (cancel-finalization fd-stream))
-     (sb!unix:unix-close (fd-stream-fd fd-stream))
-     (when (fd-stream-obuf-sap fd-stream)
-       (with-available-buffers-lock ()
-         (push (fd-stream-obuf-sap fd-stream) *available-buffers*)
-         (setf (fd-stream-obuf-sap fd-stream) nil)))
-     (when (fd-stream-ibuf-sap fd-stream)
-       (with-available-buffers-lock ()
-         (push (fd-stream-ibuf-sap fd-stream) *available-buffers*)
-         (setf (fd-stream-ibuf-sap fd-stream) nil)))
-     (sb!impl::set-closed-flame fd-stream))
+            (finish-fd-stream-output fd-stream)
+            (let ((orig (fd-stream-original fd-stream)))
+              (when (and orig (fd-stream-delete-original fd-stream))
+                (multiple-value-bind (okay err) (sb!unix:unix-unlink orig)
+                  (unless okay
+                    (error 'simple-file-error
+                           :pathname orig
+                           :format-control
+                           "~@<couldn't delete ~S while closing ~S: ~2I~_~A~:>"
+                           :format-arguments
+                           (list orig fd-stream (strerror err)))))))
+            ;; In case of no-abort close, don't *really* close the
+            ;; stream until the last moment -- the cleaning up of the
+            ;; original can be done first.
+            (release-fd-stream-resources fd-stream))))
     (:clear-input
-     (setf (fd-stream-unread fd-stream) nil)
-     (setf (fd-stream-ibuf-head fd-stream) 0)
-     (setf (fd-stream-ibuf-tail fd-stream) 0)
-     #!+win32
-     (progn
-       (sb!win32:fd-clear-input (fd-stream-fd fd-stream))
-       (setf (fd-stream-listen fd-stream) nil))
-     #!-win32
-     (catch 'eof-input-catcher
-       (loop until (sysread-may-block-p fd-stream)
-             do
-             (refill-buffer/fd fd-stream)
-             (setf (fd-stream-ibuf-head fd-stream) 0)
-             (setf (fd-stream-ibuf-tail fd-stream) 0))
-       t))
+     (fd-stream-clear-input fd-stream))
     (:force-output
      (flush-output-buffer fd-stream))
     (:finish-output
 ;;
 ;; (defun finish-fd-stream-output (fd-stream)
 ;;   (let ((timeout (fd-stream-timeout fd-stream)))
-;;     (loop while (fd-stream-output-later fd-stream)
+;;     (loop while (fd-stream-output-queue fd-stream)
 ;;        ;; FIXME: SIGINT while waiting for a timeout will
 ;;        ;; cause a timeout here.
 ;;        do (when (and (not (serve-event timeout)) timeout)
 (defun finish-fd-stream-output (stream)
   (flush-output-buffer stream)
   (do ()
-      ((null (fd-stream-output-later stream)))
+      ((null (fd-stream-output-queue stream)))
     (serve-all-events)))
 
 (defun fd-stream-get-file-position (stream)
         ;; than reported by lseek() because lseek() obviously
         ;; cannot take into account output we have not sent
         ;; yet.
-        (dolist (later (fd-stream-output-later stream))
-          (incf posn (- (caddr later) (cadr later))))
-        (incf posn (fd-stream-obuf-tail stream))
+        (dolist (buffer (fd-stream-output-queue stream))
+          (incf posn (- (buffer-tail buffer) (buffer-head buffer))))
+        (let ((obuf (fd-stream-obuf stream)))
+          (when obuf
+            (incf posn (buffer-tail obuf))))
         ;; Adjust for unread input: If there is any input
         ;; read from UNIX but not supplied to the user of the
         ;; stream, the *real* file position will smaller than
         ;; reported, because we want to look like the unread
         ;; stuff is still available.
-        (decf posn (- (fd-stream-ibuf-tail stream)
-                      (fd-stream-ibuf-head stream)))
+        (let ((ibuf (fd-stream-ibuf stream)))
+          (when ibuf
+            (decf posn (- (buffer-tail ibuf) (buffer-head ibuf)))))
         (when (fd-stream-unread stream)
           (decf posn))
         ;; Divide bytes by element size.
          (go :again))
        ;; Clear out any pending input to force the next read to go to
        ;; the disk.
-       (setf (fd-stream-unread stream) nil
-             (fd-stream-ibuf-head stream) 0
-             (fd-stream-ibuf-tail stream) 0)
+       (flush-input-buffer stream)
        ;; Trash cached value for listen, so that we check next time.
        (setf (fd-stream-listen stream) nil)
          ;; Now move it.
          (multiple-value-bind (offset origin)
              (case position-spec
-           (:start
-            (values 0 sb!unix:l_set))
-           (:end
-            (values 0 sb!unix:l_xtnd))
-           (t
-            (values (* position-spec (fd-stream-element-size stream))
-                    sb!unix:l_set)))
+               (:start
+                (values 0 sb!unix:l_set))
+               (:end
+                (values 0 sb!unix:l_xtnd))
+               (t
+                (values (* position-spec (fd-stream-element-size stream))
+                        sb!unix:l_set)))
            (declare (type (alien sb!unix:off-t) offset))
            (let ((posn (sb!unix:unix-lseek (fd-stream-fd stream)
                                            offset origin)))
                                  :buffering buffering
                                  :dual-channel-p dual-channel-p
                                  :external-format external-format
+                                 :char-size (external-format-char-size external-format)
                                  :timeout
                                  (if timeout
                                      (coerce timeout 'single-float)
                   (sb!unix:unix-close fd)
                   #!+sb-show
                   (format *terminal-io* "** closed file descriptor ~W **~%"
-                          fd))))
+                          fd))
+                :dont-save t))
     stream))
 
 ;;; Pick a name to use for the backup file for the :IF-EXISTS
 
   ;; Calculate useful stuff.
   (multiple-value-bind (input output mask)
-      (case direction
+      (ecase direction
         (:input  (values   t nil sb!unix:o_rdonly))
         (:output (values nil   t sb!unix:o_wronly))
         (:io     (values   t   t sb!unix:o_rdwr))
   (setf *trace-output* *standard-output*)
   (values))
 
+(defun stream-deinit ()
+  ;; Unbind to make sure we're not accidently dealing with it
+  ;; before we're ready (or after we think it's been deinitialized).
+  (with-available-buffers-lock ()
+    (without-package-locks
+        (makunbound '*available-buffers*))))
+
 ;;; This is called whenever a saved core is restarted.
-(defun stream-reinit ()
-  (setf *available-buffers* nil)
+(defun stream-reinit (&optional init-buffers-p)
+  (when init-buffers-p
+    (with-available-buffers-lock ()
+      (aver (not (boundp '*available-buffers*)))
+      (setf *available-buffers* nil)))
   (with-output-to-string (*error-output*)
     (setf *stdin*
           (make-fd-stream 0 :name "standard input" :input t :buffering :line