forked from dmitryvk/sbcl-win32-threads
/
fd-stream.lisp
2616 lines (2483 loc) · 114 KB
/
fd-stream.lisp
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;;;; streams for UNIX file descriptors
;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.
(in-package "SB!IMPL")
;;;; 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))
(defvar *available-buffers* ()
#!+sb-doc
"List of 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)
;; 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::with-system-spinlock (*available-buffers-spinlock*)
,@body))
(defconstant +bytes-per-buffer+ (* 4 1024)
#!+sb-doc
"Default number of bytes per 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 ()
(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*))))))
;;;; the FD-STREAM structure
(defstruct (fd-stream
(:constructor %make-fd-stream)
(:conc-name fd-stream-)
(:predicate fd-stream-p)
(:include ansi-stream
(misc #'fd-stream-misc-routine))
(:copier nil))
;; the name of this stream
(name nil)
;; the file this stream is for
(file nil)
;; the backup file namestring for the old file, for :IF-EXISTS
;; :RENAME or :RENAME-AND-DELETE.
(original nil :type (or simple-string null))
(delete-original nil) ; for :if-exists :rename-and-delete
;;; the number of bytes per element
(element-size 1 :type index)
;; the type of element being transfered
(element-type 'base-char)
;; the Unix file descriptor
(fd -1 :type fixnum)
;; controls when the output buffer is flushed
(buffering :full :type (member :full :line :none))
;; controls whether the input buffer must be cleared before output
;; (must be done for files, not for sockets, pipes and other data
;; sources where input and output aren't related). non-NIL means
;; don't clear input buffer.
(dual-channel-p nil)
;; character position if known -- this may run into bignums, but
;; we probably should flip it into null then for efficiency's sake...
(char-pos nil :type (or unsigned-byte null))
;; T if input is waiting on FD. :EOF if we hit EOF.
(listen nil :type (member nil t :eof))
;; the input buffer
(unread nil)
(ibuf nil :type (or buffer null))
;; the output buffer
(obuf nil :type (or buffer null))
;; output flushed, but not written due to non-blocking io?
(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))))
;;;; 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))))))
;;;; output routines and related noise
(defvar *output-routines* ()
#!+sb-doc
"List of all available output routines. Each element is a list of the
element-type output, the kind of buffering, the function name, and the number
of bytes per element.")
;;; common idioms for reporting low-level stream and file problems
(defun simple-stream-perror (note-format stream errno)
(error 'simple-stream-error
:stream stream
:format-control "~@<~?: ~2I~_~A~:>"
:format-arguments (list note-format (list stream) (strerror errno))))
(defun simple-file-perror (note-format pathname errno)
(error 'simple-file-error
:pathname pathname
:format-control "~@<~?: ~2I~_~A~:>"
:format-arguments
(list note-format (list pathname) (strerror errno))))
(defun stream-decoding-error (stream octets)
(error 'stream-decoding-error
:stream stream
;; FIXME: dunno how to get at OCTETS currently, or even if
;; that's the right thing to report.
:octets octets))
(defun stream-encoding-error (stream code)
(error 'stream-encoding-error
:stream stream
:code code))
(defun c-string-encoding-error (external-format code)
(error 'c-string-encoding-error
:external-format external-format
:code code))
(defun c-string-decoding-error (external-format octets)
(error 'c-string-decoding-error
:external-format external-format
:octets octets))
;;; Returning true goes into end of file handling, false will enter another
;;; round of input buffer filling followed by re-entering character decode.
(defun stream-decoding-error-and-handle (stream octet-count)
(restart-case
(stream-decoding-error stream
(let* ((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 ()
:report (lambda (stream)
(format stream
"~@<Attempt to resync the stream at a character ~
character boundary and continue.~@:>"))
(fd-stream-resync stream)
nil)
(force-end-of-file ()
:report (lambda (stream)
(format stream "~@<Force an end of file.~@:>"))
t)))
(defun stream-encoding-error-and-handle (stream code)
(restart-case
(stream-encoding-error stream code)
(output-nothing ()
:report (lambda (stream)
(format stream "~@<Skip output of this character.~@:>"))
(throw 'output-nothing nil))))
(defun external-format-encoding-error (stream code)
(if (streamp stream)
(stream-encoding-error-and-handle stream code)
(c-string-encoding-error stream code)))
(defun external-format-decoding-error (stream octet-count)
(if (streamp stream)
(stream-decoding-error stream octet-count)
(c-string-decoding-error stream octet-count)))
(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)
(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 "STREAM")))
`(let* ((,stream-var ,stream)
(obuf (fd-stream-obuf ,stream-var))
(tail (buffer-tail obuf))
(size ,size))
,(unless (eq (car buffering) :none)
`(when (<= (buffer-length obuf) (+ tail size))
(setf obuf (flush-output-buffer ,stream-var)
tail (buffer-tail obuf))))
,(unless (eq (car buffering) :none)
;; FIXME: Why this here? Doesn't seem necessary.
`(synchronize-stream-output ,stream-var))
,(if restart
`(catch 'output-nothing
,@body
(setf (buffer-tail obuf) (+ tail size)))
`(progn
,@body
(setf (buffer-tail obuf) (+ tail size))))
,(ecase (car buffering)
(:none
`(flush-output-buffer ,stream-var))
(:line
`(when (eql byte #\Newline)
(flush-output-buffer ,stream-var)))
(:full))
(values))))
(defmacro output-wrapper ((stream size buffering restart) &body body)
(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 (<= (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)
`(synchronize-stream-output ,stream-var))
,(if restart
`(catch 'output-nothing
,@body
(setf (buffer-tail obuf) (+ tail ,size)))
`(progn
,@body
(setf (buffer-tail obuf) (+ tail ,size))))
,(ecase (car buffering)
(:none
`(flush-output-buffer ,stream-var))
(:line
`(when (eql byte #\Newline)
(flush-output-buffer ,stream-var)))
(:full))
(values))))
(defmacro def-output-routines/variable-width
((name-fmt size restart external-format &rest bufferings)
&body body)
(declare (optimize (speed 1)))
(cons 'progn
(mapcar
(lambda (buffering)
(let ((function
(intern (format nil name-fmt (string (car buffering))))))
`(progn
(defun ,function (stream byte)
(declare (ignorable byte))
(output-wrapper/variable-width (stream ,size ,buffering ,restart)
,@body))
(setf *output-routines*
(nconc *output-routines*
',(mapcar
(lambda (type)
(list type
(car buffering)
function
1
external-format))
(cdr buffering)))))))
bufferings)))
;;; Define output routines that output numbers SIZE bytes long for the
;;; given bufferings. Use BODY to do the actual output.
(defmacro def-output-routines ((name-fmt size restart &rest bufferings)
&body body)
(declare (optimize (speed 1)))
(cons 'progn
(mapcar
(lambda (buffering)
(let ((function
(intern (format nil name-fmt (string (car buffering))))))
`(progn
(defun ,function (stream byte)
(output-wrapper (stream ,size ,buffering ,restart)
,@body))
(setf *output-routines*
(nconc *output-routines*
',(mapcar
(lambda (type)
(list type
(car buffering)
function
size
nil))
(cdr buffering)))))))
bufferings)))
;;; FIXME: is this used anywhere any more?
(def-output-routines ("OUTPUT-CHAR-~A-BUFFERED"
1
t
(:none character)
(:line character)
(:full character))
(if (eql byte #\Newline)
(setf (fd-stream-char-pos stream) 0)
(incf (fd-stream-char-pos stream)))
(setf (sap-ref-8 (buffer-sap obuf) tail)
(char-code byte)))
(def-output-routines ("OUTPUT-UNSIGNED-BYTE-~A-BUFFERED"
1
nil
(:none (unsigned-byte 8))
(:full (unsigned-byte 8)))
(setf (sap-ref-8 (buffer-sap obuf) tail)
byte))
(def-output-routines ("OUTPUT-SIGNED-BYTE-~A-BUFFERED"
1
nil
(:none (signed-byte 8))
(:full (signed-byte 8)))
(setf (signed-sap-ref-8 (buffer-sap obuf) tail)
byte))
(def-output-routines ("OUTPUT-UNSIGNED-SHORT-~A-BUFFERED"
2
nil
(:none (unsigned-byte 16))
(:full (unsigned-byte 16)))
(setf (sap-ref-16 (buffer-sap obuf) tail)
byte))
(def-output-routines ("OUTPUT-SIGNED-SHORT-~A-BUFFERED"
2
nil
(:none (signed-byte 16))
(:full (signed-byte 16)))
(setf (signed-sap-ref-16 (buffer-sap obuf) tail)
byte))
(def-output-routines ("OUTPUT-UNSIGNED-LONG-~A-BUFFERED"
4
nil
(:none (unsigned-byte 32))
(:full (unsigned-byte 32)))
(setf (sap-ref-32 (buffer-sap obuf) tail)
byte))
(def-output-routines ("OUTPUT-SIGNED-LONG-~A-BUFFERED"
4
nil
(:none (signed-byte 32))
(:full (signed-byte 32)))
(setf (signed-sap-ref-32 (buffer-sap obuf) tail)
byte))
#+#.(cl:if (cl:= sb!vm:n-word-bits 64) '(and) '(or))
(progn
(def-output-routines ("OUTPUT-UNSIGNED-LONG-LONG-~A-BUFFERED"
8
nil
(:none (unsigned-byte 64))
(:full (unsigned-byte 64)))
(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 (buffer-sap obuf) tail)
byte)))
;;; 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
;;; checking to see where the last newline was.
(defun fd-sout (stream thing start end)
(declare (type fd-stream stream) (type string thing))
(let ((start (or start 0))
(end (or end (length (the vector thing)))))
(declare (fixnum start end))
(let ((last-newline
(string-dispatch (simple-base-string
#!+sb-unicode
(simple-array character (*))
string)
thing
(position #\newline thing :from-end t
:start start :end end))))
(if (and (typep thing 'base-string)
(eq (fd-stream-external-format stream) :latin-1))
(ecase (fd-stream-buffering stream)
(:full
(buffer-output stream thing start end))
(:line
(buffer-output stream thing start end)
(when last-newline
(flush-output-buffer stream)))
(:none
(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))
(:line (funcall (fd-stream-output-bytes stream)
stream thing last-newline start end))
(:none (funcall (fd-stream-output-bytes stream)
stream thing t start end))))
(if last-newline
(setf (fd-stream-char-pos stream) (- end last-newline 1))
(incf (fd-stream-char-pos stream) (- end start))))))
(defvar *external-formats* ()
#!+sb-doc
"List of all available external formats. Each element is a list of the
element-type, string input function name, character input function name,
and string output function name.")
(defun get-external-format (external-format)
(dolist (entry *external-formats*)
(when (member external-format (first entry))
(return entry))))
(defun get-external-format-function (external-format index)
(let ((entry (get-external-format external-format)))
(when entry (nth index entry))))
;;; Find an output routine to use given the type and buffering. Return
;;; as multiple values the routine, the real type transfered, and the
;;; number of bytes per element.
(defun pick-output-routine (type buffering &optional external-format)
(when (subtypep type 'character)
(let ((entry (get-external-format external-format)))
(when entry
(return-from pick-output-routine
(values (symbol-function (nth (ecase buffering
(:none 4)
(:line 5)
(:full 6))
entry))
'character
1
(symbol-function (fourth entry))
(first (first entry)))))))
(dolist (entry *output-routines*)
(when (and (subtypep type (first entry))
(eq buffering (second entry))
(or (not (fifth entry))
(eq external-format (fifth entry))))
(return-from pick-output-routine
(values (symbol-function (third entry))
(first entry)
(fourth entry)))))
;; KLUDGE: dealing with the buffering here leads to excessive code
;; explosion.
;;
;; KLUDGE: also see comments in PICK-INPUT-ROUTINE
(loop for i from 40 by 8 to 1024 ; ARB (KLUDGE)
if (subtypep type `(unsigned-byte ,i))
do (return-from pick-output-routine
(values
(ecase buffering
(:none
(lambda (stream byte)
(output-wrapper (stream (/ i 8) (:none) nil)
(loop for j from 0 below (/ i 8)
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 (buffer-sap obuf)
(+ j tail))
(ldb (byte 8 (- i 8 (* j 8))) byte)))))))
`(unsigned-byte ,i)
(/ i 8))))
(loop for i from 40 by 8 to 1024 ; ARB (KLUDGE)
if (subtypep type `(signed-byte ,i))
do (return-from pick-output-routine
(values
(ecase buffering
(:none
(lambda (stream byte)
(output-wrapper (stream (/ i 8) (:none) nil)
(loop for j from 0 below (/ i 8)
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 (buffer-sap obuf)
(+ j tail))
(ldb (byte 8 (- i 8 (* j 8))) byte)))))))
`(signed-byte ,i)
(/ i 8)))))
;;;; input routines and related noise
;;; a list of all available input routines. Each element is a list of
;;; the element-type input, the function name, and the number of bytes
;;; per element.
(defvar *input-routines* ())
;;; Return whether a primitive partial read operation on STREAM's FD
;;; would (probably) block. Signal a `simple-stream-error' if the
;;; system call implementing this operation fails.
;;;
;;; It is "may" instead of "would" because "would" is not quite
;;; correct on win32. However, none of the places that use it require
;;; further assurance than "may" versus "will definitely not".
(defun sysread-may-block-p (stream)
#+win32
;; This answers T at EOF on win32, I think.
(not (sb!win32:fd-listen (fd-stream-fd stream)))
#-win32
(sb!unix:with-restarted-syscall (count errno)
(sb!alien:with-alien ((read-fds (sb!alien:struct sb!unix:fd-set)))
(sb!unix:fd-zero read-fds)
(sb!unix:fd-set (fd-stream-fd stream) read-fds)
(sb!unix:unix-fast-select (1+ (fd-stream-fd stream))
(sb!alien:addr read-fds)
nil nil 0 0))
(case count
((1) nil)
((0) t)
(otherwise
(simple-stream-perror "couldn't check whether ~S is readable"
stream
errno)))))
;;; 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-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
;; interrupt handler may use the same stream.
(if (sysread-may-block-p stream)
(go :wait-for-input)
(go :main))
;; These (:CLOSED-FLAME and :READ-ERROR) tags are here so what
;; we can signal errors outside the WITHOUT-INTERRUPTS.
:closed-flame
(closed-flame stream)
:read-error
(simple-stream-perror "couldn't read from ~S" stream errno)
:wait-for-input
;; This tag is here so we can unwind outside the WITHOUT-INTERRUPTS
;; to wait for input if read tells us EWOULDBLOCK.
(unless (wait-until-fd-usable fd :input (fd-stream-timeout stream))
(signal-timeout 'io-timeout :stream stream :direction :read
:seconds (fd-stream-timeout stream)))
:main
;; 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.
;; 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-INPUT-BUFFER until that condition is met.
(defmacro input-at-least (stream 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 (>= (- (buffer-tail ,buffer-var)
(buffer-head ,buffer-var))
,bytes-var)
(return))
(refill-input-buffer ,stream-var)))))
(defmacro input-wrapper/variable-width ((stream bytes eof-error eof-value)
&body read-forms)
(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 (fd-stream-unread ,stream-var) nil)
(setf (fd-stream-listen ,stream-var) nil))
(let ((,element-var nil)
(decode-break-reason nil))
(do ((,retry-var t))
((not ,retry-var))
(unless
(catch 'eof-input-catcher
(setf decode-break-reason
(block decode-break-reason
(input-at-least ,stream-var 1)
(let* ((byte (sap-ref-8 (buffer-sap ibuf)
(buffer-head ibuf))))
(declare (ignorable byte))
(setq size ,bytes)
(input-at-least ,stream-var size)
(setq ,element-var (locally ,@read-forms))
(setq ,retry-var nil))
nil))
(when decode-break-reason
(stream-decoding-error-and-handle stream
decode-break-reason))
t)
(let ((octet-count (- (buffer-tail ibuf)
(buffer-head ibuf))))
(when (or (zerop octet-count)
(and (not ,element-var)
(not decode-break-reason)
(stream-decoding-error-and-handle
stream octet-count)))
(setq ,retry-var nil)))))
(cond (,element-var
(incf (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 "STREAM"))
(element-var (gensym "ELT")))
`(let* ((,stream-var ,stream)
(ibuf (fd-stream-ibuf ,stream-var)))