1.0.4.106: refactoring FILE-POSITION on FD-STREAMS, some cleanups

* Make the underlying FILE-POSITION on FD-STREAMs interrupt-safe.
   This is not enough to make FILE-POSITION on FD-STREAMs interrupt
   safe, as the ANSI-STREAM layer is not -- or at least I doesn't look
   like it to me.

 * Split FD-STREAM-FILE-POSITION into two parts for easier reading,
   and make the error behaviour more ANSI compliant.

 * Move FLUSH-OUTPUT-BUFFER to FINISH-FD-STREAM-OUTPUT to make it a
   one-stop-shopping implementation of finish-output for FD-STREAMs.

 * New function: FD-STREAM-OUTPUT-FINISHED-P, which returns false if
   there is any pending output on the stream.

 * Add comments explaining why certain VECTOR-SAP usages are safe
   without pinning the vector -- at least on x86oids.

 * Instead of (IF #-WIN32 P #+WIN32 T #-WIN32 THEN #+WIN32 ELSE),
   let us use #-WIN32 ELSE #+WIN32 (IF P THEN ELSE)...
This commit is contained in:
Nikodemus Siivola 2007-04-19 12:01:04 +00:00
parent 299c01267c
commit 8cad02355d
7 changed files with 166 additions and 118 deletions

2
NEWS
View file

@ -29,6 +29,8 @@ changes in sbcl-1.0.5 relative to sbcl-1.0.4:
to global variables using SYMBOL-VALUE and a constant argument.
* enhancement: SIGINT now causes a specific condition
SB-SYS:INTERACTIVE-INTERRUPT to be signalled.
* bug fix: FILE-POSITION used to signal an error in some cases where
ANSI requires it to return NIL.
* bug fix: ADJUST-ARRAY is now interrupt-safe.
* bug fix: adding and removing fd-handlers is now interrupt-safe.
* bug fix: inlined calls to C now ensure 16byte stack alignment on

View file

@ -182,13 +182,13 @@
(defun external-format-encoding-error (stream code)
(if (streamp stream)
(stream-encoding-error-and-handle stream code)
(c-string-encoding-error stream code)))
(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)))
(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
@ -208,7 +208,10 @@
start
length)
(cond ((not count)
(if #!-win32 (= errno sb!unix:ewouldblock) #!+win32 t #!-win32
#!+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.
@ -251,19 +254,19 @@
(type (or system-area-pointer (simple-array * (*))) base)
(type index start end))
(if (not (null (fd-stream-output-later stream))) ; something buffered.
(progn
(output-later stream base start end reuse-sap)
;; ### check to see whether any of this noise can be output
)
(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)
(if #!-win32 (= errno sb!unix:ewouldblock) #!+win32 t #!-win32
#!+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)))
(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)))))))
@ -275,6 +278,10 @@
(frob-output stream (fd-stream-obuf-sap stream) 0 length t)
(setf (fd-stream-obuf-tail stream) 0))))
(defun fd-stream-output-finished-p (stream)
(and (zerop (fd-stream-obuf-tail stream))
(not (fd-stream-output-later stream))))
(defmacro output-wrapper/variable-width ((stream size buffering restart)
&body body)
(let ((stream-var (gensym)))
@ -1078,7 +1085,8 @@
(in-char-function (symbolicate "INPUT-CHAR/" name))
(size-function (symbolicate "BYTES-FOR-CHAR/" name))
(read-c-string-function (symbolicate "READ-FROM-C-STRING/" name))
(output-c-string-function (symbolicate "OUTPUT-TO-C-STRING/" name)))
(output-c-string-function (symbolicate "OUTPUT-TO-C-STRING/" name))
(n-buffer (gensym "BUFFER")))
`(progn
(defun ,size-function (byte)
(declare (ignore byte))
@ -1142,9 +1150,11 @@
,out-expr))
(defun ,in-function (stream buffer start requested eof-error-p
&aux (index start) (end (+ start requested)))
(declare (type fd-stream stream))
(declare (type index start requested index end))
(declare (type (simple-array character (#.+ansi-stream-in-buffer-length+)) buffer))
(declare (type fd-stream stream)
(type index start requested index end)
(type
(simple-array character (#.+ansi-stream-in-buffer-length+))
buffer))
(let ((unread (fd-stream-unread stream)))
(when unread
(setf (aref buffer index) unread)
@ -1188,16 +1198,18 @@
(locally
(declare (optimize (speed 3) (safety 0)))
(let* ((stream ,name)
(length (loop for head of-type index upfrom 0 by ,size
for count of-type index upto (1- ARRAY-DIMENSION-LIMIT)
for byte = (sap-ref-8 sap head)
for char of-type character = ,in-expr
until (zerop (char-code char))
finally (return count)))
(length
(loop for head of-type index upfrom 0 by ,size
for count of-type index upto (1- array-dimension-limit)
for byte = (sap-ref-8 sap head)
for char of-type character = ,in-expr
until (zerop (char-code char))
finally (return count)))
;; Inline the common cases
(string (make-string length :element-type element-type)))
(declare (ignorable stream)
(type index length)
(type string string))
(type simple-string string))
(/show0 before-copy-loop)
(loop for head of-type index upfrom 0 by ,size
for index of-type index below length
@ -1210,8 +1222,14 @@
(locally
(declare (optimize (speed 3) (safety 0)))
(let* ((length (length string))
(buffer (make-array (* (1+ length) ,size) :element-type '(unsigned-byte 8)))
(sap (vector-sap buffer))
(,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)
@ -1226,7 +1244,7 @@
(byte (code-char bits)))
(declare (ignorable bits byte))
,out-expr)
buffer)))
,n-buffer)))
(setf *external-formats*
(cons '(,external-format ,in-function ,in-char-function ,out-function
,@(mapcar #'(lambda (buffering)
@ -1247,7 +1265,8 @@
(resync-function (symbolicate "RESYNC/" name))
(size-function (symbolicate "BYTES-FOR-CHAR/" name))
(read-c-string-function (symbolicate "READ-FROM-C-STRING/" name))
(output-c-string-function (symbolicate "OUTPUT-TO-C-STRING/" name)))
(output-c-string-function (symbolicate "OUTPUT-TO-C-STRING/" name))
(n-buffer (gensym "BUFFER")))
`(progn
(defun ,size-function (byte)
(declare (ignorable byte))
@ -1313,9 +1332,11 @@
,out-expr))
(defun ,in-function (stream buffer start requested eof-error-p
&aux (total-copied 0))
(declare (type fd-stream stream))
(declare (type index start requested total-copied))
(declare (type (simple-array character (#.+ansi-stream-in-buffer-length+)) buffer))
(declare (type fd-stream stream)
(type index start requested total-copied)
(type
(simple-array character (#.+ansi-stream-in-buffer-length+))
buffer))
(let ((unread (fd-stream-unread stream)))
(when unread
(setf (aref buffer start) unread)
@ -1453,26 +1474,32 @@
(setf (aref char-length length)
(the index ,out-size-expr)))))
(tail 0)
(buffer (make-array buffer-length :element-type '(unsigned-byte 8)))
(sap (vector-sap buffer))
(,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)))
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)
buffer)))
,n-buffer)))
(setf *external-formats*
(cons '(,external-format ,in-function ,in-char-function ,out-function
@ -1903,7 +1930,6 @@
(:force-output
(flush-output-buffer fd-stream))
(:finish-output
(flush-output-buffer fd-stream)
(finish-fd-stream-output fd-stream))
(:element-type
(fd-stream-element-type fd-stream))
@ -1942,84 +1968,96 @@
(character (fd-stream-character-size fd-stream arg1))
(string (fd-stream-string-size fd-stream arg1))))
(:file-position
(fd-stream-file-position fd-stream arg1))))
(if arg1
(fd-stream-set-file-position fd-stream arg1)
(fd-stream-get-file-position fd-stream)))))
(defun finish-fd-stream-output (stream)
(flush-output-buffer stream)
(do ()
((null (fd-stream-output-later stream)))
(serve-all-events)))
(defun fd-stream-file-position (stream &optional newpos)
(declare (type fd-stream stream)
(type (or (alien sb!unix:off-t) (member nil :start :end)) newpos))
(if (null newpos)
(without-interrupts
;; First, find the position of the UNIX file descriptor in the file.
(multiple-value-bind (posn errno)
(sb!unix:unix-lseek (fd-stream-fd stream) 0 sb!unix:l_incr)
(declare (type (or (alien sb!unix:off-t) null) posn))
(cond ((integerp posn)
;; Adjust for buffered output: If there is any output
;; buffered, the *real* file position will be larger
;; 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))
;; 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)))
(when (fd-stream-unread stream)
(decf posn))
;; Divide bytes by element size.
(truncate posn (fd-stream-element-size stream)))
((eq errno sb!unix:espipe)
nil)
(t
(with-interrupts
(simple-stream-perror "failure in Unix lseek() on ~S"
stream
errno))))))
(let ((offset 0) origin)
(declare (type (alien sb!unix:off-t) offset))
;; Make sure we don't have any output pending, because if we
;; move the file pointer before writing this stuff, it will be
;; written in the wrong location.
(flush-output-buffer stream)
(finish-fd-stream-output stream)
;; Clear out any pending input to force the next read to go to
;; the disk.
(setf (fd-stream-unread stream) nil)
(setf (fd-stream-ibuf-head stream) 0)
(setf (fd-stream-ibuf-tail stream) 0)
;; Trash cached value for listen, so that we check next time.
(setf (fd-stream-listen stream) nil)
;; Now move it.
(cond ((eq newpos :start)
(setf offset 0 origin sb!unix:l_set))
((eq newpos :end)
(setf offset 0 origin sb!unix:l_xtnd))
((typep newpos '(alien sb!unix:off-t))
(setf offset (* newpos (fd-stream-element-size stream))
origin sb!unix:l_set))
(t
(error "invalid position given to FILE-POSITION: ~S" newpos)))
(multiple-value-bind (posn errno)
(sb!unix:unix-lseek (fd-stream-fd stream) offset origin)
(cond ((typep posn '(alien sb!unix:off-t))
t)
((eq errno sb!unix:espipe)
nil)
(t
(simple-stream-perror "error in Unix lseek() on ~S"
stream
errno)))))))
(defun fd-stream-get-file-position (stream)
(declare (fd-stream stream))
(without-interrupts
(let ((posn (sb!unix:unix-lseek (fd-stream-fd stream) 0 sb!unix:l_incr)))
(declare (type (or (alien sb!unix:off-t) null) posn))
;; We used to return NIL for errno==ESPIPE, and signal an error
;; in other failure cases. However, CLHS says to return NIL if
;; the position cannot be determined -- so that's what we do.
(when (integerp posn)
;; Adjust for buffered output: If there is any output
;; buffered, the *real* file position will be larger
;; 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))
;; 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)))
(when (fd-stream-unread stream)
(decf posn))
;; Divide bytes by element size.
(truncate posn (fd-stream-element-size stream))))))
(defun fd-stream-set-file-position (stream position-spec)
(declare (fd-stream stream))
(check-type position-spec
(or (alien sb!unix:off-t) (member nil :start :end))
"valid file position designator")
(tagbody
:again
;; Make sure we don't have any output pending, because if we
;; move the file pointer before writing this stuff, it will be
;; written in the wrong location.
(finish-fd-stream-output stream)
;; Disable interrupts so that interrupt handlers doing output
;; won't screw us.
(without-interrupts
(unless (fd-stream-output-finished-p stream)
;; We got interrupted and more output came our way during
;; the interrupt. Wrapping the FINISH-FD-STREAM-OUTPUT in
;; WITHOUT-INTERRUPTS gets nasty as it can signal errors,
;; so we prefer to do things like this...
(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)
;; 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)))
(declare (type (alien sb!unix:off-t) offset))
(let ((posn (sb!unix:unix-lseek (fd-stream-fd stream)
offset origin)))
;; CLHS says to return true if the file-position was set
;; succesfully, and NIL otherwise. We are to signal an error
;; only if the given position was out of bounds, and that is
;; dealt with above. In times past we used to return NIL for
;; errno==ESPIPE, and signal an error in other cases.
;;
;; FIXME: We are still liable to signal an error if flushing
;; output fails.
(return-from fd-stream-set-file-position
(typep posn '(alien sb!unix:off-t))))))))
;;;; creation routines (MAKE-FD-STREAM and OPEN)

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@ -82,6 +82,8 @@
(define-alien-type-method (c-string :deport-gen) (type value)
(declare (ignore type))
;; This SAP taking is safe as DEPORT callers pin the VALUE when
;; necessary.
`(etypecase ,value
(null (int-sap 0))
((alien (* char)) (alien-sap ,value))

View file

@ -150,6 +150,8 @@
(declare (type stream stream))
(declare (type (or index (alien sb!unix:off-t) (member nil :start :end))
position))
;; FIXME: It woud be good to comment on the stuff that is done here...
;; FIXME: This doesn't look interrupt safe.
(cond
(position
(setf (ansi-stream-in-index stream) +ansi-stream-in-buffer-length+)

View file

@ -346,8 +346,8 @@
(element-type 'character)
((:initial-element fill-char)))
#!+sb-doc
"Given a character count and an optional fill character, makes and returns
a new string COUNT long filled with the fill character."
"Given a character count and an optional fill character, makes and returns a
new string COUNT long filled with the fill character."
(declare (fixnum count))
(if fill-char
(make-string count :element-type element-type :initial-element fill-char)

View file

@ -286,7 +286,6 @@ SYSCALL-FORM. Repeat evaluation of SYSCALL-FORM if it is interrupted."
(defun unix-read (fd buf len)
(declare (type unix-fd fd)
(type (unsigned-byte 32) len))
(int-syscall ("read" int (* char) int) fd buf len))
;;; UNIX-WRITE accepts a file descriptor, a buffer, an offset, and the
@ -300,6 +299,10 @@ SYSCALL-FORM. Repeat evaluation of SYSCALL-FORM if it is interrupted."
fd
(with-alien ((ptr (* char) (etypecase buf
((simple-array * (*))
;; This SAP-taking is
;; safe as BUF remains
;; either in a register
;; or on stack.
(vector-sap buf))
(system-area-pointer
buf))))
@ -1004,7 +1007,8 @@ SYSCALL-FORM. Repeat evaluation of SYSCALL-FORM if it is interrupted."
c-sec 0
c-msec 0))
;; If two threads call this at the same time, we're still safe, I believe,
;; as long as NOW is updated before either of C-MSEC or C-SEC. --NS
;; as long as NOW is updated before either of C-MSEC or C-SEC. Same applies
;; to interrupts. --NS
(defun get-internal-real-time ()
(multiple-value-bind (sec msec) (internal-real-time-values)
(unless (and (= msec c-msec) (= sec c-sec))

View file

@ -17,4 +17,4 @@
;;; checkins which aren't released. (And occasionally for internal
;;; versions, especially for internal versions off the main CVS
;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)
"1.0.4.105"
"1.0.4.106"