scsh-0.5/scsh/newports.scm

404 lines
13 KiB
Scheme

;;; A Unix file port system to completely replace S48 file ports.
;;; We use S48 extensible ports.
;;; Copyright (c) 1993 by Olin Shivers.
(define-record fdport-data
fd ; Unix file descriptor - integer.
(closed? #f) ; Is port closed.
(peek-char #f)
(revealed 0) ; REVEALED & OLD-REVEALED are for keeping
(old-revealed 0)) ; track of whether the FD value has escaped.
;;; We could flush the PEEK-CHAR field and use stdio ungetc(), but it
;;; is only guaranteed for buffered streams. Too bad...
(define (make-input-fdport fd)
(make-extensible-input-port (make-fdport-data fd)
input-fdport-methods))
(define (make-output-fdport fd)
(make-extensible-output-port (make-fdport-data fd)
output-fdport-methods))
(define (fdport? x)
(cond ((or (and (extensible-input-port? x)
(extensible-input-port-local-data x))
(and (extensible-output-port? x)
(extensible-output-port-local-data x)))
=> (lambda (d) (fdport-data? d)))
(else #f)))
;;; Basic methods
;;; -------------
(define fdport-null-method (lambda (x) x #f))
;;; CLOSE-FDPORT*, FLUSH-FDPORT* defined in syscalls.scm.
;;; (So you must load that file before loading this file.)
(define (fdport*-read-char data)
(check-arg open-fdport-data? data fdport*-read-char)
(cond ((fdport-data:peek-char data) =>
(lambda (char)
(set-fdport-data:peek-char data #f)
char))
(else
(or (%fdport*-read-char data) eof-object))))
(define (fdport*-peek-char data)
(check-arg open-fdport-data? data fdport*-peek-char)
(or (fdport-data:peek-char data)
(cond ((%fdport*-read-char data) =>
(lambda (char)
(set-fdport-data:peek-char data char)
char))
(else eof-object))))
(define (fdport*-char-ready? data)
(check-arg open-fdport-data? data fdport*-char-ready?)
(or (fdport-data:peek-char data)
(%fdport*-char-ready? data)))
(define (fdport*-write-char data char)
(check-arg open-fdport-data? data fdport*-write-char)
(if (not (fdport-data:closed? data))
(%fdport*-write-char data char)))
(define (fdport*-write-string data string)
(check-arg open-fdport-data? data fdport*-write-string)
(generic-write-string string 0 (string-length string) ; from rw.scm
write-fdport*-substring/errno data))
(define input-fdport-methods
(make-input-port-methods close-fdport*
fdport*-read-char
fdport*-peek-char
fdport*-char-ready?
fdport-null-method ; current-column
fdport-null-method)) ; current-row
(define output-fdport-methods
(make-output-port-methods close-fdport*
fdport*-write-char
fdport*-write-string
flush-fdport* ; force-output
fdport-null-method ; fresh-line
fdport-null-method ; current-column
fdport-null-method)) ; current-row
(define (fdport-data port)
(let ((d ((cond ((extensible-input-port? port)
extensible-input-port-local-data)
((extensible-output-port? port)
extensible-output-port-local-data)
(else (error "Illegal value" port)))
port)))
(if (and d (fdport-data? d)) d
(error "fport closed" port))))
(define (%fdport-seek/errno port offset whence)
(%fdport*-seek/errno (fdport-data port) offset whence))
(define (%fdport-tell/errno port)
(%fdport*-tell/errno (fdport-data port)))
(define (%fdport-set-buffering/errno port policy size)
(%fdport*-set-buffering/errno (fdport-data port) policy size))
(define (set-port-buffering port policy . maybe-size)
(let* ((size (if (pair? maybe-size)
(if (pair? (cdr maybe-size))
(error "Too many arguments." set-port-buffering)
(check-arg (lambda (s) (and (integer? s)
(<= 0 s)))
(car maybe-size)
set-port-buffering))
-1))
(policy (if (zero? size) bufpol/none policy))
(err (%fdport-set-buffering/errno port policy size)))
(if err (errno-error err set-port-buffering port policy size))))
;;; Open & Close
;;; ------------
(define (open-file fname flags . maybe-mode)
(let* ((fd (apply open-fdes fname flags maybe-mode))
(access (bitwise-and flags open/access-mask))
(port ((if (or (= access open/read) (= access open/read+write))
make-input-fdport
make-output-fdport)
fd)))
(%install-port fd port)
port))
(define (open-input-file fname . maybe-flags)
(let ((flags (optional-arg maybe-flags 0)))
(open-file fname (deposit-bit-field flags open/access-mask open/read))))
(define (open-output-file fname . rest)
(let* ((flags (if (pair? rest) (car rest)
(bitwise-ior open/create open/truncate))) ; default
(maybe-mode (if (null? rest) '() (cdr rest)))
(flags (deposit-bit-field flags open/access-mask open/write)))
(apply open-file fname flags maybe-mode)))
;;; All these revealed-count-hacking procs have atomicity problems.
;;; They need to run uninterrupted.
(define (increment-revealed-count port delta)
(let* ((data (extensible-port-local-data port))
(count (fdport-data:revealed data)))
(set-fdport-data:revealed data (+ count delta))))
(define (release-port-handle port)
(check-arg fdport? port port->fdes)
(let* ((data (extensible-port-local-data port))
(rev (fdport-data:revealed data)))
(if (zero? rev)
(set-fdport-data:old-revealed data
(- (fdport-data:old-revealed data) 1))
(set-fdport-data:revealed data (- rev 1)))))
(define (port-revealed port)
(let ((count (fdport-data:revealed
(extensible-port-local-data
(check-arg fdport? port port-revealed)))))
(and (not (zero? count)) count)))
(define (fdes->port fd port-maker) ; local proc.
(let ((port (or (%maybe-fdes->port fd)
(let ((port (port-maker fd)))
(%install-port fd port)
port))))
(increment-revealed-count port 1)
port))
(define (fdes->inport fd) (fdes->port fd make-input-fdport))
(define (fdes->outport fd) (fdes->port fd make-output-fdport))
(define (port->fdes port)
(check-arg open-fdport? port port->fdes)
(let ((data (extensible-port-local-data port)))
(increment-revealed-count port 1)
(fdport-data:fd data)))
(define (call/fdes fd/port proc)
(cond ((integer? fd/port)
(proc fd/port))
((fdport? fd/port)
(let ((port fd/port))
(dynamic-wind
(lambda ()
(if (not port) (error "Can't throw back into call/fdes.")))
(lambda () (proc (port->fdes port)))
(lambda ()
(release-port-handle port)
(set! port #f)))))
(else (error "Not a file descriptor or fdport." fd/port))))
;;; Random predicates and arg checkers
;;; ----------------------------------
(define (open-fdport-data? x)
(and (fdport-data? x)
(not (fdport-data:closed? x))))
(define (open-fdport? x)
(cond ((or (and (extensible-input-port? x)
(extensible-input-port-local-data x))
(and (extensible-output-port? x)
(extensible-output-port-local-data x)))
=> (lambda (d) (and (fdport-data? d) (not (fdport-data:closed? d)))))
(else #f)))
(define (extensible-port-local-data xport)
((if (extensible-input-port? xport)
extensible-input-port-local-data
extensible-output-port-local-data)
xport))
(define (fdport-open? port)
(check-arg fdport? port fdport-open?)
(not (fdport-data:closed? (extensible-port-local-data port))))
;;; Initialise the system
;;; ---------------------
(define old-inport #f) ; Just because.
(define old-outport #f)
(define old-errport #f)
(define (init-fdports!)
(%init-fdports!)
(if (not (fdport? (current-input-port)))
(set! old-inport (current-input-port)))
(if (not (fdport? (current-output-port)))
(set! old-outport (current-output-port)))
(if (not (fdport? (error-output-port)))
(set! old-errport (error-output-port)))
(let ((iport (fdes->inport 0)))
(set-port-buffering iport bufpol/none) ; Stdin is unbuffered.
(set-fluid! $current-input-port iport)
(set-fluid! $current-output-port (fdes->outport 1))
(set-fluid! $error-output-port (fdes->outport 2))))
;;; Generic port operations
;;; -----------------------
;;; (close-after port f)
;;; Apply F to PORT. When F returns, close PORT, then return F's result.
;;; Does nothing special if you throw out or throw in.
(define (close-after port f)
(receive vals (f port)
(close port)
(apply values vals)))
(define (close port/fd)
((cond ((integer? port/fd) close-fdes)
((output-port? port/fd) close-output-port)
((input-port? port/fd) close-input-port)
(else (error "Not file-descriptor or port" port/fd))) port/fd))
;;; If this fd has an associated input or output port,
;;; move it to a new fd, freeing this one up.
;;; Unitialized fdport in table is set to 0, does this mean
(define (evict-ports fd)
(cond ((%maybe-fdes->port fd) => ; Shouldn't bump the revealed count.
(lambda (port)
(%move-fdport (%dup fd) port 0)))))
(define (close-fdes fd)
(evict-ports fd)
(%close-fdes fd))
;;; Extend R4RS i/o ops to handle file descriptors.
;;; -----------------------------------------------
(define s48-char-ready? (structure-ref scheme char-ready?))
(define s48-read-char (structure-ref scheme read-char))
(define-simple-syntax
(define-r4rs-input (name arg ...) stream s48name body ...)
(define (name arg ... . maybe-i/o)
(let ((stream (optional-arg maybe-i/o (current-input-port))))
(cond ((input-port? stream) (s48name arg ... stream))
((integer? stream) body ...)
(else (error "Not a port or file descriptor" stream))))))
(define-r4rs-input (char-ready?) input s48-char-ready?
(%char-ready-fdes? input))
(define-r4rs-input (read-char) input s48-read-char
(read-fdes-char input))
;structure refs changed to get reference from scheme -dalbertz
(define s48-display (structure-ref scheme display))
(define s48-newline (structure-ref scheme newline))
(define s48-write (structure-ref scheme write))
(define s48-write-char (structure-ref scheme write-char))
(define s48-format (structure-ref formats format))
(define s48-force-output (structure-ref ports force-output))
(define-simple-syntax
(define-r4rs-output (name arg ...) stream s48name body ...)
(define (name arg ... . maybe-i/o)
(let ((stream (optional-arg maybe-i/o (current-output-port))))
(cond ((output-port? stream) (s48name arg ... stream))
((integer? stream) body ...)
(else (error "Not a port or file descriptor" stream))))))
;;; This one depends upon S48's string ports.
(define-r4rs-output (display object) output s48-display
(let ((sp (make-string-output-port)))
(display object sp)
(write-string (string-output-port-output sp) output)))
(define-r4rs-output (newline) output s48-newline
(write-fdes-char #\newline output))
(define-r4rs-output (write object) output s48-write
(let ((sp (make-string-output-port)))
(write object sp)
(write-string (string-output-port-output sp) output)))
(define-r4rs-output (write-char char) output s48-write-char
(write-fdes-char char output))
;;; S48's force-output doesn't default to forcing (current-output-port).
(define-r4rs-output (force-output) output s48-force-output
(values)) ; Do nothing if applied to a file descriptor.
(define (format dest cstring . args)
(if (integer? dest)
(write-string (apply s48-format #f cstring args) dest)
(apply s48-format dest cstring args)))
;;; with-current-foo-port procs
;;; ---------------------------
(define (with-current-input-port* port thunk)
(let-fluid $current-input-port port thunk))
(define (with-current-output-port* port thunk)
(let-fluid $current-output-port port thunk))
(define (with-error-output-port* port thunk)
(let-fluid $error-output-port port thunk))
(define-simple-syntax (with-current-input-port port body ...)
(with-current-input-port* port (lambda () body ...)))
(define-simple-syntax (with-current-output-port port body ...)
(with-current-output-port* port (lambda () body ...)))
(define-simple-syntax (with-error-output-port port body ...)
(with-error-output-port* port (lambda () body ...)))
;;; call-with-foo-file with-foo-to-file
;;; -----------------------------------
;;; Copied straight from rts/port.scm, but re-defined in this module,
;;; closed over my versions of open-input-file and open-output-file.
(define (call-with-mumble-file open close)
(lambda (string proc)
(let ((port #f))
(dynamic-wind (lambda ()
(if port
(warn "throwing back into a call-with-...put-file"
string)
(set! port (open string))))
(lambda () (proc port))
(lambda ()
(if port
(close port)))))))
(define call-with-input-file
(call-with-mumble-file open-input-file close-input-port))
(define call-with-output-file
(call-with-mumble-file open-output-file close-output-port))
(define (with-input-from-file string thunk)
(call-with-input-file string
(lambda (port)
(let-fluid $current-input-port port thunk))))
(define (with-output-to-file string thunk)
(call-with-output-file string
(lambda (port)
(let-fluid $current-output-port port thunk))))