guile-gcrypt/gcrypt/utils.scm

;;; guile-gcrypt --- crypto tooling for guile
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of guile-gcrypt.
;;;
;;; guile-gcrypt is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or
;;; (at your option) any later version.
;;;
;;; guile-gcrypt is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with guile-gcrypt.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gcrypt utils)
  #:use-module (rnrs bytevectors)
  #:use-module (rnrs io ports)
  #:export (dump-port))

(define* (dump-port in out
                    #:key (buffer-size 16384)
                    (progress (lambda (t k) (k))))
  "Read as much data as possible from IN and write it to OUT, using chunks of
BUFFER-SIZE bytes.  Call PROGRESS at the beginning and after each successful
transfer of BUFFER-SIZE bytes or less, passing it the total number of bytes
transferred and the continuation of the transfer as a thunk."
  (define buffer
    (make-bytevector buffer-size))

  (define (loop total bytes)
    (or (eof-object? bytes)
        (let ((total (+ total bytes)))
          (put-bytevector out buffer 0 bytes)
          (progress total
                    (lambda ()
                      (loop total
                            (get-bytevector-n! in buffer 0 buffer-size)))))))

  ;; Make sure PROGRESS is called when we start so that it can measure
  ;; throughput.
  (progress 0
            (lambda ()
              (loop 0 (get-bytevector-n! in buffer 0 buffer-size)))))