mes/guile/guix/shell-utils.scm

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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013 Andreas Enge <andreas@enge.fr>
;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix 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.
;;;
;;; GNU Guix 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 GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (guix shell-utils)
#:use-module (ice-9 match)
#:use-module (rnrs bytevectors)
#:use-module (rnrs io ports)
#:export (dump-port
mkdir-p
with-directory-excursion))
;;;
;;; Directories.
;;;
(define (mkdir-p dir)
"Create directory DIR and all its ancestors."
(define absolute?
(string-prefix? "/" dir))
(define not-slash
(char-set-complement (char-set #\/)))
(let loop ((components (string-tokenize dir not-slash))
(root (if absolute?
""
".")))
(match components
((head tail ...)
(let ((path (string-append root "/" head)))
(catch 'system-error
(lambda ()
(mkdir path)
(loop tail path))
(lambda args
(if (= EEXIST (system-error-errno args))
(loop tail path)
(apply throw args))))))
(() #t))))
(define-syntax-rule (with-directory-excursion dir body ...)
"Run BODY with DIR as the process's current directory."
(let ((init (getcwd)))
(dynamic-wind
(lambda ()
(chdir dir))
(lambda ()
body ...)
(lambda ()
(chdir init)))))
(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)))))