guix/gnu/installer/utils.scm
Mathieu Othacehe 3ad8f7757c
installer: Add new utils.
* gnu/installer/utils.scm (nearest-exact-integer): New exported procedure,
(read-percentage): ditto,
(run-shell-command): ditto.
2019-01-17 14:04:22 +01:00

63 lines
2.2 KiB
Scheme

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com>
;;;
;;; 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 (gnu installer utils)
#:use-module (guix utils)
#:use-module (guix build utils)
#:use-module (ice-9 rdelim)
#:use-module (ice-9 regex)
#:use-module (ice-9 textual-ports)
#:export (read-lines
read-all
nearest-exact-integer
read-percentage
run-shell-command))
(define* (read-lines #:optional (port (current-input-port)))
"Read lines from PORT and return them as a list."
(let loop ((line (read-line port))
(lines '()))
(if (eof-object? line)
(reverse lines)
(loop (read-line port)
(cons line lines)))))
(define (read-all file)
"Return the content of the given FILE as a string."
(call-with-input-file file
get-string-all))
(define (nearest-exact-integer x)
"Given a real number X, return the nearest exact integer, with ties going to
the nearest exact even integer."
(inexact->exact (round x)))
(define (read-percentage percentage)
"Read PERCENTAGE string and return the corresponding percentage as a
number. If no percentage is found, return #f"
(let ((result (string-match "^([0-9]+)%$" percentage)))
(and result
(string->number (match:substring result 1)))))
(define (run-shell-command command)
(call-with-temporary-output-file
(lambda (file port)
(format port "~a~%" command)
;; (format port "exit~%")
(close port)
(invoke "bash" "--init-file" file))))