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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2017, 2019, 2020 Ludovic Courtès <ludo@gnu.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 build download-nar)
#:use-module (guix build download)
#:use-module ((guix serialization) #:hide (dump-port*))
#:autoload (zlib) (call-with-gzip-input-port)
#:use-module (guix progress)
#:use-module (web uri)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
#:use-module (ice-9 format)
#:use-module (ice-9 match)
#:export (download-nar))
;;; Commentary:
;;;
;;; Download a normalized archive or "nar", similar to what 'guix substitute'
;;; does. The intent here is to use substitute servers as content-addressed
;;; mirrors of VCS checkouts. This is mostly useful for users who have
;;; disabled substitutes.
;;;
;;; Code:
(define (urls-for-item item)
"Return the fallback nar URL for ITEM--e.g.,
\"/gnu/store/cabbag3…-foo-1.2-checkout\"."
;; Here we hard-code nar URLs without checking narinfos. That's probably OK
;; though. Use berlin.guix.gnu.org instead of its ci.guix.gnu.org front end to
;; avoid sending these requests to CDN providers without user consent.
;; TODO: Use HTTPS? The downside is the extra dependency.
(let ((bases '("http://berlin.guix.gnu.org"))
(item (basename item)))
(append (map (cut string-append <> "/nar/gzip/" item) bases)
(map (cut string-append <> "/nar/" item) bases))))
(define (restore-gzipped-nar port item size)
"Restore the gzipped nar read from PORT, of SIZE bytes (compressed), to
ITEM."
;; Since PORT is typically a non-file port (for instance because 'http-get'
;; returns a delimited port), create a child process so we're back to a file
;; port that can be passed to 'call-with-gzip-input-port'.
(match (pipe)
((input . output)
(match (primitive-fork)
(0
(dynamic-wind
(const #t)
(lambda ()
(close-port output)
(close-port port)
(catch #t
(lambda ()
(call-with-gzip-input-port input
(cut restore-file <> item)))
(lambda (key . args)
(print-exception (current-error-port)
(stack-ref (make-stack #t) 1)
key args)
(primitive-exit 1))))
(lambda ()
(primitive-exit 0))))
(child
(close-port input)
(dump-port* port output
#:reporter (progress-reporter/file item size
#:abbreviation
store-path-abbreviation))
(close-port output)
(newline)
(match (waitpid child)
((_ . status)
(unless (zero? status)
(error "nar decompression failed" status)))))))))
(define (download-nar item)
"Download and extract the normalized archive for ITEM. Return #t on
success, #f otherwise."
;; Let progress reports go through.
(setvbuf (current-error-port) 'none)
(setvbuf (current-output-port) 'none)
(let loop ((urls (urls-for-item item)))
(match urls
((url rest ...)
(format #t "Trying content-addressed mirror at ~a...~%"
(uri-host (string->uri url)))
(let-values (((port size)
(catch #t
(lambda ()
(http-fetch (string->uri url)))
(lambda args
(values #f #f)))))
(if (not port)
(loop rest)
(begin
(if size
(format #t "Downloading from ~a (~,2h MiB)...~%" url
(/ size (expt 2 20.)))
(format #t "Downloading from ~a...~%" url))
(if (string-contains url "/gzip")
(restore-gzipped-nar port item size)
(begin
;; FIXME: Add progress report.
(restore-file port item)
(close-port port)))
#t))))
(()
#f))))
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