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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016, 2017, 2018, 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 scripts perform-download)
#:use-module (guix ui)
#:use-module (guix scripts)
#:use-module (guix derivations)
#:use-module ((guix store) #:select (derivation-path? store-path?))
#:use-module (guix build download)
#:use-module (ice-9 match)
#:export (guix-perform-download))
;; This program is a helper for the daemon's 'download' built-in builder.
(define-syntax derivation-let
(syntax-rules ()
((_ drv ((id name) rest ...) body ...)
(let ((id (assoc-ref (derivation-builder-environment-vars drv)
name)))
(derivation-let drv (rest ...) body ...)))
((_ drv () body ...)
(begin body ...))))
(define %user-module
;; Module in which content-address mirror procedures are evaluated.
(let ((module (make-fresh-user-module)))
(module-use! module (resolve-interface '(guix base32)))
module))
(define* (perform-download drv #:optional output
#:key print-build-trace?)
"Perform the download described by DRV, a fixed-output derivation, to
OUTPUT.
Note: Unless OUTPUT is #f, we don't read the value of 'out' in DRV since the
actual output is different from that when we're doing a 'bmCheck' or
'bmRepair' build."
(derivation-let drv ((url "url")
(output* "out")
(executable "executable")
(mirrors "mirrors")
(content-addressed-mirrors "content-addressed-mirrors"))
(unless url
(leave (G_ "~a: missing URL~%") (derivation-file-name drv)))
(let* ((output (or output output*))
(url (call-with-input-string url read))
(drv-output (assoc-ref (derivation-outputs drv) "out"))
(algo (derivation-output-hash-algo drv-output))
(hash (derivation-output-hash drv-output)))
(unless (and algo hash)
(leave (G_ "~a is not a fixed-output derivation~%")
(derivation-file-name drv)))
;; We're invoked by the daemon, which gives us write access to OUTPUT.
(when (url-fetch url output
#:print-build-trace? print-build-trace?
#:mirrors (if mirrors
(call-with-input-file mirrors read)
'())
#:content-addressed-mirrors
(if content-addressed-mirrors
(call-with-input-file content-addressed-mirrors
(lambda (port)
(eval (read port) %user-module)))
'())
#:hashes `((,algo . ,hash))
;; Since DRV's output hash is known, X.509 certificate
;; validation is pointless.
#:verify-certificate? #f)
(when (and executable (string=? executable "1"))
(chmod output #o755))))))
(define (assert-low-privileges)
(when (zero? (getuid))
(leave (G_ "refusing to run with elevated privileges (UID ~a)~%")
(getuid))))
(define-command (guix-perform-download . args)
(category internal)
(synopsis "perform download described by fixed-output derivations")
;; This is an "out-of-band" download in that this code is executed directly
;; by the daemon and not explicitly described as an input of the derivation.
;; This allows us to sidestep bootstrapping problems, such as downloading
;; the source code of GnuTLS over HTTPS before we have built GnuTLS. See
;; <https://bugs.gnu.org/22774>.
(define print-build-trace?
(match (getenv "_NIX_OPTIONS")
(#f #f)
(str (string-contains str "print-extended-build-trace=1"))))
;; This program must be invoked by guix-daemon under an unprivileged UID to
;; prevent things downloading from 'file:///etc/shadow' or arbitrary code
;; execution via the content-addressed mirror procedures. (That means we
;; exclude users who did not pass '--build-users-group'.)
(with-error-handling
(match args
(((? derivation-path? drv) (? store-path? output))
(assert-low-privileges)
(perform-download (read-derivation-from-file drv)
output
#:print-build-trace? print-build-trace?))
(((? derivation-path? drv)) ;backward compatibility
(assert-low-privileges)
(perform-download (read-derivation-from-file drv)
#:print-build-trace? print-build-trace?))
(("--version")
(show-version-and-exit))
(x
(leave
(G_ "fixed-output derivation and output file name expected~%"))))))
;; Local Variables:
;; eval: (put 'derivation-let 'scheme-indent-function 2)
;; End:
;; perform-download.scm ends here
|
