125 lines
5.0 KiB
Scheme
125 lines
5.0 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2014, 2015 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (guix build graft)
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#:use-module (guix build utils)
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#:use-module (rnrs bytevectors)
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#:use-module (rnrs io ports)
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#:use-module (ice-9 match)
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#:use-module (ice-9 threads)
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#:export (replace-store-references
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rewrite-directory))
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;;; Commentary:
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;;;
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;;; This module supports "grafts". Grafting a directory means rewriting it,
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;;; with references to some specific items replaced by references to other
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;;; store items---the grafts.
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;;;
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;;; This method is used to provide fast security updates as only the leaves of
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;;; the dependency graph need to be grafted, even when the security updates
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;;; affect a core component such as Bash or libc. It is based on the idea of
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;;; 'replace-dependency' implemented by Shea Levy in Nixpkgs.
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;;;
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;;; Code:
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(define* (replace-store-references input output mapping
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#:optional (store (%store-directory)))
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"Read data from INPUT, replacing store references according to MAPPING, and
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writing the result to OUTPUT."
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(define pattern
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(let ((nix-base32-chars
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'(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9
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#\a #\b #\c #\d #\f #\g #\h #\i #\j #\k #\l #\m #\n
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#\p #\q #\r #\s #\v #\w #\x #\y #\z)))
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`(,@(map char-set (string->list store))
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,(char-set #\/)
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,@(make-list 32 (list->char-set nix-base32-chars))
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,(char-set #\-))))
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;; We cannot use `regexp-exec' here because it cannot deal with strings
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;; containing NUL characters, hence 'fold-port-matches'.
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(with-fluids ((%default-port-encoding #f))
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(when (file-port? input)
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(setvbuf input _IOFBF 65536))
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(when (file-port? output)
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(setvbuf output _IOFBF 65536))
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(let* ((len (+ 34 (string-length store)))
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(mapping (map (match-lambda
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((origin . replacement)
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(unless (string=? (string-drop origin len)
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(string-drop replacement len))
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(error "invalid replacement" origin replacement))
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(cons (string-take origin len)
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(string-take replacement len))))
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mapping)))
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(fold-port-matches (lambda (string result)
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(match (assoc-ref mapping string)
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(#f
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(put-bytevector output (string->utf8 string)))
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((= string->utf8 replacement)
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(put-bytevector output replacement)))
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#t)
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#f
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pattern
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input
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(lambda (char result) ;unmatched
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(put-u8 output (char->integer char))
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result)))))
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(define* (rewrite-directory directory output mapping
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#:optional (store (%store-directory)))
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"Copy DIRECTORY to OUTPUT, replacing strings according to MAPPING, a list of
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file name pairs."
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(define prefix-len
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(string-length directory))
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(define (destination file)
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(string-append output (string-drop file prefix-len)))
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(define (rewrite-leaf file)
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(let ((stat (lstat file))
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(dest (destination file)))
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(mkdir-p (dirname dest))
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(case (stat:type stat)
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((symlink)
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(let ((target (readlink file)))
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(symlink (call-with-output-string
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(lambda (output)
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(replace-store-references (open-input-string target)
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output mapping
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store)))
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dest)))
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((regular)
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(with-fluids ((%default-port-encoding #f))
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(call-with-input-file file
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(lambda (input)
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(call-with-output-file dest
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(lambda (output)
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(replace-store-references input output mapping
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store)
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(chmod output (stat:perms stat))))))))
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(else
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(error "unsupported file type" stat)))))
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(n-par-for-each (parallel-job-count)
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rewrite-leaf (find-files directory)))
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;;; graft.scm ends here
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