cd4027fa47
* guix/nar.scm (&nar-invalid-hash-error, &nar-signature-error): New
condition types.
(&nar-error): Add 'file' and 'port' fields.
(&nar-read-error): Remove 'port' and 'file' fields.
(lock-store-file, unlock-store-file, finalize-store-file,
temporary-store-directory, restore-file-set): New procedures.
* tests/nar.scm (%seed): New variable.
(random-text): New procedure.
("restore-file-set (signed, valid)", "restore-file-set (missing
signature)", "restore-file-set (corrupt)"): New tests.
* po/Makevars (XGETTEXT_OPTIONS): Add '--keyword=message'.nar fixes
* po/POTFILES.in: Add guix/nar.scm.
456 lines
17 KiB
Scheme
456 lines
17 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2012, 2013, 2014 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 nar)
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#:use-module (guix utils)
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#:use-module (guix serialization)
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#:use-module ((guix build utils)
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#:select (delete-file-recursively with-directory-excursion))
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#:use-module (guix store)
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#:use-module (guix ui) ; for '_'
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#:use-module (guix hash)
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#:use-module (guix pki)
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#:use-module (guix pk-crypto)
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#:use-module (rnrs bytevectors)
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#:use-module (rnrs io ports)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-11)
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#:use-module (srfi srfi-26)
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#:use-module (srfi srfi-34)
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#:use-module (srfi srfi-35)
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#:use-module (ice-9 ftw)
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#:use-module (ice-9 match)
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#:export (nar-error?
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nar-error-port
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nar-error-file
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nar-read-error?
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nar-read-error-token
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nar-invalid-hash-error?
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nar-invalid-hash-error-expected
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nar-invalid-hash-error-actual
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nar-signature-error?
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nar-signature-error-signature
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write-file
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restore-file
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restore-file-set))
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;;; Comment:
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;;;
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;;; Read and write Nix archives, aka. ‘nar’.
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;;;
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;;; Code:
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(define-condition-type &nar-error &error ; XXX: inherit from &nix-error ?
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nar-error?
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(file nar-error-file) ; file we were restoring, or #f
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(port nar-error-port)) ; port from which we read
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(define-condition-type &nar-read-error &nar-error
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nar-read-error?
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(token nar-read-error-token)) ; faulty token, or #f
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(define-condition-type &nar-signature-error &nar-error
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nar-signature-error?
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(signature nar-signature-error-signature)) ; faulty signature or #f
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(define-condition-type &nar-invalid-hash-error &nar-signature-error
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nar-invalid-hash-error?
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(expected nar-invalid-hash-error-expected) ; expected hash (a bytevector)
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(actual nar-invalid-hash-error-actual)) ; actual hash
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(define (dump in out size)
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"Copy SIZE bytes from IN to OUT."
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(define buf-size 65536)
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(define buf (make-bytevector buf-size))
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(let loop ((left size))
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(if (<= left 0)
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0
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(let ((read (get-bytevector-n! in buf 0 (min left buf-size))))
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(if (eof-object? read)
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left
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(begin
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(put-bytevector out buf 0 read)
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(loop (- left read))))))))
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(define (write-contents file p size)
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"Write SIZE bytes from FILE to output port P."
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(define (call-with-binary-input-file file proc)
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;; Open FILE as a binary file. This avoids scan-for-encoding, and thus
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;; avoids any initial buffering. Disable file name canonicalization to
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;; avoid stat'ing like crazy.
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(with-fluids ((%file-port-name-canonicalization #f))
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(let ((port (open-file file "rb")))
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(dynamic-wind
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(const #t)
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(cut proc port)
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(lambda ()
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(close-port port))))))
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(write-string "contents" p)
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(write-long-long size p)
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(call-with-binary-input-file file
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;; Use `sendfile' when available (Guile 2.0.8+).
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(if (compile-time-value (defined? 'sendfile))
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(cut sendfile p <> size 0)
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(cut dump <> p size)))
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(write-padding size p))
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(define (read-contents in out)
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"Read the contents of a file from the Nar at IN, write it to OUT, and return
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the size in bytes."
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(define executable?
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(match (read-string in)
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("contents"
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#f)
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("executable"
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(match (list (read-string in) (read-string in))
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(("" "contents") #t)
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(x (raise
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(condition (&message
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(message "unexpected executable file marker"))
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(&nar-read-error (port in)
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(file #f)
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(token x))))))
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#t)
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(x
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(raise
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(condition (&message (message "unsupported nar file type"))
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(&nar-read-error (port in) (file #f) (token x)))))))
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(let ((size (read-long-long in)))
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;; Note: `sendfile' cannot be used here because of port buffering on IN.
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(dump in out size)
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(when executable?
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(chmod out #o755))
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(let ((m (modulo size 8)))
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(unless (zero? m)
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(get-bytevector-n in (- 8 m))))
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size))
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(define %archive-version-1
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;; Magic cookie for Nix archives.
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"nix-archive-1")
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(define (write-file file port)
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"Write the contents of FILE to PORT in Nar format, recursing into
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sub-directories of FILE as needed."
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(define p port)
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(write-string %archive-version-1 p)
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(let dump ((f file))
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(let ((s (lstat f)))
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(write-string "(" p)
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(case (stat:type s)
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((regular)
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(write-string "type" p)
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(write-string "regular" p)
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(if (not (zero? (logand (stat:mode s) #o100)))
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(begin
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(write-string "executable" p)
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(write-string "" p)))
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(write-contents f p (stat:size s)))
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((directory)
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(write-string "type" p)
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(write-string "directory" p)
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(let ((entries (remove (cut member <> '("." ".."))
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(scandir f))))
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(for-each (lambda (e)
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(let ((f (string-append f "/" e)))
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(write-string "entry" p)
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(write-string "(" p)
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(write-string "name" p)
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(write-string e p)
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(write-string "node" p)
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(dump f)
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(write-string ")" p)))
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entries)))
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((symlink)
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(write-string "type" p)
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(write-string "symlink" p)
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(write-string "target" p)
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(write-string (readlink f) p))
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(else
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(raise (condition (&message (message "ENOSYS"))
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(&nar-error)))))
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(write-string ")" p))))
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(define (restore-file port file)
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"Read a file (possibly a directory structure) in Nar format from PORT.
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Restore it as FILE."
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(let ((signature (read-string port)))
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(unless (equal? signature %archive-version-1)
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(raise
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(condition (&message (message "invalid nar signature"))
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(&nar-read-error (port port)
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(token signature)
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(file #f))))))
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(let restore ((file file))
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(define (read-eof-marker)
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(match (read-string port)
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(")" #t)
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(x (raise
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(condition
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(&message (message "invalid nar end-of-file marker"))
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(&nar-read-error (port port) (file file) (token x)))))))
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(match (list (read-string port) (read-string port) (read-string port))
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(("(" "type" "regular")
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(call-with-output-file file (cut read-contents port <>))
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(read-eof-marker))
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(("(" "type" "symlink")
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(match (list (read-string port) (read-string port))
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(("target" target)
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(symlink target file)
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(read-eof-marker))
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(x (raise
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(condition
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(&message (message "invalid symlink tokens"))
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(&nar-read-error (port port) (file file) (token x)))))))
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(("(" "type" "directory")
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(let ((dir file))
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(mkdir dir)
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(let loop ((prefix (read-string port)))
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(match prefix
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("entry"
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(match (list (read-string port)
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(read-string port) (read-string port)
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(read-string port))
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(("(" "name" file "node")
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(restore (string-append dir "/" file))
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(match (read-string port)
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(")" #t)
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(x
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(raise
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(condition
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(&message
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(message "unexpected directory entry termination"))
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(&nar-read-error (port port)
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(file file)
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(token x))))))
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(loop (read-string port)))))
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(")" #t) ; done with DIR
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(x
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(raise
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(condition
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(&message (message "unexpected directory inter-entry marker"))
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(&nar-read-error (port port) (file file) (token x)))))))))
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(x
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(raise
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(condition
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(&message (message "unsupported nar entry type"))
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(&nar-read-error (port port) (file file) (token x))))))))
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;;;
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;;; Restoring a file set into the store.
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;;;
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;; The code below accesses the store directly and is meant to be run from
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;; "build hooks", which cannot invoke the daemon's 'import-paths' RPC since
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;; (1) the locks on the files to be restored as already held, and (2) the
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;; $NIX_HELD_LOCKS hackish environment variable cannot be set.
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;;
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;; So we're really duplicating that functionality of the daemon (well, until
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;; most of the daemon is in Scheme :-)). But note that we do use a couple of
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;; RPCs for functionality not available otherwise, like 'valid-path?'.
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(define (lock-store-file file)
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"Acquire exclusive access to FILE, a store file."
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(call-with-output-file (string-append file ".lock")
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(cut fcntl-flock <> 'write-lock)))
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(define (unlock-store-file file)
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"Release access to FILE."
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(call-with-input-file (string-append file ".lock")
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(cut fcntl-flock <> 'unlock)))
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(define* (finalize-store-file source target
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#:key (references '()) deriver (lock? #t))
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"Rename SOURCE to TARGET and register TARGET as a valid store item, with
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REFERENCES and DERIVER. When LOCK? is true, acquire exclusive locks on TARGET
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before attempting to register it; otherwise, assume TARGET's locks are already
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held."
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;; XXX: Currently we have to call out to the daemon to check whether TARGET
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;; is valid.
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(with-store store
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(unless (valid-path? store target)
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(when lock?
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(lock-store-file target))
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(unless (valid-path? store target)
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;; If FILE already exists, delete it (it's invalid anyway.)
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(when (file-exists? target)
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(delete-file-recursively target))
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;; Install the new TARGET.
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(rename-file source target)
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;; Register TARGET. As a side effect, it resets the timestamps of all
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;; its files, recursively. However, it doesn't attempt to deduplicate
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;; its files like 'importPaths' does (FIXME).
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(register-path target
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#:references references
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#:deriver deriver))
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(when lock?
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(unlock-store-file target)))))
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(define (temporary-store-directory)
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"Return the file name of a temporary directory created in the store that is
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protected from garbage collection."
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(let* ((template (string-append (%store-prefix) "/guix-XXXXXX"))
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(port (mkstemp! template)))
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(close-port port)
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(with-store store
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(add-temp-root store template))
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;; There's a small window during which the GC could delete the file. Try
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;; again if that happens.
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(if (file-exists? template)
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(begin
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;; It's up to the caller to create that file or directory.
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(delete-file template)
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template)
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(temporary-store-directory))))
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(define* (restore-file-set port
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#:key (verify-signature? #t) (lock? #t)
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(log-port (current-error-port)))
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"Restore the file set read from PORT to the store. The format of the data
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on PORT must be as created by 'export-paths'---i.e., a series of Nar-formatted
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archives with interspersed meta-data joining them together, possibly with a
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digital signature at the end. Log progress to LOG-PORT. Return the list of
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files restored.
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When LOCK? is #f, assume locks for the files to be restored are already held.
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This is the case when the daemon calls a build hook.
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Note that this procedure accesses the store directly, so it's only meant to be
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used by the daemon's build hooks since they cannot call back to the daemon
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while the locks are held."
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(define %export-magic
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;; Number used to identify genuine file set archives.
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#x4558494e)
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(define port*
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;; Keep that one around, for error conditions.
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port)
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(define (assert-valid-signature signature hash file)
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;; Bail out if SIGNATURE, an sexp, doesn't match HASH, a bytevector
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;; containing the expected hash for FILE.
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(let* ((signature (catch 'gcry-error
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(lambda ()
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(string->canonical-sexp signature))
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(lambda (err . _)
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(raise (condition
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(&message
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(message "signature is not a valid \
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s-expression"))
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(&nar-signature-error
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(file file)
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(signature signature) (port port)))))))
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(subject (signature-subject signature))
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(data (signature-signed-data signature)))
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(if (and data subject)
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(if (authorized-key? subject)
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(if (equal? (hash-data->bytevector data) hash)
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(unless (valid-signature? signature)
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(raise (condition
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(&message (message "invalid signature"))
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(&nar-signature-error
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(file file) (signature signature) (port port)))))
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(raise (condition (&message (message "invalid hash"))
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(&nar-invalid-hash-error
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(port port) (file file)
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(signature signature)
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(expected (hash-data->bytevector data))
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(actual hash)))))
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(raise (condition (&message (message "unauthorized public key"))
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(&nar-signature-error
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(signature signature) (file file) (port port)))))
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(raise (condition
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(&message (message "corrupt signature data"))
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(&nar-signature-error
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(signature signature) (file file) (port port)))))))
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(let loop ((n (read-long-long port))
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(files '()))
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(case n
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((0)
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(reverse files))
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((1)
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(let-values (((port get-hash)
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(open-sha256-input-port port)))
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(let ((temp (temporary-store-directory)))
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(restore-file port temp)
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(let ((magic (read-int port)))
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(unless (= magic %export-magic)
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(raise (condition
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(&message (message "corrupt file set archive"))
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(&nar-read-error
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(port port*) (file #f) (token #f))))))
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(let ((file (read-store-path port))
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(refs (read-store-path-list port))
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(deriver (read-string port))
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(hash (get-hash))
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(has-sig? (= 1 (read-int port))))
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(format log-port
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(_ "importing file or directory '~a'...~%")
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file)
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(let ((sig (and has-sig? (read-string port))))
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(when verify-signature?
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(if sig
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(begin
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(assert-valid-signature sig hash file)
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(format log-port
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(_ "found valid signature for '~a'~%")
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file)
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(finalize-store-file temp file
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#:references refs
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#:deriver deriver
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#:lock? lock?)
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(loop (read-long-long port)
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(cons file files)))
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(raise (condition
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(&message (message "imported file lacks \
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a signature"))
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(&nar-signature-error
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(port port*) (file file) (signature #f)))))))))))
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(else
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;; Neither 0 nor 1.
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(raise (condition
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(&message (message "invalid inter-file archive mark"))
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(&nar-read-error
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(port port) (file #f) (token #f))))))))
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;;; nar.scm ends here
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