243 lines
8.3 KiB
Scheme
243 lines
8.3 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2012, 2013 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) #:select (with-directory-excursion))
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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-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-read-error?
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nar-read-error-file
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nar-read-error-port
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nar-read-error-token
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write-file
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restore-file))
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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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(define-condition-type &nar-read-error &nar-error
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nar-read-error?
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(port nar-read-error-port) ; port from which we read
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(file nar-read-error-file) ; file we were restoring, or #f
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(token nar-read-error-token)) ; faulty token, or #f
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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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;;; nar.scm ends here
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