467 lines
16 KiB
Scheme
467 lines
16 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 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 serialization)
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#:use-module (guix combinators)
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#:use-module (rnrs bytevectors)
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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 binary-ports)
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#:use-module ((ice-9 rdelim) #:prefix rdelim:)
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#:use-module (ice-9 match)
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#:use-module (ice-9 ftw)
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#:export (write-int read-int
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write-long-long read-long-long
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write-padding
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write-bytevector write-string
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read-string read-latin1-string read-maybe-utf8-string
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write-string-list read-string-list
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write-string-pairs
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write-store-path read-store-path
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write-store-path-list read-store-path-list
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&nar-error
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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?
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nar-read-error-token
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write-file
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write-file-tree
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restore-file))
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;;; Comment:
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;;;
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;;; Serialization procedures used by the RPCs and the Nar format. This module
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;;; is for internal consumption.
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;;;
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;;; Code:
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;; Similar to serialize.cc in Nix.
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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 currently-restored-file
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;; Name of the file being restored. Used internally for error reporting.
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(make-parameter #f))
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(define (get-bytevector-n* port count)
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(let ((bv (get-bytevector-n port count)))
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(when (or (eof-object? bv)
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(< (bytevector-length bv) count))
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(raise (condition (&nar-error
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(file (currently-restored-file))
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(port port)))))
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bv))
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(define (write-int n p)
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(let ((b (make-bytevector 8 0)))
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(bytevector-u32-set! b 0 n (endianness little))
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(put-bytevector p b)))
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(define (read-int p)
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(let ((b (get-bytevector-n* p 8)))
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(bytevector-u32-ref b 0 (endianness little))))
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(define (write-long-long n p)
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(let ((b (make-bytevector 8 0)))
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(bytevector-u64-set! b 0 n (endianness little))
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(put-bytevector p b)))
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(define (read-long-long p)
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(let ((b (get-bytevector-n* p 8)))
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(bytevector-u64-ref b 0 (endianness little))))
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(define write-padding
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(let ((zero (make-bytevector 8 0)))
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(lambda (n p)
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(let ((m (modulo n 8)))
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(or (zero? m)
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(put-bytevector p zero 0 (- 8 m)))))))
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(define* (write-bytevector s p
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#:optional (l (bytevector-length s)))
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(let* ((m (modulo l 8))
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(b (make-bytevector (+ 8 l (if (zero? m) 0 (- 8 m))))))
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(bytevector-u32-set! b 0 l (endianness little))
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(bytevector-copy! s 0 b 8 l)
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(put-bytevector p b)))
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(define (write-string s p)
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(write-bytevector (string->utf8 s) p))
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(define (read-byte-string p)
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(let* ((len (read-int p))
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(m (modulo len 8))
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(bv (get-bytevector-n* p len)))
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(or (zero? m)
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(get-bytevector-n* p (- 8 m)))
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bv))
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(define (read-string p)
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(utf8->string (read-byte-string p)))
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(define (read-latin1-string p)
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"Read an ISO-8859-1 string from P."
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;; Note: do not use 'get-string-n' to work around Guile bug
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;; <http://bugs.gnu.org/19621>. See <http://bugs.gnu.org/19610> for
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;; a discussion.
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(let ((bv (read-byte-string p)))
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;; XXX: Rewrite using (ice-9 iconv).
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(list->string (map integer->char (bytevector->u8-list bv)))))
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(define (read-maybe-utf8-string p)
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"Read a serialized string from port P. Attempt to decode it as UTF-8 and
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substitute invalid byte sequences with question marks. This is a
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\"permissive\" UTF-8 decoder."
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;; XXX: We rely on the port's decoding mechanism to do permissive decoding
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;; and substitute invalid byte sequences with question marks, but this is
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;; not very efficient. Eventually Guile may provide a lightweight
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;; permissive UTF-8 decoder.
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(let* ((bv (read-byte-string p))
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(port (open-bytevector-input-port bv)))
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(set-port-encoding! port "UTF-8")
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(set-port-conversion-strategy! port 'substitute)
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(rdelim:read-string port)))
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(define (write-string-list l p)
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(write-int (length l) p)
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(for-each (cut write-string <> p) l))
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(define (write-string-pairs l p)
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(write-int (length l) p)
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(for-each (match-lambda
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((first . second)
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(write-string first p)
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(write-string second p)))
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l))
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(define (read-string-list p)
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(let ((len (read-int p)))
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(unfold (cut >= <> len)
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(lambda (i)
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(read-string p))
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1+
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0)))
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(define (write-store-path f p)
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(write-string f p)) ; TODO: assert path
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(define (read-store-path p)
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(read-string p)) ; TODO: assert path
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(define write-store-path-list write-string-list)
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(define read-store-path-list read-string-list)
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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 (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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(call-with-binary-input-file file
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(lambda (input)
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(write-contents-from-port input p size))))
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(define (write-contents-from-port input output size)
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"Write SIZE bytes from port INPUT to port OUTPUT."
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(write-string "contents" output)
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(write-long-long size output)
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;; Use 'sendfile' when both OUTPUT and INPUT are file ports.
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(if (and (file-port? output) (file-port? input))
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(sendfile output input size 0)
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(dump input output size))
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(write-padding size output))
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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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#:key (select? (const #t)))
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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. For each directory entry, call (SELECT?
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FILE STAT), where FILE is the entry's absolute file name and STAT is the
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result of 'lstat'; exclude entries for which SELECT? does not return true."
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(write-file-tree file port
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#:file-type+size
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(lambda (file)
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(let* ((stat (lstat file))
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(size (stat:size stat)))
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(case (stat:type stat)
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((directory)
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(values 'directory size))
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((regular)
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(values (if (zero? (logand (stat:mode stat)
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#o100))
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'regular
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'executable)
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size))
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(else
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(values (stat:type stat) size))))) ;bah!
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#:file-port (cut open-file <> "r0b")
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#:symlink-target readlink
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#:directory-entries
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(lambda (directory)
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;; 'scandir' defaults to 'string-locale<?' to sort files,
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;; but this happens to be case-insensitive (at least in
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;; 'en_US' locale on libc 2.18.) Conversely, we want
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;; files to be sorted in a case-sensitive fashion.
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(define basenames
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(scandir directory (negate (cut member <> '("." "..")))
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string<?))
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(filter-map (lambda (base)
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(let ((file (string-append directory
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"/" base)))
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(and (select? file (lstat file))
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base)))
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basenames))
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;; The 'scandir' call above gives us filtered and sorted
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;; entries, so no post-processing is needed.
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#:postprocess-entries identity))
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(define (filter/sort-directory-entries lst)
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"Remove dot and dot-dot entries from LST, and sort it in lexicographical
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order."
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(delete-duplicates
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(sort (remove (cute member <> '("." "..")) lst)
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string<?)
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string=?))
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(define* (write-file-tree file port
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#:key
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file-type+size
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file-port
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symlink-target
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directory-entries
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(postprocess-entries filter/sort-directory-entries))
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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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This procedure does not make any file-system I/O calls. Instead, it calls the
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user-provided FILE-TYPE+SIZE, FILE-PORT, SYMLINK-TARGET, and DIRECTORY-ENTRIES
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procedures, which roughly correspond to 'lstat', 'readlink', and 'scandir'.
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POSTPROCESS-ENTRIES ensures that directory entries are valid; leave it as-is
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unless you know that DIRECTORY-ENTRIES provide filtered and sorted entries, in
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which case you can use 'identity'."
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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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(define-values (type size)
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(file-type+size f))
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(write-string "(" p)
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(case type
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((regular executable)
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(write-string "type" p)
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(write-string "regular" p)
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(when (eq? 'executable type)
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(write-string "executable" p)
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(write-string "" p))
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(let ((input (file-port f)))
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(dynamic-wind
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(const #t)
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(lambda ()
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(write-contents-from-port input p size))
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(lambda ()
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(close-port input)))))
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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 (postprocess-entries (directory-entries 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 (symlink-target f) p))
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(else
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(raise (condition (&message (message "unsupported file type"))
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(&nar-error (file f) (port port))))))
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(write-string ")" p)))
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(define port-conversion-strategy
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(fluid->parameter %default-port-conversion-strategy))
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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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(parameterize ((currently-restored-file file)
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;; Error out if we can convert file names to the current
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;; locale. (XXX: We'd prefer UTF-8 encoding for file names
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;; regardless of the locale, but that's what Guile gives us
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;; so far.)
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(port-conversion-strategy 'error))
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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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(currently-restored-file file)
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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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;;; Local Variables:
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;;; eval: (put 'call-with-binary-input-file 'scheme-indent-function 1)
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;;; End:
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;;; serialization.scm ends here
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