241 lines
8.0 KiB
Scheme
241 lines
8.0 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 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 cpio)
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#:use-module ((guix build utils) #:select (dump-port))
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#:use-module (srfi srfi-9)
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#:use-module (srfi srfi-11)
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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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#:export (cpio-header?
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make-cpio-header
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file->cpio-header
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write-cpio-header
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read-cpio-header
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write-cpio-archive))
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;;; Commentary:
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;;;
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;;; This module implements the cpio "new ASCII" format, bit-for-bit identical
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;;; to GNU cpio with the '-H newc' option.
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;;;
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;;; Code:
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;; Values for 'mode', OR'd together.
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(define C_IRUSR #o000400)
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(define C_IWUSR #o000200)
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(define C_IXUSR #o000100)
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(define C_IRGRP #o000040)
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(define C_IWGRP #o000020)
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(define C_IXGRP #o000010)
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(define C_IROTH #o000004)
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(define C_IWOTH #o000002)
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(define C_IXOTH #o000001)
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(define C_ISUID #o004000)
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(define C_ISGID #o002000)
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(define C_ISVTX #o001000)
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(define C_FMT #o170000) ;bit mask
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(define C_ISBLK #o060000)
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(define C_ISCHR #o020000)
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(define C_ISDIR #o040000)
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(define C_ISFIFO #o010000)
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(define C_ISSOCK #o0140000)
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(define C_ISLNK #o0120000)
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(define C_ISCTG #o0110000)
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(define C_ISREG #o0100000)
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(define MAGIC
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;; The "new" portable format with ASCII header, as produced by GNU cpio with
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;; '-H newc'.
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(string->number "070701" 16))
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(define (read-header-field size port)
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(string->number (get-string-n port size) 16))
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(define (write-header-field value size port)
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(put-bytevector port
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(string->utf8
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(string-pad (string-upcase (number->string value 16))
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size #\0))))
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(define-syntax define-pack
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(syntax-rules ()
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((_ type ctor pred write read (field-names field-sizes field-getters) ...)
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(begin
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(define-record-type type
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(ctor field-names ...)
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pred
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(field-names field-getters) ...)
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(define (read port)
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(set-port-encoding! port "ISO-8859-1")
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(ctor (read-header-field field-sizes port)
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...))
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(define (write obj port)
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(let* ((size (+ field-sizes ...)))
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(match obj
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(($ type field-names ...)
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(write-header-field field-names field-sizes port)
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...))))))))
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;; cpio header in "new ASCII" format, without checksum.
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(define-pack <cpio-header>
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%make-cpio-header cpio-header?
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write-cpio-header read-cpio-header
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(magic 6 cpio-header-magic)
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(ino 8 cpio-header-inode)
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(mode 8 cpio-header-mode)
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(uid 8 cpio-header-uid)
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(gid 8 cpio-header-gid)
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(nlink 8 cpio-header-nlink)
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(mtime 8 cpio-header-mtime)
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(file-size 8 cpio-header-file-size)
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(dev-maj 8 cpio-header-device-major)
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(dev-min 8 cpio-header-device-minor)
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(rdev-maj 8 cpio-header-rdevice-major)
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(rdev-min 8 cpio-header-rdevice-minor)
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(name-size 8 cpio-header-name-size)
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(checksum 8 cpio-header-checksum)) ;0 for "newc" format
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(define* (make-cpio-header #:key
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(inode 0)
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(mode (logior C_ISREG C_IRUSR))
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(uid 0) (gid 0)
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(nlink 1) (mtime 0) (size 0)
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(dev 0) (rdev 0) (name-size 0))
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"Return a new cpio file header."
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(let-values (((major minor) (device->major+minor dev))
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((rmajor rminor) (device->major+minor rdev)))
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(%make-cpio-header MAGIC
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inode mode uid gid
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nlink mtime
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(if (= C_ISDIR (logand mode C_FMT))
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0
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size)
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major minor rmajor rminor
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(+ name-size 1) ;include trailing zero
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0))) ;checksum
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(define (mode->type mode)
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"Given the number MODE, return a symbol representing the kind of file MODE
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denotes, similar to 'stat:type'."
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(let ((fmt (logand mode C_FMT)))
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(cond ((= C_ISREG fmt) 'regular)
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((= C_ISDIR fmt) 'directory)
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((= C_ISLNK fmt) 'symlink)
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(else
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(error "unsupported file type" mode)))))
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(define (device-number major minor) ;see <sys/sysmacros.h>
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"Return the device number for the device with MAJOR and MINOR, for use as
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the last argument of `mknod'."
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(+ (* major 256) minor))
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(define (device->major+minor device)
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"Return two values: the major and minor device numbers that make up DEVICE."
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(values (ash device -8)
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(logand device #xff)))
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(define* (file->cpio-header file #:optional (file-name file)
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#:key (stat lstat))
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"Return a cpio header corresponding to the info returned by STAT for FILE,
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using FILE-NAME as its file name."
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(let ((st (stat file)))
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(make-cpio-header #:inode (stat:ino st)
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#:mode (stat:mode st)
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#:uid (stat:uid st)
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#:gid (stat:gid st)
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#:nlink (stat:nlink st)
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#:mtime (stat:mtime st)
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#:size (stat:size st)
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#:dev (stat:dev st)
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#:rdev (stat:rdev st)
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#:name-size (string-length file-name))))
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(define %trailer
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"TRAILER!!!")
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(define %last-header
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;; The header that marks the end of the archive.
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(make-cpio-header #:mode 0
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#:name-size (string-length %trailer)))
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(define* (write-cpio-archive files port
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#:key (file->header file->cpio-header))
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"Write to PORT a cpio archive in \"new ASCII\" format containing all of FILES.
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The archive written to PORT is intended to be bit-identical to what GNU cpio
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produces with the '-H newc' option."
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(define (write-padding offset port)
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(let ((padding (modulo (- 4 (modulo offset 4)) 4)))
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(put-bytevector port (make-bytevector padding))))
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(define (pad-block port)
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;; Write padding to PORT such that we finish with a 512-byte block.
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;; XXX: We rely on PORT's internal state, assuming it's a file port.
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(let* ((offset (seek port 0 SEEK_CUR))
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(padding (modulo (- 512 (modulo offset 512)) 512)))
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(put-bytevector port (make-bytevector padding))))
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(define (dump-file file)
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(let* ((header (file->header file))
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(size (cpio-header-file-size header)))
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(write-cpio-header header port)
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(put-bytevector port (string->utf8 file))
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(put-u8 port 0)
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;; We're padding the header + following file name + trailing zero, and
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;; the header is 110 byte long.
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(write-padding (+ 110 1 (string-length file)) port)
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(case (mode->type (cpio-header-mode header))
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((regular)
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(call-with-input-file file
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(lambda (input)
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(dump-port input port))))
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((symlink)
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(let ((target (readlink file)))
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(put-string port target)))
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((directory)
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#t)
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(else
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(error "file type not supported")))
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;; Pad the file content.
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(write-padding size port)))
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(set-port-encoding! port "ISO-8859-1")
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(for-each dump-file files)
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(write-cpio-header %last-header port)
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(put-bytevector port (string->utf8 %trailer))
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(write-padding (string-length %trailer) port)
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;; Pad so the last block is 512-byte long.
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(pad-block port))
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;;; cpio.scm ends here
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