Initial commit

This commit is contained in:
Lassi Kortela 2019-06-22 22:30:44 +03:00
parent 601621f7dc
commit 36e400b72a
3 changed files with 77 additions and 16 deletions

33
LICENSE
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MIT License
Copyright (c) 2019 Scheme Documentation
Copyright 2019 Lassi Kortela
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

54
trivial-tar-writer.scm Normal file
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;;; Copyright (c) 2019 Lassi Kortela
;;; SPDX-License-Identifier: ISC
(define nulls (make-bytevector 512 0))
(define zeros (make-bytevector 12 (char->integer #\0)))
(define (tar-poke-string header at nbyte string)
(let* ((bytes (string->utf8 string))
(nnull (- nbyte (bytevector-length bytes))))
(when (< nnull 0) (error "tar: string too long"))
(bytevector-copy! header at bytes)))
(define (tar-poke-octal header at nbyte number)
(unless (integer? number) (error "tar: not an integer"))
(when (< number 0) (error "tar: negative integer"))
(let* ((bytes (string->utf8 (number->string number 8)))
(nzero (- nbyte 1 (bytevector-length bytes))))
(when (< nzero 0) (error "tar: number too big"))
(bytevector-copy! header at zeros 0 nzero)
(bytevector-copy! header (+ at nzero) bytes)
(bytevector-u8-set! header (+ at nbyte -1) 0)))
(define (tar-header-checksum header)
(let ((n (bytevector-length header)))
(let loop ((i 0) (sum 0))
(if (= i n)
(truncate-remainder sum (expt 8 6))
(loop (+ i 1) (+ sum (bytevector-u8-ref header i)))))))
(define (tar-write-file fake-path bytes)
(let* ((header (make-bytevector 512 0))
(nbyte (bytevector-length bytes))
(nnull (- 512 (truncate-remainder nbyte 512)))
(unix-time-now 0))
(tar-poke-string header 0 100 fake-path)
(tar-poke-octal header 100 8 #o644)
(tar-poke-octal header 108 8 0)
(tar-poke-octal header 116 8 0)
(tar-poke-octal header 124 12 nbyte)
(tar-poke-octal header 136 12 unix-time-now)
(bytevector-copy! header 148 (make-bytevector 8 (char->integer #\space)))
(bytevector-u8-set! header 156 (char->integer #\0))
(tar-poke-string header 157 100 "")
(tar-poke-string header 257 8 "ustar ")
(tar-poke-string header 265 32 "root")
(tar-poke-string header 297 32 "root")
(tar-poke-octal header 148 7 (tar-header-checksum header))
(write-bytevector header)
(write-bytevector bytes)
(write-bytevector nulls (current-output-port) 0 nnull)))
(define (tar-poke-end)
(write-bytevector nulls)
(write-bytevector nulls))

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trivial-tar-writer.sld Normal file
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(define-library (trivial-tar-writer)
(export tar-write-file)
(import (scheme base)
(scheme char)
(scheme write))
(include "trivial-tar-writer.scm"))