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file/untar: allow leading as well as trailing blanks (#2553)

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Some really old tar files can have both leading and trailing
blanks (nul/space characters) in the same octal number field in the
header.
This commit is contained in:
Lassi Kortela 2019-03-25 02:33:52 +02:00 committed by Matthew Flatt
parent 683492f6fe
commit 1600bc5dc6
1 changed files with 7 additions and 1 deletions
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8
racket/collects/file/untar.rkt
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@ -212,6 +212,12 @@
#f]
[else
;; traditional:
(define skip-head
(or (for/or ([i (in-range len)])
(case (integer->char (bytes-ref bstr i))
[(#\space #\nul) #f]
[else i]))
(error 'untar "bad number ~e at ~a" bstr (file-position in))))
(define skip-tail
(- len
(or (for/or ([i (in-range len 0 -1)])
@ -219,7 +225,7 @@
[(#\space #\nul) #f]
[else i]))
(error 'untar "bad number ~e at ~a" bstr (file-position in)))))
(for/fold ([v 0]) ([i (in-range (- len skip-tail))])
(for/fold ([v 0]) ([i (in-range skip-head (- len skip-tail))])
(define b (bytes-ref bstr i))
(if (<= (char->integer #\0) b (char->integer #\7))
(+ (* v 8) (- b (char->integer #\0)))