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Handle data descriptor signatures in file/unzip

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http://www.pkware.com/documents/casestudies/APPNOTE.TXT specifies that a data
descriptor signature may be placed after the compressed data and before the
data descriptor. file/unzip now handles this case.
This commit is contained in:
Marc Burns 2014-09-02 13:35:33 -04:00 committed by Matthew Flatt
parent 478b01b0e3
commit 467786fc1c
1 changed files with 12 additions and 1 deletions
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13
racket/collects/file/unzip.rkt
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@ -211,12 +211,23 @@
(msdos-date+time->seconds date time utc?)))
(read-entry filename dir? in))
;; Read until the end of the deflated stream when compressed size unknown
(when (bitwise-bit-set? bits 3)
(let loop () (unless (eof-object? (read-bytes 1024 in)) (loop))))
(when t (kill-thread t)))
(lambda ()
;; appnote VI-C : if bit 3 is set, then the file data
;; is immediately followed by a data descriptor
;; appnote 4.3.9.3 : the value 0x08074b50 may appear
;; as a data descriptor signature immediately
;; following the file data
(if (bitwise-bit-set? bits 3)
(skip-bytes 12 in)
;; Read possibly signed data descriptor
(let ([maybe-signature (read-int 4)])
(skip-bytes (if (= maybe-signature #x08074b50) 12 8)
in))
(skip-bytes (- (+ mark compressed) (file-position in)) in)))))
(void))))