115 lines
5.5 KiB
Plaintext
115 lines
5.5 KiB
Plaintext
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Known, current PKZIP bugs/limitations:
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-------------------------------------
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- PKUNZIP 2.04g is reported to corrupt some files when compressing them with
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the -ex option; when tested, the files fail the CRC check, and comparison
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with the original file shows bogus data (6K in one case) embedded in the
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middle. PKWARE apparently characterized this as a "known problem."
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- PKUNZIP 2.04g considers volume labels valid only if originated on a FAT
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file system, but other OSes and file systems (e.g., Amiga and OS/2 HPFS)
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support volume labels, too.
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- PKUNZIP 2.04g can restore volume labels created by Zip 2.x but not by
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PKZIP 2.04g (OS/2 DOS box only??).
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- PKUNZIP 2.04g gives an error message for stored directory entries created
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under other OSes (although it creates the directory anyway), and PKZIP -vt
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does not report the directory attribute bit as being set, even if it is.
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- PKZIP 2.04g mangles unknown extra fields (especially OS/2 extended attri-
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butes) when adding new files to an existing zipfile [example: Walnut Creek
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Hobbes March 1995 CD-ROM, FILE_ID.DIZ additions].
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- PKUNZIP 2.04g is unable to detect or deal with prepended junk in a zipfile,
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reporting CRC errors in valid compressed data.
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- PKUNZIP 2.04g (registered version) incorrectly updates/freshens the AV extra
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field in authenticated archives. The resultant extra block length and total
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extra field length are inconsistent.
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- [Windows version 2.01] Win95 long filenames (VFAT) are stored OK, but the
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file system is always listed as ordinary DOS FAT.
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- [Windows version 2.50] NT long filenames (NTFS) are stored OK, but the
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file system is always listed as ordinary DOS FAT.
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- PKZIP 2.04 for DOS encrypts using the OEM code page for 8-bit passwords,
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while PKZIP 2.50 for Windows uses Latin-1 (ISO 8859-1). This means an
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archive encrypted with an 8-bit password with one of the two PKZIP versions
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cannot be decrypted with the other version.
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- PKZIP for Windows GUI (v 2.60), PKZIP for Windows command line (v 2.50) and
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PKZIP for Unix (v 2.51) save the host's native file timestamps, but
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only in a local extra field. Thus, timestamp-related selections (update
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or freshen, both in extraction or archiving operations) use the DOS-format
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localtime records in the Zip archives for comparisons. This may result
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in wrong decisions of the program when updating archives that were
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previously created in a different local time zone.
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- PKZIP releases newer than PKZIP for DOS 2.04g (PKZIP for Windows, both
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GUI v 2.60 and console v 2.50; PKZIP for Unix v 2.51; probably others too)
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use different code pages for storing filenames in central (OEM Codepage)
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and local (ANSI / ISO 8859-1 Codepage) headers. When a stored filename
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contains extended-ASCII characters, the local and central filename fields
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do not match. As a consequence, Info-ZIP's Zip program considers such
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archives as being corrupt and does not allow to modify them. Beginning
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with release 5.41, Info-ZIP's UnZip contains a workaround to list AND
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extract such archives with the correct filenames.
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Maybe PKWARE has implemented this "feature" to allow extraction of their
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"made-by-PKZIP for Unix/Windows" archives using old (v5.2 and earlier)
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versions of Info-ZIP's UnZip for Unix/WinNT ??? (UnZip versions before
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v 5.3 assumed that all archive entries were encoded in the codepage of
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the UnZip program's host system.)
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- PKUNZIP 2.04g is reported to have problems with archives created on and/or
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copied from Iomega ZIP drives (irony, eh?).
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Known, current WinZip bugs/limitations:
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--------------------------------------
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- [16-bit version 6.1a] NT short filenames (FAT) are stored OK, but the
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file system is always listed as NTFS.
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- WinZip doesn't allow 8-bit passwords, which means it cannot decrypt an
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archive created with an 8-bit password (by PKZIP or Info-ZIP's Zip).
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- WinZip (at least Versions 6.3 PL1, 7.0 SR1) fails to remove old extra
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fields when freshening existing archive entries. When updating archives
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created by Info-ZIP's Zip that contain UT time stamp extra field blocks,
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UnZip cannot display or restore the updated (DOS) time stamps of the
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freshened archive members.
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Known, current other third-party Zip utils bugs/limitations:
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------------------------------------------------------------
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- Asi's PKZip clones for Macintosh (versions 2.3 and 2.10d) are thoroughly
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broken. They create invalid Zip archives!
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a) For the first entry, both compressed size and uncompressed length
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are recorded as 0, despite the fact that compressed data of non-zero
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length has been added.
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b) Their program creates extra fields with an (undocumented) internal
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structure that violates the requirements of PKWARE's Zip format
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specification document "appnote.txt": Their extra field seems to
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contain pure data; the 4-byte block header consisting of block ID
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and data length is missing.
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Possibly current PKZIP bugs:
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---------------------------
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- PKZIP (2.04g?) can silently ignore read errors on network drives, storing
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the correct CRC and compressed length but an incorrect and inconsistent
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uncompressed length.
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- PKZIP (2.04g?), when deleting files from within a zipfile on a Novell
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drive, sometimes only zeros out the data while failing to shrink the
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zipfile.
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Other limitations:
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-----------------
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- PKZIP 1.x and 2.x encryption has been cracked (known-plaintext approach;
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see http://www.cryptography.com/ for details).
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[many other bugs in PKZIP 1.0, 1.1, 1.93a, 2.04c and 2.04e]
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