gcj/246: Zipfile lossage on non-Unix systems

[zastai@hotmail.com]

>Number:         246
>Category:       gcj
>Synopsis:       Zipfile lossage on non-Unix systems
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    apbianco
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 26 00:40:00 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     zastai@hotmail.com
>Release:        gcj-2.95.2
>Organization:
>Environment:
i386-pc-msdosdjgpp
>Description:
 * ZIP support is broken (at least for ZIP files created
    with zip 2.3).
   Solution: lseek to zipd->filestart - 4 in open_in_zip
    (jcf-io.c).
   This _may_ be the result of having local extra fields
    in the zipfile (my version stores UTC modification
    time), but I doubt it.
   This _may_ be the result of zipfiles having different-
    sized headers on different platforms (ie Unix-based,
    DOS-based, OS/2-based and VMS-based zipfiles are all
    handled by zip, but might have different header sizes.
    This seems the most likely cause.
>How-To-Repeat:
Try to have gcj find classes in a zipfile that originated on MSDOS.
>Fix:
Offset seeks in zipfile; offset used may be dependent on the OS the zipfile originated on.
>Release-Note:
>Audit-Trail:
>Unformatted: