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MIME-Version: 1.0
Subject: Re: debugging unzip
From: Thomas L Roche <tlroche AT us DOT ibm DOT com>
Message-ID: <OF386A608E.AF51114C-ON85256E3A.0002739B-85256E3A.000441B4@us.ibm.com>
Date: Fri, 13 Feb 2004 19:46:28 -0500
Content-Type: text/plain; charset="US-ASCII"

cygwin1-20040213 no fix for unzip

I reran

gdb --args ./usr/bin/unzip.exe 
/d/eclipse/zips/wsa-jdk-20040210_1925-WB213-AD-V512D-W5.zip

from an xterm started with the snapshot. Failure was similar to
previous, though it seemed to take longer:

>   inflating: 
runtimes/base_v5/installedApps/localhost/adminconsole.ear/adminconsole.war/com.ibm.ws.console.webservices/nl/zh_TW/504.gif 
 
>     545 [main] unzip 1896 cmalloc: cmalloc returned NULL

> Program received signal SIGSEGV, Segmentation fault.
> 0x610cb584 in memcpy () from /usr/bin/cygwin1.dll

However

Igor Pechtchanski 02/13/2004 06:58:42 PM:
> The above messages might indicate that there is more than one version
> of the cygwin DLL on your system.  Instead of moving the old 
> cygwin1.dll out of the way, could you please rename it to something
> that doesn't end in .dll (e.g., cygwin1.dll-old), and, just to make
> sure, make it non-executable?

I'll do that, before

Igor Pechtchanski 02/13/2004 06:34:59 PM:
> Try doing "where" or go "up" a few frames, and see where in *unzip*
> it calls the memcpy that crashes.  Also, you may want to set a 
> breakpoint at the call to cmalloc, and re-run the program, just to
> see what the values passed to cmalloc are.

OK: assistance with <gdb commands|insight gestures> is appreciated.

> It's quite possible that the size of the region is computed
> incorrectly (negative number wrapping, or something), and unzip is
> requesting a huge region allocated, which obviously fails

Umm, _very_ doubtful. Remember:

* I have now, on a disk, a zip that I used to build an eclipse target
  platform with 'unzip' and cygwin-1.5.5-1.

* The same zip failed to unzip with cygwin-1.5.6-1, and fails to unzip
  with cygwin-1.5.7-1

* bash-2.05b$ unzip -v
> UnZip 5.50 of 17 February 2002, by Info-ZIP.
<snip>
> Compiled with gcc 3.2 20020927 (prerelease) for Unix (Intel 386) on
> Aug  9 2003.

So even if unzip is behaving badly (which I doubt, but will check),
cygwin-1.5.5-1 could handle it gracefully, unlike its successors.


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