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From: Jim Cant <jimc@voicebox.com>
To: "cygwin@cygwin.com" <cygwin@cygwin.com>
Subject: Can't trigger system debugger when program launched (via backticks) by Cygwin's Perl crashes
Date: Thu, 14 Nov 2013 14:01:00 +0000
Message-ID: <9B03E68568EAB74A93EB698EB537B20D0269E2F6@mail02.voiceboxtechnologies.com>
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If a program started by Cygwin's Perl using backticks fails do to a divide-by-zero, the Windos system debugger is not called; it is called if another Perl (ActiveState) is used.

I have Perl  scripts that launch arbitrary processes using backticks. Occasionally, a crash will occur (zero divide, for example) and  I need to get a core dump for analysis when that happens.  These scripts run unattended and a core dump needs to be generated automatically.

I have registered a perl script as crash handler with the operating system (this in Windows 7 - I knew you wanted to know) which gets called with the PID of the crash; the handler attaches Microsoft's 'cdb' debugger which creates the needed dump. My test 'crasher' program is a C++ executable that does a divide-by-zero (Crasher.exe). 

The Problem: When I use Cygwin's Perl implementation, the program crash never triggers the crash handler. My suspicion is that Perl is catching the problem and silently dropping it. All works fine with a Perl from ActiveState. 

The Question: How can I get Cygwin's Perl to get out of the way and let the error propagate all the way back to the system.  We use Cygwin's Perl on a lot of testing machines and are reluctant to change to another perl implementation.

Here's an example that uses ActiveState perl that triggers the crash handler and produces a core dump
 C:> \tools\Perl\bin\perl.exe -e "`Crasher.exe`;" 
But using Cygwin does not 
C:> \cygwin\bin\perl.exe -e "`Crasher.exe`;" 

Also, if I start Crasher.exe directly in Cygwin's shell (rather than a Windows console window), the crash handler is not called; neither is it called if started via backticks using either Cygwin or ActriveState Perl in the Cygwin shell. 

I thank you in advance for any help or suggestions!. 

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