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Date: Mon, 17 Nov 2014 09:09:49 -0500
Message-ID: <CABa6CEnkEf==p=eBsw2T0_YKYd73CwxiMnJRbsxrHmc79Wz25w@mail.gmail.com>
Subject: Re: Question about having msvcrt*.dll and cygwin1.dll in one process
From: cyg Simple <cygsimple AT gmail DOT com>
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On Mon, Nov 17, 2014 at 4:48 AM, Jan Nijtmanswrote:
> 2014-11-17 9:47 GMT+01:00 Jing Zhao :
>> The outputs:
>> welcome to linux world
>> res: 7777777
>> it's over
>>
>> So everything look fine. According to the FAQ 6.15, is there anything
>> that's potentially dangerous that I should be aware of, when linking both
>> msvcrt.dll and cygwin1.dll? Thanks a lot!
>
> If it works, then you are simply lucky. Some pitfalls I know off:
>

Certainly lucky and usually won't work on all systems or even the same
system consistently.

> - when using stdin/stdout/stderr, msvcrt and cygwin1.dll have
>   their own implementation, which might conflict: locking over
>   multiple threads works differently, buffering is different. So
>   if both your application and the dll write to stdout, the
>   order in which both outputs are intermixed is not guaranteed.
> - exception handling is different. Don't expect an exception being
>   thrown in the dll to be handled gracefully in the application.
> - threading functions are different, same story.
> - dll initialization is different (recently a bug was fixed
>   regarding this, in a pre-fix version of cygwin1.dll your
>   current example might simply crash)
>

Memory control is the biggest issue.  Two different runtimes
controlling the same memory segments will not work!

-- 
cyg Simple

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