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Message-ID: <42FB7FF2.3020709@club-internet.fr>
Date: Thu, 11 Aug 2005 18:42:26 +0200
From: Louis Lecaroz <louis DOT lecaroz AT club-internet DOT fr>
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To: cygwin AT cygwin DOT com
Subject: Re: "Segmentation fault" CygWin tools with code Injection-MS Detours
References: <42FB7644 DOT 8020905 AT le-resistant DOT com> <20050811163305 DOT GB6935 AT trixie DOT casa DOT cgf DOT cx>
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>I can't really tell from your description.  It looks like the LD_PRELOAD
>stuff won't be called in the forkee, but I don't know if that's what you're
>seeing or not.  It still works when a process is execed, so it seems
>like it should be working most of the time.  I've fixed this in CVS.
>
>I'll generate a snapshot with this change today.
>  
>
Ok, the behavior I would like to have, is the LD_PRELOAD also called by 
the forkee, this willl allow the forkee to load the DLL I have declared 
in the LD_PRELOAD environment variable & allowing me to manipulate 
memories & Win32 functions addresses/pointers to perform hook inside.

>  
>
>>If yes, & if it is possible to correct this special really interresting 
>>undocumented CygWin Feature, I think, it will allow me to trace systems 
>>Win32 native call (not cygwin call like strace), in all cygwin tools. 
>>    
>>
>
>Sorry, but no, this is a cygwin-only solution.  It doesn't work with
>non-cygwin DLLs.
>  
>
I understand well that this is a cygwin only solution but it appears to 
work with non cygwin dlls as DllMain entries are standard & my code to 
install the hook is executed from the DllMain entry ;). It is sure, I 
cannot know how it impact the Cygwin Tools stability, but it works... 
(only in the forker ! not in the forkee ! as We saw above :( ).
I really understand this & your point of view & declining 
responsabilities or future behavior on this ;)

Just only having the forkee working with the LD_PRELOAD will be I 
suppose, not a solution for me... but a good workaround....
Louis

>cgf
>
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