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Message-ID: <3B96DA8B.3B50CB67@hszk.bme.hu>
Date: Thu, 06 Sep 2001 04:08:11 +0200
From: Nemeth Marton <nm127 AT hszk DOT bme DOT hu>
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To: cygwin AT cygwin DOT com
Subject: How to build a "function call logger" .dll?
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Hi!

I want to build a "function call logger" .dll which could write out each
function call with the call parameters to a logfile.

Original working of a "program.exe" and "funcs.dll":

 --------------------			-------------------------
 |  program.exe     |			| funcs.dll		|
 |                  |			|			|
 |  imports: func_a <==================== exports: func_a	|
 |                  |			|			|
 --------------------			-------------------------

If I want to log what functions the "program.exe" calls I have to make
an other "funcs.dll" as a replacement. The original "funcs.dll" can be
renamed as "funcs-orig.dll".
Now this should work as follows:

 --------------------	--------------------	-------------------------
 |  program.exe     |	| funcs.dll	   |	| funcs-orig.dll	|
 |                  |	|		   |	| 			|
 |		    |	|   imports: func_a <===== exports: func_a	|
 |  imports: func_a <====exports: func_a   |	|			|
 |                  |	|		   |	|			|
 --------------------	---------|-----------	-------------------------
				 |
				\|/
			    logfile.txt

The problem is that in the new source code I have to use 2 func_a: the
first one to export to the program.exe and the second one to import from
funcs-orig.dll like this:

void func_a() {		// this is the new exported function
	// log to logfile.txt
	func_a();	// this shoud be a call to funcs-orig.dll's func_a()
}

Is it possible to make something like this?

Thanks,

	NMarci

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