Calling a DLL function that returns a struct in NSIS.

Hi experts I have created an NSIS installer that is now required to check the version of a DLL before it installs the file. The DLL is written in C and the function I am trying to call is the following:

EXPORT int __stdcall getVersion(VERSION_STRUCT* version){
      
            version->major = verMajor;
            version->minor = verMinor;
            version->revision = verRevision;
            
            return 1;
}            

My question is how can you create a struct in the .nsi script, assign values to this struct by calling the getVersion function in the DLL from the .nsi script,  and finally how can I compare the components of the struct to other integers to check if the DLL is a new version or not.

A VBScript solution is also possible, but not preferred.

Thanks.
jonathan_hillsAsked:
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jkrCommented:
Take a look at http://nsis.sourceforge.net/Calling_an_external_DLL_using_the_System.dll_plugin ("Calling an external DLL using the System.dll plugin") - the scoop would be to

System::Call 'YourDllName::YourDllFunction(i, *i, t) i(.r0, r1, .r2) .r3'
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jonathan_hillsAuthor Commented:
Okay thank-you I will try to make i work and I will get back to you.
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jonathan_hillsAuthor Commented:
So far I have this in my function in the .nsi script:


SetOutPath $TEMP\eInspect                               ; create temp directory
      file "..\bin\myDLL.dll"            ; copy dll there

       # allocate
      System::Alloc 12

      Pop $0
      System::Call "*$0(i 5, i 2, i 513)"

      # call
      System::Call "..\bin\myDLL.dll::getVersion(i r0)"

      # get       
      System::Call "*$0(i.r0, i.r1, i.r2)"
      
      # print
      DetailPrint "Major: $0"
      DetailPrint "Minor: $1"
      DetailPrint "Revision: $2"
      #free
      System::Free $0

And in my dll function I have

EXPORT int __stdcall getVersion(VERSION_STRUCT* version){
      
            version->major = verMajor;
            version->minor = verMinor;
            version->revision = verRevision;
            
            return 1;
}                  


It runs it is just the numbers contained in the struct do not change from the initial values I give them. What am I doing wrong with the DLL function call?

SetOutPath $TEMP\eInspect             			; create temp directory
	file "..\bin\myDLL.dll"            ; copy dll there

	 # allocate
	System::Alloc 12

	Pop $0
	System::Call "*$0(i 5, i 2, i 513)"

	# call
	System::Call "..\bin\myDLL.dll::getVersion(i r0)"

	# get	 
	System::Call "*$0(i.r0, i.r1, i.r2)"
	
	# print free
	DetailPrint "Major: $0"
	DetailPrint "Minor: $1"
	DetailPrint "Revision: $2"
	#free
	System::Free $0

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jonathan_hillsAuthor Commented:
Sorry duplicate code posted in that post above.
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jonathan_hillsAuthor Commented:
Never mind I ended up figuring it out, thanks for the help jkr.
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jonathan_hillsAuthor Commented:
Not a complete answer to the question, but still pointed me in the correct direction.
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