Wireshark-dev: Re: [Wireshark-dev] Windows build for VS 2008
From: Graham Bloice <graham.bloice@xxxxxxxxxxxxx>
Date: Mon, 28 Jul 2008 10:38:29 +0100
Nathan Jennings wrote:
On 7/25/2008 11:50 AM, Graham Bloice wrote:
  
Gerald Combs wrote:
    
According to
http://kobyk.wordpress.com/2007/07/20/dynamically-linking-with-msvcrtdll-using-visual-c-2005/ 

it's possible to use newer versions of Visual C++ to link against the 
"classic"
msvcrt.dll instead of msvcr[789]?.dll. This might let us get rid of 
some of the
complexity in the current Windows build environment and let us use a 
newer
compiler for the official builds.
_______________________________________________

  
      
Hmm.  The article seems to imply some other complexity as the debug CRT 
isn't available so you have to use the one for your compiler toolchain 
when debugging.  In addition, AFAIK, our CRT problems come from using 
compiled binaries from other projects (adns, etc.) that *currently* use 
the VS 6 CRT but may switch at any time.  I think we'd still have to 
ensure all components we use are running with the same CRT thus the 
hassles with having to compile them with the CRT of the developers 
toolchain.

    
Thanks for the link to the bug id.

So how does it work now? I mean tracking the CRT for other projects 
Wireshark calls into/depends on?
  
Manually, by fiddling the makefiles and ensuring that the dlls get rebuilt with the users current toolchain (and crt) for the problematic cases.
I'm guessing the big ones are GTK/Glib and WinPcap? So do they use MSVC 
2005 EE or, at least, the same CRT?
  
The problem ones are adns and zlib.  GTK relies on Glib and Glib doesn't import any specific CRT.  Using depends (http://www.dependencywalker.com/) can help you identify the linkages.
If I'm reading/understanding Gerald's link to the post and Graham's 
message correctly, then you can link/import to any CRT you'd like 
regardless of compiler version (i.e. use CRT v8 with VS 2008 or CRT v7 
with VS2005)?
  
I'm not sure about that.  The article seems to be talking about getting around the issue of linking to a specific CRT that isn't installed on the target machine.  By using the tricks described, it would seem that an app can be made to use whatever CRT is available.  I don't think it gets around the issue of different components of an app using different versions of CRT, but I'm assuming Gerald's thinking was that we could make wireshark itself link to the VC 6 CRT on all toolchains, and hence have no issues with the third part dll's that also do that.
What I'm getting at is Wireshark could potentially call into three 
different CRTs if there were two other binary projects and they were 
compiled to two different CRT versions, correct?

I.e. Wireshark CRTv8, GTK/Glib CRTv7, WinPcap MSVCRT.

  
I don't think you can do that within the same app.

-- 
Regards,

Graham Bloice