On Aug 18, 2007, at 8:01 PM, Brian Dessent wrote:

> It would be nice of you as a convenience to your users to include the
> ABI version as part of the library's filename, as it is still possible
> to have conflicts between projects -- this happens if you have a
> brain-dead installer that copies unversioned libraries into
> %WINDIR%\System32, or if the user adds the app's directory to PATH,
> which exposes its DLLs to potentially be searched during process
> startup
> for all processes.

Excellent write-up! I thought that I would expand on a couple of things:

Firstly, programs are required to not install "re-distributable DLL
files" into %WINDIR%\System32 to pass the "Designed for Windows"
certification. Microsoft has made the official recommendation that
programs that require specific versions of a library ship with the
library in the program's directory. Yes, this is a waste of space,
and its main cause is the lack of support in the PE file format for a
program to request libraries at certain revision levels (Such as
"libcurl.dll at version 7.16.4"). Recent UNIX-variants have gotten
around the issue by adding symbol versioning to the dynamic loader.
Of course, the addition of this badly needed feature to Windows might
break a number of "creative" assumptions made by 3rd-party vendors.

Second, during DLL path resolution, the directory where the program/
DLL resides is usually searched first, unless some magic is passed to
LoadLibraryEx().

The following links are excellent reference material on the matter:

http://www.microsoft.com/whdc/archive/wfp.mspx
http://msdn2.microsoft.com/en-us/library/ms682586.aspx
http://msdn2.microsoft.com/en-us/library/ms686203.aspx

Cheers,

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Received on 2007-08-19