Using pre-built library wimlib with GLP/LGPL dual licensing in closed source commercial product

Question

Need help with a **complicated GPL/LGPL Dual Licensing issue**. We need to read the contents of a .ESD file which which is nothing but a LZMA compressed .WIM file.

I am planning to use the wimlib prebuilt binaries as it is in my product. The pre-built wimlib binaries are available here https://wimlib.net/downloads/wimlib-1.13.2-windows-x86_64-bin.zip.

Out of all these files we will be needing only the libwim-15.dll file. We are thinking of redistributing this pre-built DLL file as it is with our installer.

The licensing information is a but tricky and is available here: https://wimlib.net/git/?p=wimlib;a=blob;f=COPYING;h=c26af332a990696e75a452abbd43f278ccdcc503;hb=HEAD

I already know that a software with LGPL license can be definitely redistributed in the pre-built binary form as long as we clearly mention it and also include the license text in the installer. But this is a bit tricky situation here; the documentation says ;

Alternatively, when not prohibited by conflict with a third-party software license, the library portion of wimlib may be redistributed and/or modified under the terams of the GNU Lesser General Public License; either version 3 of the License, or (at your option) any later version.

NOTE! The primary reason for the GPL/LGPL "dual licensing" for the library is that on UNIX-like systems, wimlib can optionally be linked to the third-party library "libntfs-3g", which is licensed GPLv2+. Under some interpretations of the GPL, this would require that wimlib be licensed under the GPL as well. However, a binary copy of wimlib that was compiled without libntfs-3g support (for example; the exception may be applicable in other situations as well) logically cannot be affected by libntfs-3g's license and should therefore be free to be redistributed under the LGPL instead of the GPL.

Now since I am using it on Native windows I really do not need any of the libntfs-3g functionality as the Windows apis natively support NTFS. So based on this fact can I consider that only LGPL licensing terms apply here in this case and I can use the pre-built binary DLL as it is in my commercial closed source product? I will definitely mention the library name in credits and add the appropriate licensing files in the installer.

Answer 1

Going by what you quote, you only need to worry about the binary being subject to gpl license under Linux. Even under Linux you could use and distribute in a version without the mentioned library compiled into the library: it is a dependency which can be part but need not be, so you could use version without that library compiled into it). And if you choose a version which does not depend on gpl code, you handed the choice to use it under LGPL or GPL as by the license.

In summary: IMHO you should be safe to proceed like you describe. IANAL though