Automate copying third-party dlls for make install DESTDIR=...

[jimklimov]

We want to bundle third-party libraries with NUT to make a single usable package for WIN32 builds.
Recursive ldd may be an option - see build-mingw-nut.sh for a single-walk PoC, but this should become part of make package kind of call.

[jimklimov]

It seems that not all mingw environments ship an ldd easily usable for this, and the system Linux ldd does not walk Windows PE (exe/dll) files :)

However, ARCH-dependent mingw builds of objdump may be used (recursively) to inspect available DLLs (and so copy out those present in the build environment), as automated by https://osdn.net/users/keith/pf/mingw-ldd/scm/blobs/master/mingw32-ldd.sh / https://osdn.net/users/keith/pf/mingw-ldd/wiki/FrontPage (note the script aims to be very portable but currently depends on bash syntax a bit with type -p CMDNAME vs command -v CMDNAME):

$ x86_64-w64-mingw32-ldd  nut/scripts/Windows/nut_install/bin/netxml-ups.exe
nut/scripts/Windows/nut_install/bin/netxml-ups.exe
 +- ADVAPI32.dll
 +- KERNEL32.dll
 +- msvcrt.dll
 +- WS2_32.dll
 +- libneon-27.dll
     +- KERNEL32.dll
     +- msvcrt.dll
     +- WS2_32.dll
     +- libxml2-2.dll
         +- KERNEL32.dll
         +- msvcrt.dll
         +- WS2_32.dll
         +- liblzma-5.dll
             +- KERNEL32.dll
             +- msvcrt.dll

executed AFTER placing the custom-built DLLs into the nut_install/bin dir.

Before preparing that location, we see just the top level (which we can iterate using files from MinGW bin and lib dirs if present):

$ x86_64-w64-mingw32-ldd  nut/scripts/Windows/nut_build/drivers/.libs/netxml-ups.exe
nut/scripts/Windows/nut_build/drivers/.libs/netxml-ups.exe
 +- ADVAPI32.dll
 +- KERNEL32.dll
 +- msvcrt.dll
 +- WS2_32.dll
 +- libneon-27.dll

[jimklimov]

UPDATE: It seems the system objdump in Ubuntu 20.10 and Debian 11 (used among CI testbeds for cross-mingw experiments) can read PE files, even on a system where mingw bits are not installed:

$ which objdump ;  objdump -x nut/scripts/Windows/nut_install/bin/netxml-ups.exe  | grep -i 'dll name'
/usr/bin/objdump
        DLL Name: ADVAPI32.dll
        DLL Name: KERNEL32.dll
        DLL Name: msvcrt.dll
        DLL Name: WS2_32.dll
        DLL Name: libneon-27.dll

so this is a viable way forward.

[jimklimov]

Now build-mingw-nut.sh does a recursive walk to fetch many (open-source third-party) DLLs from mingw build environment.

In the end they are dumped to bin dir (for drivers and tools), with links added later into sbin dir per needs of system daemons, because run-time DLLs must be near EXE (if not in system paths).

Further packaging for Windows was not yet explored => #1485

[jimklimov]

With #1581 in place, make DESTDIR='/tmp/nut_install' install-win-bundle is a thing!