From: Daniel Berger <djberg96@...>
Date: 2005-10-26T07:42:03+09:00
Subject: Re: mkmf, linking against a specific DLL on windows


nobuyoshi nakada wrote:
> Hi,
>
> At Tue, 18 Oct 2005 02:16:42 +0900,
> Daniel Berger wrote in [ruby-talk:160905]:
> > How do I link against a specific DLL on Windows again?  I tried have_library,
> > but that always looks for the .lib file apparently.
>
> What do you want to link against?  AFAIK, VC link.exe can't
> handle DLL files as input, without import library files (i.e.,
> lib files).
>
> --
> Nobu Nakada

Ok, but you can generate a .lib file from a .def, and you can generate
a .def from a .dll.  Here's a script I cobbled together that did the
trick:

# libmaker.rb
require "Win32API"
GetShortPathName =
Win32API.new("kernel32","GetShortPathName","PPL","L")
MAX_PATH = 260

# Create a .def file from the results of a 'link -dump -exports'
def create_def(dll_file, def_file = nil)
   raise "not a dll" unless File.extname(dll_file).downcase == ".dll"
   if def_file.nil?
      def_file = dll_file[0..-5] + ".def"
   end

   funcs = []

   # Dunno if I've caught all the junk here.  Seems to work.
   `link -dump -exports "#{dll_file}"`.each{ |line|
      func = line.split.last
      next if func.nil?
      next if func.empty?
      next if func.split("").first !~ /[A-Z]/
      next if func == "Summary"
      next if func.upcase == "DLL"
      next if File.basename(func) == File.basename(dll_file)
      funcs.push(func)
   }

   File.open(def_file, "w+"){ |fh|
      fh.puts "NAME " + File.basename(dll_file)
      fh.puts "EXPORTS"
      funcs.each{ |func|
         fh.puts "\t#{func}"
      }
   }

   return def_file
end

# Create a .lib file from a .def file.  Note that the lib command
doesn't
# seem to like long path names, so we'll shorten them.
def create_lib(def_file, lib_file = nil)
   raise "not a .def" unless File.extname(def_file).downcase == ".def"
   if lib_file.nil?
      lib_file = def_file[0..-5] + ".lib"
   end

   buf = 0.chr * MAX_PATH
   buf[0..def_file.length-1] = def_file
   GetShortPathName.call(def_file, buf, buf.length)
   def_file = buf.split(0.chr).first
   lib_file = File.dirname(def_file) + "\\" + File.basename(lib_file)

   # This may generate a warning which you can ignore
   system("lib /DEF:#{def_file} /OUT:#{lib_file}")
end

dll_file = "C:\\foo\\bar\\baz.dll"
def_file = "C:\\foo\\bar\\baz.def"

def_file = create_def(dll_file)
create_lib(def_file)