cygwin problem: Could not open library 'libgeom.dll'

[Michael Jørgensen]

Hi,

I'm writing a small cross-platform C-library to do geometric calculations (because it is approx five times faster than in ruby).

It works fine, when running on Linux (Fedora 20), but fails when running on Windows 8 with Cygwin with the following error:

C:/Ruby193/lib/ruby/gems/1.9.1/gems/ffi-1.9.3-x86-mingw32/lib/ffi/library.rb:133:in `block in ffi_lib': Could not open library 'libgeom': x▒K. (LoadError)

Could not open library 'libgeom.dll':L

        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/ffi-1.9.3-x86-mingw32/lib/ffi/library.rb:100:in `map'

        from C:/Ruby193/lib/ruby/gems/1.9.1/gems/ffi-1.9.3-x86-mingw32/lib/ffi/library.rb:100:in `ffi_lib'

        from C:/rubytest/geom.rb:6:in `<module:Geom>'

        from C:/rubytest/geom.rb:1:in `<top (required)>'

        from main.rb:2:in `require_relative'

        from main.rb:2:in `<main>'

So in the file geom.rb I have the following:

    extend FFI::Library

    ffi_lib "libgeom"

On Linux I have the file libgeom.so and on Windows I have the file libgeom.dll

I'm using 64-bit cygwin and compiling the shared library with the following command:

    gcc -Wall -shared geom.c -o libgeom.dll

I'm using ruby 1.9.3

I've tried supplying a full path name to the dll, but that did not make a difference. I've tried adding the current directory to PATH, but still no luck.

The .dll library is completely self-contained, and requires no other libraries. (not even -lm).

I'm quite new to ruby, but was very happy with the immediate success on my Linux machine. Now I just need to get it working on Windows too.

Any ideas on a work-around?

Sincerely,

Michael.

[Charles Oliver Nutter]

Are you certain the Ruby you're using is also 64-bit?

- Charlie

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[Michael Jørgensen]

Ahh!

You are right, Charles. I'm combining 32-bit ruby with 64-bit Cygwin. That is why it's not working. I've removed Cygwin, and changed to 32-bit Cygwin. And now it works!

Thanks,

-Michael.

[Charles Oliver Nutter]

Ok great!

I wish we had a better way to indicate this, but I don't know enough
native voodoo to tell when we're loading a 64-bit library into a
32-bit process.

- Charlie