Struggling with jnr.ffi.provider.jffi.AsmRuntime.newUnsatisifiedLinkError

[gotson]

Hi,

i am trying to use jnr-ffi to access libwebp. It works for some simpler functions, but i can't make it work for more complex ones.

For example, the following function works (source):

int WebPGetInfo(const uint8_t* data, size_t data_size, int* width, int* height);

Which I translated to:

boolean WebPGetInfo(
        @In Buffer data,
        @In @size_t long data_size,
        @Out IntByReference width,
        @Out IntByReference height
);

However, for something a bit more complex, like (source):

VP8StatusCode WebPGetFeatures(
    const uint8_t* data, size_t data_size,
    WebPBitstreamFeatures* features)

struct WebPBitstreamFeatures {
  int width;          // Width in pixels, as read from the bitstream.
  int height;         // Height in pixels, as read from the bitstream.
  int has_alpha;      // True if the bitstream contains an alpha channel.
  int has_animation;  // True if the bitstream is an animation.
  int format;         // 0 = undefined (/mixed), 1 = lossy, 2 = lossless

  uint32_t pad[5];    // padding for later use
};

which I translated to:

VP8StatusCode WebPGetFeatures(
        @In Buffer data, @In @size_t long data_size, WebPBitstreamFeatures features
);

public class WebPBitstreamFeatures extends Struct {
  public Signed32 width = new Signed32();
  public Signed32 height = new Signed32();
  public Boolean has_alpha = new Boolean();
  public Boolean has_animation = new Boolean();
  public Signed8 format = new Signed8();
  public Struct.u_int32_t[] pad = new u_int32_t[5];

  public WebPBitstreamFeatures(Runtime runtime) {
    super(runtime);
  }
}

I call the function like so:

public Info getFeatures(byte[] webpData) throws WebpException {
    WebPBitstreamFeatures features = new WebPBitstreamFeatures(runtime);
    VP8StatusCode rv =
        lib.WebPGetFeatures(ByteBuffer.wrap(webpData), webpData.length, features);
    if (rv != VP8StatusCode.VP8_STATUS_OK) {
      throw new WebpException("Could not decode headers");
    }

    return new Info(features.width.get(), features.height.get());
  }

But i always get an error:

java.lang.UnsatisfiedLinkError: unknown

	at jnr.ffi.provider.jffi.AsmRuntime.newUnsatisifiedLinkError(AsmRuntime.java:48)
	at de.digitalcollections.webp.lib.libwebp$jnr$ffi$0.WebPGetFeatures(Unknown Source)

The library is loading correctly, as simpler functions are working fine.

Maybe my translation is incorrect? Or maybe it's because the function is static ? Or because it's inline ? Or something to do with the pad that i didn't get correctly?

Any help would be appreciated ! 🙏🏻