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 * The contents of this file are subject to the Eclipse Public
 * License Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
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 * implied. See the License for the specific language governing
 * rights and limitations under the License.
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 * Copyright (C) 2009 JRuby project
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package org.jruby.ext.ffi;

import java.io.EOFException;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.jruby.Ruby;
import org.jruby.RubyIO;
import org.jruby.RubyModule;
import org.jruby.RubyNumeric;
import org.jruby.anno.JRubyMethod;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.util.io.OpenFile;

import static com.headius.backport9.buffer.Buffers.limitBuffer;

/**
* FFI specific I/O routines
 */
public class IOModule {

    public static void createIOModule(Ruby runtime, RubyModule ffi) {
        RubyModule module = ffi.defineModuleUnder("IO");
        module.defineAnnotatedMethods(IOModule.class);
    }

    @JRubyMethod(name = "native_read", module = true)
    public static final IRubyObject native_read(ThreadContext context, IRubyObject self,
            IRubyObject src, IRubyObject dst, IRubyObject rbLength) {
        if (!(src instanceof RubyIO)) {
            throw context.runtime.newTypeError("wrong argument (expected IO)");
        }

        if (!(dst instanceof AbstractMemory)) {
            throw context.runtime.newTypeError("wrong argument (expected FFI memory)");
        }

        Ruby runtime = context.runtime;
        try {
            OpenFile openFile = ((RubyIO) src).getOpenFile();
            openFile.checkClosed();
            openFile.checkReadable(context);


            ByteBuffer buffer = ((AbstractMemory) dst).getMemoryIO().asByteBuffer();
            int count = RubyNumeric.num2int(rbLength);

            if (count > buffer.remaining()) {
                throw runtime.newIndexError("read count too big for output buffer");
            }

            if (count < buffer.remaining()) {
                buffer = buffer.duplicate();
                limitBuffer(buffer, count);
            }

            // TODO: This used to use ChannelStream and honor its buffers; it does not honor OpenFile buffers now
            return runtime.newFixnum(openFile.readChannel().read(buffer));
        } catch (EOFException e) {
            return runtime.newFixnum(-1);
        } catch (IOException e) {
            throw runtime.newIOErrorFromException(e);
        }
    }
}
