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package com.oracle.graal.python.builtins.objects.mmap;

import com.oracle.graal.python.builtins.objects.buffer.PythonBufferAccessLibrary;
import com.oracle.graal.python.builtins.objects.buffer.PythonBufferAcquireLibrary;
import com.oracle.graal.python.builtins.objects.object.PythonObject;
import com.oracle.graal.python.nodes.PConstructAndRaiseNode;
import com.oracle.graal.python.nodes.util.CastToJavaIntExactNode;
import com.oracle.graal.python.runtime.PosixSupportLibrary;
import com.oracle.graal.python.runtime.PosixSupportLibrary.PosixException;
import com.oracle.graal.python.runtime.PythonContext;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Cached.Exclusive;
import com.oracle.truffle.api.library.CachedLibrary;
import com.oracle.truffle.api.library.ExportLibrary;
import com.oracle.truffle.api.library.ExportMessage;
import com.oracle.truffle.api.object.Shape;
import com.oracle.truffle.api.profiles.BranchProfile;

@ExportLibrary(PythonBufferAcquireLibrary.class)
@ExportLibrary(PythonBufferAccessLibrary.class)
public final class PMMap extends PythonObject {
    public static final int ACCESS_DEFAULT = 0;
    public static final int ACCESS_READ = 1;
    public static final int ACCESS_WRITE = 2;
    public static final int ACCESS_COPY = 3;

    private Object handle;
    private long pos;
    private final int fd; // -1 for anonymous mapping
    private final long length;
    private final int access;

    public PMMap(Object pythonClass, Shape instanceShape, Object handle, int fd, long length, int access) {
        super(pythonClass, instanceShape);
        assert handle != null;
        this.handle = handle;
        this.length = length;
        this.access = access;
        this.fd = fd;
    }

    public Object getPosixSupportHandle() {
        return handle;
    }

    void close(PosixSupportLibrary lib, Object posix) throws PosixException {
        if (handle != null) {
            if (fd != -1) {
                lib.close(posix, fd);
            }
            lib.mmapUnmap(posix, handle, length);
            handle = null;
        }
    }

    boolean isClosed() {
        return handle == null;
    }

    public boolean isWriteable() {
        return access != ACCESS_READ;
    }

    public int getAccess() {
        return access;
    }

    public long getLength() {
        return length;
    }

    public long getPos() {
        return pos;
    }

    public void setPos(long pos) {
        this.pos = pos;
    }

    public long getRemaining() {
        return pos < length ? length - pos : 0;
    }

    @ExportMessage
    @SuppressWarnings("static-method")
    boolean isBuffer() {
        return true;
    }

    @ExportMessage
    int getBufferLength(
                    @Exclusive @Cached CastToJavaIntExactNode castToIntNode) {
        return castToIntNode.execute(length);
    }

    @ExportMessage
    byte readByte(int byteOffset,
                    @CachedLibrary(limit = "1") PosixSupportLibrary posixLib,
                    @Cached BranchProfile gotException,
                    @Cached PConstructAndRaiseNode raiseNode) {
        try {
            return posixLib.mmapReadByte(PythonContext.get(raiseNode).getPosixSupport(), getPosixSupportHandle(), byteOffset);
        } catch (PosixException e) {
            // TODO(fa) how to handle?
            gotException.enter();
            throw raiseNode.raiseOSError(null, e.getErrorCode(), e.getMessage(), null, null);
        }
    }

    @ExportMessage
    Object acquire(@SuppressWarnings("unused") int flags) {
        return this;
    }

    @ExportMessage
    @SuppressWarnings("static-method")
    boolean hasBuffer() {
        return true;
    }
}
