NativeBuffer.java
/*
** Module : NativeBuffer.java
** Abstract : descriptor for memptr as an argument or return value to a native function
**
** Copyright (c) 2014-2023, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description---------------------------------
** 001 GES 20140107 First version.
** 002 JJD 20220524 Zero-length pointers are no longer treated as NULL. These arise from external
** FFI calls.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
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** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
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*/
package com.goldencode.p2j.library;
import java.io.*;
import java.math.*;
import com.goldencode.p2j.util.*;
/**
* A descriptor for memptr as an argument or return value to a native function.
*/
public class NativeBuffer
extends BaseNativeType
{
/** The stored value. */
protected memptr value;
/**
* Default constructor.
*/
public NativeBuffer()
{
super();
type = LibraryManager.TYPE_POINTER;
}
/**
* Access the data element.
*
* @return The buffer.
*/
public memptr getValue()
{
return value;
}
/**
* Assign the data element.
*
* @param value
* The buffer.
*/
public void setValue(memptr value)
{
this.value = value;
}
/**
* Replacement for the default object reading method. The latest
* state is read from the input source. The parent's state is
* read first.
*
* @param in
* The input source from which fields will be restored.
*
* @throws IOException
* In case of I/O errors.
* @throws ClassNotFoundException
* If payload can't be instantiated.
*/
public void readExternal(ObjectInput in)
throws IOException,
ClassNotFoundException
{
super.readExternal(in);
value = (memptr) in.readObject();
}
/**
* Replacement for the default object writing method. The latest
* state is written to the output destination. The parent's state is
* written first.
*
* @param out
* The output destination to which fields will be saved.
*
* @throws IOException
* In case of I/O errors.
*/
public void writeExternal(ObjectOutput out)
throws IOException
{
super.writeExternal(out);
out.writeObject(value);
}
/**
* Report the size (in bytes) of the native memory needed to store this instance.
* <p>
* This should never be called on the server, only on the client side.
*
* @return This is always the size of a pointer on the client platform.
*/
public int size()
{
return LibraryManager.ptrSize();
}
/**
* Render the data's address into native memory if an explicit address is provided and
* return the data's address to the caller.
* <p>
* This should never be called on the server, only on the client side.
*
* @param addr
* The memory address to which the data should be rendered, if the caller
* is supplying a buffer or 0 if the target address should be returned
* directly (without further allocation or writing the address to any
* buffer).
*
* @return The memory address of the data value or 0 if there is no data to output.
*/
public long render(long addr)
{
long target = 0;
// null, unknown value, uninitialized or are written as a null
// pointer (any failures for these cases have already been screened out, so
// by the time we get here it is OK to output the 0 (null pointer address)
//
// Note that 0-size values are not treated as a null pointer here, as 0-size
// memptr values may be returned from C FFI functions.
if (value != null && !value.isUnknown() && !value.isUninitialized())
{
target = value.getPointerValue().longValue();
}
// - return parms (always scalar) do not call through here
// - non-return scalar parm types will have addr == 0 and we just need to return the
// target address of our memptr
// - array elements will be called with addr != 0 because the address needs to be
// written to memory controlled by the caller
if (addr != 0)
{
memptr local = new memptr();
local.setPointerValue(addr);
if (size() == 4)
{
local.setLong(target, 1);
}
else
{
local.setInt64(target, 1);
}
}
return target;
}
/**
* Copy back (if necessary) data from the native memory, if given.
* <p>
* This should never be called on the server, only on the client side.
*
* @param addr
* The memory address from which the data should be restored, if the caller
* is supplying a buffer or 0 if there is no data to copy back.
*/
public void restore(long addr)
{
// only process if the setup code on the server marked this as a case in which to
// copy back
if (copyOut)
{
// - return parms (always scalar) will have addr != 0 and we must read the pointer
// at that address and set it into our instance data
// - non-return scalar parm types will have addr == 0 and must have had a valid data
// address during render() so there is nothing to do here
// target address of our memptr
// - array elements will be called with addr != 0 because the address needs to be
// copied back from memory controlled by the caller
if (addr != 0)
{
memptr local = new memptr();
local.setPointerValue(addr);
int64 val = null;
if (size() == 4)
{
val = local.getLong(1);
}
else
{
val = local.getInt64(1);
}
if (!val.isUnknown())
{
long target = val.longValue();
if (value == null)
value = new memptr();
value.setPointerValue(target);
}
}
}
}
}