/*

* Licensed to the Apache Software Foundation (ASF) under one or more

* contributor license agreements. See the NOTICE file distributed with

* this work for additional information regarding copyright ownership.

* The ASF licenses this file to You under the Apache 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.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

package org.apache.arrow.c;

import java.nio.Buffer;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.nio.charset.StandardCharsets;

import org.apache.arrow.memory.ArrowBuf;

import org.apache.arrow.memory.BufferAllocator;

import org.apache.arrow.memory.util.MemoryUtil;

/** Utility functions for working with native memory. */

public final class NativeUtil {

public static final byte NULL = 0;

static final int MAX_STRING_LENGTH = Short.MAX_VALUE;

private NativeUtil() {}

/**

* Convert a pointer to a null terminated string into a Java String.

*

* @param cstringPtr pointer to C string

* @return Converted string

*/

public static String toJavaString(long cstringPtr) {

if (cstringPtr == NULL) {

return null;

}

ByteBuffer reader =

MemoryUtil.directBuffer(cstringPtr, MAX_STRING_LENGTH).order(ByteOrder.nativeOrder());

int length = 0;

while (reader.get() != NULL) {

length++;

}

byte[] bytes = new byte[length];

// Force use of base class rewind() to avoid breaking change of ByteBuffer.rewind in JDK9+

((ByteBuffer) ((Buffer) reader).rewind()).get(bytes);

return new String(bytes, 0, length, StandardCharsets.UTF_8);

}

/**

* Convert a native array pointer (void**) to Java array of pointers.

*

* @param arrayPtr Array pointer

* @param size Array size

* @return Array of pointer values as longs

*/

public static long[] toJavaArray(long arrayPtr, int size) {

if (arrayPtr == NULL) {

return null;

}

if (size < 0) {

throw new IllegalArgumentException("Invalid native array size");

}

long[] result = new long[size];

ByteBuffer reader =

MemoryUtil.directBuffer(arrayPtr, Long.BYTES * size).order(ByteOrder.nativeOrder());

for (int i = 0; i < size; i++) {

result[i] = reader.getLong();

}

return result;

}

/**

* Convert Java string to a null terminated string.

*

* @param allocator Buffer allocator for allocating the native string

* @param string Input String to convert

* @return Buffer with a null terminated string or null if the input is null

*/

public static ArrowBuf toNativeString(BufferAllocator allocator, String string) {

if (string == null) {

return null;

}

byte[] bytes = string.getBytes(StandardCharsets.UTF_8);

ArrowBuf buffer = allocator.buffer(bytes.length + 1);

buffer.writeBytes(bytes);

buffer.writeByte(NULL);

return buffer;

}

/**

* Close a buffer if it's not null.

*

* @param buf Buffer to close

*/

public static void closeBuffer(ArrowBuf buf) {

if (buf != null) {

buf.close();

}

}

/**

* Get the address of a buffer or {@value #NULL} if the input buffer is null.

*

* @param buf Buffer to get the address of

* @return Memory address or {@value #NULL}

*/

public static long addressOrNull(ArrowBuf buf) {

if (buf == null) {

return NULL;

}

return buf.memoryAddress();

}

/**

* Get the address of a C Data Interface struct or {@value #NULL} if the input struct is null.

*

* @param struct C Data Interface struct to get the address of

* @return Memory address or {@value #NULL}

*/

public static long addressOrNull(BaseStruct struct) {

if (struct == null) {

return NULL;

}

return struct.memoryAddress();

}

}