/*
* Copyright 2017-present Facebook, Inc.
*
* Licensed 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 com.facebook.buck.android.resources;
import com.google.common.collect.ImmutableList;
import java.nio.ByteBuffer;
import java.util.List;
class ChunkUtils {
private ChunkUtils() {}
/**
* Finds all chunks in the buffer with the requested type. This is useful for tests to find chunks
* of a certain type without needing to understand all the other encountered chunks.
*
* @return A list of offsets in the buffer to chunks of the requested type.
*/
static List<Integer> findChunks(ByteBuffer data, int wantedType) {
ByteBuffer buf = ResChunk.slice(data, 0);
ImmutableList.Builder<Integer> offsetsBuilder = ImmutableList.builder();
int offset = 0;
while (offset < buf.limit()) {
int type = buf.getShort(offset);
if (type == wantedType) {
offsetsBuilder.add(offset);
}
int headerSize = buf.getShort(offset + 2);
int chunkSize = buf.getInt(offset + 4);
// These chunks consist of lists of sub-chunks after their headers.
if (type == ResChunk.CHUNK_RESOURCE_TABLE
|| type == ResChunk.CHUNK_RES_TABLE_PACKAGE
|| type == ResChunk.CHUNK_XML_TREE) {
int subchunksStart = offset + headerSize;
int subchunksLength = chunkSize - headerSize;
for (int subOffset :
findChunks(ResChunk.slice(buf, subchunksStart, subchunksLength), wantedType)) {
offsetsBuilder.add(subchunksStart + subOffset);
}
}
offset += chunkSize;
}
return offsetsBuilder.build();
}
}