61 lines
2.2 KiB
Java
61 lines
2.2 KiB
Java
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/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.util.apk;
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import android.annotation.NonNull;
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import android.os.incremental.IncrementalManager;
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import java.io.FileDescriptor;
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import java.io.IOException;
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import java.security.DigestException;
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/** Source of data to be digested. */
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interface DataSource {
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/**
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* Returns the size (in bytes) of the data offered by this source.
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*/
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long size();
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/**
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* Feeds the specified region of this source's data into the provided digester.
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*
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* @param offset offset of the region inside this data source.
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* @param size size (in bytes) of the region.
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*/
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void feedIntoDataDigester(DataDigester md, long offset, int size)
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throws IOException, DigestException;
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/**
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* Creates a DataSource that can handle the passed fd in the most efficient and safe manner.
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* @param fd file descriptor to read from
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* @param pos starting offset
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* @param size size of the region
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* @return created DataSource object
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*/
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static @NonNull DataSource create(@NonNull FileDescriptor fd, long pos, long size) {
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if (IncrementalManager.isIncrementalFileFd(fd)) {
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// IncFS-based files may have missing pages, and reading those via mmap() results
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// in a SIGBUS signal. Java doesn't have a good way of catching it, ending up killing
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// the process by default. Going back to read() is the safest option for these files.
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return new ReadFileDataSource(fd, pos, size);
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} else {
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return new MemoryMappedFileDataSource(fd, pos, size);
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}
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}
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}
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