| /* |
| * Copyright (C) 2010 The Android Open Source Project |
| * |
| * 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 libcore.io; |
| |
| import java.io.FileDescriptor; |
| import java.io.IOException; |
| import java.io.RandomAccessFile; |
| import java.nio.ByteOrder; |
| import java.nio.NioUtils; |
| import java.nio.channels.FileChannel; |
| import libcore.io.ErrnoException; |
| import libcore.io.Libcore; |
| import libcore.io.Memory; |
| import static libcore.io.OsConstants.*; |
| |
| /** |
| * A memory-mapped file. Use {@link #mmap} to map a file, {@link #close} to unmap a file, |
| * and either {@link #bigEndianIterator} or {@link #littleEndianIterator} to get a seekable |
| * {@link BufferIterator} over the mapped data. |
| */ |
| public final class MemoryMappedFile implements AutoCloseable { |
| private long address; |
| private final long size; |
| |
| /** |
| * Use this if you've called {@code mmap} yourself. |
| */ |
| public MemoryMappedFile(long address, long size) { |
| this.address = address; |
| this.size = size; |
| } |
| |
| /** |
| * Use this to mmap the whole file read-only. |
| */ |
| public static MemoryMappedFile mmapRO(String path) throws ErrnoException { |
| FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0); |
| long size = Libcore.os.fstat(fd).st_size; |
| long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0); |
| Libcore.os.close(fd); |
| return new MemoryMappedFile(address, size); |
| } |
| |
| /** |
| * Unmaps this memory-mapped file using munmap(2). This is a no-op if close has already been |
| * called. Note that this class does <i>not</i> use finalization; you must call {@code close} |
| * yourself. |
| * |
| * Calling this method invalidates any iterators over this {@code MemoryMappedFile}. It is an |
| * error to use such an iterator after calling {@code close}. |
| */ |
| public synchronized void close() throws ErrnoException { |
| if (address != 0) { |
| Libcore.os.munmap(address, size); |
| address = 0; |
| } |
| } |
| |
| /** |
| * Returns a new iterator that treats the mapped data as big-endian. |
| */ |
| public BufferIterator bigEndianIterator() { |
| return new NioBufferIterator((int) address, (int) size, ByteOrder.nativeOrder() != ByteOrder.BIG_ENDIAN); |
| } |
| |
| /** |
| * Returns a new iterator that treats the mapped data as little-endian. |
| */ |
| public BufferIterator littleEndianIterator() { |
| return new NioBufferIterator((int) address, (int) size, ByteOrder.nativeOrder() != ByteOrder.LITTLE_ENDIAN); |
| } |
| |
| /** |
| * Returns the size in bytes of the memory-mapped region. |
| */ |
| public long size() { |
| return size; |
| } |
| } |