| /* |
| * 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 android.compat.annotation.UnsupportedAppUsage; |
| import android.system.ErrnoException; |
| |
| import java.io.FileDescriptor; |
| import java.nio.ByteOrder; |
| |
| import static android.system.OsConstants.MAP_SHARED; |
| import static android.system.OsConstants.O_RDONLY; |
| import static android.system.OsConstants.PROT_READ; |
| |
| /** |
| * A memory-mapped file. Use {@link #mmapRO} 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. This class is not thread safe. |
| */ |
| public final class MemoryMappedFile implements AutoCloseable { |
| private boolean closed; |
| private final long address; |
| private final int size; |
| |
| /** Public for layoutlib only. */ |
| public MemoryMappedFile(long address, long size) { |
| this.address = address; |
| // For simplicity when bounds checking, only sizes up to Integer.MAX_VALUE are supported. |
| if (size < 0 || size > Integer.MAX_VALUE) { |
| throw new IllegalArgumentException("Unsupported file size=" + size); |
| } |
| this.size = (int) size; |
| } |
| |
| /** |
| * Use this to mmap the whole file read-only. |
| */ |
| @UnsupportedAppUsage |
| public static MemoryMappedFile mmapRO(String path) throws ErrnoException { |
| FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0); |
| try { |
| long size = Libcore.os.fstat(fd).st_size; |
| long address = Libcore.os.mmap(0L, size, PROT_READ, MAP_SHARED, fd, 0); |
| return new MemoryMappedFile(address, size); |
| } finally { |
| Libcore.os.close(fd); |
| } |
| } |
| |
| /** |
| * 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 void close() throws ErrnoException { |
| if (!closed) { |
| closed = true; |
| Libcore.os.munmap(address, size); |
| } |
| } |
| |
| public boolean isClosed() { |
| return closed; |
| } |
| |
| /** |
| * Returns a new iterator that treats the mapped data as big-endian. |
| */ |
| @UnsupportedAppUsage |
| public BufferIterator bigEndianIterator() { |
| return new NioBufferIterator( |
| this, address, size, ByteOrder.nativeOrder() != ByteOrder.BIG_ENDIAN); |
| } |
| |
| /** |
| * Returns a new iterator that treats the mapped data as little-endian. |
| */ |
| public BufferIterator littleEndianIterator() { |
| return new NioBufferIterator( |
| this, this.address, this.size, ByteOrder.nativeOrder() != ByteOrder.LITTLE_ENDIAN); |
| } |
| |
| /** Throws {@link IllegalStateException} if the file is closed. */ |
| void checkNotClosed() { |
| if (closed) { |
| throw new IllegalStateException("MemoryMappedFile is closed"); |
| } |
| } |
| |
| /** |
| * Returns the size in bytes of the memory-mapped region. |
| */ |
| public int size() { |
| checkNotClosed(); |
| return size; |
| } |
| } |