/services/java/com/android/server/RandomBlock.java
https://github.com/aizuzi/platform_frameworks_base · Java · 101 lines · 68 code · 12 blank · 21 comment · 6 complexity · 2f74142cfd210f8cfafc42f541d1bb63 MD5 · raw file
- /*
- * Copyright (C) 2009 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 com.android.server;
- import android.util.Slog;
- import java.io.Closeable;
- import java.io.DataOutput;
- import java.io.EOFException;
- import java.io.FileInputStream;
- import java.io.IOException;
- import java.io.InputStream;
- import java.io.RandomAccessFile;
- /**
- * A block of 512 random {@code byte}s.
- */
- class RandomBlock {
- private static final String TAG = "RandomBlock";
- private static final boolean DEBUG = false;
- private static final int BLOCK_SIZE = 512;
- private byte[] block = new byte[BLOCK_SIZE];
- private RandomBlock() { }
- static RandomBlock fromFile(String filename) throws IOException {
- if (DEBUG) Slog.v(TAG, "reading from file " + filename);
- InputStream stream = null;
- try {
- stream = new FileInputStream(filename);
- return fromStream(stream);
- } finally {
- close(stream);
- }
- }
- private static RandomBlock fromStream(InputStream in) throws IOException {
- RandomBlock retval = new RandomBlock();
- int total = 0;
- while(total < BLOCK_SIZE) {
- int result = in.read(retval.block, total, BLOCK_SIZE - total);
- if (result == -1) {
- throw new EOFException();
- }
- total += result;
- }
- return retval;
- }
- void toFile(String filename, boolean sync) throws IOException {
- if (DEBUG) Slog.v(TAG, "writing to file " + filename);
- RandomAccessFile out = null;
- try {
- out = new RandomAccessFile(filename, sync ? "rws" : "rw");
- toDataOut(out);
- truncateIfPossible(out);
- } finally {
- close(out);
- }
- }
- private static void truncateIfPossible(RandomAccessFile f) {
- try {
- f.setLength(BLOCK_SIZE);
- } catch (IOException e) {
- // ignore this exception. Sometimes, the file we're trying to
- // write is a character device, such as /dev/urandom, and
- // these character devices do not support setting the length.
- }
- }
- private void toDataOut(DataOutput out) throws IOException {
- out.write(block);
- }
- private static void close(Closeable c) {
- try {
- if (c == null) {
- return;
- }
- c.close();
- } catch (IOException e) {
- Slog.w(TAG, "IOException thrown while closing Closeable", e);
- }
- }
- }