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143 lines
3.7 KiB
143 lines
3.7 KiB
4 years ago
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/*
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* Copyright 2012 dorkbox, llc
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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 dorkbox.cabParser;
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import java.io.IOException;
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import java.io.InputStream;
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final class CabInputStream extends InputStream {
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private InputStream inputStream;
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private long position;
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private long a;
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private boolean markSupported;
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@Override
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public void close() throws IOException {
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this.inputStream.close();
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}
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@Override
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public synchronized void reset() throws IOException {
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if (this.markSupported) {
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this.inputStream.reset();
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this.position = this.a;
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return;
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}
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throw new IOException();
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}
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CabInputStream(InputStream inputStream) {
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this.inputStream = inputStream;
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this.position = 0L;
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this.markSupported = this.inputStream.markSupported();
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}
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@Override
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public int read() throws IOException {
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int i = this.inputStream.read();
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if (i >= 0) {
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this.position += 1L;
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}
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return i;
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}
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@Override
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public int read(byte[] bytes) throws IOException {
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int i = this.inputStream.read(bytes);
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if (i > 0) {
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this.position += i;
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}
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return i;
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}
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@Override
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public int read(byte[] bytes, int offset, int length) throws IOException {
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int i = this.inputStream.read(bytes, offset, length);
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if (i > 0) {
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this.position += i;
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}
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return i;
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}
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@Override
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public int available() throws IOException {
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throw new IOException();
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}
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@Override
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public synchronized void mark(int paramInt) {
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if (this.markSupported) {
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this.a = this.position;
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this.inputStream.mark(paramInt);
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}
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}
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public long getCurrentPosition() {
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return this.position;
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}
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@Override
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public boolean markSupported() {
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return this.markSupported;
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}
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public void seek(long location) throws IOException {
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if (location < this.position) {
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throw new IOException("Cannot seek backwards");
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}
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if (location > this.position) {
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skip(location - this.position);
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}
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}
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@Override
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public long skip(long ammount) throws IOException {
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long l = betterSkip(this.inputStream, ammount);
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this.position += (int) l;
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return l;
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}
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/**
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* Reliably skips over and discards n bytes of data from the input stream
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* @param is input stream
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* @param n the number of bytes to be skipped
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* @return the actual number of bytes skipped
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* @throws IOException
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*/
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public static long betterSkip(InputStream is, long n) throws IOException {
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long left = n;
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while(left > 0) {
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long l = is.skip(left);
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if(l > 0) {
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left -= l;
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} else if(l == 0) { // should we retry? lets read one byte
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if(is.read() == -1) // EOF
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break;
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else
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left--;
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} else {
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throw new IOException("skip() returned a negative value. This should never happen");
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}
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}
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return n - left;
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}
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}
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