96 lines
2.4 KiB
Java
96 lines
2.4 KiB
Java
package android.content.pm;
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import com.android.internal.util.ArrayUtils;
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import java.io.FilterInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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/**
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* A class that limits the amount of data that is read from an InputStream. When
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* the specified length is reached, the stream returns an EOF even if the
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* underlying stream still has more data.
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*
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* @hide
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*/
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public class LimitedLengthInputStream extends FilterInputStream {
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/**
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* The end of the stream where we don't want to allow more data to be read.
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*/
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private final long mEnd;
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/**
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* Current offset in the stream.
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*/
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private long mOffset;
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/**
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* @param in underlying stream to wrap
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* @param offset offset into stream where data starts
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* @param length length of data at offset
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* @throws IOException if an error occurred with the underlying stream
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*/
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public LimitedLengthInputStream(InputStream in, long offset, long length) throws IOException {
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super(in);
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if (in == null) {
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throw new IOException("in == null");
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}
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if (offset < 0) {
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throw new IOException("offset < 0");
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}
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if (length < 0) {
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throw new IOException("length < 0");
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}
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if (length > Long.MAX_VALUE - offset) {
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throw new IOException("offset + length > Long.MAX_VALUE");
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}
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mEnd = offset + length;
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skip(offset);
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mOffset = offset;
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}
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@Override
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public synchronized int read() throws IOException {
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if (mOffset >= mEnd) {
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return -1;
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}
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mOffset++;
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return super.read();
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}
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@Override
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public int read(byte[] buffer, int offset, int byteCount) throws IOException {
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if (mOffset >= mEnd) {
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return -1;
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}
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final int arrayLength = buffer.length;
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ArrayUtils.throwsIfOutOfBounds(arrayLength, offset, byteCount);
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if (mOffset > Long.MAX_VALUE - byteCount) {
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throw new IOException("offset out of bounds: " + mOffset + " + " + byteCount);
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}
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if (mOffset + byteCount > mEnd) {
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byteCount = (int) (mEnd - mOffset);
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}
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final int numRead = super.read(buffer, offset, byteCount);
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mOffset += numRead;
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return numRead;
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}
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@Override
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public int read(byte[] buffer) throws IOException {
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return read(buffer, 0, buffer.length);
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}
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}
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