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// Protocol Buffers - Google's data interchange format// Copyright 2008 Google Inc. All rights reserved.// http://code.google.com/p/protobuf///// Redistribution and use in source and binary forms, with or without// modification, are permitted provided that the following conditions are// met://// * Redistributions of source code must retain the above copyright// notice, this list of conditions and the following disclaimer.// * Redistributions in binary form must reproduce the above// copyright notice, this list of conditions and the following disclaimer// in the documentation and/or other materials provided with the// distribution.// * Neither the name of Google Inc. nor the names of its// contributors may be used to endorse or promote products derived from// this software without specific prior written permission.//// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.package com.google.protobuf;import java.io.IOException;import java.io.InputStream;import java.util.ArrayList;import java.util.List;/*** Reads and decodes protocol message fields.** This class contains two kinds of methods: methods that read specific* protocol message constructs and field types (e.g. {@link #readTag()} and* {@link #readInt32()}) and methods that read low-level values (e.g.* {@link #readRawVarint32()} and {@link #readRawBytes}). If you are reading* encoded protocol messages, you should use the former methods, but if you are* reading some other format of your own design, use the latter.** @author kenton@google.com Kenton Varda*/public final class CodedInputStream {/*** Create a new CodedInputStream wrapping the given InputStream.*/public static CodedInputStream newInstance(final InputStream input) {return new CodedInputStream(input);}/*** Create a new CodedInputStream wrapping the given byte array.*/public static CodedInputStream newInstance(final byte[] buf) {return newInstance(buf, 0, buf.length);}/*** Create a new CodedInputStream wrapping the given byte array slice.*/public static CodedInputStream newInstance(final byte[] buf, final int off,final int len) {CodedInputStream result = new CodedInputStream(buf, off, len);try {// Some uses of CodedInputStream can be more efficient if they know// exactly how many bytes are available. By pushing the end point of the// buffer as a limit, we allow them to get this information via// getBytesUntilLimit(). Pushing a limit that we know is at the end of// the stream can never hurt, since we can never past that point anyway.result.pushLimit(len);} catch (InvalidProtocolBufferException ex) {// The only reason pushLimit() might throw an exception here is if len// is negative. Normally pushLimit()'s parameter comes directly off the// wire, so it's important to catch exceptions in case of corrupt or// malicious data. However, in this case, we expect that len is not a// user-supplied value, so we can assume that it being negative indicates// a programming error. Therefore, throwing an unchecked exception is// appropriate.throw new IllegalArgumentException(ex);}return result;}// -----------------------------------------------------------------/*** Attempt to read a field tag, returning zero if we have reached EOF.* Protocol message parsers use this to read tags, since a protocol message* may legally end wherever a tag occurs, and zero is not a valid tag number.*/public int readTag() throws IOException {if (isAtEnd()) {lastTag = 0;return 0;}lastTag = readRawVarint32();if (WireFormat.getTagFieldNumber(lastTag) == 0) {// If we actually read zero (or any tag number corresponding to field// number zero), that's not a valid tag.throw InvalidProtocolBufferException.invalidTag();}return lastTag;}/*** Verifies that the last call to readTag() returned the given tag value.* This is used to verify that a nested group ended with the correct* end tag.** @throws InvalidProtocolBufferException {@code value} does not match the* last tag.*/public void checkLastTagWas(final int value)throws InvalidProtocolBufferException {if (lastTag != value) {throw InvalidProtocolBufferException.invalidEndTag();}}/*** Reads and discards a single field, given its tag value.** @return {@code false} if the tag is an endgroup tag, in which case* nothing is skipped. Otherwise, returns {@code true}.*/public boolean skipField(final int tag) throws IOException {switch (WireFormat.getTagWireType(tag)) {case WireFormat.WIRETYPE_VARINT:readInt32();return true;case WireFormat.WIRETYPE_FIXED64:readRawLittleEndian64();return true;case WireFormat.WIRETYPE_LENGTH_DELIMITED:skipRawBytes(readRawVarint32());return true;case WireFormat.WIRETYPE_START_GROUP:skipMessage();checkLastTagWas(WireFormat.makeTag(WireFormat.getTagFieldNumber(tag),WireFormat.WIRETYPE_END_GROUP));return true;case WireFormat.WIRETYPE_END_GROUP:return false;case WireFormat.WIRETYPE_FIXED32:readRawLittleEndian32();return true;default:throw InvalidProtocolBufferException.invalidWireType();}}/*** Reads and discards an entire message. This will read either until EOF* or until an endgroup tag, whichever comes first.*/public void skipMessage() throws IOException {while (true) {final int tag = readTag();if (tag == 0 || !skipField(tag)) {return;}}}// -----------------------------------------------------------------/** Read a {@code double} field value from the stream. */public double readDouble() throws IOException {return Double.longBitsToDouble(readRawLittleEndian64());}/** Read a {@code float} field value from the stream. */public float readFloat() throws IOException {return Float.intBitsToFloat(readRawLittleEndian32());}/** Read a {@code uint64} field value from the stream. */public long readUInt64() throws IOException {return readRawVarint64();}/** Read an {@code int64} field value from the stream. */public long readInt64() throws IOException {return readRawVarint64();}/** Read an {@code int32} field value from the stream. */public int readInt32() throws IOException {return readRawVarint32();}/** Read a {@code fixed64} field value from the stream. */public long readFixed64() throws IOException {return readRawLittleEndian64();}/** Read a {@code fixed32} field value from the stream. */public int readFixed32() throws IOException {return readRawLittleEndian32();}/** Read a {@code bool} field value from the stream. */public boolean readBool() throws IOException {return readRawVarint32() != 0;}/** Read a {@code string} field value from the stream. */public String readString() throws IOException {final int size = readRawVarint32();if (size <= (bufferSize - bufferPos) && size > 0) {// Fast path: We already have the bytes in a contiguous buffer, so// just copy directly from it.final String result = new String(buffer, bufferPos, size, "UTF-8");bufferPos += size;return result;} else {// Slow path: Build a byte array first then copy it.return new String(readRawBytes(size), "UTF-8");}}/** Read a {@code group} field value from the stream. */public void readGroup(final int fieldNumber,final MessageLite.Builder builder,final ExtensionRegistryLite extensionRegistry)throws IOException {if (recursionDepth >= recursionLimit) {throw InvalidProtocolBufferException.recursionLimitExceeded();}++recursionDepth;builder.mergeFrom(this, extensionRegistry);checkLastTagWas(WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_END_GROUP));--recursionDepth;}/*** Reads a {@code group} field value from the stream and merges it into the* given {@link UnknownFieldSet}.** @deprecated UnknownFieldSet.Builder now implements MessageLite.Builder, so* you can just call {@link #readGroup}.*/@Deprecatedpublic void readUnknownGroup(final int fieldNumber,final MessageLite.Builder builder)throws IOException {// We know that UnknownFieldSet will ignore any ExtensionRegistry so it// is safe to pass null here. (We can't call// ExtensionRegistry.getEmptyRegistry() because that would make this// class depend on ExtensionRegistry, which is not part of the lite// library.)readGroup(fieldNumber, builder, null);}/** Read an embedded message field value from the stream. */public void readMessage(final MessageLite.Builder builder,final ExtensionRegistryLite extensionRegistry)throws IOException {final int length = readRawVarint32();if (recursionDepth >= recursionLimit) {throw InvalidProtocolBufferException.recursionLimitExceeded();}final int oldLimit = pushLimit(length);++recursionDepth;builder.mergeFrom(this, extensionRegistry);checkLastTagWas(0);--recursionDepth;popLimit(oldLimit);}/** Read a {@code bytes} field value from the stream. */public ByteString readBytes() throws IOException {final int size = readRawVarint32();if (size == 0) {return ByteString.EMPTY;} else if (size <= (bufferSize - bufferPos) && size > 0) {// Fast path: We already have the bytes in a contiguous buffer, so// just copy directly from it.final ByteString result = ByteString.copyFrom(buffer, bufferPos, size);bufferPos += size;return result;} else {// Slow path: Build a byte array first then copy it.return ByteString.copyFrom(readRawBytes(size));}}/** Read a {@code uint32} field value from the stream. */public int readUInt32() throws IOException {return readRawVarint32();}/*** Read an enum field value from the stream. Caller is responsible* for converting the numeric value to an actual enum.*/public int readEnum() throws IOException {return readRawVarint32();}/** Read an {@code sfixed32} field value from the stream. */public int readSFixed32() throws IOException {return readRawLittleEndian32();}/** Read an {@code sfixed64} field value from the stream. */public long readSFixed64() throws IOException {return readRawLittleEndian64();}/** Read an {@code sint32} field value from the stream. */public int readSInt32() throws IOException {return decodeZigZag32(readRawVarint32());}/** Read an {@code sint64} field value from the stream. */public long readSInt64() throws IOException {return decodeZigZag64(readRawVarint64());}// =================================================================/*** Read a raw Varint from the stream. If larger than 32 bits, discard the* upper bits.*/public int readRawVarint32() throws IOException {byte tmp = readRawByte();if (tmp >= 0) {return tmp;}int result = tmp & 0x7f;if ((tmp = readRawByte()) >= 0) {result |= tmp << 7;} else {result |= (tmp & 0x7f) << 7;if ((tmp = readRawByte()) >= 0) {result |= tmp << 14;} else {result |= (tmp & 0x7f) << 14;if ((tmp = readRawByte()) >= 0) {result |= tmp << 21;} else {result |= (tmp & 0x7f) << 21;result |= (tmp = readRawByte()) << 28;if (tmp < 0) {// Discard upper 32 bits.for (int i = 0; i < 5; i++) {if (readRawByte() >= 0) {return result;}}throw InvalidProtocolBufferException.malformedVarint();}}}}return result;}/*** Reads a varint from the input one byte at a time, so that it does not* read any bytes after the end of the varint. If you simply wrapped the* stream in a CodedInputStream and used {@link #readRawVarint32(InputStream)}* then you would probably end up reading past the end of the varint since* CodedInputStream buffers its input.*/static int readRawVarint32(final InputStream input) throws IOException {final int firstByte = input.read();if (firstByte == -1) {throw InvalidProtocolBufferException.truncatedMessage();}return readRawVarint32(firstByte, input);}/*** Like {@link #readRawVarint32(InputStream)}, but expects that the caller* has already read one byte. This allows the caller to determine if EOF* has been reached before attempting to read.*/public static int readRawVarint32(final int firstByte, final InputStream input) throws IOException {if ((firstByte & 0x80) == 0) {return firstByte;}int result = firstByte & 0x7f;int offset = 7;for (; offset < 32; offset += 7) {final int b = input.read();if (b == -1) {throw InvalidProtocolBufferException.truncatedMessage();}result |= (b & 0x7f) << offset;if ((b & 0x80) == 0) {return result;}}// Keep reading up to 64 bits.for (; offset < 64; offset += 7) {final int b = input.read();if (b == -1) {throw InvalidProtocolBufferException.truncatedMessage();}if ((b & 0x80) == 0) {return result;}}throw InvalidProtocolBufferException.malformedVarint();}/** Read a raw Varint from the stream. */public long readRawVarint64() throws IOException {int shift = 0;long result = 0;while (shift < 64) {final byte b = readRawByte();result |= (long)(b & 0x7F) << shift;if ((b & 0x80) == 0) {return result;}shift += 7;}throw InvalidProtocolBufferException.malformedVarint();}/** Read a 32-bit little-endian integer from the stream. */public int readRawLittleEndian32() throws IOException {final byte b1 = readRawByte();final byte b2 = readRawByte();final byte b3 = readRawByte();final byte b4 = readRawByte();return (((int)b1 & 0xff) ) |(((int)b2 & 0xff) << 8) |(((int)b3 & 0xff) << 16) |(((int)b4 & 0xff) << 24);}/** Read a 64-bit little-endian integer from the stream. */public long readRawLittleEndian64() throws IOException {final byte b1 = readRawByte();final byte b2 = readRawByte();final byte b3 = readRawByte();final byte b4 = readRawByte();final byte b5 = readRawByte();final byte b6 = readRawByte();final byte b7 = readRawByte();final byte b8 = readRawByte();return (((long)b1 & 0xff) ) |(((long)b2 & 0xff) << 8) |(((long)b3 & 0xff) << 16) |(((long)b4 & 0xff) << 24) |(((long)b5 & 0xff) << 32) |(((long)b6 & 0xff) << 40) |(((long)b7 & 0xff) << 48) |(((long)b8 & 0xff) << 56);}/*** Decode a ZigZag-encoded 32-bit value. ZigZag encodes signed integers* into values that can be efficiently encoded with varint. (Otherwise,* negative values must be sign-extended to 64 bits to be varint encoded,* thus always taking 10 bytes on the wire.)** @param n An unsigned 32-bit integer, stored in a signed int because* Java has no explicit unsigned support.* @return A signed 32-bit integer.*/public static int decodeZigZag32(final int n) {return (n >>> 1) ^ -(n & 1);}/*** Decode a ZigZag-encoded 64-bit value. ZigZag encodes signed integers* into values that can be efficiently encoded with varint. (Otherwise,* negative values must be sign-extended to 64 bits to be varint encoded,* thus always taking 10 bytes on the wire.)** @param n An unsigned 64-bit integer, stored in a signed int because* Java has no explicit unsigned support.* @return A signed 64-bit integer.*/public static long decodeZigZag64(final long n) {return (n >>> 1) ^ -(n & 1);}// -----------------------------------------------------------------private final byte[] buffer;private int bufferSize;private int bufferSizeAfterLimit;private int bufferPos;private final InputStream input;private int lastTag;/*** The total number of bytes read before the current buffer. The total* bytes read up to the current position can be computed as* {@code totalBytesRetired + bufferPos}. This value may be negative if* reading started in the middle of the current buffer (e.g. if the* constructor that takes a byte array and an offset was used).*/private int totalBytesRetired;/** The absolute position of the end of the current message. */private int currentLimit = Integer.MAX_VALUE;/** See setRecursionLimit() */private int recursionDepth;private int recursionLimit = DEFAULT_RECURSION_LIMIT;/** See setSizeLimit() */private int sizeLimit = DEFAULT_SIZE_LIMIT;private static final int DEFAULT_RECURSION_LIMIT = 64;private static final int DEFAULT_SIZE_LIMIT = 64 << 20; // 64MBprivate static final int BUFFER_SIZE = 4096;private CodedInputStream(final byte[] buffer, final int off, final int len) {this.buffer = buffer;bufferSize = off + len;bufferPos = off;totalBytesRetired = -off;input = null;}private CodedInputStream(final InputStream input) {buffer = new byte[BUFFER_SIZE];bufferSize = 0;bufferPos = 0;totalBytesRetired = 0;this.input = input;}/*** Set the maximum message recursion depth. In order to prevent malicious* messages from causing stack overflows, {@code CodedInputStream} limits* how deeply messages may be nested. The default limit is 64.** @return the old limit.*/public int setRecursionLimit(final int limit) {if (limit < 0) {throw new IllegalArgumentException("Recursion limit cannot be negative: " + limit);}final int oldLimit = recursionLimit;recursionLimit = limit;return oldLimit;}/*** Set the maximum message size. In order to prevent malicious* messages from exhausting memory or causing integer overflows,* {@code CodedInputStream} limits how large a message may be.* The default limit is 64MB. You should set this limit as small* as you can without harming your app's functionality. Note that* size limits only apply when reading from an {@code InputStream}, not* when constructed around a raw byte array (nor with* {@link ByteString#newCodedInput}).* <p>* If you want to read several messages from a single CodedInputStream, you* could call {@link #resetSizeCounter()} after each one to avoid hitting the* size limit.** @return the old limit.*/public int setSizeLimit(final int limit) {if (limit < 0) {throw new IllegalArgumentException("Size limit cannot be negative: " + limit);}final int oldLimit = sizeLimit;sizeLimit = limit;return oldLimit;}/*** Resets the current size counter to zero (see {@link #setSizeLimit(int)}).*/public void resetSizeCounter() {totalBytesRetired = -bufferPos;}/*** Sets {@code currentLimit} to (current position) + {@code byteLimit}. This* is called when descending into a length-delimited embedded message.** <p>Note that {@code pushLimit()} does NOT affect how many bytes the* {@code CodedInputStream} reads from an underlying {@code InputStream} when* refreshing its buffer. If you need to prevent reading past a certain* point in the underlying {@code InputStream} (e.g. because you expect it to* contain more data after the end of the message which you need to handle* differently) then you must place a wrapper around you {@code InputStream}* which limits the amount of data that can be read from it.** @return the old limit.*/public int pushLimit(int byteLimit) throws InvalidProtocolBufferException {if (byteLimit < 0) {throw InvalidProtocolBufferException.negativeSize();}byteLimit += totalBytesRetired + bufferPos;final int oldLimit = currentLimit;if (byteLimit > oldLimit) {throw InvalidProtocolBufferException.truncatedMessage();}currentLimit = byteLimit;recomputeBufferSizeAfterLimit();return oldLimit;}private void recomputeBufferSizeAfterLimit() {bufferSize += bufferSizeAfterLimit;final int bufferEnd = totalBytesRetired + bufferSize;if (bufferEnd > currentLimit) {// Limit is in current buffer.bufferSizeAfterLimit = bufferEnd - currentLimit;bufferSize -= bufferSizeAfterLimit;} else {bufferSizeAfterLimit = 0;}}/*** Discards the current limit, returning to the previous limit.** @param oldLimit The old limit, as returned by {@code pushLimit}.*/public void popLimit(final int oldLimit) {currentLimit = oldLimit;recomputeBufferSizeAfterLimit();}/*** Returns the number of bytes to be read before the current limit.* If no limit is set, returns -1.*/public int getBytesUntilLimit() {if (currentLimit == Integer.MAX_VALUE) {return -1;}final int currentAbsolutePosition = totalBytesRetired + bufferPos;return currentLimit - currentAbsolutePosition;}/*** Returns true if the stream has reached the end of the input. This is the* case if either the end of the underlying input source has been reached or* if the stream has reached a limit created using {@link #pushLimit(int)}.*/public boolean isAtEnd() throws IOException {return bufferPos == bufferSize && !refillBuffer(false);}/*** The total bytes read up to the current position. Calling* {@link #resetSizeCounter()} resets this value to zero.*/public int getTotalBytesRead() {return totalBytesRetired + bufferPos;}/*** Called with {@code this.buffer} is empty to read more bytes from the* input. If {@code mustSucceed} is true, refillBuffer() gurantees that* either there will be at least one byte in the buffer when it returns* or it will throw an exception. If {@code mustSucceed} is false,* refillBuffer() returns false if no more bytes were available.*/private boolean refillBuffer(final boolean mustSucceed) throws IOException {if (bufferPos < bufferSize) {throw new IllegalStateException("refillBuffer() called when buffer wasn't empty.");}if (totalBytesRetired + bufferSize == currentLimit) {// Oops, we hit a limit.if (mustSucceed) {throw InvalidProtocolBufferException.truncatedMessage();} else {return false;}}totalBytesRetired += bufferSize;bufferPos = 0;bufferSize = (input == null) ? -1 : input.read(buffer);if (bufferSize == 0 || bufferSize < -1) {throw new IllegalStateException("InputStream#read(byte[]) returned invalid result: " + bufferSize +"\nThe InputStream implementation is buggy.");}if (bufferSize == -1) {bufferSize = 0;if (mustSucceed) {throw InvalidProtocolBufferException.truncatedMessage();} else {return false;}} else {recomputeBufferSizeAfterLimit();final int totalBytesRead =totalBytesRetired + bufferSize + bufferSizeAfterLimit;if (totalBytesRead > sizeLimit || totalBytesRead < 0) {throw InvalidProtocolBufferException.sizeLimitExceeded();}return true;}}/*** Read one byte from the input.** @throws InvalidProtocolBufferException The end of the stream or the current* limit was reached.*/public byte readRawByte() throws IOException {if (bufferPos == bufferSize) {refillBuffer(true);}return buffer[bufferPos++];}/*** Read a fixed size of bytes from the input.** @throws InvalidProtocolBufferException The end of the stream or the current* limit was reached.*/public byte[] readRawBytes(final int size) throws IOException {if (size < 0) {throw InvalidProtocolBufferException.negativeSize();}if (totalBytesRetired + bufferPos + size > currentLimit) {// Read to the end of the stream anyway.skipRawBytes(currentLimit - totalBytesRetired - bufferPos);// Then fail.throw InvalidProtocolBufferException.truncatedMessage();}if (size <= bufferSize - bufferPos) {// We have all the bytes we need already.final byte[] bytes = new byte[size];System.arraycopy(buffer, bufferPos, bytes, 0, size);bufferPos += size;return bytes;} else if (size < BUFFER_SIZE) {// Reading more bytes than are in the buffer, but not an excessive number// of bytes. We can safely allocate the resulting array ahead of time.// First copy what we have.final byte[] bytes = new byte[size];int pos = bufferSize - bufferPos;System.arraycopy(buffer, bufferPos, bytes, 0, pos);bufferPos = bufferSize;// We want to use refillBuffer() and then copy from the buffer into our// byte array rather than reading directly into our byte array because// the input may be unbuffered.refillBuffer(true);while (size - pos > bufferSize) {System.arraycopy(buffer, 0, bytes, pos, bufferSize);pos += bufferSize;bufferPos = bufferSize;refillBuffer(true);}System.arraycopy(buffer, 0, bytes, pos, size - pos);bufferPos = size - pos;return bytes;} else {// The size is very large. For security reasons, we can't allocate the// entire byte array yet. The size comes directly from the input, so a// maliciously-crafted message could provide a bogus very large size in// order to trick the app into allocating a lot of memory. We avoid this// by allocating and reading only a small chunk at a time, so that the// malicious message must actually *be* extremely large to cause// problems. Meanwhile, we limit the allowed size of a message elsewhere.// Remember the buffer markers since we'll have to copy the bytes out of// it later.final int originalBufferPos = bufferPos;final int originalBufferSize = bufferSize;// Mark the current buffer consumed.totalBytesRetired += bufferSize;bufferPos = 0;bufferSize = 0;// Read all the rest of the bytes we need.int sizeLeft = size - (originalBufferSize - originalBufferPos);final List<byte[]> chunks = new ArrayList<byte[]>();while (sizeLeft > 0) {final byte[] chunk = new byte[Math.min(sizeLeft, BUFFER_SIZE)];int pos = 0;while (pos < chunk.length) {final int n = (input == null) ? -1 :input.read(chunk, pos, chunk.length - pos);if (n == -1) {throw InvalidProtocolBufferException.truncatedMessage();}totalBytesRetired += n;pos += n;}sizeLeft -= chunk.length;chunks.add(chunk);}// OK, got everything. Now concatenate it all into one buffer.final byte[] bytes = new byte[size];// Start by copying the leftover bytes from this.buffer.int pos = originalBufferSize - originalBufferPos;System.arraycopy(buffer, originalBufferPos, bytes, 0, pos);// And now all the chunks.for (final byte[] chunk : chunks) {System.arraycopy(chunk, 0, bytes, pos, chunk.length);pos += chunk.length;}// Done.return bytes;}}/*** Reads and discards {@code size} bytes.** @throws InvalidProtocolBufferException The end of the stream or the current* limit was reached.*/public void skipRawBytes(final int size) throws IOException {if (size < 0) {throw InvalidProtocolBufferException.negativeSize();}if (totalBytesRetired + bufferPos + size > currentLimit) {// Read to the end of the stream anyway.skipRawBytes(currentLimit - totalBytesRetired - bufferPos);// Then fail.throw InvalidProtocolBufferException.truncatedMessage();}if (size <= bufferSize - bufferPos) {// We have all the bytes we need already.bufferPos += size;} else {// Skipping more bytes than are in the buffer. First skip what we have.int pos = bufferSize - bufferPos;bufferPos = bufferSize;// Keep refilling the buffer until we get to the point we wanted to skip// to. This has the side effect of ensuring the limits are updated// correctly.refillBuffer(true);while (size - pos > bufferSize) {pos += bufferSize;bufferPos = bufferSize;refillBuffer(true);}bufferPos = size - pos;}}}