/**
* Exactly like skipRawBytes, but caller must have already checked the fast path: (size <=
* (bufferSize - pos) && size >= 0)
*/
private void skipRawBytesSlowPath(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();
}
// 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(1);
while (size - pos > bufferSize) {
pos += bufferSize;
bufferPos = bufferSize;
refillBuffer(1);
}
bufferPos = size - pos;
}
/**
* 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 your {@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;
}
/**
* Exactly like readRawBytes, but caller must have already checked the fast path: (size <=
* (bufferSize - pos) && size > 0)
*/
private byte[] readRawBytesSlowPath(final int size) throws IOException {
if (size <= 0) {
if (size == 0) {
return Internal.EMPTY_BYTE_ARRAY;
} else {
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 < 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 refill the buffer and then copy from the buffer into our
// byte array rather than reading directly into our byte array because
// the input may be unbuffered.
ensureAvailable(size - pos);
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;
}
}
