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- /* Copyright (C) 2002-2005 RealVNC Ltd. All Rights Reserved.
- *
- * This is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This software is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this software; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
- * USA.
- */
-
- //
- // rdr::InStream marshalls data from a buffer stored in RDR (RFB Data
- // Representation).
- //
-
- abstract public class InStream {
-
- // check() ensures there is buffer data for at least one item of size
- // itemSize bytes. Returns the number of items in the buffer (up to a
- // maximum of nItems).
-
- public final int check(int itemSize, int nItems) throws Exception {
- if (ptr + itemSize * nItems > end) {
- if (ptr + itemSize > end)
- return overrun(itemSize, nItems);
-
- nItems = (end - ptr) / itemSize;
- }
- return nItems;
- }
-
- public final void check(int itemSize) throws Exception {
- if (ptr + itemSize > end)
- overrun(itemSize, 1);
- }
-
- // readU/SN() methods read unsigned and signed N-bit integers.
-
- public final int readS8() throws Exception {
- check(1); return b[ptr++];
- }
-
- public final int readS16() throws Exception {
- check(2); int b0 = b[ptr++];
- int b1 = b[ptr++] & 0xff; return b0 << 8 | b1;
- }
-
- public final int readS32() throws Exception {
- check(4); int b0 = b[ptr++];
- int b1 = b[ptr++] & 0xff;
- int b2 = b[ptr++] & 0xff;
- int b3 = b[ptr++] & 0xff;
- return b0 << 24 | b1 << 16 | b2 << 8 | b3;
- }
-
- public final int readU8() throws Exception {
- return readS8() & 0xff;
- }
-
- public final int readU16() throws Exception {
- return readS16() & 0xffff;
- }
-
- public final int readU32() throws Exception {
- return readS32() & 0xffffffff;
- }
-
- // readString() reads a string - a U32 length followed by the data.
-
- public final String readString() throws Exception {
- int len = readU32();
- if (len > maxStringLength)
- throw new Exception("InStream max string length exceeded");
-
- char[] str = new char[len];
- int i = 0;
- while (i < len) {
- int j = i + check(1, len - i);
- while (i < j) {
- str[i++] = (char)b[ptr++];
- }
- }
-
- return new String(str);
- }
-
- // maxStringLength protects against allocating a huge buffer. Set it
- // higher if you need longer strings.
-
- public static int maxStringLength = 65535;
-
- public final void skip(int bytes) throws Exception {
- while (bytes > 0) {
- int n = check(1, bytes);
- ptr += n;
- bytes -= n;
- }
- }
-
- // readBytes() reads an exact number of bytes into an array at an offset.
-
- public void readBytes(byte[] data, int offset, int length) throws Exception {
- int offsetEnd = offset + length;
- while (offset < offsetEnd) {
- int n = check(1, offsetEnd - offset);
- System.arraycopy(b, ptr, data, offset, n);
- ptr += n;
- offset += n;
- }
- }
-
- // readOpaqueN() reads a quantity "without byte-swapping". Because java has
- // no byte-ordering, we just use big-endian.
-
- public final int readOpaque8() throws Exception {
- return readU8();
- }
-
- public final int readOpaque16() throws Exception {
- return readU16();
- }
-
- public final int readOpaque32() throws Exception {
- return readU32();
- }
-
- public final int readOpaque24A() throws Exception {
- check(3); int b0 = b[ptr++];
- int b1 = b[ptr++]; int b2 = b[ptr++];
- return b0 << 24 | b1 << 16 | b2 << 8;
- }
-
- public final int readOpaque24B() throws Exception {
- check(3); int b0 = b[ptr++];
- int b1 = b[ptr++]; int b2 = b[ptr++];
- return b0 << 16 | b1 << 8 | b2;
- }
-
- // pos() returns the position in the stream.
-
- abstract public int pos();
-
- // bytesAvailable() returns true if at least one byte can be read from the
- // stream without blocking. i.e. if false is returned then readU8() would
- // block.
-
- public boolean bytesAvailable() { return end != ptr; }
-
- // getbuf(), getptr(), getend() and setptr() are "dirty" methods which allow
- // you to manipulate the buffer directly. This is useful for a stream which
- // is a wrapper around an underlying stream.
-
- public final byte[] getbuf() { return b; }
- public final int getptr() { return ptr; }
- public final int getend() { return end; }
- public final void setptr(int p) { ptr = p; }
-
- // overrun() is implemented by a derived class to cope with buffer overrun.
- // It ensures there are at least itemSize bytes of buffer data. Returns
- // the number of items in the buffer (up to a maximum of nItems). itemSize
- // is supposed to be "small" (a few bytes).
-
- abstract protected int overrun(int itemSize, int nItems) throws Exception;
-
- protected InStream() {}
- protected byte[] b;
- protected int ptr;
- protected int end;
- }
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