1 /* 2 * Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 /* @test 25 * @bug 4400571 26 * @summary Verify that ObjectInputStream.available() functions properly when 27 * called at the beginning of a data block, and that it does not 28 * attempt any read operations that may potentially block. 29 */ 30 31 import java.io.*; 32 33 public class Available { main(String[] args)34 public static void main(String[] args) throws Exception { 35 ObjectOutputStream oout; 36 ByteArrayOutputStream bout; 37 byte[] buf; 38 39 // write stream containing short data block 40 oout = new ObjectOutputStream(bout = new ByteArrayOutputStream()); 41 oout.write(new byte[100]); 42 oout.close(); 43 buf = bout.toByteArray(); 44 45 // 4 byte stream header + 2 byte block header + data 46 if ((getAvailable(buf, 4) != 0) || (getAvailable(buf, 5) != 0)) { 47 throw new Error(); 48 } 49 for (int i = 0; i < 100; i++) { 50 if (getAvailable(buf, 6 + i) != i) { 51 throw new Error(); 52 } 53 } 54 55 // write stream containing long data block 56 oout = new ObjectOutputStream(bout = new ByteArrayOutputStream()); 57 oout.write(new byte[500]); 58 oout.close(); 59 buf = bout.toByteArray(); 60 61 // 4 byte stream header + 5 byte block header + data 62 for (int i = 4; i < 9; i++) { 63 if (getAvailable(buf, i) != 0) { 64 throw new Error(); 65 } 66 } 67 for (int i = 0; i < 500; i++) { 68 if (getAvailable(buf, 9 + i) != i) { 69 throw new Error(); 70 } 71 } 72 } 73 74 /** 75 * Given a byte array containing a serialized stream, creates a copy of the 76 * given data truncated to the specified length, then returns the result of 77 * a call to available() on an ObjectInputStream created on top of the 78 * truncated data. As a side effect, a StreamCorrupted or EOFException 79 * will get thrown if the available() call attempts to read past the 80 * underlying stream's available data. 81 */ getAvailable(byte[] data, int truncateLen)82 static int getAvailable(byte[] data, int truncateLen) throws IOException { 83 byte[] trunc = new byte[truncateLen]; 84 System.arraycopy(data, 0, trunc, 0, truncateLen); 85 return new ObjectInputStream( 86 new ByteArrayInputStream(trunc)).available(); 87 } 88 } 89