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/* TestOfPR27372.java
Copyright (C) 2006 Free Software Foundation, Inc.
This file is part of Mauve.
Mauve 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, or (at your option)
any later version.
Mauve 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 Mauve; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.
*/
// Tags: JDK1.2
package gnu.testlet.java.math.BigInteger;
import gnu.testlet.TestHarness;
import gnu.testlet.Testlet;
import java.math.BigInteger;
import java.security.SecureRandom;
import java.util.Arrays;
/**
* Regression test for PR Classpath/27372
*/
public class TestOfPR27372
implements Testlet
{
/** A control value. */
private static final byte[] BYTES = { 0x12, 0x34, 0x56, 0x78 };
/** Set to <code>true</code> if BigInteger is using the GNU MP native code. */
private boolean usingNativeImpl = Arrays.equals(BYTES,
new BigInteger(BYTES).toByteArray());
public void test(TestHarness harness)
{
harness.checkPoint("TestOfPR27372");
SecureRandom prng1, prng2;
byte[] ba, bb;
try
{
prng1 = SecureRandom.getInstance("SHA1PRNG");
prng1.setSeed(98243647L);
prng2 = SecureRandom.getInstance("SHA1PRNG");
prng2.setSeed(98243647L);
// from here on the two PRNGs are in sync. they should consume as
// little bytes as possible, and continue to be in sync
for (int numBytes = 1; numBytes < 10; numBytes++)
{
ba = new BigInteger(8 * numBytes, prng1).toByteArray();
bb = new byte[numBytes];
prng2.nextBytes(bb);
harness.check(areEqual(ba, bb),
"BigInteger(int, Random) SHOULD consume as little "
+ "bytes as possible from Random (and SecureRandom): "
+ numBytes);
}
}
catch (Exception x)
{
harness.debug(x);
harness.fail("TestOfPR27372: " + x);
}
}
/**
* In both cases --the pure Java implementation, and the native one based on
* the GNU MP library-- a BigInteger's toByteArray(), can produce an extra
* 0x00 byte as the most significant byte. This method ensures that there
* is no more than just one zero-byte at the high end, and then channels the
* call to the appropriate are-equal method depending on the type of the
* underlying implementation of the MPI.
*
* @param a the result of a {@link BigInteger#toByteArray()} of an instance
* constructed with {@link BigInteger#BigInteger(int, Random)}.
* @param b a non-null byte array filled with randomly generated values.
* @return <code>true</code> if the two byte arrays contain the same values
* taking into consideration how our BigInteger constructs its
* internal data structures.
*/
private boolean areEqual(byte[] a, byte[] b)
{
int offset = 0;
switch (a.length - b.length)
{
case 0:
break;
case 1:
if (a[0] != 0)
return false;
offset = 1;
break;
default:
return false;
}
if (usingNativeImpl)
return areEqualNativeBI(a, offset, b);
return areEqualJavaBI(a, offset, b);
}
/**
* Special byte array comparison method used to compare the result of
* <code>byte[] a = new BigInteger(numBits, random).toByteArray()</code> with
* a byte array filled with randomly generated values.
* <p>
* This method takes into consideration how an array of bytes is used to
* fill the (pure java) <code>BigInteger</code>'s internal data structure. As
* an example, here is what the two byte arrays may look like from the
* outside:
*
* <pre>
* a = 009ECB38BFD4C6
* b = CB9EC6D4BF38
* </pre>
*
* @param a the result of a {@link BigInteger#toByteArray()} of an instance
* constructed with {@link BigInteger#BigInteger(int, Random)}.
* @param <code>0</code> or <code>1</code> depending on the value of the
* leftmost byte (at index #0) of <code>a</code>.
* @param b a non-null byte array filled with randomly generated values.
* @return <code>true</code> if the two byte arrays contain the same values
* taking into consideration how our BigInteger constructs its
* internal data structures.
*/
private boolean areEqualJavaBI(byte[] a, int offset, byte[] b)
{
for (int i = b.length - 1, j, k; i >= 0; )
{
j = i - 3;
if (j < 0)
j = 0;
for (k = 0; k < 4; k++)
{
if (a[offset + j++] != b[i--])
return false;
if (i < 0)
break;
}
}
return true;
}
/**
* Straight equality check, byte-for-byte, of the two designated arrays. The
* first starting from either <code>0</code> or <code>1</code>, while the
* second always starting from <code>0</code>. This is used with GMP-based
* MPIs.
*
* @param a the result of a {@link BigInteger#toByteArray()} of an instance
* constructed with {@link BigInteger#BigInteger(int, Random)}.
* @param <code>0</code> or <code>1</code> depending on the value of the
* leftmost byte (at index #0) of <code>a</code>.
* @param b a non-null byte array filled with randomly generated values.
* @return <code>true</code> if the two byte arrays contain the same values
* taking into consideration how our BigInteger constructs its
* internal data structures.
*/
private boolean areEqualNativeBI(byte[] a, int offset, byte[] b)
{
for (int i = 0; i < b.length; i++)
if (a[offset + i] != b[i])
return false;
return true;
}
}
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