libgcj/6311: BigInteger Constructor Creates False Results (crypto failures?).

[ray at xmission dot com]

>Number:         6311
>Category:       libgcj
>Synopsis:       BigInteger Constructor Creates False Results (crypto failures?).
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Apr 15 10:16:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Ray Whitmer
>Release:        3.0.4
>Organization:
>Environment:
Installing 3.x gcc tools including gcj from the Mandrake 8.2 release installation disk
>Description:
Java.math.BigInteger has a constructor which accepts a byte array.  By getting the byte array, this makes it possible to easily construct a BigInteger which has the same value.  In the libgcj implementation, some byte arrays produce the wrong big integer.  Attached is a very short test program that demonstrates the problem.  If run in a sun java implementation, the BigInteger constructed from the byteArray is correct.  But if run against libgcj, the BigInteger constructed from the byte array is 0 instead of the correct value.
This could cause Java cryptographic methods to fail.  It only fails on certain numbers.

I haven't looked at the source to determine the cause of the failure.
>How-To-Repeat:
This is simple enough and my gcj build is recent enough (and I produced it on prior builds, but didn't know exactly what caused the problem since it was a large functioning program under a Sun JVM.

The compilation is very straitforward:

gcj --main=BigIntBug -o BigIntBug BigIntBug.java
or on the JVM
javac BigIntBug.java

If I now run BigIntBug, I get:

./BigIntBug
The value is 8483895
Byte 0 is 0
Byte 1 is -127
Byte 2 is 116
Byte 3 is 55
After creating from its own internal array, the value is 0

Notice that a 0 is produced.

If running under a jvm, I get the following:
java -cp . BigIntBug
The value is 8483895
Byte 0 is 0
Byte 1 is -127
Byte 2 is 116
Byte 3 is 55
After creating from its own internal array, the value is 8483895
Notice that the correct result is produced.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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