Kevin Langman created WICKET-6531:
-------------------------------------
Summary: Crash in Unsafe.getObject when running on the J9 VM
Key: WICKET-6531
URL: https://issues.apache.org/jira/browse/WICKET-6531
Project: Wicket
Issue Type: Bug
Components: wicket
Affects Versions: 8.0.0-M8
Environment: J9 VM (Java7) on AIX
Reporter: Kevin Langman
The CheckingObjectOutputStream class is using introspection of JVM internals to
load object fields and array elements during serialization. This is a risky
business given that there is no guarantee that all JVM implementations will
implement the serialization internals in the same way. For the crash I am
reporting here, we are checking an object that extends BigDecimal, but the J9
VM has its own implementation of BigDecimal and therefore has special handling
of BigDecimal serialization so that it can (for compatibility reasons) mimic
the byte-stream that would be produced by OpenJDK. This results in the
CheckingObjectOutputStream code attempting to read fields out of an object that
does not actually exist in the object, but only reflects the fields that will
be written out to the serialization byte-stream.
In CheckingObjectOutputStream.checkFields() there is code to prevent checking
objects that are instances of String, Number, Date, Boolean and Class. If this
check was also done prior to checking array elements in internalCheck() then
the the crash I am reporting here would not have occurred and therefore I am
proposing that we add the following 'if statement' into the code:
CheckingObjectOutputStream.internalCheck() – Line 394:
for (int i = 0; i < objs.length; i++)
{
*if (objs[i] instanceof String || objs[i] instanceof Number ||*
*objs[i] instanceof Date || objs[i] instanceof Boolean ||*
*objs[i] instanceof Class)*
*{*
*// filter out common cases*
*}else{*
CharSequence arrayPos = new
StringBuilder(4).append('[').append(i).append(']');
simpleName = arrayPos;
fieldDescription += arrayPos;
check(objs[i]);
*}*
}
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