byte area for lengths is read in platform endian, but expects big endian
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Key: JENA-91
URL: https://issues.apache.org/jira/browse/JENA-91
Project: Jena
Issue Type: Bug
Components: TDB
Environment: Windows (and I presume any little endian system)
Reporter: Simon Helsen
Priority: Critical
I tried to debug the OME and check why a bytebuffer is causing my native memory
to explode in almost no time. It all seems to happen in this bit of code in
com.hp.hpl.jena.tdb.base.objectfile.ObjectFileStorage (lines 243 onwards)
// No - it's in the underlying file storage.
lengthBuffer.clear() ;
int x = file.read(lengthBuffer, loc) ;
if ( x != 4 )
throw new
FileException("ObjectFile.read("+loc+")["+filesize+"]["+file.size()+"]: Failed
to read the length : got "+x+" bytes") ;
int len = lengthBuffer.getInt(0) ;
ByteBuffer bb = ByteBuffer.allocate(len) ;
My debugger shows that x==4. It also shows the lengthBuffer has the following
content: [111, 110, 61, 95], however the value of len=1869495647, which is
rather a lot :-) Obviously, the next statement (ByteBuffer.allocate) causes the
OME
So, looking into it, lengthBuffer.getInt(0)==1869495647, but
lenghtBuffer.get(0)==111, which seems more correct. Then I noticed that the
bytebuffer also says bigEndian==true. I am running all of this on Windows 7.
which is to the best of my knowledge little endian
I think this can only work correctly if the byteBuffer for lengths (at least)
have their order explicitly set to that of the platform. So, somewhere in the
code, you'd need to make sure to set
lengthBuffer.order(ByteOrder.nativeOrder())
I think this only affects this particular one because it manages lengths, but I
don't know the code well enough to know if there are other places that may be
affected
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