[jboss-jira] [JBoss JIRA] (JASSIST-175) NPE while replacing FieldAccess with an instruction
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https://issues.jboss.org/browse/JASSIST-175?page=com.atlassian.jira.plugi...
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Shigeru Chiba commented on JASSIST-175:
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I found that the problem was that dead code was included in the bytecode after the code
translation. If bytecode includes a dead code block, it is not possible to generate a
stack map table since its specification does not accept dead code. The reason that the
bytecode included dead code is not a bug of Javassist, rather, a wrong way to use
Javassist --- the last "return $_;". (I agree that Javassist reports it is a
wrong way but checking this would introduce extra runtime overheads.)
I modified Javassist so that it will throw an exception when the bytecode includes a dead
code block (or it will try to remove the dead code.)
NPE while replacing FieldAccess with an instruction
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Key: JASSIST-175
URL: https://issues.jboss.org/browse/JASSIST-175
Project: Javassist
Issue Type: Bug
Reporter: Celestino Bellone
Assignee: Shigeru Chiba
Attachments: testNPE.tar.gz
Hi guys,
I built an application that plays with load-time instrumentation. It worked well until I
tested it on java7.
I had the same problem of PowerMock people (class VerifyError) so I switched to 3.17
snapshot; then I got the followin error while replacing a field access:
{noformat}
java.lang.NullPointerException
at javassist.bytecode.stackmap.MapMaker.fixTypes(MapMaker.java:285)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:140)
at javassist.bytecode.stackmap.MapMaker.make(MapMaker.java:99)
at javassist.bytecode.MethodInfo.rebuildStackMap(MethodInfo.java:423)
at javassist.bytecode.MethodInfo.rebuildStackMapIf6(MethodInfo.java:405)
at javassist.expr.ExprEditor.doit(ExprEditor.java:113)
at javassist.CtClassType.instrument(CtClassType.java:1398)
at com.ejisto.core.classloading.ClassTransformer.transform(ClassTransformer.java:182)
at com.ejisto.core.classloading.ClassTransformer.transform(ClassTransformer.java:137)
at sun.instrument.TransformerManager.transform(TransformerManager.java:188)
at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:424)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:791)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at
org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2901)
at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1170)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1678)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1556)
at org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1209)
[cut]
{noformat}
I found this issue running my application with javassist 3.17 on both java7 and java6.
here attached you can find the code that reproduces this error.
Many thanks for your help!
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