[jboss-jira] [JBoss JIRA] (JASSIST-221) Got NPE when replacing a method in `instrument()`

[ https://issues.jboss.org/browse/JASSIST-221?page=com.atlassian.jira.plugi... ] Goro Fuji updated JASSIST-221: ------------------------------ Description: I'm trying to modify some code in static initializer with {{m.replace("$_ = ($r)false;")}}, but I got NPE: {code} Caused by: java.lang.NullPointerException at javassist.bytecode.ConstPool.getMethodrefNameAndType(ConstPool.java:418) at javassist.expr.MethodCall.getNameAndType(MethodCall.java:43) at javassist.expr.MethodCall.getMethodName(MethodCall.java:107) at com.github.gfx.debugassert.DebugAssertPlugin$2.edit(DebugAssertPlugin.groovy:82) at javassist.expr.ExprEditor.loopBody(ExprEditor.java:192) at javassist.expr.ExprEditor.doit(ExprEditor.java:91) at javassist.CtBehavior.instrument(CtBehavior.java:712) at javassist.CtBehavior$instrument.call(Unknown Source) {code} I guess it is because the static initializer has no method name, but ClassPool expects a method (behavior) should have a name. ref. https://github.com/jboss-javassist/javassist/blob/master/src/main/javassi... The NEP is thrown there: https://github.com/gfx/Gradle-DebugAssertPlugin/blob/master/buildSrc/src/... (Currently I use a patched version of javassist which is stored in the repo, so the project works as expected.) {code} // line 77 at DebugAssertPlugin.groovy CtClass c = classPool.getCtClass(className) c.getClassInitializer()?.instrument(new ExprEditor() { @Override void edit(MethodCall m) throws CannotCompileException { if (m.className == "java.lang.Class" && m.methodName == "desiredAssertionStatus") { m.replace('{ $_ = ($r)true; }') // raises NPE! } } }) {code} FYI, I have correct results with the following patch: {code} diff --git a/src/main/javassist/bytecode/ConstPool.java b/src/main/javassist/bytecode/ConstPool.java index f102421..9e62c89 100644 --- a/src/main/javassist/bytecode/ConstPool.java +++ b/src/main/javassist/bytecode/ConstPool.java @@ -265,6 +265,9 @@ public final class ConstPool { */ public int getNameAndTypeName(int index) { NameAndTypeInfo ntinfo = (NameAndTypeInfo)getItem(index); + if (ntinfo == null) { + return 0; + } return ntinfo.memberName; } @@ -415,6 +418,9 @@ public final class ConstPool { */ public int getMethodrefNameAndType(int index) { MethodrefInfo minfo = (MethodrefInfo)getItem(index); + if (minfo == null) { + return 0; + } return minfo.nameAndTypeIndex; } @@ -635,6 +641,9 @@ public final class ConstPool { */ public String getUtf8Info(int index) { Utf8Info utf = (Utf8Info)getItem(index); + if (utf == null) { + return null; + } return utf.string; } {code} was: I'm trying to modify some code in static initializer with {{m.replace("$_ = ($r)false;")}}, but I got NPE: {code} Caused by: java.lang.NullPointerException at javassist.bytecode.ConstPool.getMethodrefNameAndType(ConstPool.java:418) at javassist.expr.MethodCall.getNameAndType(MethodCall.java:43) at javassist.expr.MethodCall.getMethodName(MethodCall.java:107) at com.github.gfx.javassistexamp.JavassistExample$2.edit(JavassistExample.groovy:29) at javassist.expr.ExprEditor.loopBody(ExprEditor.java:192) at javassist.expr.ExprEditor.doit(ExprEditor.java:91) at javassist.CtBehavior.instrument(CtBehavior.java:712) at javassist.CtBehavior$instrument.call(Unknown Source) {code} I guess it is because the static initializer has no method name, but ClassPool expects a method (behavior) should have a name. ref. https://github.com/jboss-javassist/javassist/blob/master/src/main/javassi... The NEP is caused by here: https://github.com/gfx/Gradle-DebugAssertPlugin/blob/master/buildSrc/src/... (Currently I use a patched version of javassist which is stored in the repo, so the project works as expected.) FYI, I have correct results with the following patch: {code} diff --git a/src/main/javassist/bytecode/ConstPool.java b/src/main/javassist/bytecode/ConstPool.java index f102421..9e62c89 100644 --- a/src/main/javassist/bytecode/ConstPool.java +++ b/src/main/javassist/bytecode/ConstPool.java @@ -265,6 +265,9 @@ public final class ConstPool { */ public int getNameAndTypeName(int index) { NameAndTypeInfo ntinfo = (NameAndTypeInfo)getItem(index); + if (ntinfo == null) { + return 0; + } return ntinfo.memberName; } @@ -415,6 +418,9 @@ public final class ConstPool { */ public int getMethodrefNameAndType(int index) { MethodrefInfo minfo = (MethodrefInfo)getItem(index); + if (minfo == null) { + return 0; + } return minfo.nameAndTypeIndex; } @@ -635,6 +641,9 @@ public final class ConstPool { */ public String getUtf8Info(int index) { Utf8Info utf = (Utf8Info)getItem(index); + if (utf == null) { + return null; + } return utf.string; } {code} -- This message was sent by Atlassian JIRA (v6.2.3#6260)