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  1. JDK
  2. JDK-4400462

Class format checker doesn't reject classes with duplicated fields/methods



    • generic
    • generic


      Name: viR10068 Date: 12/22/2000

      This bug is a copy of bug 4349751 which was integrated in kest-linux-rc1
      on Jun 30 2000. However, the same bug shows in Merlin-beta-b45 and prevents
      from passing two JCK tests:

      > ======================================================================
      > Class format checker doesn't reject classes with duplicated fields or
      > methods because of the error in heap sort algorithm implementation.
      > It looks like duplicated members detection depends on the fields/methods ordering.
      > We suppose that the bug occurs because of error in implementation of heap sort
      > algorithm in class format checker.
      > We believe that the following fix will help.
      > In file /src/share/native/common/check_format.c (line 1902) variable secondChild
      > should be initialized like this
      > int secondChild = firstChild + 2;
      > instead of
      > int secondChild = firstChild + 4;
      > ======================================================================


      I can't find the JCK tests that failed. Please add a pointer to the test sources or attach the test files. Thanks.

      wei.tao@eng 2001/03/30

      The following example from the bug report 4349751 allows to reproduce this failure:

      "Classes t1 and t2 in example below are nearly equal except of the different
      order of their fields. Class t1 is rejected but t2 is loaded successfully.

      -------------------------------------------------------------- t1.jasm --
      class t1 {
      Field f:I;
      Field f:I;
      Field g:I;
      Field h:I;

      public static Method main:"([Ljava/lang/String;)V"
              stack 0 locals 1
      } // end Class t1

      ------------------------------------------------------------- t2.jasm --
      class t2 {
      Field f:I;
      Field g:I;
      Field f:I;
      Field h:I;

      public static Method main:"([Ljava/lang/String;)V"
              stack 0 locals 1
      } // end Class t2

      Execution log:
      % uname -a
      SunOS novo79 5.8 Generic_108528-03 sun4u sparc SUNW,Ultra-1
      % /export/ld25/java/dest/jdk1.4.0beta-b37/solsparc/bin/java -version
      java version "1.4.0beta"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0beta-b37)
      Java HotSpot(TM) Client VM (build 1.4beta-B37, mixed mode)
      % /export/ld25/java/dest/jdk1.4.0beta-b37/solsparc/bin/java t1
      Exception in thread "main" java.lang.ClassFormatError: t1 (Repeative field name/signature)
              at java.lang.ClassLoader.defineClass0(Native Method)
              at java.lang.ClassLoader.defineClass(ClassLoader.java:486)
              at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:111)
              at java.net.URLClassLoader.defineClass(URLClassLoader.java:248)
              at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
              at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
              at java.security.AccessController.doPrivileged(Native Method)
              at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
              at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
              at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:286)
              at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
              at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)
      % /export/ld25/java/dest/jdk1.4.0beta-b37/solsparc/bin/java t2;echo $status

      The same behavior may be demonstrated for methods too. We tested class which has
      4 methods (init, main and two duplicated) in all possible order combinations
      (24 combinations in total) and found out that JVM was failed to reject class in 50%
      of cases."

      Compiled classes t1.class and t2.class are in the attachment.

      ###@###.### 2001-04-02


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              wtaosunw Wei Tao (Inactive)
              vivsunw Viv Viv (Inactive)
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