8041918: BootstrapMethods attribute cannot be empty.

Summary: Allow a BootstrapMethods attribute that contains an empty bootstrap_methods table where num_bootstrap_methods is equal to zero.
Reviewed-by: coleenp, hseigel

src/share/vm/classfile/classFileParser.cpp

@@ -2777,7 +2777,7 @@ void ClassFileParser::parse_classfile_bootstrap_methods_attribute(u4 attribute_b
                      "Short length on BootstrapMethods in class file %s",
                      CHECK);
 
-  guarantee_property(attribute_byte_length > sizeof(u2),
+  guarantee_property(attribute_byte_length >= sizeof(u2),
                      "Invalid BootstrapMethods attribute length %u in class file %s",
                      attribute_byte_length,
                      CHECK);

test/runtime/classFileParserBug/TestEmptyBootstrapMethodsAttr.java

+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test TestEmptyBootstrapMethodsAttr
+ * @bug 8041918
+ * @library /testlibrary
+ * @summary Test empty bootstrap_methods table within BootstrapMethods attribute
+ * @compile TestEmptyBootstrapMethodsAttr.java
+ * @run main TestEmptyBootstrapMethodsAttr
+ */
+
+import java.io.File;
+import com.oracle.java.testlibrary.*;
+
+public class TestEmptyBootstrapMethodsAttr {
+
+    public static void main(String args[]) throws Throwable {
+        System.out.println("Regression test for bug 8041918");
+        String jarFile = System.getProperty("test.src") + File.separator + "emptynumbootstrapmethods.jar";
+
+        // ====== extract the test case
+        ProcessBuilder pb = new ProcessBuilder(new String[] { JDKToolFinder.getJDKTool("jar"), "xvf", jarFile } );
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+        output.shouldHaveExitValue(0);
+
+        // Test case #1:
+        // Try loading class with empty bootstrap_methods table where no
+        // other attributes are following BootstrapMethods in attribute table.
+        String className = "emptynumbootstrapmethods1";
+
+        // ======= execute test case #1
+        // Expect a lack of main method, this implies that the class loaded correctly
+        // with an empty bootstrap_methods and did not generate a ClassFormatError.
+        pb = ProcessTools.createJavaProcessBuilder("-cp", ".", className);
+        output = new OutputAnalyzer(pb.start());
+        output.shouldNotContain("java.lang.ClassFormatError");
+        output.shouldContain("Main method not found in class " + className);
+        output.shouldHaveExitValue(1);
+
+        // Test case #2:
+        // Try loading class with empty bootstrap_methods table where an
+        // AnnotationDefault attribute follows the BootstrapMethods in the attribute table.
+        className = "emptynumbootstrapmethods2";
+
+        // ======= execute test case #2
+        // Expect a lack of main method, this implies that the class loaded correctly
+        // with an empty bootstrap_methods and did not generate ClassFormatError.
+        pb = ProcessTools.createJavaProcessBuilder("-cp", ".", className);
+        output = new OutputAnalyzer(pb.start());
+        output.shouldNotContain("java.lang.ClassFormatError");
+        output.shouldContain("Main method not found in class " + className);
+        output.shouldHaveExitValue(1);
+    }
+}

test/runtime/classFileParserBug/emptynumbootstrapmethods1.jcod

+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This test contains a BootstrapMethods attribute with an empty
+ * bootstrap_methods table.  This yields a BootstrapMethods
+ * attribute length of 2 and should not cause a
+ * java.lang.ClassFormatError to be thrown.
+ */
+class emptynumbootstrapmethods1 {
+  0xCAFEBABE;
+  0; // minor version
+  51; // version
+  [12] { // Constant Pool
+    ; // first element is empty
+    class #2; // #1     at 0x0A
+    Utf8 "emptynumbootstrapmethods1"; // #2     at 0x0D
+    class #4; // #3     at 0x1F
+    Utf8 "java/lang/Object"; // #4     at 0x22
+    MethodHandle 5b #9; // #5     at 0x35
+    NameAndType #7 #8; // #6     at 0x39
+    Utf8 "equals"; // #7     at 0x3E
+    Utf8 "(Ljava/lang/Object;)Z"; // #8     at 0x47
+    Method #3 #6; // #9     at 0x5F
+    Utf8 "equalsx"; // #10    at 0x3E
+    Utf8 "BootstrapMethods"; // #11     at 0x69
+  } // Constant Pool
+
+  0x0001; // access
+  #1;// this_cpx
+  #3;// super_cpx
+
+  [0] { // Interfaces
+  } // Interfaces
+
+  [0] { // fields
+  } // fields
+
+  [0] { // methods
+  } // methods
+
+  [1] { // Attributes
+    Attr(#11, 2) { // BootstrapMethods at 0x8A
+      [0] { // bootstrap_methods
+      }
+    } // end BootstrapMethods
+  } // Attributes
+} // end class atrbsm00101m10p

test/runtime/classFileParserBug/emptynumbootstrapmethods2.jcod

+/*
+ * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This test contains a BootstrapMethods attribute with an empty
+ * bootstrap_methods table.  This yields a BootstrapMethods
+ * attribute length of 2 and should not cause a
+ * java.lang.ClassFormatError to be thrown. To ensure that an empty
+ * bootstrap_methods table is parsed correctly, another attribute,
+ * AnnotationDefault, follows the BootstrapMethods attribute in 
+ * the attribute table.
+ */
+
+class emptynumbootstrapmethods2 {
+  0xCAFEBABE;
+  0; // minor version
+  51; // version
+  [14] { // Constant Pool
+    ; // first element is empty
+    class #2; // #1     at 0x0A
+    Utf8 "emptynumbootstrapmethods2"; // #2     at 0x0D
+    class #4; // #3     at 0x1F
+    Utf8 "java/lang/Object"; // #4     at 0x22
+    MethodHandle 5b #9; // #5     at 0x35
+    NameAndType #7 #8; // #6     at 0x39
+    Utf8 "equals"; // #7     at 0x3E
+    Utf8 "(Ljava/lang/Object;)Z"; // #8     at 0x47
+    Method #3 #6; // #9     at 0x5F
+    Utf8 "equalsx"; // #10    at 0x3E
+    Utf8 "BootstrapMethods"; // #11     at 0x69
+    Utf8 "AnnotationDefault"; // #12
+    Utf8 "LAnnotationDefaultI;"; // #13
+  } // Constant Pool
+
+  0x0001; // access
+  #1;// this_cpx
+  #3;// super_cpx
+
+  [0] { // Interfaces
+  } // Interfaces
+
+  [0] { // fields
+  } // fields
+
+  [0] { // methods
+  } // methods
+
+  [2] { // Attributes
+    Attr(#11, 2) { // BootstrapMethods at 0x8A
+      [0] { // bootstrap_methods
+      }
+    } // end BootstrapMethods
+    ;
+    Attr(#12) { // AnnotationDefault
+      [] { // type annotations
+        { // type annotation
+          0x00;  // target_type
+          0x00;  // type_parameter_index
+          []b { //  type_path
+          }
+
+          #13; // type_index
+          [] { // element_value_pairs
+          } // element_value_pairs
+        } // type annotation
+      } // type annotations
+    } // end AnnotationDefault
+  } // Attributes
+} // end class atrbsm00101m10p