test/jdk/java/lang/instrument/NamedBuffer.java

*** 1,7 ****
  /*
!  * Copyright (c) 2003, 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.
--- 1,7 ----
  /*
!  * Copyright (c) 2003, 2019, 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.
*** 82,87 ****
--- 82,142 ----
                              resultBuffer,
                              0,
                              actualSize);
          return resultBuffer;
      }
+ 
+     static final String DEST = System.getProperty("test.classes");
+     static final boolean VERBOSE = false;
+ 
+     static boolean checkMatch(byte[] buf, byte[] name, int begIdx) {
+         if (buf.length < name.length + begIdx) {
+             return false;
+         }
+         for (int i = 0; i < name.length; i++) {
+             if (buf[i + begIdx] != name[i]) {
+                 return false;
+             }
+         }
+         return true;
+     }
+ 
+     // This function reads a class file from disk and replaces the first character of
+     // the name with the one passed as "replace".  Then goes through the bytecodes to
+     // replace all instances of the name of the class with the new name.  The
+     // redefinition tests use this to redefine Host$ classes with precompiled class files
+     // Xost.java, Yost.java and Zost.java.
+     static byte[]
+     bytesForHostClass(char replace, String className) throws Throwable {
+         String tail = className.substring(1);
+         String origClassName = "" + replace + tail;
+         File clsfile = new File(DEST + "/" + origClassName + ".class");
+ 
+         if (VERBOSE) {
+             System.out.println("   Reading bytes from " + clsfile);
+         }
+         byte[] buf = null;
+         try (FileInputStream str = new FileInputStream(clsfile)) {
+             buf = loadBufferFromStream(str);
+         }
+ 
+         boolean found = false;
+         int dollarSignIdx = className.indexOf('$');
+         int ptrnLen = (dollarSignIdx == -1) ? className.length() : dollarSignIdx;
+         byte[] ptrnBytes = origClassName.substring(0, ptrnLen).getBytes();
+         byte firstByte = className.getBytes()[0];
+ 
+         for (int i = 0; i < buf.length - ptrnLen; i++) {
+             if (checkMatch(buf, ptrnBytes, i)) {
+                 if (VERBOSE) {
+                     System.out.println("Appear to have found " + origClassName + " starting at " + i);
+                 }
+                 buf[i] = firstByte;
+                 found = true;
+             }
+         }
+         if (!found) {
+             throw new Error("Could not locate '" + ptrnBytes + "' name in byte array");
+         }
+         return buf;
+     }
  }