--- a/langtools/src/share/classes/com/sun/tools/javac/util/Log.java	Thu Mar 06 10:07:25 2008 -0800
+++ b/langtools/src/share/classes/com/sun/tools/javac/util/Log.java	Thu Mar 06 10:25:04 2008 -0800
@@ -203,6 +203,10 @@
      */
     private char[] buf = null;
 
+    /** The length of useful data in buf
+     */
+    private int bufLen = 0;
+
     /** The position in the buffer at which last error was reported
      */
     private int bp;
@@ -256,6 +260,7 @@
      */
     protected void setBuf(char[] newBuf) {
         buf = newBuf;
+        bufLen = buf.length;
         bp = 0;
         lineStart = 0;
         line = 1;
@@ -324,7 +329,7 @@
             return;
 
         int lineEnd = lineStart;
-        while (lineEnd < buf.length && buf[lineEnd] != CR && buf[lineEnd] != LF)
+        while (lineEnd < bufLen && buf[lineEnd] != CR && buf[lineEnd] != LF)
             lineEnd++;
         if (lineEnd - lineStart == 0)
             return;
@@ -336,12 +341,15 @@
         writer.flush();
     }
 
-    protected static char[] getCharContent(JavaFileObject fileObject) throws IOException {
+    protected void initBuf(JavaFileObject fileObject) throws IOException {
         CharSequence cs = fileObject.getCharContent(true);
         if (cs instanceof CharBuffer) {
-            return JavacFileManager.toArray((CharBuffer)cs);
+            CharBuffer cb = (CharBuffer) cs;
+            buf = JavacFileManager.toArray(cb);
+            bufLen = cb.limit();
         } else {
-            return cs.toString().toCharArray();
+            buf = cs.toString().toCharArray();
+            bufLen = buf.length;
         }
     }
 
@@ -353,7 +361,7 @@
             return false;
         try {
             if (buf == null) {
-                buf = getCharContent(currentSource());
+                initBuf(currentSource());
                 lineStart = 0;
                 line = 1;
             } else if (lineStart > pos) { // messages don't come in order
@@ -361,10 +369,10 @@
                 line = 1;
             }
             bp = lineStart;
-            while (bp < buf.length && bp < pos) {
+            while (bp < bufLen && bp < pos) {
                 switch (buf[bp++]) {
                 case CR:
-                    if (bp < buf.length && buf[bp] == LF) bp++;
+                    if (bp < bufLen && buf[bp] == LF) bp++;
                     line++;
                     lineStart = bp;
                     break;
@@ -374,7 +382,7 @@
                     break;
                 }
             }
-            return bp <= buf.length;
+            return bp <= bufLen;
         } catch (IOException e) {
             //e.printStackTrace();
             // FIXME: include e.getLocalizedMessage() in error message
@@ -704,7 +712,7 @@
         if (findLine(pos)) {
             int column = 0;
             for (bp = lineStart; bp < pos; bp++) {
-                if (bp >= buf.length)
+                if (bp >= bufLen)
                     return 0;
                 if (buf[bp] == '\t')
                     column = (column / TabInc * TabInc) + TabInc;

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/T6668802.java	Thu Mar 06 10:25:04 2008 -0800
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2008 Sun Microsystems, Inc.  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.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * @test
+ * @bug 6668802
+ * @summary javac handles diagnostics for last line badly, if line not terminated by newline
+ */
+
+import java.io.*;
+import java.util.*;
+
+public class T6668802
+{
+    public static void main(String[] args) throws Exception {
+        new T6668802().run();
+    }
+
+    void run() throws Exception {
+        String test = "public class Test {";
+        File f = writeTestFile("Test.java", test);
+        String[] out = compileBadFile(f);
+        for (String line: out)
+            System.err.println(">>>" + line + "<<<");
+        if (!out[1].equals(test)) {
+            show("expected", test);
+            show("  actual", out[1]);
+            throw new Error("test failed");
+        }
+    }
+
+    File writeTestFile(String path, String contents) throws IOException {
+        File f = new File(path);
+        FileWriter out = new FileWriter(f);
+        out.write(contents);
+        out.close();
+        return f;
+    }
+
+    String[] compileBadFile(File file) throws IOException {
+        List<String> options = new ArrayList<String>();
+        options.add(file.getPath());
+        System.err.println("compile: " + options);
+        String[] opts = options.toArray(new String[options.size()]);
+        StringWriter sw = new StringWriter();
+        PrintWriter out = new PrintWriter(sw);
+        int rc = com.sun.tools.javac.Main.compile(opts, out);
+        if (rc == 0)
+            throw new Error("compilation succeeded unexpectedly");
+        out.close();
+        return sw.toString().split("[\n\r]+");
+    }
+
+    void show(String prefix, String text) {
+        System.err.println(prefix + ": (" + text.length() + ") " + text);
+    }
+}