Index: lucene/contrib/misc/src/java/org/apache/lucene/store/WindowsDirectory.java
===================================================================
--- lucene/contrib/misc/src/java/org/apache/lucene/store/WindowsDirectory.java	(revision 1190231)
+++ lucene/contrib/misc/src/java/org/apache/lucene/store/WindowsDirectory.java	(working copy)
@@ -76,6 +76,7 @@
   protected static class WindowsIndexInput extends BufferedIndexInput {
     private final long fd;
     private final long length;
+    private final File path;
     boolean isClone;
     boolean isOpen;
     
@@ -84,6 +85,7 @@
       fd = WindowsDirectory.open(file.getPath());
       length = WindowsDirectory.length(fd);
       isOpen = true;
+      this.path = file;
     }
     
     @Override
@@ -116,6 +118,11 @@
       clone.isClone = true;
       return clone;
     }
+
+    @Override
+    public String toString() {
+      return getClass().getSimpleName() + " path=" + path;
+    }
   }
   
   /** Opens a handle to a file. */
Index: lucene/contrib/misc/src/java/org/apache/lucene/store/DirectIOLinuxDirectory.java
===================================================================
--- lucene/contrib/misc/src/java/org/apache/lucene/store/DirectIOLinuxDirectory.java	(revision 1190231)
+++ lucene/contrib/misc/src/java/org/apache/lucene/store/DirectIOLinuxDirectory.java	(working copy)
@@ -237,6 +237,7 @@
     private final FileInputStream fis;
     private final FileChannel channel;
     private final int bufferSize;
+    private final File path;
 
     private boolean isOpen;
     private boolean isClone;
@@ -254,7 +255,9 @@
       isClone = false;
       filePos = -bufferSize;
       bufferPos = bufferSize;
-      //System.out.println("D open " + path + " this=" + this);
+      //System.out.println("D open " + path + " this=" +
+      //this);
+      this.path = path;
     }
 
     // for clone
@@ -269,6 +272,7 @@
       isClone = true;
       //System.out.println("D clone this=" + this);
       seek(other.getFilePointer());
+      this.path = other.path;
     }
 
     @Override
@@ -368,5 +372,10 @@
         throw new RuntimeException(ioe);
       }
     }
+
+    @Override
+    public String toString() {
+      return getClass().getSimpleName() + " path=" + path;
+    }
   }
 }
Index: lucene/src/test/org/apache/lucene/index/TestBackwardsCompatibility.java
===================================================================
--- lucene/src/test/org/apache/lucene/index/TestBackwardsCompatibility.java	(revision 1190231)
+++ lucene/src/test/org/apache/lucene/index/TestBackwardsCompatibility.java	(working copy)
@@ -122,7 +122,7 @@
                                       "31.optimized.nocfs",
   };
   
-  /** This test checks that *only* IndexFormatTooOldExceptions are throws when you open and operate on too old indexes! */
+  /** This test checks that *only* IndexFormatTooOldExceptions are thrown when you open and operate on too old indexes! */
   public void testUnsupportedOldIndexes() throws Exception {
     for(int i=0;i<unsupportedNames.length;i++) {
       if (VERBOSE) {
@@ -154,6 +154,8 @@
           System.out.println("TEST: got expected exc:");
           e.printStackTrace(System.out);
         }
+        // Make sure exc message includes a path=
+        assertTrue(e.getMessage().indexOf("path=") != -1);
       } finally {
         // we should fail to open IW, and so it should be null when we get here.
         // However, if the test fails (i.e., IW did not fail on open), we need
Index: lucene/src/test/org/apache/lucene/store/TestHugeRamFile.java
===================================================================
--- lucene/src/test/org/apache/lucene/store/TestHugeRamFile.java	(revision 1190231)
+++ lucene/src/test/org/apache/lucene/store/TestHugeRamFile.java	(working copy)
@@ -85,7 +85,7 @@
     }
     out.close();
     // input part
-    RAMInputStream in = new RAMInputStream(f);
+    RAMInputStream in = new RAMInputStream(null, f);
     assertEquals("input length must match",n,in.length());
     //System.out.println("input length = "+in.length()+" % 1024 = "+in.length()%1024);
     for (int j=0; j<L; j++) {
Index: lucene/src/java/org/apache/lucene/index/PrefixCodedTerms.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/PrefixCodedTerms.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/PrefixCodedTerms.java	(working copy)
@@ -56,7 +56,7 @@
 
     PrefixCodedTermsIterator() {
       try {
-        input = new RAMInputStream(buffer);
+        input = new RAMInputStream(null, buffer);
       } catch (IOException e) {
         throw new RuntimeException(e);
       }
Index: lucene/src/java/org/apache/lucene/index/FieldInfos.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/FieldInfos.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/FieldInfos.java	(working copy)
@@ -688,10 +688,10 @@
     format = input.readVInt();
 
     if (format > FORMAT_MINIMUM) {
-      throw new IndexFormatTooOldException(fileName, format, FORMAT_MINIMUM, FORMAT_CURRENT);
+      throw new IndexFormatTooOldException(input, format, FORMAT_MINIMUM, FORMAT_CURRENT);
     }
     if (format < FORMAT_CURRENT) {
-      throw new IndexFormatTooNewException(fileName, format, FORMAT_MINIMUM, FORMAT_CURRENT);
+      throw new IndexFormatTooNewException(input, format, FORMAT_MINIMUM, FORMAT_CURRENT);
     }
 
     final int size = input.readVInt(); //read in the size
Index: lucene/src/java/org/apache/lucene/index/values/Bytes.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/values/Bytes.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/values/Bytes.java	(working copy)
@@ -334,17 +334,17 @@
       IndexInput indexIn = null;
       boolean success = false;
       try {
-      dataIn = dir.openInput(IndexFileNames.segmentFileName(id, "",
-            Writer.DATA_EXTENSION), context);
-      version = CodecUtil.checkHeader(dataIn, codecName, maxVersion, maxVersion);
-      if (doIndex) {
-        indexIn = dir.openInput(IndexFileNames.segmentFileName(id, "",
-            Writer.INDEX_EXTENSION), context);
-        final int version2 = CodecUtil.checkHeader(indexIn, codecName,
-            maxVersion, maxVersion);
-        assert version == version2;
-      }
-      success = true;
+        dataIn = dir.openInput(IndexFileNames.segmentFileName(id, "",
+                                                              Writer.DATA_EXTENSION), context);
+        version = CodecUtil.checkHeader(dataIn, codecName, maxVersion, maxVersion);
+        if (doIndex) {
+          indexIn = dir.openInput(IndexFileNames.segmentFileName(id, "",
+                                                                 Writer.INDEX_EXTENSION), context);
+          final int version2 = CodecUtil.checkHeader(indexIn, codecName,
+                                                     maxVersion, maxVersion);
+          assert version == version2;
+        }
+        success = true;
       } finally {
         if (!success) {
           IOUtils.closeWhileHandlingException(dataIn, indexIn);
Index: lucene/src/java/org/apache/lucene/index/IndexFormatTooOldException.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/IndexFormatTooOldException.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/IndexFormatTooOldException.java	(working copy)
@@ -17,21 +17,31 @@
 
 package org.apache.lucene.index;
 
+import org.apache.lucene.store.DataInput;
+
 /**
  * This exception is thrown when Lucene detects
  * an index that is too old for this Lucene version
  */
 public class IndexFormatTooOldException extends CorruptIndexException {
 
-  public IndexFormatTooOldException(String filename, String version) {
-    super("Format version is not supported" + (filename!=null ? (" in file '" + filename + "'") : "") +
+  public IndexFormatTooOldException(String resource, String version) {
+    super("Format version is not supported" + (resource!=null ? (" in " + resource) : "") +
         ": " + version + ". This version of Lucene only supports indexes created with release 3.0 and later.");
   }
+
+  public IndexFormatTooOldException(DataInput in, String version) {
+    this(in.toString(), version);
+  }
   
-  public IndexFormatTooOldException(String filename, int version, int minVersion, int maxVersion) {
-    super("Format version is not supported" + (filename!=null ? (" in file '" + filename + "'") : "") +
+  public IndexFormatTooOldException(String resource, int version, int minVersion, int maxVersion) {
+    super("Format version is not supported" + (resource!=null ? (" in " + resource) : "") +
         ": " + version + " (needs to be between " + minVersion + " and " + maxVersion +
     "). This version of Lucene only supports indexes created with release 3.0 and later.");
   }
 
+  public IndexFormatTooOldException(DataInput resource, int version, int minVersion, int maxVersion) {
+    this(resource.toString(), version, minVersion, maxVersion);
+  }
+
 }
Index: lucene/src/java/org/apache/lucene/index/IndexFormatTooNewException.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/IndexFormatTooNewException.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/IndexFormatTooNewException.java	(working copy)
@@ -17,15 +17,21 @@
 
 package org.apache.lucene.index;
 
+import org.apache.lucene.store.DataInput;
+
 /**
  * This exception is thrown when Lucene detects
  * an index that is newer than this Lucene version.
  */
 public class IndexFormatTooNewException extends CorruptIndexException {
 
-  public IndexFormatTooNewException(String filename, int version, int minVersion, int maxVersion) {
-    super("Format version is not supported" + (filename!=null ? (" in file '" + filename + "'") : "") +
+  public IndexFormatTooNewException(String resource, int version, int minVersion, int maxVersion) {
+    super("Format version is not supported" + (resource!=null ? (" in " + resource) : "") +
       ": " + version + " (needs to be between " + minVersion + " and " + maxVersion + ")");
   }
 
+  public IndexFormatTooNewException(DataInput resource, int version, int minVersion, int maxVersion) {
+    this(resource.toString(), version, minVersion, maxVersion);
+  }
+
 }
Index: lucene/src/java/org/apache/lucene/index/TermVectorsReader.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/TermVectorsReader.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/TermVectorsReader.java	(working copy)
@@ -17,12 +17,9 @@
  * limitations under the License.
  */
 
-import org.apache.lucene.index.MergePolicy.OneMerge;
-import org.apache.lucene.store.BufferedIndexInput;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.IOContext;
 import org.apache.lucene.store.IndexInput;
-import org.apache.lucene.store.IOContext.Context;
 import org.apache.lucene.util.ArrayUtil;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.IOUtils;
@@ -186,9 +183,9 @@
   {
     int format = in.readInt();
     if (format < FORMAT_MINIMUM)
-      throw new IndexFormatTooOldException(fn, format, FORMAT_MINIMUM, FORMAT_CURRENT);
+      throw new IndexFormatTooOldException(in, format, FORMAT_MINIMUM, FORMAT_CURRENT);
     if (format > FORMAT_CURRENT)
-      throw new IndexFormatTooNewException(fn, format, FORMAT_MINIMUM, FORMAT_CURRENT);
+      throw new IndexFormatTooNewException(in, format, FORMAT_MINIMUM, FORMAT_CURRENT);
     return format;
   }
 
Index: lucene/src/java/org/apache/lucene/index/codecs/preflex/SegmentTermEnum.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/codecs/preflex/SegmentTermEnum.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/codecs/preflex/SegmentTermEnum.java	(working copy)
@@ -18,12 +18,13 @@
  */
 
 import java.io.IOException;
-import org.apache.lucene.store.IndexInput;
+
+import org.apache.lucene.index.CorruptIndexException;
 import org.apache.lucene.index.FieldInfos;
+import org.apache.lucene.index.IndexFormatTooNewException;
+import org.apache.lucene.index.IndexFormatTooOldException;
 import org.apache.lucene.index.Term;
-import org.apache.lucene.index.CorruptIndexException;
-import org.apache.lucene.index.IndexFormatTooOldException;
-import org.apache.lucene.index.IndexFormatTooNewException;
+import org.apache.lucene.store.IndexInput;
 
 /**
  * @deprecated (4.0) No longer used with flex indexing, except for
@@ -70,7 +71,7 @@
     isIndex = isi;
     maxSkipLevels = 1; // use single-level skip lists for formats > -3 
     
-    int firstInt = input.readInt();
+    int firstInt = i.readInt();
     if (firstInt >= 0) {
       // original-format file, without explicit format version number
       format = 0;
@@ -85,9 +86,9 @@
 
       // check that it is a format we can understand
       if (format > FORMAT_MINIMUM)
-        throw new IndexFormatTooOldException(null, format, FORMAT_MINIMUM, FORMAT_CURRENT);
+        throw new IndexFormatTooOldException(i, format, FORMAT_MINIMUM, FORMAT_CURRENT);
       if (format < FORMAT_CURRENT)
-        throw new IndexFormatTooNewException(null, format, FORMAT_MINIMUM, FORMAT_CURRENT);
+        throw new IndexFormatTooNewException(i, format, FORMAT_MINIMUM, FORMAT_CURRENT);
 
       size = input.readLong();                    // read the size
       
Index: lucene/src/java/org/apache/lucene/index/codecs/DefaultSegmentInfosReader.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/codecs/DefaultSegmentInfosReader.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/codecs/DefaultSegmentInfosReader.java	(working copy)
@@ -48,10 +48,10 @@
   
       // check that it is a format we can understand
       if (format > DefaultSegmentInfosWriter.FORMAT_MINIMUM)
-        throw new IndexFormatTooOldException(segmentsFileName, format,
+        throw new IndexFormatTooOldException(input, format,
           DefaultSegmentInfosWriter.FORMAT_MINIMUM, DefaultSegmentInfosWriter.FORMAT_CURRENT);
       if (format < DefaultSegmentInfosWriter.FORMAT_CURRENT)
-        throw new IndexFormatTooNewException(segmentsFileName, format,
+        throw new IndexFormatTooNewException(input, format,
           DefaultSegmentInfosWriter.FORMAT_MINIMUM, DefaultSegmentInfosWriter.FORMAT_CURRENT);
   
       infos.version = input.readLong(); // read version
@@ -92,7 +92,7 @@
           // If it's a 3x index touched by 3.1+ code, then segments record their
           // version, whether they are 2.x ones or not. We detect that and throw
           // appropriate exception.
-          throw new IndexFormatTooOldException(si.name, si.getVersion());
+          throw new IndexFormatTooOldException(input, si.getVersion());
         }
         infos.add(si);
       }
Index: lucene/src/java/org/apache/lucene/index/codecs/DefaultFieldsReader.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/codecs/DefaultFieldsReader.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/index/codecs/DefaultFieldsReader.java	(working copy)
@@ -88,9 +88,9 @@
     try {
       int format = idxStream.readInt();
       if (format < DefaultFieldsWriter.FORMAT_MINIMUM)
-        throw new IndexFormatTooOldException(indexStreamFN, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
+        throw new IndexFormatTooOldException(idxStream, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
       if (format > DefaultFieldsWriter.FORMAT_CURRENT)
-        throw new IndexFormatTooNewException(indexStreamFN, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
+        throw new IndexFormatTooNewException(idxStream, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
     } finally {
       idxStream.close();
     }
@@ -128,9 +128,9 @@
       format = cloneableIndexStream.readInt();
 
       if (format < DefaultFieldsWriter.FORMAT_MINIMUM)
-        throw new IndexFormatTooOldException(indexStreamFN, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
+        throw new IndexFormatTooOldException(cloneableIndexStream, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
       if (format > DefaultFieldsWriter.FORMAT_CURRENT)
-        throw new IndexFormatTooNewException(indexStreamFN, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
+        throw new IndexFormatTooNewException(cloneableIndexStream, format, DefaultFieldsWriter.FORMAT_MINIMUM, DefaultFieldsWriter.FORMAT_CURRENT);
 
       fieldsStream = (IndexInput) cloneableFieldsStream.clone();
 
@@ -271,33 +271,4 @@
 
     return fieldsStream;
   }
-
-  /**
-   * Skip the field.  We still have to read some of the information about the field, but can skip past the actual content.
-   * This will have the most payoff on large fields.
-   */
-  private void skipField(int numeric) throws IOException {
-    final int numBytes;
-    switch(numeric) {
-      case 0:
-        numBytes = fieldsStream.readVInt();
-        break;
-      case DefaultFieldsWriter.FIELD_IS_NUMERIC_INT:
-      case DefaultFieldsWriter.FIELD_IS_NUMERIC_FLOAT:
-        numBytes = 4;
-        break;
-      case DefaultFieldsWriter.FIELD_IS_NUMERIC_LONG:
-      case DefaultFieldsWriter.FIELD_IS_NUMERIC_DOUBLE:
-        numBytes = 8;
-        break;
-      default:
-        throw new FieldReaderException("Invalid numeric type: " + Integer.toHexString(numeric));
-    }
-    
-    skipFieldBytes(numBytes);
-  }
-  
-  private void skipFieldBytes(int toRead) throws IOException {
-    fieldsStream.seek(fieldsStream.getFilePointer() + toRead);
-  }
 }
Index: lucene/src/java/org/apache/lucene/store/NIOFSDirectory.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/NIOFSDirectory.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/store/NIOFSDirectory.java	(working copy)
@@ -83,8 +83,8 @@
   public IndexInputSlicer createSlicer(final String name,
       final IOContext context) throws IOException {
     ensureOpen();
-    final File file = new File(getDirectory(), name);
-    final Descriptor descriptor = new Descriptor(file, "r");
+    final File path = new File(getDirectory(), name);
+    final Descriptor descriptor = new Descriptor(path, "r");
     return new Directory.IndexInputSlicer() {
 
       @Override
@@ -94,7 +94,7 @@
 
       @Override
       public IndexInput openSlice(long offset, long length) throws IOException {
-        return new NIOFSIndexInput(descriptor, descriptor.getChannel(), offset,
+        return new NIOFSIndexInput(path, descriptor, descriptor.getChannel(), offset,
             length, BufferedIndexInput.bufferSize(context), getReadChunkSize());
       }
 
@@ -119,8 +119,8 @@
       channel = file.getChannel();
     }
     
-    public NIOFSIndexInput(Descriptor file, FileChannel fc, long off, long length, int bufferSize, int chunkSize) throws IOException {
-      super(file, off, length, bufferSize, chunkSize);
+    public NIOFSIndexInput(File path, Descriptor file, FileChannel fc, long off, long length, int bufferSize, int chunkSize) throws IOException {
+      super(path, file, off, length, bufferSize, chunkSize);
       channel = fc;
       isClone = true;
     }
Index: lucene/src/java/org/apache/lucene/store/MMapDirectory.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/MMapDirectory.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/store/MMapDirectory.java	(working copy)
@@ -213,7 +213,7 @@
     File f = new File(getDirectory(), name);
     RandomAccessFile raf = new RandomAccessFile(f, "r");
     try {
-      return new MMapIndexInput(raf, 0, raf.length(), chunkSizePower);
+      return new MMapIndexInput(f, raf, 0, raf.length(), chunkSizePower);
     } finally {
       raf.close();
     }
@@ -221,7 +221,7 @@
   
   public IndexInputSlicer createSlicer(final String name, final IOContext context) throws IOException {
     ensureOpen();
-    File f = new File(getDirectory(), name);
+    final File f = new File(getDirectory(), name);
     final RandomAccessFile raf = new RandomAccessFile(f, "r");
     return new IndexInputSlicer() {
       @Override
@@ -231,7 +231,7 @@
 
       @Override
       public IndexInput openSlice(long offset, long length) throws IOException {
-        return new MMapIndexInput(raf, offset, length, chunkSizePower);
+        return new MMapIndexInput(f, raf, offset, length, chunkSizePower);
       }
 
       @Override
@@ -256,8 +256,11 @@
     private ByteBuffer curBuf; // redundant for speed: buffers[curBufIndex]
   
     private boolean isClone = false;
+
+    private final File path;
     
-    MMapIndexInput(RandomAccessFile raf, long offset, long length, int chunkSizePower) throws IOException {
+    MMapIndexInput(File path, RandomAccessFile raf, long offset, long length, int chunkSizePower) throws IOException {
+      this.path = path;
       this.length = length;
       this.chunkSizePower = chunkSizePower;
       this.chunkSize = 1L << chunkSizePower;
@@ -420,6 +423,11 @@
         buffers = null;
       }
     }
+
+    @Override
+    public String toString() {
+      return getClass().getSimpleName() + ": path=" + path;
+    }
   }
 
 }
Index: lucene/src/java/org/apache/lucene/store/Directory.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/Directory.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/store/Directory.java	(working copy)
@@ -344,5 +344,10 @@
         base.copyBytes(out, numBytes);
       }
     }
+
+    @Override
+    public String toString() {
+      return getClass().getSimpleName() + "(" + base + ")";
+    }
   }
 }
Index: lucene/src/java/org/apache/lucene/store/RAMDirectory.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/RAMDirectory.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/store/RAMDirectory.java	(working copy)
@@ -183,7 +183,7 @@
     if (file == null) {
       throw new FileNotFoundException(name);
     }
-    return new RAMInputStream(file);
+    return new RAMInputStream(name, file);
   }
 
   /** Closes the store to future operations, releasing associated memory. */
Index: lucene/src/java/org/apache/lucene/store/SimpleFSDirectory.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/SimpleFSDirectory.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/store/SimpleFSDirectory.java	(working copy)
@@ -74,7 +74,7 @@
 
       @Override
       public IndexInput openSlice(long offset, long length) throws IOException {
-        return new SimpleFSIndexInput(descriptor, offset,
+        return new SimpleFSIndexInput(file, descriptor, offset,
             length, BufferedIndexInput.bufferSize(context), getReadChunkSize());
       }
 
@@ -116,17 +116,20 @@
     protected final int chunkSize;
     protected final long off;
     protected final long end;
+    protected final File path;
     
     public SimpleFSIndexInput(File path, IOContext context, int chunkSize) throws IOException {
       super(context);
+      this.path = path;
       this.file = new Descriptor(path, "r"); 
       this.chunkSize = chunkSize;
       this.off = 0L;
       this.end = file.length;
     }
     
-    public SimpleFSIndexInput(Descriptor file, long off, long length, int bufferSize, int chunkSize) throws IOException {
+    public SimpleFSIndexInput(File path, Descriptor file, long off, long length, int bufferSize, int chunkSize) throws IOException {
       super(bufferSize);
+      this.path = path;
       this.file = file;
       this.chunkSize = chunkSize;
       this.off = off;
@@ -211,5 +214,10 @@
       // If out is FSIndexOutput, the copy will be optimized
       out.copyBytes(this, numBytes);
     }
+
+    @Override
+    public String toString() {
+      return getClass().getSimpleName() + ": path=" + path;
+    }
   }
 }
Index: lucene/src/java/org/apache/lucene/store/ChecksumIndexInput.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/ChecksumIndexInput.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/store/ChecksumIndexInput.java	(working copy)
@@ -73,4 +73,9 @@
   public long length() {
     return main.length();
   }
+
+  @Override
+  public String toString() {
+    return getClass().getSimpleName() + "(" + main.toString() + ")";
+  }
 }
Index: lucene/src/java/org/apache/lucene/store/RAMInputStream.java
===================================================================
--- lucene/src/java/org/apache/lucene/store/RAMInputStream.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/store/RAMInputStream.java	(working copy)
@@ -34,8 +34,9 @@
   private int bufferPosition;
   private long bufferStart;
   private int bufferLength;
+  private final String name;
 
-  public RAMInputStream(RAMFile f) throws IOException {
+  public RAMInputStream(String name, RAMFile f) throws IOException {
     file = f;
     length = file.length;
     if (length/BUFFER_SIZE >= Integer.MAX_VALUE) {
@@ -46,6 +47,7 @@
     // first needed buffer lazily
     currentBufferIndex = -1;
     currentBuffer = null;
+    this.name = name;
   }
 
   @Override
@@ -137,4 +139,9 @@
     }
     bufferPosition = (int) (pos % BUFFER_SIZE);
   }
+
+  @Override
+  public String toString() {
+    return getClass().getSimpleName() + " name=" + name;
+  }
 }
Index: lucene/src/java/org/apache/lucene/util/CodecUtil.java
===================================================================
--- lucene/src/java/org/apache/lucene/util/CodecUtil.java	(revision 1190231)
+++ lucene/src/java/org/apache/lucene/util/CodecUtil.java	(working copy)
@@ -18,14 +18,14 @@
  */
 
 
-import org.apache.lucene.store.DataInput;
-import org.apache.lucene.store.DataOutput;
+import java.io.IOException;
+
 import org.apache.lucene.index.CorruptIndexException;
 import org.apache.lucene.index.IndexFormatTooNewException;
 import org.apache.lucene.index.IndexFormatTooOldException;
+import org.apache.lucene.store.DataInput;
+import org.apache.lucene.store.DataOutput;
 
-import java.io.IOException;
-
 /**
  * @lucene.experimental
  */
@@ -58,20 +58,20 @@
     // Safety to guard against reading a bogus string:
     final int actualHeader = in.readInt();
     if (actualHeader != CODEC_MAGIC) {
-      throw new CorruptIndexException("codec header mismatch: actual header=" + actualHeader + " vs expected header=" + CODEC_MAGIC);
+      throw new CorruptIndexException("codec header mismatch: actual header=" + actualHeader + " vs expected header=" + CODEC_MAGIC + "; input=" + in);
     }
 
     final String actualCodec = in.readString();
     if (!actualCodec.equals(codec)) {
-      throw new CorruptIndexException("codec mismatch: actual codec=" + actualCodec + " vs expected codec=" + codec);
+      throw new CorruptIndexException("codec mismatch: actual codec=" + actualCodec + " vs expected codec=" + codec + "; input=" + in);
     }
 
     final int actualVersion = in.readInt();
     if (actualVersion < minVersion) {
-      throw new IndexFormatTooOldException(null, actualVersion, minVersion, maxVersion);
+      throw new IndexFormatTooOldException(in, actualVersion, minVersion, maxVersion);
     }
     if (actualVersion > maxVersion) {
-      throw new IndexFormatTooNewException(null, actualVersion, minVersion, maxVersion);
+      throw new IndexFormatTooNewException(in, actualVersion, minVersion, maxVersion);
     }
 
     return actualVersion;