Fix FSDirectory.createOutput() to always create new files.

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@179609 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -164,6 +164,12 @@ Bug fixes
     a given amount of milliseconds, but this didn't work.
     (John Wang via Daniel Naber, Bug #33799)
  
+ 8. Fix FSDirectory.createOutput() to always create new files.
+    Previously, existing files were overwritten, and an index could be
+    corrupted when the old version of a file was longer than the new.
+    Now any existing file is first removed.  (Doug Cutting)
+
+
 Optimizations
      
  1. Disk usage (peak requirements during indexing and optimization)

src/java/org/apache/lucene/store/FSDirectory.java

@@ -241,7 +241,7 @@ public class FSDirectory extends Directory {
   public void deleteFile(String name) throws IOException {
     File file = new File(directory, name);
     if (!file.delete())
-      throw new IOException("Cannot delete " + name);
+      throw new IOException("Cannot delete " + file);
   }
 
   /** Renames an existing file in the directory. */
@@ -256,7 +256,7 @@ public class FSDirectory extends Directory {
 
     if (nu.exists())
       if (!nu.delete())
-        throw new IOException("Cannot delete " + to);
+        throw new IOException("Cannot delete " + nu);
 
     // Rename the old file to the new one. Unfortunately, the renameTo()
     // method does not work reliably under some JVMs.  Therefore, if the
@@ -282,7 +282,7 @@ public class FSDirectory extends Directory {
         old.delete();
       }
       catch (IOException ioe) {
-        throw new IOException("Cannot rename " + from + " to " + to);
+        throw new IOException("Cannot rename " + old + " to " + nu);
       }
       finally {
         if (in != null) {
@@ -306,7 +306,11 @@ public class FSDirectory extends Directory {
   /** Creates a new, empty file in the directory with the given name.
       Returns a stream writing this file. */
   public IndexOutput createOutput(String name) throws IOException {
-    return new FSIndexOutput(new File(directory, name));
+    File file = new File(directory, name);
+    if (file.exists() && !file.delete())          // delete existing, if any
+      throw new IOException("Cannot overwrite: " + file);
+
+    return new FSIndexOutput(file);
   }
 
   /** Returns a stream reading an existing file. */