From a153fcd8f2a009b0c5ef35a02ee32f131d0a8d0a Mon Sep 17 00:00:00 2001
From: Dmitry Avdeev <Dmitry.Avdeev@jetbrains.com>
Date: Fri, 11 Nov 2011 12:02:48 +0400
Subject: [PATCH] EA-30655 - CME:
 JspFileViewProviderImpl.getKnownTaglibPrefixes IDEA-76746 Complete freeze of
 the UI

---
 .../src/com/intellij/openapi/vfs/newvfs/VfsImplUtil.java  | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/VfsImplUtil.java b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/VfsImplUtil.java
index 95faccc432d0..e2ac1f0a0d2d 100644
--- a/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/VfsImplUtil.java
+++ b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/VfsImplUtil.java
@@ -15,6 +15,7 @@
  */
 package com.intellij.openapi.vfs.newvfs;
 
+import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NonNls;
@@ -24,8 +25,14 @@ import org.jetbrains.annotations.Nullable;
 import java.io.File;
 
 public class VfsImplUtil {
+  
+  private static final Logger LOG = Logger.getInstance("#com.intellij.openapi.vfs.newvfs.VfsImplUtil");
+  
   @NonNls private static final String FILE_SEPARATORS = "/" + File.separator;
 
+  private VfsImplUtil() {
+  }
+
   @Nullable
   public static VirtualFile findFileByPath(NewVirtualFileSystem vfs, @NotNull @NonNls final String path) {
     final String normalizedPath = vfs.normalize(path);
@@ -83,6 +90,7 @@ public class VfsImplUtil {
     NewVirtualFile file = ManagingFS.getInstance().findRoot(basePath, vfs);
     if (file == null || !file.exists()) return null;
 
+    LOG.assertTrue(basePath.length() <= normalizedPath.length(), vfs + " failed to extract root path: " + basePath + " from " + normalizedPath);
     for (String pathElement : StringUtil.tokenize(normalizedPath.substring(basePath.length()), FILE_SEPARATORS)) {
       if (pathElement.length() == 0 || ".".equals(pathElement)) continue;
       if ("..".equals(pathElement)) {