Fixes bug in file_util::ReplaceExtension that could chop off path...

base/file_util.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/file_util.h"
 
 #include <fstream>
 
 #include "base/logging.h"
 #include "base/string_util.h"
@@ skipping 176 matching lines @@
     if (illegal_characters.contains(wstr[i])) {
       (*file_name)[i] = replace_char;
     }
     ++i;
   }
 #else
 #error wchar_t* should be either UTF-16 or UTF-32
 #endif
 }
 
+// Appends the extension to file adding a '.' if extension doesn't contain one.
+// This does nothing if extension is empty or '.'. This is used internally by
+// ReplaceExtension.
+static void AppendExtension(const std::wstring& extension,
+                            std::wstring* file) {
+  if (!extension.empty() && extension != L".") {
+    if (extension[0] != L'.')
+      file->append(L".");
+    file->append(extension);
+  }
+}
+
 void ReplaceExtension(std::wstring* file_name, const std::wstring& extension) {
   const std::wstring::size_type last_dot = file_name->rfind(L'.');
+  if (last_dot == std::wstring::npos) {
+    // No extension, just append the supplied extension.
+    AppendExtension(extension, file_name);
+    return;
+  }
+  const std::wstring::size_type last_separator =
+      file_name->rfind(kPathSeparator);
+  if (last_separator != std::wstring::npos && last_dot < last_separator) {
+    // File name doesn't have extension, but one of the directories does; don't
+    // replace it, just append the supplied extension. For example
+    // 'c:\tmp.bar\foo'.
+    AppendExtension(extension, file_name);
+    return;
+  }
   std::wstring result = file_name->substr(0, last_dot);
-  if (!extension.empty() && extension != L".") {
-    if (extension.at(0) != L'.')
-      result.append(L".");
-    result.append(extension);
-  }
+  AppendExtension(extension, &result);
   file_name->swap(result);
 }
 
 bool ContentsEqual(const std::wstring& filename1,
                    const std::wstring& filename2) {
   // We open the file in binary format even if they are text files because
   // we are just comparing that bytes are exactly same in both files and not
   // doing anything smart with text formatting.
 #if defined(OS_WIN)
   std::ifstream file1(filename1.c_str(), std::ios::in | std::ios::binary);
@@ skipping 48 matching lines @@
   while ((len = fread(buf, 1, sizeof(buf), file)) > 0) {
     contents->append(buf, len);
   }
   fclose(file);
 
   return true;
 }
 
 }  // namespace