Negative check for a HANDLE is invalid.

base/platform_file_win.cc

 // Copyright (c) 2012 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/platform_file.h"
 
 #include <io.h>
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 103 matching lines @@
 
 bool ClosePlatformFile(PlatformFile file) {
   base::ThreadRestrictions::AssertIOAllowed();
   return (CloseHandle(file) != 0);
 }
 
 int64 SeekPlatformFile(PlatformFile file,
                        PlatformFileWhence whence,
                        int64 offset) {
   base::ThreadRestrictions::AssertIOAllowed();
-  if (file < 0 || offset < 0)
+  if (file == kInvalidPlatformFileValue || offset < 0)
     return -1;
 
   LARGE_INTEGER distance, res;
   distance.QuadPart = offset;
   DWORD move_method = static_cast<DWORD>(whence);
   if (!SetFilePointerEx(file, distance, &res, move_method))
     return -1;
   return res.QuadPart;
 }
 
@@ skipping 157 matching lines @@
     case ERROR_DISK_CORRUPT:
       return PLATFORM_FILE_ERROR_IO;
     default:
       UMA_HISTOGRAM_SPARSE_SLOWLY("PlatformFile.UnknownErrors.Windows",
                                   last_error);
       return PLATFORM_FILE_ERROR_FAILED;
   }
 }
 
 }  // namespace base