Truncate the download file name if it exceeds the filesystem limit.

base/file_util.h

 // 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.
 
 // This file contains utility functions for dealing with the local
 // filesystem.
 
 #ifndef BASE_FILE_UTIL_H_
 #define BASE_FILE_UTIL_H_
 
@@ skipping 404 matching lines @@
 // Is |path| writable only by a user with administrator privileges?
 // This function uses Mac OS conventions.  The super user is assumed to have
 // uid 0, and the administrator group is assumed to be named "admin".
 // Testing that |path|, and every parent directory including the root of
 // the filesystem, are owned by the superuser, controlled by the group
 // "admin", are not writable by all users, and contain no symbolic links.
 // Will return false if |path| does not exist.
 BASE_EXPORT bool VerifyPathControlledByAdmin(const base::FilePath& path);
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 
+// Returns the maximum length of path component on the volume containing
+// the directory |path|, in the number of FilePath::CharType, or -1 on failure.
+BASE_EXPORT int GetMaximumPathComponentLength(const base::FilePath& path);
+
 // A class to handle auto-closing of FILE*'s.
 class ScopedFILEClose {
  public:
   inline void operator()(FILE* x) const {
     if (x) {
       fclose(x);
     }
   }
 };
 
@@ skipping 196 matching lines @@
 
 // Attempts determine the FileSystemType for |path|.
 // Returns false if |path| doesn't exist.
 BASE_EXPORT bool GetFileSystemType(const base::FilePath& path,
                                    FileSystemType* type);
 #endif
 
 }  // namespace file_util
 
 #endif  // BASE_FILE_UTIL_H_