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 // 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.

 #ifndef BASE_PATH_SERVICE_H_

 #define BASE_PATH_SERVICE_H_

 #include <string>

 #include "base/base_export.h"

 #include "base/base_paths.h"

 #include "base/gtest_prod_util.h"

 #include "build/build_config.h"

 namespace base {

 class FilePath;

 class ScopedPathOverride;

 }  // namespace

 // The path service is a global table mapping keys to file system paths.  It is

 // OK to use this service from multiple threads.

 //

 class BASE_EXPORT PathService {

  public:

   // Retrieves a path to a special directory or file and places it into the

   // string pointed to by 'path'. If you ask for a directory it is guaranteed

   // to NOT have a path separator at the end. For example, "c:\windows\temp"

   // Directories are also guaranteed to exist when this function succeeds.

   //

   // Returns true if the directory or file was successfully retrieved. On

   // failure, 'path' will not be changed.

   static bool Get(int key, base::FilePath* path);

   // Overrides the path to a special directory or file.  This cannot be used to

   // change the value of DIR_CURRENT, but that should be obvious.  Also, if the

   // path specifies a directory that does not exist, the directory will be

   // created by this method.  This method returns true if successful.

   //

   // If the given path is relative, then it will be resolved against

   // DIR_CURRENT.

   //

   // WARNING: Consumers of PathService::Get may expect paths to be constant

   // over the lifetime of the app, so this method should be used with caution.

   static bool Override(int key, const base::FilePath& path);

   // This function does the same as PathService::Override but it takes an extra

   // parameter |create| which guides whether the directory to be overriden must

   // be created in case it doesn't exist already.

   static bool OverrideAndCreateIfNeeded(int key,

                                         const base::FilePath& path,

                                         bool create);

   // To extend the set of supported keys, you can register a path provider,

   // which is just a function mirroring PathService::Get.  The ProviderFunc

   // returns false if it cannot provide a non-empty path for the given key.

   // Otherwise, true is returned.

   //

   // WARNING: This function could be called on any thread from which the

   // PathService is used, so a the ProviderFunc MUST BE THREADSAFE.

   //

   typedef bool (*ProviderFunc)(int, base::FilePath*);

   // Call to register a path provider.  You must specify the range "[key_start,

   // key_end)" of supported path keys.

   static void RegisterProvider(ProviderFunc provider,

                                int key_start,

                                int key_end);

   // Disable internal cache.

   static void DisableCache();

  private:

   friend class base::ScopedPathOverride;

   FRIEND_TEST_ALL_PREFIXES(PathServiceTest, RemoveOverride);

   // Removes an override for a special directory or file. Returns true if there

   // was an override to remove or false if none was present.

   // NOTE: This function is intended to be used by tests only!

   static bool RemoveOverride(int key);

 };

 #endif  // BASE_PATH_SERVICE_H_