michael@0: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_PATH_SERVICE_H_
michael@0: #define BASE_PATH_SERVICE_H_
michael@0: 
michael@0: #include <string>
michael@0: 
michael@0: #include "base/base_export.h"
michael@0: #include "base/base_paths.h"
michael@0: #include "base/gtest_prod_util.h"
michael@0: #include "build/build_config.h"
michael@0: 
michael@0: namespace base {
michael@0: class FilePath;
michael@0: class ScopedPathOverride;
michael@0: }  // namespace
michael@0: 
michael@0: // The path service is a global table mapping keys to file system paths.  It is
michael@0: // OK to use this service from multiple threads.
michael@0: //
michael@0: class BASE_EXPORT PathService {
michael@0:  public:
michael@0:   // Retrieves a path to a special directory or file and places it into the
michael@0:   // string pointed to by 'path'. If you ask for a directory it is guaranteed
michael@0:   // to NOT have a path separator at the end. For example, "c:\windows\temp"
michael@0:   // Directories are also guaranteed to exist when this function succeeds.
michael@0:   //
michael@0:   // Returns true if the directory or file was successfully retrieved. On
michael@0:   // failure, 'path' will not be changed.
michael@0:   static bool Get(int key, base::FilePath* path);
michael@0: 
michael@0:   // Overrides the path to a special directory or file.  This cannot be used to
michael@0:   // change the value of DIR_CURRENT, but that should be obvious.  Also, if the
michael@0:   // path specifies a directory that does not exist, the directory will be
michael@0:   // created by this method.  This method returns true if successful.
michael@0:   //
michael@0:   // If the given path is relative, then it will be resolved against
michael@0:   // DIR_CURRENT.
michael@0:   //
michael@0:   // WARNING: Consumers of PathService::Get may expect paths to be constant
michael@0:   // over the lifetime of the app, so this method should be used with caution.
michael@0:   static bool Override(int key, const base::FilePath& path);
michael@0: 
michael@0:   // This function does the same as PathService::Override but it takes an extra
michael@0:   // parameter |create| which guides whether the directory to be overriden must
michael@0:   // be created in case it doesn't exist already.
michael@0:   static bool OverrideAndCreateIfNeeded(int key,
michael@0:                                         const base::FilePath& path,
michael@0:                                         bool create);
michael@0: 
michael@0:   // To extend the set of supported keys, you can register a path provider,
michael@0:   // which is just a function mirroring PathService::Get.  The ProviderFunc
michael@0:   // returns false if it cannot provide a non-empty path for the given key.
michael@0:   // Otherwise, true is returned.
michael@0:   //
michael@0:   // WARNING: This function could be called on any thread from which the
michael@0:   // PathService is used, so a the ProviderFunc MUST BE THREADSAFE.
michael@0:   //
michael@0:   typedef bool (*ProviderFunc)(int, base::FilePath*);
michael@0: 
michael@0:   // Call to register a path provider.  You must specify the range "[key_start,
michael@0:   // key_end)" of supported path keys.
michael@0:   static void RegisterProvider(ProviderFunc provider,
michael@0:                                int key_start,
michael@0:                                int key_end);
michael@0: 
michael@0:   // Disable internal cache.
michael@0:   static void DisableCache();
michael@0: 
michael@0:  private:
michael@0:   friend class base::ScopedPathOverride;
michael@0:   FRIEND_TEST_ALL_PREFIXES(PathServiceTest, RemoveOverride);
michael@0: 
michael@0:   // Removes an override for a special directory or file. Returns true if there
michael@0:   // was an override to remove or false if none was present.
michael@0:   // NOTE: This function is intended to be used by tests only!
michael@0:   static bool RemoveOverride(int key);
michael@0: };
michael@0: 
michael@0: #endif  // BASE_PATH_SERVICE_H_