path_service.h - mozsearch

// 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;

// 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, 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.

//

  // Unit tests generally should use ScopedPathOverride instead. Overrides from

  // one test should not carry over to another.

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

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

  // parameters:

  // - |is_absolute| indicates that |path| has already been expanded into an

  // absolute path, otherwise MakeAbsoluteFilePath() will be used. This is

  // useful to override paths that may not exist yet, since MakeAbsoluteFilePath

  // fails for those. Note that MakeAbsoluteFilePath also expands symbolic

  // links, even if path.IsAbsolute() is already true.

  // - |create| guides whether the directory to be overriden must

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

  static bool OverrideAndCreateIfNeeded(int key,

                                        const FilePath& path,

                                        bool is_absolute,

                                        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, 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 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);

};

}  // namespace base

#endif  // BASE_PATH_SERVICE_H_