1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_PATH_SERVICE_H_
6#define BASE_PATH_SERVICE_H_
7#pragma once
8
9#include <string>
10
11#include "base/base_api.h"
12#include "base/base_paths.h"
13#include "build/build_config.h"
14
15class FilePath;
16
17// The path service is a global table mapping keys to file system paths.  It is
18// OK to use this service from multiple threads.
19//
20class BASE_API PathService {
21 public:
22  // Retrieves a path to a special directory or file and places it into the
23  // string pointed to by 'path'. If you ask for a directory it is guaranteed
24  // to NOT have a path separator at the end. For example, "c:\windows\temp"
25  // Directories are also guaranteed to exist when this function succeeds.
26  //
27  // Returns true if the directory or file was successfully retrieved. On
28  // failure, 'path' will not be changed.
29  static bool Get(int key, FilePath* path);
30
31  // Overrides the path to a special directory or file.  This cannot be used to
32  // change the value of DIR_CURRENT, but that should be obvious.  Also, if the
33  // path specifies a directory that does not exist, the directory will be
34  // created by this method.  This method returns true if successful.
35  //
36  // If the given path is relative, then it will be resolved against
37  // DIR_CURRENT.
38  //
39  // WARNING: Consumers of PathService::Get may expect paths to be constant
40  // over the lifetime of the app, so this method should be used with caution.
41  static bool Override(int key, const FilePath& path);
42
43  // To extend the set of supported keys, you can register a path provider,
44  // which is just a function mirroring PathService::Get.  The ProviderFunc
45  // returns false if it cannot provide a non-empty path for the given key.
46  // Otherwise, true is returned.
47  //
48  // WARNING: This function could be called on any thread from which the
49  // PathService is used, so a the ProviderFunc MUST BE THREADSAFE.
50  //
51  typedef bool (*ProviderFunc)(int, FilePath*);
52
53  // Call to register a path provider.  You must specify the range "[key_start,
54  // key_end)" of supported path keys.
55  static void RegisterProvider(ProviderFunc provider,
56                               int key_start,
57                               int key_end);
58 private:
59  static bool GetFromCache(int key, FilePath* path);
60  static bool GetFromOverrides(int key, FilePath* path);
61  static void AddToCache(int key, const FilePath& path);
62};
63
64#endif  // BASE_PATH_SERVICE_H_
65