1 // Copyright (c) 2012 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 8 #include <string> 9 10 #include "base/base_export.h" 11 #include "base/base_paths.h" 12 #include "base/gtest_prod_util.h" 13 #include "build/build_config.h" 14 15 namespace base { 16 17 class FilePath; 18 class ScopedPathOverride; 19 20 // The path service is a global table mapping keys to file system paths. It is 21 // OK to use this service from multiple threads. 22 // 23 class BASE_EXPORT PathService { 24 public: 25 // Populates |path| with a special directory or file. Returns true on success, 26 // in which case |path| is guaranteed to have a non-empty value. On failure, 27 // |path| will not be changed. 28 static bool Get(int key, FilePath* path); 29 30 // Returns the corresponding path; CHECKs that the operation succeeds. 31 static FilePath CheckedGet(int key); 32 33 // Overrides the path to a special directory or file. This cannot be used to 34 // change the value of DIR_CURRENT, but that should be obvious. Also, if the 35 // path specifies a directory that does not exist, the directory will be 36 // created by this method. This method returns true if successful. 37 // 38 // If the given path is relative, then it will be resolved against 39 // DIR_CURRENT. 40 // 41 // WARNING: Consumers of PathService::Get may expect paths to be constant 42 // over the lifetime of the app, so this method should be used with caution. 43 // 44 // Unit tests generally should use ScopedPathOverride instead. Overrides from 45 // one test should not carry over to another. 46 static bool Override(int key, const FilePath& path); 47 48 // This function does the same as PathService::Override but it takes extra 49 // parameters: 50 // - |is_absolute| indicates that |path| has already been expanded into an 51 // absolute path, otherwise MakeAbsoluteFilePath() will be used. This is 52 // useful to override paths that may not exist yet, since MakeAbsoluteFilePath 53 // fails for those. Note that MakeAbsoluteFilePath also expands symbolic 54 // links, even if path.IsAbsolute() is already true. 55 // - |create| guides whether the directory to be overriden must 56 // be created in case it doesn't exist already. 57 static bool OverrideAndCreateIfNeeded(int key, 58 const FilePath& path, 59 bool is_absolute, 60 bool create); 61 62 // To extend the set of supported keys, you can register a path provider, 63 // which is just a function mirroring PathService::Get. The ProviderFunc 64 // returns false if it cannot provide a non-empty path for the given key. 65 // Otherwise, true is returned. 66 // 67 // WARNING: This function could be called on any thread from which the 68 // PathService is used, so a the ProviderFunc MUST BE THREADSAFE. 69 // 70 typedef bool (*ProviderFunc)(int, FilePath*); 71 72 // Call to register a path provider. You must specify the range "[key_start, 73 // key_end)" of supported path keys. 74 static void RegisterProvider(ProviderFunc provider, 75 int key_start, 76 int key_end); 77 78 // Disable internal cache. 79 static void DisableCache(); 80 81 private: 82 friend class ScopedPathOverride; 83 FRIEND_TEST_ALL_PREFIXES(PathServiceTest, RemoveOverride); 84 85 // Removes an override for a special directory or file. Returns true if there 86 // was an override to remove or false if none was present. 87 // NOTE: This function is intended to be used by tests only! 88 static bool RemoveOverride(int key); 89 }; 90 91 } // namespace base 92 93 #endif // BASE_PATH_SERVICE_H_ 94