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 #include "base/path_service.h" 6 7 #if defined(OS_WIN) 8 #include <windows.h> 9 #include <shellapi.h> 10 #include <shlobj.h> 11 #endif 12 13 #include "base/containers/hash_tables.h" 14 #include "base/file_util.h" 15 #include "base/files/file_path.h" 16 #include "base/lazy_instance.h" 17 #include "base/logging.h" 18 #include "base/synchronization/lock.h" 19 20 using base::FilePath; 21 using base::MakeAbsoluteFilePath; 22 23 namespace base { 24 bool PathProvider(int key, FilePath* result); 25 #if defined(OS_WIN) 26 bool PathProviderWin(int key, FilePath* result); 27 #elif defined(OS_MACOSX) 28 bool PathProviderMac(int key, FilePath* result); 29 #elif defined(OS_ANDROID) 30 bool PathProviderAndroid(int key, FilePath* result); 31 #elif defined(OS_POSIX) 32 // PathProviderPosix is the default path provider on POSIX OSes other than 33 // Mac and Android. 34 bool PathProviderPosix(int key, FilePath* result); 35 #endif 36 } 37 38 namespace { 39 40 typedef base::hash_map<int, FilePath> PathMap; 41 42 // We keep a linked list of providers. In a debug build we ensure that no two 43 // providers claim overlapping keys. 44 struct Provider { 45 PathService::ProviderFunc func; 46 struct Provider* next; 47 #ifndef NDEBUG 48 int key_start; 49 int key_end; 50 #endif 51 bool is_static; 52 }; 53 54 Provider base_provider = { 55 base::PathProvider, 56 NULL, 57 #ifndef NDEBUG 58 base::PATH_START, 59 base::PATH_END, 60 #endif 61 true 62 }; 63 64 #if defined(OS_WIN) 65 Provider base_provider_win = { 66 base::PathProviderWin, 67 &base_provider, 68 #ifndef NDEBUG 69 base::PATH_WIN_START, 70 base::PATH_WIN_END, 71 #endif 72 true 73 }; 74 #endif 75 76 #if defined(OS_MACOSX) 77 Provider base_provider_mac = { 78 base::PathProviderMac, 79 &base_provider, 80 #ifndef NDEBUG 81 base::PATH_MAC_START, 82 base::PATH_MAC_END, 83 #endif 84 true 85 }; 86 #endif 87 88 #if defined(OS_ANDROID) 89 Provider base_provider_android = { 90 base::PathProviderAndroid, 91 &base_provider, 92 #ifndef NDEBUG 93 base::PATH_ANDROID_START, 94 base::PATH_ANDROID_END, 95 #endif 96 true 97 }; 98 #endif 99 100 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID) 101 Provider base_provider_posix = { 102 base::PathProviderPosix, 103 &base_provider, 104 #ifndef NDEBUG 105 base::PATH_POSIX_START, 106 base::PATH_POSIX_END, 107 #endif 108 true 109 }; 110 #endif 111 112 113 struct PathData { 114 base::Lock lock; 115 PathMap cache; // Cache mappings from path key to path value. 116 PathMap overrides; // Track path overrides. 117 Provider* providers; // Linked list of path service providers. 118 bool cache_disabled; // Don't use cache if true; 119 120 PathData() : cache_disabled(false) { 121 #if defined(OS_WIN) 122 providers = &base_provider_win; 123 #elif defined(OS_MACOSX) 124 providers = &base_provider_mac; 125 #elif defined(OS_ANDROID) 126 providers = &base_provider_android; 127 #elif defined(OS_POSIX) 128 providers = &base_provider_posix; 129 #endif 130 } 131 132 ~PathData() { 133 Provider* p = providers; 134 while (p) { 135 Provider* next = p->next; 136 if (!p->is_static) 137 delete p; 138 p = next; 139 } 140 } 141 }; 142 143 static base::LazyInstance<PathData> g_path_data = LAZY_INSTANCE_INITIALIZER; 144 145 static PathData* GetPathData() { 146 return g_path_data.Pointer(); 147 } 148 149 // Tries to find |key| in the cache. |path_data| should be locked by the caller! 150 bool LockedGetFromCache(int key, const PathData* path_data, FilePath* result) { 151 if (path_data->cache_disabled) 152 return false; 153 // check for a cached version 154 PathMap::const_iterator it = path_data->cache.find(key); 155 if (it != path_data->cache.end()) { 156 *result = it->second; 157 return true; 158 } 159 return false; 160 } 161 162 // Tries to find |key| in the overrides map. |path_data| should be locked by the 163 // caller! 164 bool LockedGetFromOverrides(int key, PathData* path_data, FilePath* result) { 165 // check for an overridden version. 166 PathMap::const_iterator it = path_data->overrides.find(key); 167 if (it != path_data->overrides.end()) { 168 if (!path_data->cache_disabled) 169 path_data->cache[key] = it->second; 170 *result = it->second; 171 return true; 172 } 173 return false; 174 } 175 176 } // namespace 177 178 // TODO(brettw): this function does not handle long paths (filename > MAX_PATH) 179 // characters). This isn't supported very well by Windows right now, so it is 180 // moot, but we should keep this in mind for the future. 181 // static 182 bool PathService::Get(int key, FilePath* result) { 183 PathData* path_data = GetPathData(); 184 DCHECK(path_data); 185 DCHECK(result); 186 DCHECK_GE(key, base::DIR_CURRENT); 187 188 // special case the current directory because it can never be cached 189 if (key == base::DIR_CURRENT) 190 return base::GetCurrentDirectory(result); 191 192 Provider* provider = NULL; 193 { 194 base::AutoLock scoped_lock(path_data->lock); 195 if (LockedGetFromCache(key, path_data, result)) 196 return true; 197 198 if (LockedGetFromOverrides(key, path_data, result)) 199 return true; 200 201 // Get the beginning of the list while it is still locked. 202 provider = path_data->providers; 203 } 204 205 FilePath path; 206 207 // Iterating does not need the lock because only the list head might be 208 // modified on another thread. 209 while (provider) { 210 if (provider->func(key, &path)) 211 break; 212 DCHECK(path.empty()) << "provider should not have modified path"; 213 provider = provider->next; 214 } 215 216 if (path.empty()) 217 return false; 218 219 if (path.ReferencesParent()) { 220 // Make sure path service never returns a path with ".." in it. 221 path = MakeAbsoluteFilePath(path); 222 if (path.empty()) 223 return false; 224 } 225 *result = path; 226 227 base::AutoLock scoped_lock(path_data->lock); 228 if (!path_data->cache_disabled) 229 path_data->cache[key] = path; 230 231 return true; 232 } 233 234 // static 235 bool PathService::Override(int key, const FilePath& path) { 236 // Just call the full function with true for the value of |create|, and 237 // assume that |path| may not be absolute yet. 238 return OverrideAndCreateIfNeeded(key, path, false, true); 239 } 240 241 // static 242 bool PathService::OverrideAndCreateIfNeeded(int key, 243 const FilePath& path, 244 bool is_absolute, 245 bool create) { 246 PathData* path_data = GetPathData(); 247 DCHECK(path_data); 248 DCHECK_GT(key, base::DIR_CURRENT) << "invalid path key"; 249 250 FilePath file_path = path; 251 252 // For some locations this will fail if called from inside the sandbox there- 253 // fore we protect this call with a flag. 254 if (create) { 255 // Make sure the directory exists. We need to do this before we translate 256 // this to the absolute path because on POSIX, MakeAbsoluteFilePath fails 257 // if called on a non-existent path. 258 if (!base::PathExists(file_path) && 259 !base::CreateDirectory(file_path)) 260 return false; 261 } 262 263 // We need to have an absolute path. 264 if (!is_absolute) { 265 file_path = MakeAbsoluteFilePath(file_path); 266 if (file_path.empty()) 267 return false; 268 } 269 DCHECK(file_path.IsAbsolute()); 270 271 base::AutoLock scoped_lock(path_data->lock); 272 273 // Clear the cache now. Some of its entries could have depended 274 // on the value we are overriding, and are now out of sync with reality. 275 path_data->cache.clear(); 276 277 path_data->overrides[key] = file_path; 278 279 return true; 280 } 281 282 // static 283 bool PathService::RemoveOverride(int key) { 284 PathData* path_data = GetPathData(); 285 DCHECK(path_data); 286 287 base::AutoLock scoped_lock(path_data->lock); 288 289 if (path_data->overrides.find(key) == path_data->overrides.end()) 290 return false; 291 292 // Clear the cache now. Some of its entries could have depended on the value 293 // we are going to remove, and are now out of sync. 294 path_data->cache.clear(); 295 296 path_data->overrides.erase(key); 297 298 return true; 299 } 300 301 // static 302 void PathService::RegisterProvider(ProviderFunc func, int key_start, 303 int key_end) { 304 PathData* path_data = GetPathData(); 305 DCHECK(path_data); 306 DCHECK_GT(key_end, key_start); 307 308 Provider* p; 309 310 p = new Provider; 311 p->is_static = false; 312 p->func = func; 313 #ifndef NDEBUG 314 p->key_start = key_start; 315 p->key_end = key_end; 316 #endif 317 318 base::AutoLock scoped_lock(path_data->lock); 319 320 #ifndef NDEBUG 321 Provider *iter = path_data->providers; 322 while (iter) { 323 DCHECK(key_start >= iter->key_end || key_end <= iter->key_start) << 324 "path provider collision"; 325 iter = iter->next; 326 } 327 #endif 328 329 p->next = path_data->providers; 330 path_data->providers = p; 331 } 332 333 // static 334 void PathService::DisableCache() { 335 PathData* path_data = GetPathData(); 336 DCHECK(path_data); 337 338 base::AutoLock scoped_lock(path_data->lock); 339 path_data->cache.clear(); 340 path_data->cache_disabled = true; 341 } 342
