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