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.
5 #include "base/path_service.h"
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"
21 using base::MakeAbsoluteFilePath;
24 bool PathProvider(int key, FilePath* result);
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
34 bool PathProviderPosix(int key, FilePath* result);
40 typedef base::hash_map<int, FilePath> PathMap;
42 // We keep a linked list of providers. In a debug build we ensure that no two
43 // providers claim overlapping keys.
45 PathService::ProviderFunc func;
46 struct Provider* next;
54 Provider base_provider = {
65 Provider base_provider_win = {
66 base::PathProviderWin,
76 #if defined(OS_MACOSX)
77 Provider base_provider_mac = {
78 base::PathProviderMac,
88 #if defined(OS_ANDROID)
89 Provider base_provider_android = {
90 base::PathProviderAndroid,
93 base::PATH_ANDROID_START,
94 base::PATH_ANDROID_END,
100 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
101 Provider base_provider_posix = {
102 base::PathProviderPosix,
105 base::PATH_POSIX_START,
106 base::PATH_POSIX_END,
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;
120 PathData() : cache_disabled(false) {
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;
133 Provider* p = providers;
135 Provider* next = p->next;
143 static base::LazyInstance<PathData> g_path_data = LAZY_INSTANCE_INITIALIZER;
145 static PathData* GetPathData() {
146 return g_path_data.Pointer();
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)
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;
162 // Tries to find |key| in the overrides map. |path_data| should be locked by the
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;
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.
182 bool PathService::Get(int key, FilePath* result) {
183 PathData* path_data = GetPathData();
186 DCHECK_GE(key, base::DIR_CURRENT);
188 // special case the current directory because it can never be cached
189 if (key == base::DIR_CURRENT)
190 return file_util::GetCurrentDirectory(result);
192 Provider* provider = NULL;
194 base::AutoLock scoped_lock(path_data->lock);
195 if (LockedGetFromCache(key, path_data, result))
198 if (LockedGetFromOverrides(key, path_data, result))
201 // Get the beginning of the list while it is still locked.
202 provider = path_data->providers;
207 // Iterating does not need the lock because only the list head might be
208 // modified on another thread.
210 if (provider->func(key, &path))
212 DCHECK(path.empty()) << "provider should not have modified path";
213 provider = provider->next;
219 if (path.ReferencesParent()) {
220 // Make sure path service never returns a path with ".." in it.
221 path = MakeAbsoluteFilePath(path);
227 base::AutoLock scoped_lock(path_data->lock);
228 if (!path_data->cache_disabled)
229 path_data->cache[key] = path;
235 bool PathService::Override(int key, const FilePath& path) {
236 // Just call the full function with true for the value of |create|.
237 return OverrideAndCreateIfNeeded(key, path, true);
241 bool PathService::OverrideAndCreateIfNeeded(int key,
242 const FilePath& path,
244 PathData* path_data = GetPathData();
246 DCHECK_GT(key, base::DIR_CURRENT) << "invalid path key";
248 FilePath file_path = path;
250 // For some locations this will fail if called from inside the sandbox there-
251 // fore we protect this call with a flag.
253 // Make sure the directory exists. We need to do this before we translate
254 // this to the absolute path because on POSIX, MakeAbsoluteFilePath fails
255 // if called on a non-existent path.
256 if (!base::PathExists(file_path) &&
257 !file_util::CreateDirectory(file_path))
261 // We need to have an absolute path.
262 file_path = MakeAbsoluteFilePath(file_path);
263 if (file_path.empty())
266 base::AutoLock scoped_lock(path_data->lock);
268 // Clear the cache now. Some of its entries could have depended
269 // on the value we are overriding, and are now out of sync with reality.
270 path_data->cache.clear();
272 path_data->overrides[key] = file_path;
278 bool PathService::RemoveOverride(int key) {
279 PathData* path_data = GetPathData();
282 base::AutoLock scoped_lock(path_data->lock);
284 if (path_data->overrides.find(key) == path_data->overrides.end())
287 // Clear the cache now. Some of its entries could have depended on the value
288 // we are going to remove, and are now out of sync.
289 path_data->cache.clear();
291 path_data->overrides.erase(key);
297 void PathService::RegisterProvider(ProviderFunc func, int key_start,
299 PathData* path_data = GetPathData();
301 DCHECK_GT(key_end, key_start);
306 p->is_static = false;
309 p->key_start = key_start;
310 p->key_end = key_end;
313 base::AutoLock scoped_lock(path_data->lock);
316 Provider *iter = path_data->providers;
318 DCHECK(key_start >= iter->key_end || key_end <= iter->key_start) <<
319 "path provider collision";
324 p->next = path_data->providers;
325 path_data->providers = p;
329 void PathService::DisableCache() {
330 PathData* path_data = GetPathData();
333 base::AutoLock scoped_lock(path_data->lock);
334 path_data->cache.clear();
335 path_data->cache_disabled = true;