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 #include "base/path_service.h"
6
7 #ifdef OS_WIN
8 #include <windows.h>
9 #include <shellapi.h>
10 #include <shlobj.h>
11 #endif
12
13 #include "base/file_path.h"
14 #include "base/file_util.h"
15 #include "base/hash_tables.h"
16 #include "base/lazy_instance.h"
17 #include "base/logging.h"
18 #include "base/synchronization/lock.h"
19
20 namespace base {
21 bool PathProvider(int key, FilePath* result);
22 #if defined(OS_WIN)
23 bool PathProviderWin(int key, FilePath* result);
24 #elif defined(OS_MACOSX)
25 bool PathProviderMac(int key, FilePath* result);
26 #elif defined(OS_POSIX)
27 bool PathProviderPosix(int key, FilePath* result);
28 #endif
29 }
30
31 namespace {
32
33 typedef base::hash_map<int, FilePath> PathMap;
34
35 // We keep a linked list of providers. In a debug build we ensure that no two
36 // providers claim overlapping keys.
37 struct Provider {
38 PathService::ProviderFunc func;
39 struct Provider* next;
40 #ifndef NDEBUG
41 int key_start;
42 int key_end;
43 #endif
44 bool is_static;
45 };
46
47 static Provider base_provider = {
48 base::PathProvider,
49 NULL,
50 #ifndef NDEBUG
51 base::PATH_START,
52 base::PATH_END,
53 #endif
54 true
55 };
56
57 #if defined(OS_WIN)
58 static Provider base_provider_win = {
59 base::PathProviderWin,
60 &base_provider,
61 #ifndef NDEBUG
62 base::PATH_WIN_START,
63 base::PATH_WIN_END,
64 #endif
65 true
66 };
67 #endif
68
69 #if defined(OS_MACOSX)
70 static Provider base_provider_mac = {
71 base::PathProviderMac,
72 &base_provider,
73 #ifndef NDEBUG
74 base::PATH_MAC_START,
75 base::PATH_MAC_END,
76 #endif
77 true
78 };
79 #endif
80
81 #if defined(OS_POSIX) && !defined(OS_MACOSX)
82 static Provider base_provider_posix = {
83 base::PathProviderPosix,
84 &base_provider,
85 #ifndef NDEBUG
86 0,
87 0,
88 #endif
89 true
90 };
91 #endif
92
93
94 struct PathData {
95 base::Lock lock;
96 PathMap cache; // Cache mappings from path key to path value.
97 PathMap overrides; // Track path overrides.
98 Provider* providers; // Linked list of path service providers.
99
PathData__anona9bf1da50111::PathData100 PathData() {
101 #if defined(OS_WIN)
102 providers = &base_provider_win;
103 #elif defined(OS_MACOSX)
104 providers = &base_provider_mac;
105 #elif defined(OS_POSIX)
106 providers = &base_provider_posix;
107 #endif
108 }
109
~PathData__anona9bf1da50111::PathData110 ~PathData() {
111 Provider* p = providers;
112 while (p) {
113 Provider* next = p->next;
114 if (!p->is_static)
115 delete p;
116 p = next;
117 }
118 }
119 };
120
121 static base::LazyInstance<PathData> g_path_data(base::LINKER_INITIALIZED);
122
GetPathData()123 static PathData* GetPathData() {
124 return g_path_data.Pointer();
125 }
126
127 } // namespace
128
129
130 // static
GetFromCache(int key,FilePath * result)131 bool PathService::GetFromCache(int key, FilePath* result) {
132 PathData* path_data = GetPathData();
133 base::AutoLock scoped_lock(path_data->lock);
134
135 // check for a cached version
136 PathMap::const_iterator it = path_data->cache.find(key);
137 if (it != path_data->cache.end()) {
138 *result = it->second;
139 return true;
140 }
141 return false;
142 }
143
144 // static
GetFromOverrides(int key,FilePath * result)145 bool PathService::GetFromOverrides(int key, FilePath* result) {
146 PathData* path_data = GetPathData();
147 base::AutoLock scoped_lock(path_data->lock);
148
149 // check for an overriden version.
150 PathMap::const_iterator it = path_data->overrides.find(key);
151 if (it != path_data->overrides.end()) {
152 *result = it->second;
153 return true;
154 }
155 return false;
156 }
157
158 // static
AddToCache(int key,const FilePath & path)159 void PathService::AddToCache(int key, const FilePath& path) {
160 PathData* path_data = GetPathData();
161 base::AutoLock scoped_lock(path_data->lock);
162 // Save the computed path in our cache.
163 path_data->cache[key] = path;
164 }
165
166 // TODO(brettw): this function does not handle long paths (filename > MAX_PATH)
167 // characters). This isn't supported very well by Windows right now, so it is
168 // moot, but we should keep this in mind for the future.
169 // static
Get(int key,FilePath * result)170 bool PathService::Get(int key, FilePath* result) {
171 PathData* path_data = GetPathData();
172 DCHECK(path_data);
173 DCHECK(result);
174 DCHECK_GE(key, base::DIR_CURRENT);
175
176 // special case the current directory because it can never be cached
177 if (key == base::DIR_CURRENT)
178 return file_util::GetCurrentDirectory(result);
179
180 if (GetFromCache(key, result))
181 return true;
182
183 if (GetFromOverrides(key, result))
184 return true;
185
186 FilePath path;
187
188 // search providers for the requested path
189 // NOTE: it should be safe to iterate here without the lock
190 // since RegisterProvider always prepends.
191 Provider* provider = path_data->providers;
192 while (provider) {
193 if (provider->func(key, &path))
194 break;
195 DCHECK(path.empty()) << "provider should not have modified path";
196 provider = provider->next;
197 }
198
199 if (path.empty())
200 return false;
201
202 AddToCache(key, path);
203
204 *result = path;
205 return true;
206 }
207
Override(int key,const FilePath & path)208 bool PathService::Override(int key, const FilePath& path) {
209 PathData* path_data = GetPathData();
210 DCHECK(path_data);
211 DCHECK_GT(key, base::DIR_CURRENT) << "invalid path key";
212
213 FilePath file_path = path;
214
215 // Make sure the directory exists. We need to do this before we translate
216 // this to the absolute path because on POSIX, AbsolutePath fails if called
217 // on a non-existant path.
218 if (!file_util::PathExists(file_path) &&
219 !file_util::CreateDirectory(file_path))
220 return false;
221
222 // We need to have an absolute path, as extensions and plugins don't like
223 // relative paths, and will glady crash the browser in CHECK()s if they get a
224 // relative path.
225 if (!file_util::AbsolutePath(&file_path))
226 return false;
227
228 base::AutoLock scoped_lock(path_data->lock);
229
230 // Clear the cache now. Some of its entries could have depended
231 // on the value we are overriding, and are now out of sync with reality.
232 path_data->cache.clear();
233
234 path_data->cache[key] = file_path;
235 path_data->overrides[key] = file_path;
236
237 return true;
238 }
239
RegisterProvider(ProviderFunc func,int key_start,int key_end)240 void PathService::RegisterProvider(ProviderFunc func, int key_start,
241 int key_end) {
242 PathData* path_data = GetPathData();
243 DCHECK(path_data);
244 DCHECK_GT(key_end, key_start);
245
246 base::AutoLock scoped_lock(path_data->lock);
247
248 Provider* p;
249
250 #ifndef NDEBUG
251 p = path_data->providers;
252 while (p) {
253 DCHECK(key_start >= p->key_end || key_end <= p->key_start) <<
254 "path provider collision";
255 p = p->next;
256 }
257 #endif
258
259 p = new Provider;
260 p->is_static = false;
261 p->func = func;
262 p->next = path_data->providers;
263 #ifndef NDEBUG
264 p->key_start = key_start;
265 p->key_end = key_end;
266 #endif
267 path_data->providers = p;
268 }
269