michael@0: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #include "base/path_service.h"
michael@0: 
michael@0: #if defined(OS_WIN)
michael@0: #include <windows.h>
michael@0: #include <shellapi.h>
michael@0: #include <shlobj.h>
michael@0: #endif
michael@0: 
michael@0: #include "base/containers/hash_tables.h"
michael@0: #include "base/file_util.h"
michael@0: #include "base/files/file_path.h"
michael@0: #include "base/lazy_instance.h"
michael@0: #include "base/logging.h"
michael@0: #include "base/synchronization/lock.h"
michael@0: 
michael@0: using base::FilePath;
michael@0: using base::MakeAbsoluteFilePath;
michael@0: 
michael@0: namespace base {
michael@0:   bool PathProvider(int key, FilePath* result);
michael@0: #if defined(OS_WIN)
michael@0:   bool PathProviderWin(int key, FilePath* result);
michael@0: #elif defined(OS_MACOSX)
michael@0:   bool PathProviderMac(int key, FilePath* result);
michael@0: #elif defined(OS_ANDROID)
michael@0:   bool PathProviderAndroid(int key, FilePath* result);
michael@0: #elif defined(OS_POSIX)
michael@0:   // PathProviderPosix is the default path provider on POSIX OSes other than
michael@0:   // Mac and Android.
michael@0:   bool PathProviderPosix(int key, FilePath* result);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: namespace {
michael@0: 
michael@0: typedef base::hash_map<int, FilePath> PathMap;
michael@0: 
michael@0: // We keep a linked list of providers.  In a debug build we ensure that no two
michael@0: // providers claim overlapping keys.
michael@0: struct Provider {
michael@0:   PathService::ProviderFunc func;
michael@0:   struct Provider* next;
michael@0: #ifndef NDEBUG
michael@0:   int key_start;
michael@0:   int key_end;
michael@0: #endif
michael@0:   bool is_static;
michael@0: };
michael@0: 
michael@0: Provider base_provider = {
michael@0:   base::PathProvider,
michael@0:   NULL,
michael@0: #ifndef NDEBUG
michael@0:   base::PATH_START,
michael@0:   base::PATH_END,
michael@0: #endif
michael@0:   true
michael@0: };
michael@0: 
michael@0: #if defined(OS_WIN)
michael@0: Provider base_provider_win = {
michael@0:   base::PathProviderWin,
michael@0:   &base_provider,
michael@0: #ifndef NDEBUG
michael@0:   base::PATH_WIN_START,
michael@0:   base::PATH_WIN_END,
michael@0: #endif
michael@0:   true
michael@0: };
michael@0: #endif
michael@0: 
michael@0: #if defined(OS_MACOSX)
michael@0: Provider base_provider_mac = {
michael@0:   base::PathProviderMac,
michael@0:   &base_provider,
michael@0: #ifndef NDEBUG
michael@0:   base::PATH_MAC_START,
michael@0:   base::PATH_MAC_END,
michael@0: #endif
michael@0:   true
michael@0: };
michael@0: #endif
michael@0: 
michael@0: #if defined(OS_ANDROID)
michael@0: Provider base_provider_android = {
michael@0:   base::PathProviderAndroid,
michael@0:   &base_provider,
michael@0: #ifndef NDEBUG
michael@0:   base::PATH_ANDROID_START,
michael@0:   base::PATH_ANDROID_END,
michael@0: #endif
michael@0:   true
michael@0: };
michael@0: #endif
michael@0: 
michael@0: #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
michael@0: Provider base_provider_posix = {
michael@0:   base::PathProviderPosix,
michael@0:   &base_provider,
michael@0: #ifndef NDEBUG
michael@0:   base::PATH_POSIX_START,
michael@0:   base::PATH_POSIX_END,
michael@0: #endif
michael@0:   true
michael@0: };
michael@0: #endif
michael@0: 
michael@0: 
michael@0: struct PathData {
michael@0:   base::Lock lock;
michael@0:   PathMap cache;        // Cache mappings from path key to path value.
michael@0:   PathMap overrides;    // Track path overrides.
michael@0:   Provider* providers;  // Linked list of path service providers.
michael@0:   bool cache_disabled;  // Don't use cache if true;
michael@0: 
michael@0:   PathData() : cache_disabled(false) {
michael@0: #if defined(OS_WIN)
michael@0:     providers = &base_provider_win;
michael@0: #elif defined(OS_MACOSX)
michael@0:     providers = &base_provider_mac;
michael@0: #elif defined(OS_ANDROID)
michael@0:     providers = &base_provider_android;
michael@0: #elif defined(OS_POSIX)
michael@0:     providers = &base_provider_posix;
michael@0: #endif
michael@0:   }
michael@0: 
michael@0:   ~PathData() {
michael@0:     Provider* p = providers;
michael@0:     while (p) {
michael@0:       Provider* next = p->next;
michael@0:       if (!p->is_static)
michael@0:         delete p;
michael@0:       p = next;
michael@0:     }
michael@0:   }
michael@0: };
michael@0: 
michael@0: static base::LazyInstance<PathData> g_path_data = LAZY_INSTANCE_INITIALIZER;
michael@0: 
michael@0: static PathData* GetPathData() {
michael@0:   return g_path_data.Pointer();
michael@0: }
michael@0: 
michael@0: // Tries to find |key| in the cache. |path_data| should be locked by the caller!
michael@0: bool LockedGetFromCache(int key, const PathData* path_data, FilePath* result) {
michael@0:   if (path_data->cache_disabled)
michael@0:     return false;
michael@0:   // check for a cached version
michael@0:   PathMap::const_iterator it = path_data->cache.find(key);
michael@0:   if (it != path_data->cache.end()) {
michael@0:     *result = it->second;
michael@0:     return true;
michael@0:   }
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: // Tries to find |key| in the overrides map. |path_data| should be locked by the
michael@0: // caller!
michael@0: bool LockedGetFromOverrides(int key, PathData* path_data, FilePath* result) {
michael@0:   // check for an overridden version.
michael@0:   PathMap::const_iterator it = path_data->overrides.find(key);
michael@0:   if (it != path_data->overrides.end()) {
michael@0:     if (!path_data->cache_disabled)
michael@0:       path_data->cache[key] = it->second;
michael@0:     *result = it->second;
michael@0:     return true;
michael@0:   }
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: }  // namespace
michael@0: 
michael@0: // TODO(brettw): this function does not handle long paths (filename > MAX_PATH)
michael@0: // characters). This isn't supported very well by Windows right now, so it is
michael@0: // moot, but we should keep this in mind for the future.
michael@0: // static
michael@0: bool PathService::Get(int key, FilePath* result) {
michael@0:   PathData* path_data = GetPathData();
michael@0:   DCHECK(path_data);
michael@0:   DCHECK(result);
michael@0:   DCHECK_GE(key, base::DIR_CURRENT);
michael@0: 
michael@0:   // special case the current directory because it can never be cached
michael@0:   if (key == base::DIR_CURRENT)
michael@0:     return file_util::GetCurrentDirectory(result);
michael@0: 
michael@0:   Provider* provider = NULL;
michael@0:   {
michael@0:     base::AutoLock scoped_lock(path_data->lock);
michael@0:     if (LockedGetFromCache(key, path_data, result))
michael@0:       return true;
michael@0: 
michael@0:     if (LockedGetFromOverrides(key, path_data, result))
michael@0:       return true;
michael@0: 
michael@0:     // Get the beginning of the list while it is still locked.
michael@0:     provider = path_data->providers;
michael@0:   }
michael@0: 
michael@0:   FilePath path;
michael@0: 
michael@0:   // Iterating does not need the lock because only the list head might be
michael@0:   // modified on another thread.
michael@0:   while (provider) {
michael@0:     if (provider->func(key, &path))
michael@0:       break;
michael@0:     DCHECK(path.empty()) << "provider should not have modified path";
michael@0:     provider = provider->next;
michael@0:   }
michael@0: 
michael@0:   if (path.empty())
michael@0:     return false;
michael@0: 
michael@0:   if (path.ReferencesParent()) {
michael@0:     // Make sure path service never returns a path with ".." in it.
michael@0:     path = MakeAbsoluteFilePath(path);
michael@0:     if (path.empty())
michael@0:       return false;
michael@0:   }
michael@0:   *result = path;
michael@0: 
michael@0:   base::AutoLock scoped_lock(path_data->lock);
michael@0:   if (!path_data->cache_disabled)
michael@0:     path_data->cache[key] = path;
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // static
michael@0: bool PathService::Override(int key, const FilePath& path) {
michael@0:   // Just call the full function with true for the value of |create|.
michael@0:   return OverrideAndCreateIfNeeded(key, path, true);
michael@0: }
michael@0: 
michael@0: // static
michael@0: bool PathService::OverrideAndCreateIfNeeded(int key,
michael@0:                                             const FilePath& path,
michael@0:                                             bool create) {
michael@0:   PathData* path_data = GetPathData();
michael@0:   DCHECK(path_data);
michael@0:   DCHECK_GT(key, base::DIR_CURRENT) << "invalid path key";
michael@0: 
michael@0:   FilePath file_path = path;
michael@0: 
michael@0:   // For some locations this will fail if called from inside the sandbox there-
michael@0:   // fore we protect this call with a flag.
michael@0:   if (create) {
michael@0:     // Make sure the directory exists. We need to do this before we translate
michael@0:     // this to the absolute path because on POSIX, MakeAbsoluteFilePath fails
michael@0:     // if called on a non-existent path.
michael@0:     if (!base::PathExists(file_path) &&
michael@0:         !file_util::CreateDirectory(file_path))
michael@0:       return false;
michael@0:   }
michael@0: 
michael@0:   // We need to have an absolute path.
michael@0:   file_path = MakeAbsoluteFilePath(file_path);
michael@0:   if (file_path.empty())
michael@0:     return false;
michael@0: 
michael@0:   base::AutoLock scoped_lock(path_data->lock);
michael@0: 
michael@0:   // Clear the cache now. Some of its entries could have depended
michael@0:   // on the value we are overriding, and are now out of sync with reality.
michael@0:   path_data->cache.clear();
michael@0: 
michael@0:   path_data->overrides[key] = file_path;
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // static
michael@0: bool PathService::RemoveOverride(int key) {
michael@0:   PathData* path_data = GetPathData();
michael@0:   DCHECK(path_data);
michael@0: 
michael@0:   base::AutoLock scoped_lock(path_data->lock);
michael@0: 
michael@0:   if (path_data->overrides.find(key) == path_data->overrides.end())
michael@0:     return false;
michael@0: 
michael@0:   // Clear the cache now. Some of its entries could have depended on the value
michael@0:   // we are going to remove, and are now out of sync.
michael@0:   path_data->cache.clear();
michael@0: 
michael@0:   path_data->overrides.erase(key);
michael@0: 
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: // static
michael@0: void PathService::RegisterProvider(ProviderFunc func, int key_start,
michael@0:                                    int key_end) {
michael@0:   PathData* path_data = GetPathData();
michael@0:   DCHECK(path_data);
michael@0:   DCHECK_GT(key_end, key_start);
michael@0: 
michael@0:   Provider* p;
michael@0: 
michael@0:   p = new Provider;
michael@0:   p->is_static = false;
michael@0:   p->func = func;
michael@0: #ifndef NDEBUG
michael@0:   p->key_start = key_start;
michael@0:   p->key_end = key_end;
michael@0: #endif
michael@0: 
michael@0:   base::AutoLock scoped_lock(path_data->lock);
michael@0: 
michael@0: #ifndef NDEBUG
michael@0:   Provider *iter = path_data->providers;
michael@0:   while (iter) {
michael@0:     DCHECK(key_start >= iter->key_end || key_end <= iter->key_start) <<
michael@0:       "path provider collision";
michael@0:     iter = iter->next;
michael@0:   }
michael@0: #endif
michael@0: 
michael@0:   p->next = path_data->providers;
michael@0:   path_data->providers = p;
michael@0: }
michael@0: 
michael@0: // static
michael@0: void PathService::DisableCache() {
michael@0:   PathData* path_data = GetPathData();
michael@0:   DCHECK(path_data);
michael@0: 
michael@0:   base::AutoLock scoped_lock(path_data->lock);
michael@0:   path_data->cache.clear();
michael@0:   path_data->cache_disabled = true;
michael@0: }