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