blob: e72ae7deff9af69156ab2ed994de7431009ca5d8 [file] [log] [blame]
// Copyright (c) 2011 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"
#ifdef OS_WIN
#include <windows.h>
#include <shellapi.h>
#include <shlobj.h>
#endif
#include "base/file_path.h"
#include "base/file_util.h"
#include "base/hash_tables.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/synchronization/lock.h"
namespace base {
bool PathProvider(int key, FilePath* result);
#if defined(OS_WIN)
bool PathProviderWin(int key, FilePath* result);
#elif defined(OS_MACOSX)
bool PathProviderMac(int key, FilePath* result);
#elif defined(OS_POSIX)
bool PathProviderPosix(int key, FilePath* result);
#endif
}
namespace {
typedef base::hash_map<int, FilePath> 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;
};
static Provider base_provider = {
base::PathProvider,
NULL,
#ifndef NDEBUG
base::PATH_START,
base::PATH_END,
#endif
true
};
#if defined(OS_WIN)
static Provider base_provider_win = {
base::PathProviderWin,
&base_provider,
#ifndef NDEBUG
base::PATH_WIN_START,
base::PATH_WIN_END,
#endif
true
};
#endif
#if defined(OS_MACOSX)
static Provider base_provider_mac = {
base::PathProviderMac,
&base_provider,
#ifndef NDEBUG
base::PATH_MAC_START,
base::PATH_MAC_END,
#endif
true
};
#endif
#if defined(OS_POSIX) && !defined(OS_MACOSX)
static Provider base_provider_posix = {
base::PathProviderPosix,
&base_provider,
#ifndef NDEBUG
0,
0,
#endif
true
};
#endif
struct PathData {
base::Lock lock;
PathMap cache; // Cache mappings from path key to path value.
PathMap overrides; // Track path overrides.
Provider* providers; // Linked list of path service providers.
PathData() {
#if defined(OS_WIN)
providers = &base_provider_win;
#elif defined(OS_MACOSX)
providers = &base_provider_mac;
#elif defined(OS_POSIX)
providers = &base_provider_posix;
#endif
}
~PathData() {
Provider* p = providers;
while (p) {
Provider* next = p->next;
if (!p->is_static)
delete p;
p = next;
}
}
};
static base::LazyInstance<PathData> g_path_data(base::LINKER_INITIALIZED);
static PathData* GetPathData() {
return g_path_data.Pointer();
}
} // namespace
// static
bool PathService::GetFromCache(int key, FilePath* result) {
PathData* path_data = GetPathData();
base::AutoLock scoped_lock(path_data->lock);
// check for a cached version
PathMap::const_iterator it = path_data->cache.find(key);
if (it != path_data->cache.end()) {
*result = it->second;
return true;
}
return false;
}
// static
bool PathService::GetFromOverrides(int key, FilePath* result) {
PathData* path_data = GetPathData();
base::AutoLock scoped_lock(path_data->lock);
// check for an overriden version.
PathMap::const_iterator it = path_data->overrides.find(key);
if (it != path_data->overrides.end()) {
*result = it->second;
return true;
}
return false;
}
// static
void PathService::AddToCache(int key, const FilePath& path) {
PathData* path_data = GetPathData();
base::AutoLock scoped_lock(path_data->lock);
// Save the computed path in our cache.
path_data->cache[key] = path;
}
// 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_GE(key, base::DIR_CURRENT);
// special case the current directory because it can never be cached
if (key == base::DIR_CURRENT)
return file_util::GetCurrentDirectory(result);
if (GetFromCache(key, result))
return true;
if (GetFromOverrides(key, result))
return true;
FilePath path;
// search providers for the requested path
// NOTE: it should be safe to iterate here without the lock
// since RegisterProvider always prepends.
Provider* provider = path_data->providers;
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;
AddToCache(key, path);
*result = path;
return true;
}
bool PathService::Override(int key, const FilePath& path) {
PathData* path_data = GetPathData();
DCHECK(path_data);
DCHECK_GT(key, base::DIR_CURRENT) << "invalid path key";
FilePath file_path = path;
// Make sure the directory exists. We need to do this before we translate
// this to the absolute path because on POSIX, AbsolutePath fails if called
// on a non-existant path.
if (!file_util::PathExists(file_path) &&
!file_util::CreateDirectory(file_path))
return false;
// We need to have an absolute path, as extensions and plugins don't like
// relative paths, and will glady crash the browser in CHECK()s if they get a
// relative path.
if (!file_util::AbsolutePath(&file_path))
return false;
base::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->cache[key] = file_path;
path_data->overrides[key] = file_path;
return true;
}
void PathService::RegisterProvider(ProviderFunc func, int key_start,
int key_end) {
PathData* path_data = GetPathData();
DCHECK(path_data);
DCHECK_GT(key_end, key_start);
base::AutoLock scoped_lock(path_data->lock);
Provider* p;
#ifndef NDEBUG
p = path_data->providers;
while (p) {
DCHECK(key_start >= p->key_end || key_end <= p->key_start) <<
"path provider collision";
p = p->next;
}
#endif
p = new Provider;
p->is_static = false;
p->func = func;
p->next = path_data->providers;
#ifndef NDEBUG
p->key_start = key_start;
p->key_end = key_end;
#endif
path_data->providers = p;
}