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// 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"
#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_ANDROID)
bool PathProviderAndroid(int key, FilePath* result);
#elif defined(OS_POSIX)
// PathProviderPosix is the default path provider on POSIX OSes other than
// Mac and Android.
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;
};
Provider base_provider = {
base::PathProvider,
NULL,
#ifndef NDEBUG
base::PATH_START,
base::PATH_END,
#endif
true
};
#if defined(OS_WIN)
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)
Provider base_provider_mac = {
base::PathProviderMac,
&base_provider,
#ifndef NDEBUG
base::PATH_MAC_START,
base::PATH_MAC_END,
#endif
true
};
#endif
#if defined(OS_ANDROID)
Provider base_provider_android = {
base::PathProviderAndroid,
&base_provider,
#ifndef NDEBUG
base::PATH_ANDROID_START,
base::PATH_ANDROID_END,
#endif
true
};
#endif
#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
Provider base_provider_posix = {
base::PathProviderPosix,
&base_provider,
#ifndef NDEBUG
base::PATH_POSIX_START,
base::PATH_POSIX_END,
#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_ANDROID)
providers = &base_provider_android;
#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 = LAZY_INSTANCE_INITIALIZER;
static PathData* GetPathData() {
return g_path_data.Pointer();
}
// Tries to find |key| in the cache. |path_data| should be locked by the caller!
bool LockedGetFromCache(int key, const PathData* path_data, FilePath* result) {
// 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;
}
// Tries to find |key| in the overrides map. |path_data| should be locked by the
// caller!
bool LockedGetFromOverrides(int key, PathData* path_data, FilePath* result) {
// check for an overridden version.
PathMap::const_iterator it = path_data->overrides.find(key);
if (it != path_data->overrides.end()) {
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_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);
Provider* provider = NULL;
{
base::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;
*result = path;
base::AutoLock scoped_lock(path_data->lock);
path_data->cache[key] = path;
return true;
}
// static
bool PathService::Override(int key, const FilePath& path) {
// Just call the full function with true for the value of |create|.
return OverrideAndCreateIfNeeded(key, path, true);
}
// static
bool PathService::OverrideAndCreateIfNeeded(int key,
const FilePath& path,
bool create) {
PathData* path_data = GetPathData();
DCHECK(path_data);
DCHECK_GT(key, base::DIR_CURRENT) << "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, AbsolutePath fails if called
// on a non-existent 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 gladly 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->overrides[key] = file_path;
return true;
}
// static
bool PathService::RemoveOverride(int key) {
PathData* path_data = GetPathData();
DCHECK(path_data);
base::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
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
base::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;
}
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