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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "idmap2/FileUtils.h"
#include <string>
#include "android-base/file.h"
#include "android-base/macros.h"
#include "android-base/stringprintf.h"
#include "private/android_filesystem_config.h"
namespace android::idmap2::utils {
#ifdef __ANDROID__
bool UidHasWriteAccessToPath(uid_t uid, const std::string& path) {
// resolve symlinks and relative paths; the directories must exist
std::string canonical_path;
if (!base::Realpath(base::Dirname(path), &canonical_path)) {
return false;
}
const std::string cache_subdir = base::StringPrintf("%s/", kIdmapCacheDir);
if (canonical_path == kIdmapCacheDir ||
canonical_path.compare(0, cache_subdir.size(), cache_subdir) == 0) {
// limit access to /data/resource-cache to root and system
return uid == AID_ROOT || uid == AID_SYSTEM;
}
return true;
}
#else
bool UidHasWriteAccessToPath(uid_t uid ATTRIBUTE_UNUSED, const std::string& path ATTRIBUTE_UNUSED) {
return true;
}
#endif
std::string RandomStringForPath(const size_t length) {
constexpr char kChars[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
constexpr size_t kCharLastIndex = sizeof(kChars) - 1;
std::string out_rand;
out_rand.reserve(length);
std::random_device rd;
std::uniform_int_distribution<int> dist(0, kCharLastIndex);
for (size_t i = 0; i < length; i++) {
out_rand[i] = kChars[dist(rd) % (kCharLastIndex)];
}
return out_rand;
}
} // namespace android::idmap2::utils
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