277 lines
10 KiB
C++
277 lines
10 KiB
C++
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/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* Tool to create a directory with the right SELinux context applied, or
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* apply the context if it's absent. Also fixes mode, uid, gid.
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*/
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#include <iostream>
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#include <string>
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#include <vector>
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#include <dirent.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <android-base/logging.h>
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#include <android-base/scopeguard.h>
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#include <cutils/fs.h>
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#include <selinux/android.h>
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#include "Utils.h"
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#include "android/os/IVold.h"
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#include <private/android_filesystem_config.h>
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static void usage(const char* progname) {
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std::cerr << "Usage: " << progname << " [ prepare | destroy ] <volume_uuid> <user_id> <flags>"
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<< std::endl;
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exit(-1);
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}
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static bool small_int(const std::string& s) {
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return !s.empty() && s.size() < 7 && s.find_first_not_of("0123456789") == std::string::npos;
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}
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static bool valid_uuid(const std::string& s) {
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return s.size() < 40 && s.find_first_not_of("0123456789abcdefABCDEF-_") == std::string::npos;
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}
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static bool prepare_dir_for_user(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
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const std::string& path, uid_t user_id) {
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auto clearfscreatecon = android::base::make_scope_guard([] { setfscreatecon(nullptr); });
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auto secontext = std::unique_ptr<char, void (*)(char*)>(nullptr, freecon);
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if (sehandle) {
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char* tmp_secontext;
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if (selabel_lookup(sehandle, &tmp_secontext, path.c_str(), S_IFDIR) == 0) {
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secontext.reset(tmp_secontext);
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if (user_id != (uid_t)-1) {
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if (selinux_android_context_with_level(secontext.get(), &tmp_secontext, user_id,
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(uid_t)-1) != 0) {
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PLOG(ERROR) << "Unable to create context with level for: " << path;
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return false;
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}
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secontext.reset(tmp_secontext); // Free the context
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}
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}
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}
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LOG(DEBUG) << "Setting up mode " << std::oct << mode << std::dec << " uid " << uid << " gid "
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<< gid << " context " << (secontext ? secontext.get() : "null")
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<< " on path: " << path;
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if (secontext) {
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if (setfscreatecon(secontext.get()) != 0) {
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PLOG(ERROR) << "Unable to setfscreatecon for: " << path;
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return false;
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}
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}
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if (fs_prepare_dir(path.c_str(), mode, uid, gid) != 0) {
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return false;
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}
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if (secontext) {
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char* tmp_oldsecontext = nullptr;
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if (lgetfilecon(path.c_str(), &tmp_oldsecontext) < 0) {
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PLOG(ERROR) << "Unable to read secontext for: " << path;
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return false;
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}
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auto oldsecontext = std::unique_ptr<char, void (*)(char*)>(tmp_oldsecontext, freecon);
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if (strcmp(secontext.get(), oldsecontext.get()) != 0) {
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LOG(INFO) << "Relabelling from " << ((char*)oldsecontext.get()) << " to "
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<< ((char*)secontext.get()) << ": " << path;
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if (lsetfilecon(path.c_str(), secontext.get()) != 0) {
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PLOG(ERROR) << "Relabelling failed for: " << path;
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return false;
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}
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}
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}
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return true;
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}
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static bool prepare_dir(struct selabel_handle* sehandle, mode_t mode, uid_t uid, gid_t gid,
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const std::string& path) {
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return prepare_dir_for_user(sehandle, mode, uid, gid, path, (uid_t)-1);
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}
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static bool rmrf_contents(const std::string& path) {
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auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir(path.c_str()), closedir);
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if (!dirp) {
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PLOG(ERROR) << "Unable to open directory: " << path;
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return false;
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}
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bool res = true;
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for (;;) {
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errno = 0;
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auto const entry = readdir(dirp.get());
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if (!entry) {
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if (errno) {
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PLOG(ERROR) << "readdir failed on: " << path;
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return false;
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}
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return res;
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}
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if (entry->d_name[0] == '.') continue;
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auto subdir = path + "/" + entry->d_name;
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if (0 !=
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android::vold::ForkExecvp(std::vector<std::string>{"/system/bin/rm", "-rf", subdir})) {
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LOG(ERROR) << "rm -rf failed on " << subdir;
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res = false;
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}
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}
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}
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static bool prepare_apex_subdirs(struct selabel_handle* sehandle, const std::string& path) {
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if (!prepare_dir(sehandle, 0711, 0, 0, path + "/apexdata")) return false;
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auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir("/apex"), closedir);
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if (!dirp) {
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PLOG(ERROR) << "Unable to open apex directory";
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return false;
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}
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struct dirent* entry;
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while ((entry = readdir(dirp.get())) != nullptr) {
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if (entry->d_type != DT_DIR) continue;
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const char* name = entry->d_name;
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// skip any starting with "."
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if (name[0] == '.') continue;
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if (strchr(name, '@') != NULL) continue;
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if (!prepare_dir(sehandle, 0771, AID_ROOT, AID_SYSTEM, path + "/apexdata/" + name)) {
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return false;
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}
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}
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return true;
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}
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static bool prepare_subdirs(const std::string& volume_uuid, int user_id, int flags) {
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struct selabel_handle* sehandle = selinux_android_file_context_handle();
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if (flags & android::os::IVold::STORAGE_FLAG_DE) {
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auto user_de_path = android::vold::BuildDataUserDePath(volume_uuid, user_id);
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if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, user_de_path, user_id)) {
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return false;
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}
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if (volume_uuid.empty()) {
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auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
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if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/vold")) return false;
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if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/storaged")) return false;
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if (!prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/rollback")) return false;
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// TODO: Return false if this returns false once sure this should succeed.
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prepare_dir(sehandle, 0700, 0, 0, misc_de_path + "/apexrollback");
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prepare_apex_subdirs(sehandle, misc_de_path);
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auto profiles_de_path = android::vold::BuildDataProfilesDePath(user_id);
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if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, profiles_de_path,
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user_id)) {
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return false;
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}
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auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
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if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, vendor_de_path + "/fpdata")) {
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return false;
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}
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auto facedata_path = vendor_de_path + "/facedata";
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if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, facedata_path)) {
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return false;
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}
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}
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}
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if (flags & android::os::IVold::STORAGE_FLAG_CE) {
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auto user_ce_path = android::vold::BuildDataUserCePath(volume_uuid, user_id);
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if (!prepare_dir_for_user(sehandle, 0771, AID_SYSTEM, AID_SYSTEM, user_ce_path, user_id)) {
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return false;
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}
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if (volume_uuid.empty()) {
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auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
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if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/vold")) return false;
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if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/storaged")) return false;
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if (!prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/rollback")) return false;
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// TODO: Return false if this returns false once sure this should succeed.
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prepare_dir(sehandle, 0700, 0, 0, misc_ce_path + "/apexrollback");
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prepare_apex_subdirs(sehandle, misc_ce_path);
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auto system_ce_path = android::vold::BuildDataSystemCePath(user_id);
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if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, system_ce_path + "/backup")) {
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return false;
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}
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if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM,
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system_ce_path + "/backup_stage")) {
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return false;
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}
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auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
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auto facedata_path = vendor_ce_path + "/facedata";
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if (!prepare_dir(sehandle, 0700, AID_SYSTEM, AID_SYSTEM, facedata_path)) {
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return false;
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}
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}
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}
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return true;
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}
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static bool destroy_subdirs(const std::string& volume_uuid, int user_id, int flags) {
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bool res = true;
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if (volume_uuid.empty()) {
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if (flags & android::os::IVold::STORAGE_FLAG_CE) {
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auto misc_ce_path = android::vold::BuildDataMiscCePath(user_id);
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res &= rmrf_contents(misc_ce_path);
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auto vendor_ce_path = android::vold::BuildDataVendorCePath(user_id);
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res &= rmrf_contents(vendor_ce_path);
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}
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if (flags & android::os::IVold::STORAGE_FLAG_DE) {
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auto misc_de_path = android::vold::BuildDataMiscDePath(user_id);
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res &= rmrf_contents(misc_de_path);
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auto vendor_de_path = android::vold::BuildDataVendorDePath(user_id);
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res &= rmrf_contents(vendor_de_path);
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}
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}
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return res;
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}
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int main(int argc, const char* const argv[]) {
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android::base::InitLogging(const_cast<char**>(argv));
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std::vector<std::string> args(argv + 1, argv + argc);
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if (args.size() != 4 || !valid_uuid(args[1]) || !small_int(args[2]) || !small_int(args[3])) {
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usage(argv[0]);
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return -1;
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}
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auto volume_uuid = args[1];
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int user_id = stoi(args[2]);
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int flags = stoi(args[3]);
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if (args[0] == "prepare") {
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if (!prepare_subdirs(volume_uuid, user_id, flags)) return -1;
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} else if (args[0] == "destroy") {
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if (!destroy_subdirs(volume_uuid, user_id, flags)) return -1;
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} else {
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usage(argv[0]);
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return -1;
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}
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return 0;
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}
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