fs/Apfs.cpp

/*
 * Copyright (C) 2008 The Android Open Source Project
 * Copyright (C) 2010-2021 Tuxera Inc.
 *
 * 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 <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <linux/fs.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <linux/kdev_t.h>

#define LOG_TAG "Vold::Apfs"

#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <selinux/selinux.h>

#include <logwrap/logwrap.h>

#include "Utils.h"
#include "Apfs.h"
#include "VoldUtil.h"

using android::base::StringPrintf;

namespace android {
namespace vold {
namespace apfs {

status_t Detect(const std::string& source, bool *outResult) {
    const char *const fsPath = source.c_str();

    int retval = -1;

    int fd = open(fsPath, O_RDONLY | O_CLOEXEC);
    if (fd != -1) {
        loff_t seek_res = lseek64(fd, 0, SEEK_SET);
        if (seek_res == 0) {
            char sb_region[4096];
            ssize_t read_res = read(fd, sb_region, 4096);
            if (read_res >= 512) {
                if (!memcmp(&sb_region[32], "NXSB", 4)) {
                    LOG(INFO) << "APFS filesystem detected.";
                    *outResult = true;
                }
                else {
                    LOG(VERBOSE) << "Filesystem detection failed (not an APFS "
                                 << "filesystem).";
                    *outResult = false;
                }

                retval = 0;
            }
            else if (read_res != -1) {
                int err = errno ? errno : EIO;
                LOG(ERROR) << "Error while reading 4096 bytes from device "
                           << "offset 0: " << strerror(errno) << " (" << errno
                           << ")";
                errno = err;
            }
        }
        else if (seek_res != -1) {
            int err = errno ? errno : EIO;
            LOG(ERROR) << "Error while seeking to device offset 0: "
                       << strerror(errno) << " (" << errno << ")";
            errno = err;
        }

        close(fd);
    }

    return retval;
}

}  // namespace apfs
}  // namespace vold
}  // namespace android