volume_manager/fs/Vfat.cpp

/*
 * Copyright (C) 2008 The Android Open Source Project
 * Copyright (C) 2019 The LineageOS 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 <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"

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

#include <logwrap/logwrap.h>

#include "Utils.h"
#include "Vfat.h"

using android::base::StringPrintf;

namespace android {
namespace volmgr {
namespace vfat {

status_t Mount(const std::string& source, const std::string& target, bool ro, bool remount,
               bool executable, int ownerUid, int ownerGid, int permMask, bool createLost) {
    int rc;
    unsigned long flags;
    char mountData[255];

    const char* c_source = source.c_str();
    const char* c_target = target.c_str();

    flags = MS_NODEV | MS_NOSUID | MS_DIRSYNC | MS_NOATIME;

    flags |= (executable ? 0 : MS_NOEXEC);
    flags |= (ro ? MS_RDONLY : 0);
    flags |= (remount ? MS_REMOUNT : 0);

    snprintf(mountData, sizeof(mountData), "utf8,uid=%d,gid=%d,fmask=%o,dmask=%o,shortname=mixed",
             ownerUid, ownerGid, permMask, permMask);

    rc = mount(c_source, c_target, "vfat", flags, mountData);

    if (rc && errno == EROFS) {
        SLOGE("%s appears to be a read only filesystem - retrying mount RO", c_source);
        flags |= MS_RDONLY;
        rc = mount(c_source, c_target, "vfat", flags, mountData);
    }

    if (rc == 0 && createLost) {
        char* lost_path;
        asprintf(&lost_path, "%s/LOST.DIR", c_target);
        if (access(lost_path, F_OK)) {
            /*
             * Create a LOST.DIR in the root so we have somewhere to put
             * lost cluster chains (fsck_msdos doesn't currently do this)
             */
            if (mkdir(lost_path, 0755)) {
                SLOGE("Unable to create LOST.DIR (%s)", strerror(errno));
            }
        }
        free(lost_path);
    }

    return rc;
}

}  // namespace vfat
}  // namespace volmgr
}  // namespace android