fs/Exfat.cpp

/*
 * 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 <sys/mount.h>

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

#include <logwrap/logwrap.h>

#include "Exfat.h"
#include "Utils.h"

using android::base::StringPrintf;

namespace android {
namespace vold {
namespace exfat {

static const char* kMkfsPath = "/system/bin/mkfs.exfat";
static const char* kFsckPath = "/system/bin/fsck.exfat";

bool IsSupported() {
    return access(kMkfsPath, X_OK) == 0 && access(kFsckPath, X_OK) == 0 &&
           IsFilesystemSupported("exfat");
}

status_t Check(const std::string& source) {
    std::vector<std::string> cmd;
    cmd.push_back(kFsckPath);
    cmd.push_back("-y");
    cmd.push_back(source);

    int rc = ForkExecvpTimeout(cmd, kUntrustedFsckSleepTime, sFsckUntrustedContext);
    if (rc == 0) {
        LOG(INFO) << "Check OK";
        return 0;
    } else if (rc == 1) {
        LOG(INFO) << "Filesystem errors corrected";
        return 0;
    } else {
        LOG(ERROR) << "Check failed (code " << rc << ")";
        errno = EIO;
        return -1;
    }
}

status_t DoMount(const std::string& source, const std::string& target, int ownerUid, int ownerGid,
                 int permMask) {
    int mountFlags = MS_NODEV | MS_NOSUID | MS_DIRSYNC | MS_NOATIME | MS_NOEXEC;
    auto mountData = android::base::StringPrintf("uid=%d,gid=%d,fmask=%o,dmask=%o", ownerUid,
                                                 ownerGid, permMask, permMask);

    if (mount(source.c_str(), target.c_str(), "exfat", mountFlags, mountData.c_str()) == 0) {
        return 0;
    }

    PLOG(ERROR) << "Mount failed; attempting read-only";
    mountFlags |= MS_RDONLY;
    if (mount(source.c_str(), target.c_str(), "exfat", mountFlags, mountData.c_str()) == 0) {
        return 0;
    }

    return -1;
}

struct mount_args {
    const std::string& source;
    const std::string& target;
    int ownerUid;
    int ownerGid;
    int permMask;
};

int DoMountWrapper(void* args) {
    struct mount_args* m_args = (struct mount_args*)args;

    return DoMount(m_args->source, m_args->target, m_args->ownerUid, m_args->ownerGid,
                   m_args->permMask);
}

status_t Mount(const std::string& source, const std::string& target, int ownerUid, int ownerGid,
               int permMask) {
    struct mount_args args = {source, target, ownerUid, ownerGid, permMask};
    return ForkTimeout(DoMountWrapper, &args, kUntrustedMountSleepTime);
}

status_t Format(const std::string& source) {
    std::vector<std::string> cmd;
    cmd.push_back(kMkfsPath);
    cmd.push_back("-n");
    cmd.push_back("External");
    cmd.push_back(source);

    int rc = ForkExecvp(cmd);
    if (rc == 0) {
        LOG(INFO) << "Format OK";
        return 0;
    } else {
        LOG(ERROR) << "Format failed (code " << rc << ")";
        errno = EIO;
        return -1;
    }
    return 0;
}

}  // namespace exfat
}  // namespace vold
}  // namespace android