ext4_utils/wipe.cpp

/*
 * Copyright (C) 2011 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 "ext4_utils/wipe.h"

#include "ext4_utils/ext4_utils.h"

#include <android-base/file.h>

#if WIPE_IS_SUPPORTED

#if defined(__linux__)

#include <linux/fs.h>
#include <sys/ioctl.h>

#include "helpers.h"

#ifndef BLKDISCARD
#define BLKDISCARD _IO(0x12, 119)
#endif

#ifndef BLKSECDISCARD
#define BLKSECDISCARD _IO(0x12, 125)
#endif

int wipe_block_device(int fd, s64 len) {
    u64 range[2];
    int ret;

    if (!is_block_device_fd(fd)) {
        // Wiping only makes sense on a block device.
        return 0;
    }

    range[0] = 0;
    range[1] = len;
    ret = ioctl(fd, BLKSECDISCARD, &range);
    if (ret < 0) {
        range[0] = 0;
        range[1] = len;
        ret = ioctl(fd, BLKDISCARD, &range);
        if (ret < 0) {
            warn("Discard failed\n");
            return 1;
        } else {
            char buf[4096] = {0};

            if (!android::base::WriteFully(fd, buf, 4096)) {
                warn("Writing zeros failed\n");
                return 1;
            }
            fsync(fd);
            warn("Wipe via secure discard failed, used discard instead\n");
            return 0;
        }
    }

    return 0;
}

#else /* __linux__ */
#error "Missing block device wiping implementation for this platform!"
#endif

#else /* WIPE_IS_SUPPORTED */

int wipe_block_device(int fd __attribute__((unused)), s64 len __attribute__((unused))) {
    /* Wiping is not supported on this platform. */
    return 1;
}

#endif /* WIPE_IS_SUPPORTED */