lzo_wrapper.c

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/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2010 LG Electronics
 * Chan Jeong <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * lzo_wrapper.c
 */

#include <linux/mutex.h>
#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/lzo.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "decompressor.h"

struct squashfs_lzo {
    void    *input;
    void    *output;
};

static void *lzo_init(struct squashfs_sb_info *msblk, void *buff, int len)
{
    int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);

    struct squashfs_lzo *stream = kzalloc(sizeof(*stream), GFP_KERNEL);
    if (stream == NULL)
        goto failed;
    stream->input = vmalloc(block_size);
    if (stream->input == NULL)
        goto failed;
    stream->output = vmalloc(block_size);
    if (stream->output == NULL)
        goto failed2;

    return stream;

failed2:
    vfree(stream->input);
failed:
    ERROR("Failed to allocate lzo workspace\n");
    kfree(stream);
    return ERR_PTR(-ENOMEM);
}


static void lzo_free(void *strm)
{
    struct squashfs_lzo *stream = strm;

    if (stream) {
        vfree(stream->input);
        vfree(stream->output);
    }
    kfree(stream);
}


static int lzo_uncompress(struct squashfs_sb_info *msblk, void **buffer,
    struct buffer_head **bh, int b, int offset, int length, int srclength,
    int pages)
{
    struct squashfs_lzo *stream = msblk->stream;
    void *buff = stream->input;
    int avail, i, bytes = length, res;
    size_t out_len = srclength;

    mutex_lock(&msblk->read_data_mutex);

    for (i = 0; i < b; i++) {
        wait_on_buffer(bh[i]);
        if (!buffer_uptodate(bh[i]))
            goto block_release;

        avail = min(bytes, msblk->devblksize - offset);
        memcpy(buff, bh[i]->b_data + offset, avail);
        buff += avail;
        bytes -= avail;
        offset = 0;
        put_bh(bh[i]);
    }

    res = lzo1x_decompress_safe(stream->input, (size_t)length,
                    stream->output, &out_len);
    if (res != LZO_E_OK)
        goto failed;

    res = bytes = (int)out_len;
    for (i = 0, buff = stream->output; bytes && i < pages; i++) {
        avail = min_t(int, bytes, PAGE_CACHE_SIZE);
        memcpy(buffer[i], buff, avail);
        buff += avail;
        bytes -= avail;
    }

    mutex_unlock(&msblk->read_data_mutex);
    return res;

block_release:
    for (; i < b; i++)
        put_bh(bh[i]);

failed:
    mutex_unlock(&msblk->read_data_mutex);

    ERROR("lzo decompression failed, data probably corrupt\n");
    return -EIO;
}

const struct squashfs_decompressor squashfs_lzo_comp_ops = {
    .init = lzo_init,
    .free = lzo_free,
    .decompress = lzo_uncompress,
    .id = LZO_COMPRESSION,
    .name = "lzo",
    .supported = 1
};