zlib_wrapper.c

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/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
 * Phillip Lougher <[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.
 *
 * zlib_wrapper.c
 */


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

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

static void *zlib_init(struct squashfs_sb_info *dummy, void *buff, int len)
{
    z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
    if (stream == NULL)
        goto failed;
    stream->workspace = vmalloc(zlib_inflate_workspacesize());
    if (stream->workspace == NULL)
        goto failed;

    return stream;

failed:
    ERROR("Failed to allocate zlib workspace\n");
    kfree(stream);
    return ERR_PTR(-ENOMEM);
}


static void zlib_free(void *strm)
{
    z_stream *stream = strm;

    if (stream)
        vfree(stream->workspace);
    kfree(stream);
}


static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
    struct buffer_head **bh, int b, int offset, int length, int srclength,
    int pages)
{
    int zlib_err, zlib_init = 0;
    int k = 0, page = 0;
    z_stream *stream = msblk->stream;

    mutex_lock(&msblk->read_data_mutex);

    stream->avail_out = 0;
    stream->avail_in = 0;

    do {
        if (stream->avail_in == 0 && k < b) {
            int avail = min(length, msblk->devblksize - offset);
            length -= avail;
            wait_on_buffer(bh[k]);
            if (!buffer_uptodate(bh[k]))
                goto release_mutex;

            stream->next_in = bh[k]->b_data + offset;
            stream->avail_in = avail;
            offset = 0;
        }

        if (stream->avail_out == 0 && page < pages) {
            stream->next_out = buffer[page++];
            stream->avail_out = PAGE_CACHE_SIZE;
        }

        if (!zlib_init) {
            zlib_err = zlib_inflateInit(stream);
            if (zlib_err != Z_OK) {
                ERROR("zlib_inflateInit returned unexpected "
                    "result 0x%x, srclength %d\n",
                    zlib_err, srclength);
                goto release_mutex;
            }
            zlib_init = 1;
        }

        zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);

        if (stream->avail_in == 0 && k < b)
            put_bh(bh[k++]);
    } while (zlib_err == Z_OK);

    if (zlib_err != Z_STREAM_END) {
        ERROR("zlib_inflate error, data probably corrupt\n");
        goto release_mutex;
    }

    zlib_err = zlib_inflateEnd(stream);
    if (zlib_err != Z_OK) {
        ERROR("zlib_inflate error, data probably corrupt\n");
        goto release_mutex;
    }

    if (k < b) {
        ERROR("zlib_uncompress error, data remaining\n");
        goto release_mutex;
    }

    length = stream->total_out;
    mutex_unlock(&msblk->read_data_mutex);
    return length;

release_mutex:
    mutex_unlock(&msblk->read_data_mutex);

    for (; k < b; k++)
        put_bh(bh[k]);

    return -EIO;
}

const struct squashfs_decompressor squashfs_zlib_comp_ops = {
    .init = zlib_init,
    .free = zlib_free,
    .decompress = zlib_uncompress,
    .id = ZLIB_COMPRESSION,
    .name = "zlib",
    .supported = 1
};