lzo.c

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/*
 * Cryptographic API.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * 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, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/vmalloc.h>
#include <linux/lzo.h>

struct lzo_ctx {
    void *lzo_comp_mem;
};

static int lzo_init(struct crypto_tfm *tfm)
{
    struct lzo_ctx *ctx = crypto_tfm_ctx(tfm);

    ctx->lzo_comp_mem = vmalloc(LZO1X_MEM_COMPRESS);
    if (!ctx->lzo_comp_mem)
        return -ENOMEM;

    return 0;
}

static void lzo_exit(struct crypto_tfm *tfm)
{
    struct lzo_ctx *ctx = crypto_tfm_ctx(tfm);

    vfree(ctx->lzo_comp_mem);
}

static int lzo_compress(struct crypto_tfm *tfm, const u8 *src,
                unsigned int slen, u8 *dst, unsigned int *dlen)
{
    struct lzo_ctx *ctx = crypto_tfm_ctx(tfm);
    size_t tmp_len = *dlen; /* size_t(ulong) <-> uint on 64 bit */
    int err;

    err = lzo1x_1_compress(src, slen, dst, &tmp_len, ctx->lzo_comp_mem);

    if (err != LZO_E_OK)
        return -EINVAL;

    *dlen = tmp_len;
    return 0;
}

static int lzo_decompress(struct crypto_tfm *tfm, const u8 *src,
                  unsigned int slen, u8 *dst, unsigned int *dlen)
{
    int err;
    size_t tmp_len = *dlen; /* size_t(ulong) <-> uint on 64 bit */

    err = lzo1x_decompress_safe(src, slen, dst, &tmp_len);

    if (err != LZO_E_OK)
        return -EINVAL;

    *dlen = tmp_len;
    return 0;

}

static struct crypto_alg alg = {
    .cra_name       = "lzo",
    .cra_flags      = CRYPTO_ALG_TYPE_COMPRESS,
    .cra_ctxsize        = sizeof(struct lzo_ctx),
    .cra_module     = THIS_MODULE,
    .cra_init       = lzo_init,
    .cra_exit       = lzo_exit,
    .cra_u          = { .compress = {
    .coa_compress       = lzo_compress,
    .coa_decompress     = lzo_decompress } }
};

static int __init lzo_mod_init(void)
{
    return crypto_register_alg(&alg);
}

static void __exit lzo_mod_fini(void)
{
    crypto_unregister_alg(&alg);
}

module_init(lzo_mod_init);
module_exit(lzo_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LZO Compression Algorithm");