/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
 * Copyright (c) 2013, 2018 by Delphix. All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/compress.h>
#include <sys/spa.h>
#include <sys/zfeature.h>
#include <sys/zio.h>
#include <sys/zio_compress.h>

/*
 * If nonzero, every 1/X decompression attempts will fail, simulating
 * an undetected memory error.
 */
uint64_t zio_decompress_fail_fraction = 0;

/*
 * Compression vectors.
 */
zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS] = {
        {"inherit",             0,      NULL,           NULL},
        {"on",                  0,      NULL,           NULL},
        {"uncompressed",        0,      NULL,           NULL},
        {"lzjb",                0,      lzjb_compress,  lzjb_decompress},
        {"empty",               0,      NULL,           NULL},
        {"gzip-1",              1,      gzip_compress,  gzip_decompress},
        {"gzip-2",              2,      gzip_compress,  gzip_decompress},
        {"gzip-3",              3,      gzip_compress,  gzip_decompress},
        {"gzip-4",              4,      gzip_compress,  gzip_decompress},
        {"gzip-5",              5,      gzip_compress,  gzip_decompress},
        {"gzip-6",              6,      gzip_compress,  gzip_decompress},
        {"gzip-7",              7,      gzip_compress,  gzip_decompress},
        {"gzip-8",              8,      gzip_compress,  gzip_decompress},
        {"gzip-9",              9,      gzip_compress,  gzip_decompress},
        {"zle",                 64,     zle_compress,   zle_decompress},
        {"lz4",                 0,      lz4_compress,   lz4_decompress}
};

enum zio_compress
zio_compress_select(spa_t *spa, enum zio_compress child,
    enum zio_compress parent)
{
        enum zio_compress result;

        ASSERT(child < ZIO_COMPRESS_FUNCTIONS);
        ASSERT(parent < ZIO_COMPRESS_FUNCTIONS);
        ASSERT(parent != ZIO_COMPRESS_INHERIT);

        result = child;
        if (result == ZIO_COMPRESS_INHERIT)
                result = parent;

        if (result == ZIO_COMPRESS_ON) {
                if (spa_feature_is_active(spa, SPA_FEATURE_LZ4_COMPRESS))
                        result = ZIO_COMPRESS_LZ4_ON_VALUE;
                else
                        result = ZIO_COMPRESS_LEGACY_ON_VALUE;
        }

        return (result);
}

/*ARGSUSED*/
static int
zio_compress_zeroed_cb(void *data, size_t len, void *private)
{
        uint64_t *end = (uint64_t *)((char *)data + len);
        for (uint64_t *word = (uint64_t *)data; word < end; word++)
                if (*word != 0)
                        return (1);

        return (0);
}

size_t
zio_compress_data(enum zio_compress c, abd_t *src, void *dst, size_t s_len)
{
        size_t c_len, d_len;
        zio_compress_info_t *ci = &zio_compress_table[c];

        ASSERT((uint_t)c < ZIO_COMPRESS_FUNCTIONS);
        ASSERT((uint_t)c == ZIO_COMPRESS_EMPTY || ci->ci_compress != NULL);

        /*
         * If the data is all zeroes, we don't even need to allocate
         * a block for it.  We indicate this by returning zero size.
         */
        if (abd_iterate_func(src, 0, s_len, zio_compress_zeroed_cb, NULL) == 0)
                return (0);

        if (c == ZIO_COMPRESS_EMPTY)
                return (s_len);

        /* Compress at least 12.5% */
        d_len = s_len - (s_len >> 3);

        /* No compression algorithms can read from ABDs directly */
        void *tmp = abd_borrow_buf_copy(src, s_len);
        c_len = ci->ci_compress(tmp, dst, s_len, d_len, ci->ci_level);
        abd_return_buf(src, tmp, s_len);

        if (c_len > d_len)
                return (s_len);

        ASSERT3U(c_len, <=, d_len);
        return (c_len);
}

int
zio_decompress_data_buf(enum zio_compress c, void *src, void *dst,
    size_t s_len, size_t d_len)
{
        zio_compress_info_t *ci = &zio_compress_table[c];
        if ((uint_t)c >= ZIO_COMPRESS_FUNCTIONS || ci->ci_decompress == NULL)
                return (SET_ERROR(EINVAL));

        return (ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level));
}

void *zio_decompress_failed_buf;

int
zio_decompress_data(enum zio_compress c, abd_t *src, void *dst,
    size_t s_len, size_t d_len)
{
        void *tmp = abd_borrow_buf_copy(src, s_len);
        int ret = zio_decompress_data_buf(c, tmp, dst, s_len, d_len);

        /*
         * Decompression shouldn't fail, because we've already verified
         * the checksum.  However, for extra protection (e.g. against bitflips
         * in non-ECC RAM), we handle this error (and test it).
         */
        if (ret != 0) {
                zio_decompress_failed_buf = kmem_alloc(s_len, KM_SLEEP);
                bcopy(tmp, zio_decompress_failed_buf, s_len);
                panic("decompression failed "
                    "err=%u c=%u buf=%p s_len=%u d_len=%u",
                    ret, (int)c, zio_decompress_failed_buf,
                    (int)s_len, (int)d_len);
        }

        abd_return_buf(src, tmp, s_len);

        if (zio_decompress_fail_fraction != 0 &&
            spa_get_random(zio_decompress_fail_fraction) == 0)
                ret = SET_ERROR(EINVAL);

        return (ret);
}