/*
 * Copyright (c) Huawei Technologies Co., Ltd. 2014-2021. All rights reserved.
 * Licensed under Mulan PSL v2.
 * You can use this software according to the terms and conditions of the Mulan PSL v2.
 * You may obtain a copy of Mulan PSL v2 at:
 *          http://license.coscl.org.cn/MulanPSL2
 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
 * See the Mulan PSL v2 for more details.
 * Description: memmove_s function
 * Create: 2014-02-25
 */
/*
 * [Standardize-exceptions] Use unsafe function: Portability
 * [reason] Use unsafe function to implement security function to maintain platform compatibility.
 *          And sufficient input validation is performed before calling
 */

#include "securecutil.h"

#ifdef SECUREC_NOT_CALL_LIBC_CORE_API
/*
 * Implementing memory data movement
 */
SECUREC_INLINE void SecUtilMemmove(void *dst, const void *src, size_t count)
{
    unsigned char *pDest = (unsigned char *)dst;
    const unsigned char *pSrc = (const unsigned char *)src;
    size_t maxCount = count;

    if (dst <= src || pDest >= (pSrc + maxCount)) {
        /*
         * Non-Overlapping Buffers
         * Copy from lower addresses to higher addresses
         */
        while (maxCount > 0) {
            --maxCount;
            *pDest = *pSrc;
            ++pDest;
            ++pSrc;
        }
    } else {
        /*
         * Overlapping Buffers
         * Copy from higher addresses to lower addresses
         */
        pDest = pDest + maxCount - 1;
        pSrc = pSrc + maxCount - 1;
        while (maxCount > 0) {
            --maxCount;
            *pDest = *pSrc;
            --pDest;
            --pSrc;
        }
    }
}
#endif

/*
 * <FUNCTION DESCRIPTION>
 *    The memmove_s function copies count bytes of characters from src to dest.
 *    This function can be assigned correctly when memory overlaps.
 * <INPUT PARAMETERS>
 *    dest                    Destination object.
 *    destMax                 Size of the destination buffer.
 *    src                     Source object.
 *    count                   Number of characters to copy.
 *
 * <OUTPUT PARAMETERS>
 *    dest buffer             is updated.
 *
 * <RETURN VALUE>
 *    EOK                     Success
 *    EINVAL                  dest is  NULL and destMax != 0 and destMax <= SECUREC_MEM_MAX_LEN
 *    EINVAL_AND_RESET        dest != NULL and src is NULL and destMax != 0 and destMax <= SECUREC_MEM_MAX_LEN
 *    ERANGE                  destMax > SECUREC_MEM_MAX_LEN or destMax is 0
 *    ERANGE_AND_RESET        count > destMax and dest  !=  NULL and src != NULL and destMax != 0
 *                            and destMax <= SECUREC_MEM_MAX_LEN
 *
 *    If an error occurred, dest will  be filled with 0 when dest and destMax valid.
 *    If some regions of the source area and the destination overlap, memmove_s
 *    ensures that the original source bytes in the overlapping region are copied
 *    before being overwritten.
 */
errno_t memmove_s(void *dest, size_t destMax, const void *src, size_t count)
{
    if (destMax == 0 || destMax > SECUREC_MEM_MAX_LEN) {
        SECUREC_ERROR_INVALID_RANGE("memmove_s");
        return ERANGE;
    }
    if (dest == NULL || src == NULL) {
        SECUREC_ERROR_INVALID_PARAMTER("memmove_s");
        if (dest != NULL) {
            (void)SECUREC_MEMSET_FUNC_OPT(dest, 0, destMax);
            return EINVAL_AND_RESET;
        }
        return EINVAL;
    }
    if (count > destMax) {
        (void)SECUREC_MEMSET_FUNC_OPT(dest, 0, destMax);
        SECUREC_ERROR_INVALID_RANGE("memmove_s");
        return ERANGE_AND_RESET;
    }
    if (dest == src) {
        return EOK;
    }

    if (count > 0) {
#ifdef SECUREC_NOT_CALL_LIBC_CORE_API
        SecUtilMemmove(dest, src, count);
#else
        /* Use underlying memmove for performance consideration */
        (void)memmove(dest, src, count);
#endif
    }
    return EOK;
}

#if SECUREC_EXPORT_KERNEL_SYMBOL
EXPORT_SYMBOL(memmove_s);
#endif