memcpy_s.c

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#include "common/use_annex_k.h"
#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
 
#include "common/constraint_handler.h"
 
errno_t memcpy_s(void* _RESTRICT s1, rsize_t s1max, const void* _RESTRICT s2, rsize_t n)
{
    uint8_t* d = (uint8_t*)s1;
    const uint8_t* s = (const uint8_t*)s2;
 
    if (s1 == NULL || s2 == NULL || s1max > RSIZE_MAX || n > RSIZE_MAX || n > s1max)
    {
        goto runtime_constraint_violation;
    }
 
    if ((d < s && d + n > s) || (s < d && s + n > d))
    {
        goto runtime_constraint_violation;
    }
 
    while (((uintptr_t)d & 7) && n)
    {
        *d++ = *s++;
        n--;
    }
 
    while (n >= 64)
    {
        *(uint64_t*)(d + 0) = *(const uint64_t*)(s + 0);
        *(uint64_t*)(d + 8) = *(const uint64_t*)(s + 8);
        *(uint64_t*)(d + 16) = *(const uint64_t*)(s + 16);
        *(uint64_t*)(d + 24) = *(const uint64_t*)(s + 24);
        *(uint64_t*)(d + 32) = *(const uint64_t*)(s + 32);
        *(uint64_t*)(d + 40) = *(const uint64_t*)(s + 40);
        *(uint64_t*)(d + 48) = *(const uint64_t*)(s + 48);
        *(uint64_t*)(d + 56) = *(const uint64_t*)(s + 56);
        d += 64;
        s += 64;
        n -= 64;
    }
 
    while (n >= 8)
    {
        *(uint64_t*)d = *(const uint64_t*)s;
        d += 8;
        s += 8;
        n -= 8;
    }
 
    while (n--)
    {
        *d++ = *s++;
    }
 
    return 0;
 
runtime_constraint_violation:
    if (s1 != NULL && s1max <= RSIZE_MAX)
    {
        memset(s1, 0, s1max);
    }
 
    _constraintHandler(_CONSTRAINT_VIOLATION(EINVAL));
    return EINVAL;
}