extern "C" void __cdecl _aligned_free(void* const block)
{
#ifdef _DEBUG
_aligned_free_dbg(block);
#else
_aligned_free_base(block);
#endif
}
FREE_CALL void __cdecl _aligned_free( void *memblock )
{
_aligned_free_base(memblock);
}
extern "C" void* __cdecl _aligned_offset_realloc_base(
void* block,
size_t size,
size_t align,
size_t offset
)
{
uintptr_t ptr, retptr, gap, stptr, diff;
uintptr_t movsz, reqsz;
int bFree = 0;
/* special cases */
if (block == nullptr)
{
return _aligned_offset_malloc_base(size, align, offset);
}
if (size == 0)
{
_aligned_free_base(block);
return nullptr;
}
/* validation section */
_VALIDATE_RETURN(IS_2_POW_N(align), EINVAL, nullptr);
_VALIDATE_RETURN(offset == 0 || offset < size, EINVAL, nullptr);
stptr = (uintptr_t)block;
/* ptr points to the pointer to starting of the memory block */
stptr = (stptr & ~(PTR_SZ -1)) - PTR_SZ;
/* ptr is the pointer to the start of memory block*/
stptr = *((uintptr_t *)stptr);
align = (align > PTR_SZ ? align : PTR_SZ) -1;
/* gap = number of bytes needed to round up offset to align with PTR_SZ*/
gap = (0 -offset)&(PTR_SZ -1);
diff = (uintptr_t)block - stptr;
/* Mov size is min of the size of data available and sizw requested.
*/
#pragma warning(push)
#pragma warning(disable: 22018) // Silence prefast about overflow/underflow
movsz = _msize((void *)stptr) - ((uintptr_t)block - stptr);
#pragma warning(pop)
movsz = movsz > size ? size : movsz;
reqsz = PTR_SZ + gap + align + size;
_VALIDATE_RETURN_NOEXC(size <= reqsz, ENOMEM, nullptr);
/* First check if we can expand(reducing or expanding using expand) data
* safely, ie no data is lost. eg, reducing alignment and keeping size
* same might result in loss of data at the tail of data block while
* expanding.
*
* If no, use malloc to allocate the new data and move data.
*
* If yes, expand and then check if we need to move the data.
*/
if ((stptr +align +PTR_SZ +gap)<(uintptr_t)block)
{
if ((ptr = (uintptr_t)malloc(reqsz)) == (uintptr_t) nullptr)
return nullptr;
bFree = 1;
}
else
{
/* we need to save errno, which can be modified by _expand */
errno_t save_errno = errno;
if ((ptr = (uintptr_t)_expand((void *)stptr, reqsz)) == (uintptr_t)nullptr)
{
errno = save_errno;
if ((ptr = (uintptr_t)malloc(reqsz)) == (uintptr_t) nullptr)
return nullptr;
bFree = 1;
}
else
stptr = ptr;
}
if ( ptr == ((uintptr_t)block - diff)
&& !( ((size_t)block + gap +offset) & ~(align) ))
{
return block;
}
retptr =((ptr +PTR_SZ +gap +align +offset)&~align)- offset;
memmove((void *)retptr, (void *)(stptr + diff), movsz);
if ( bFree)
free ((void *)stptr);
((uintptr_t *)(retptr - gap))[-1] = ptr;
return (void *)retptr;
}