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Reactos
1//
2// realloc_base.cpp
3//
4// Copyright (c) Microsoft Corporation. All rights reserved.
5//
6// Implementation of _realloc_base(). This is defined in a different source
7// file from the realloc() function to allow realloc() to be replaced by the
8// user.
9//
10#include <corecrt_internal.h>
11#include <malloc.h>
12#include <new.h>
13
14
15
16// This function implements the logic of realloc(). It is called directly by
17// the realloc() and _recalloc() functions in the Release CRT and is called by
18// the debug heap in the Debug CRT.
19//
20// This function must be marked noinline, otherwise realloc and
21// _realloc_base will have identical COMDATs, and the linker will fold
22// them when calling one from the CRT. This is necessary because realloc
23// needs to support users patching in custom implementations.
24extern "C" __declspec(noinline) _CRTRESTRICT void* __cdecl _realloc_base(
25 void* const block,
26 size_t const size
27 )
28{
29 // If the block is a nullptr, just call malloc:
30 if (block == nullptr)
31 return _malloc_base(size);
32
33 // If the new size is 0, just call free and return nullptr:
34 if (size == 0)
35 {
36 _free_base(block);
37 return nullptr;
38 }
39
40 // Ensure that the requested size is not too large:
41 _VALIDATE_RETURN_NOEXC(_HEAP_MAXREQ >= size, ENOMEM, nullptr);
42
43 for (;;)
44 {
45 void* const new_block = HeapReAlloc(__acrt_heap, 0, block, size);
46 if (new_block)
47 return new_block;
48
49 // Otherwise, see if we need to call the new handler, and if so call it.
50 // If the new handler fails, just return nullptr:
51 if (_query_new_mode() == 0 || !_callnewh(size))
52 {
53 errno = ENOMEM;
54 return nullptr;
55 }
56
57 // The new handler was successful; try to allocate again...
58 }
59}