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#include <foundation/types.h>
#include <foundation/malloc.h>
#include <foundation/platform.h>
//------------------------------------------------------------------------------
struct Header
{
enum : uint32 { Magic = 0xaa55aa55 };
size_t size;
uint32 bias;
uint32 canary;
uint8 ptr[];
};
static bool g_add_canaries = false;
//------------------------------------------------------------------------------
#ifdef _WIN32
template <typename T=uint8>
static T* tt_malloc_norm(size_t size, size_t alignment)
{
alignment = uint32(std::max(alignment, alignof(std::max_align_t)));
if (!g_add_canaries)
return (T*)_aligned_malloc(size, alignment);
uint32 lead_size = uint32(sizeof(Header) + alignment - 1) & ~uint32(alignment - 1);
size_t alloc_size = lead_size + size + sizeof(uint32);
auto* alloc_ptr = (uint8*)_aligned_malloc(alloc_size, alignment);
auto* header = (Header*)(alloc_ptr + lead_size - sizeof(Header));
header->bias = lead_size;
header->size = size;
header->canary = Header::Magic;
std::memcpy(header->ptr + size, &header->canary, sizeof(uint32));
return header->ptr;
}
static void tt_free_norm(void* address)
{
if (address == nullptr)
return;
if (!g_add_canaries)
return _aligned_free(address);
auto* header = (Header*)address - 1;
auto is_canary = [] (void* ptr) {
uint32 canary = Header::Magic;
return !std::memcmp(ptr, &canary, sizeof(uint32));
};
if (!is_canary(&header->canary)) __debugbreak();
if (!is_canary(header->ptr + header->size)) __debugbreak();
_aligned_free(header->ptr - header->bias);
}
#else // POSIX
template <typename T=uint8>
static T* tt_malloc_norm(size_t size, size_t alignment)
{
alignment = std::max(alignment, alignof(std::max_align_t));
// std::aligned_alloc requires size to be a multiple of alignment
size_t aligned_size = (size + alignment - 1) & ~(alignment - 1);
if (aligned_size == 0)
aligned_size = alignment;
if (!g_add_canaries)
return (T*)std::aligned_alloc(alignment, aligned_size);
uint32 lead_size = uint32(sizeof(Header) + alignment - 1) & ~uint32(alignment - 1);
size_t alloc_size = lead_size + size + sizeof(uint32);
size_t alloc_aligned = (alloc_size + alignment - 1) & ~(alignment - 1);
auto* alloc_ptr = (uint8*)std::aligned_alloc(alignment, alloc_aligned);
auto* header = (Header*)(alloc_ptr + lead_size - sizeof(Header));
header->bias = lead_size;
header->size = size;
header->canary = Header::Magic;
std::memcpy(header->ptr + size, &header->canary, sizeof(uint32));
return header->ptr;
}
static void tt_free_norm(void* address)
{
if (address == nullptr)
return;
if (!g_add_canaries)
return std::free(address);
auto* header = (Header*)address - 1;
auto is_canary = [] (void* ptr) {
uint32 canary = Header::Magic;
return !std::memcmp(ptr, &canary, sizeof(uint32));
};
if (!is_canary(&header->canary)) __builtin_trap();
if (!is_canary(header->ptr + header->size)) __builtin_trap();
std::free(header->ptr - header->bias);
}
#endif
//------------------------------------------------------------------------------
void tt_memory_canaries_on()
{
g_add_canaries = true;
}
//------------------------------------------------------------------------------
void* (*tt_malloc_impl)(size_t, size_t) = tt_malloc_norm;
void (*tt_free)(void*) = tt_free_norm;
//------------------------------------------------------------------------------
#ifdef _WIN32
template <typename T=uint8>
static T* tt_malloc_stomp(size_t size, size_t alignment)
{
enum { PAGE_SIZE = 64 << 10 };
size = (size + (alignment - 1)) & ~(alignment - 1);
size_t alloc_size = (size + (2 * PAGE_SIZE)) & ~(PAGE_SIZE - 1);
auto* ptr = (uint8*)VirtualAlloc(nullptr, alloc_size, MEM_COMMIT, PAGE_READWRITE);
ptr += alloc_size - PAGE_SIZE;
DWORD unused;
VirtualProtect(ptr, PAGE_SIZE, PAGE_NOACCESS, &unused);
return (T*)(ptr - size);
}
static void tt_free_stomp(void* address)
{
if (address == nullptr)
return;
*(uint32*)address = 0x30493049;
MEMORY_BASIC_INFORMATION info;
VirtualQuery(address, &info, sizeof(info));
DWORD unused;
VirtualProtect(info.AllocationBase, info.RegionSize, PAGE_NOACCESS, &unused);
}
#else // POSIX
static size_t tt_get_page_size()
{
static size_t page_size = size_t(sysconf(_SC_PAGESIZE));
return page_size;
}
struct StompHeader
{
void* base;
size_t total_size;
};
template <typename T=uint8>
static T* tt_malloc_stomp(size_t size, size_t alignment)
{
size_t page_size = tt_get_page_size();
size = (size + (alignment - 1)) & ~(alignment - 1);
size_t needed = sizeof(StompHeader) + size + page_size;
size_t alloc_size = (needed + (page_size - 1)) & ~(page_size - 1);
auto* base = (uint8*)mmap(nullptr, alloc_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (base == MAP_FAILED)
return nullptr;
// Guard page at the end
uint8* guard = base + alloc_size - page_size;
mprotect(guard, page_size, PROT_NONE);
// User allocation right before the guard, header right before that
T* user_ptr = (T*)(guard - size);
auto* hdr = (StompHeader*)((uint8*)user_ptr - sizeof(StompHeader));
hdr->base = base;
hdr->total_size = alloc_size;
return user_ptr;
}
static void tt_free_stomp(void* address)
{
if (address == nullptr)
return;
*(uint32*)address = 0x30493049;
auto* hdr = (StompHeader*)((uint8*)address - sizeof(StompHeader));
mprotect(hdr->base, hdr->total_size, PROT_NONE);
}
#endif
//------------------------------------------------------------------------------
void tt_memory_stomp_on()
{
tt_malloc_impl = tt_malloc_stomp;
tt_free = tt_free_stomp;
}
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