65 lines
1.3 KiB
C++
65 lines
1.3 KiB
C++
// adapted from https://github.com/mifki/df-sizecheck/blob/master/b.cpp
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// usage:
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// linux: PRELOAD_LIB=hack/libsizecheck.so ./dfhack
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#include <cstdint>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <memory>
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using namespace std;
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const uint32_t MAGIC = 0xdfdf4ac8;
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bool initialized = false;
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int perturb = -1;
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void init() {
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#ifndef _LINUX
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if (getenv("MALLOC_PERTURB_")) {
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perturb = atoi(getenv("MALLOC_PERTURB_"));
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}
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#endif
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initialized = true;
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}
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void* alloc(size_t n) {
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if (!initialized) {
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init();
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}
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void* addr;
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if (posix_memalign(&addr, 32, n + 16) != 0) {
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return addr;
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}
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memset(addr, 0, 16);
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*(size_t*)addr = n;
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*(uint32_t*)((uint8_t*)addr + 8) = MAGIC;
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if (perturb > 0) {
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memset((uint8_t*)addr + 16, ~(perturb & 0xff), n);
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}
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return (uint8_t*)addr + 16;
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}
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void dealloc(void* addr) {
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if (!initialized) {
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init();
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}
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if (uintptr_t(addr) % 32 == 16 && *(uint32_t*)((uint8_t*)addr - 8) == MAGIC) {
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addr = (void*)((uint8_t*)addr - 16);
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memset((uint8_t*)addr + 16, perturb & 0xff, *(size_t*)addr);
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}
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free(addr);
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}
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void* operator new (size_t n, const nothrow_t& tag) {
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return alloc(n);
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}
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void* operator new (size_t n) {
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return alloc(n);
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}
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void operator delete (void* addr) {
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return dealloc(addr);
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}
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