dfhack/depends/sizecheck/sizecheck.cpp

65 lines
1.3 KiB
C++

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