How to get total heap memory allocated by the user when AddressSanitizer or ThreadSanitizer are enabled?

I want to get the amount of heap memory allocated with mallinfo2():

/*
 * File: main.c
*/

#include <malloc.h>
#include <stddef.h>
#include <stdio.h>

size_t GetHeapMemoryUsed() {
    struct mallinfo2 mi = mallinfo2();
    return mi.uordblks + mi.hblkhd;
}

int main(void) {
    size_t mem1 = GetHeapMemoryUsed();
    char *p = (char *)malloc(65536);
    size_t mem2 = GetHeapMemoryUsed();
    printf("Heap memory used: %zu\n", mem2 - mem1);
    free(p);
    return 0;
}

When I compile it with GCC (gcc -std=c99 main.c && ./a.out or g++ -std=c++11 main.cpp && ./a.out), it can give me the correct result:

Heap memory used: 65552

However, when I use AddressSanitizer or ThreadSanitizer (add an option -fsanitize=address or -fsanitize=thread), it gives me zero:

Heap memory used: 0

And mem1 and mem2 are all zero:

-    printf("Heap memory used: %zu\n", mem2 - mem1);
+    printf("Heap memory used: %zu\nmem1: %zu, mem2: %zu\n", mem2 - mem1, mem1, mem2);

Heap memory used: 0
mem1: 0, mem2: 0

It seems that AddressSanitizer and ThreadSanitizer take over the job of the malloc function and mallinfo2 cannot give the memory allocated.

Then how can I get the amount of heap memory allocated with AddressSanitizer or ThreadSanitizer enabled?

AFAICT, the sanitizer does not support mallinfo.

Looking at the source for gcc to get the source for libasan.*, it specifically treats it as a dummy implementation ...

From libsanitizer/asan/asan_malloc_linux.cc:

#if SANITIZER_INTERCEPT_MALLOPT_AND_MALLINFO
// We avoid including malloc.h for portability reasons.
// man mallinfo says the fields are "long", but the implementation uses int.
// It doesn't matter much -- we just need to make sure that the libc's mallinfo
// is not called.
struct fake_mallinfo {
  int x[10];
};

INTERCEPTOR(struct fake_mallinfo, mallinfo, void) {
  struct fake_mallinfo res;
  REAL(memset)(&res, 0, sizeof(res));
  return res;
}

INTERCEPTOR(int, mallopt, int cmd, int value) {
  return -1;
}
#endif // SANITIZER_INTERCEPT_MALLOPT_AND_MALLINFO

From libsanitizer/sanitizer_common/sanitizer_platform_interceptors.h:

#define SANITIZER_INTERCEPT_MALLOPT_AND_MALLINFO \
  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && SI_NOT_FUCHSIA)