CPT test exam compiling code

Hello all
I am new to programming and trying to compile this code

#include <asm/unistd.h>
#include <sys/mman.h>
#include <unistd.h>
#include <errno.h>
 
#define MREMAP_MAYMOVE 1
#define MREMAP_FIXED 2
 
#define __NR_real_mremap __NR_mremap
 
static inline _syscall5( void *, real_mremap, void *, old_address,
size_t, old_size, size_t, new_size,
unsigned long, flags, void *, new_address );
 
int main( void )
{
void *base;
 
base = mmap( NULL, 8192, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, 0, 0 );
 
real_mremap( base, 0, 0, MREMAP_MAYMOVE | MREMAP_FIXED,
(void *) 0xC0000000 );
 
fork();
 
return( 0 );
}

This is for a practice exam for the CPT (Certified Penetration Tester). I am not sure about resolving the errors.

Thanks

That code is linux specific for one thing, and depends on linux kernel headers for another, and probably a specific version of linux kernel headers. It certainly doesn't work here any more.

Thanks