#define _GNU_SOURCE
#include <string.h>
#include <assert.h>
#include <sys/mman.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>

int
main (void)
{
  const size_t ps = sysconf (_SC_PAGESIZE);
  void *search_buf_page = mmap (NULL, ps + ps, PROT_READ | PROT_WRITE,
				MAP_SHARED | MAP_ANONYMOUS, -1, 0);
  assert (search_buf_page != MAP_FAILED);
  int i = mprotect (search_buf_page + ps, ps, PROT_NONE);
  assert (i == 0);
  const size_t nr_search_bytes = 5;
  const char search_buf_data[5] = { 0x56, 0x34, 0x12, 0x78, 0x78 };
  void *search_buf = search_buf_page + ps - nr_search_bytes;
  memcpy (search_buf, search_buf_data, nr_search_bytes);
  const size_t pattern_len = 2;
  const char pattern[2] = { 0x78, 0x56 };
  return (memmem (search_buf, nr_search_bytes, pattern, pattern_len) == NULL
	  ? EXIT_SUCCESS : EXIT_FAILURE);
}