#include <stdio.h>
#include <sys/auxv.h>

#ifdef GETAUXVAL_BACKPORT_ELF64
typedef Elf64_auxv_t __auxv_t;
#else
typedef Elf32_auxv_t __auxv_t;
#endif

#define AUXV_FILE "/proc/self/auxv"

unsigned long getauxval(unsigned long type) {
#ifdef GETAUXVAL_BACKPORT_DEBUG
  printf("getauxval: search started for type: %lu\n", type);
#endif

  FILE *f = fopen(AUXV_FILE, "rb");
  if (f == NULL)
    return 1;

  unsigned long val = AT_NULL;
  __auxv_t aux;

#ifdef GETAUXVAL_BACKPORT_DEBUG
  unsigned int i = 0;
#endif

  while (fread(&aux, sizeof(aux), 1, f) == 1 && aux.a_type != AT_NULL) {
#ifdef GETAUXVAL_BACKPORT_DEBUG
    printf("getauxval: current type: %u [%u]\n", aux.a_type, i);
#endif

    if (aux.a_type == type) {
#ifdef GETAUXVAL_BACKPORT_DEBUG
      printf("getauxval: found %u with value: 0x%x\n", aux.a_type,
             aux.a_un.a_val);
#endif

      val = aux.a_un.a_val;
      break;
    }

#ifdef GETAUXVAL_BACKPORT_DEBUG
    i++;
#endif
  }

  fclose(f);

  return val;
}