#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int startsWith (const char* s1, const char* s2)
{
   while ((*s1 != 0) && (*s2 != 0) && (*s1 == *s2)) {
      ++s1;
      ++s2;
   }
   return (*s2 == 0);
}

void printMemInfo (void)
{
   char*    filename;
   FILE*    status;
   char     buffer[128];

   asprintf (&filename, "/proc/%d/status", getpid());
   status = fopen (filename, "r");
   free (filename);

   while (fgets (buffer, sizeof (buffer), status) != NULL)
      if (startsWith (buffer, "VmSize")) {
         printf ("%s", buffer);
         break;
      }

   fclose (status);
}

void** allocate (int n)
{
   void**   result = NULL;
   int      i;

   for (i = 0; i < n; ++i) {
      void**    next = malloc (sizeof (void**));
      *next          = result;
      result         = next;
   }
   return result;
}

void release (void** list)
{
   while (list != NULL) {
      void**    next = *list;
      free (list);
      list           = next;
   }
}

int main (int argc, char** argv)
{
   void**   list;

   printf ("At the beginning:\n");
   printMemInfo();

   list = allocate (1024*1024);
   printf ("After allocating the memory:\n");
   printMemInfo();

   release (list);
   printf ("After releasing the memory:\n");
   printMemInfo();

   return 0;
}