/*
 * This program tries to allocate as much memory as possible, then writes
 * to every page of it.
 *
 * To compile in normal mode:
 *
 * gcc -o eatmem eatmem.c
 *
 * To compile in sbrk() mode:
 *
 * gcc -DUSE_SBRK -o eatmem eatmem.c
 *
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>

long getvalue(char *fname,char *field){
  char s[129],*p;
  FILE *f;
  f=fopen(fname,"rt");
  if(!f) return -1;
  while(fgets(s,129,f)){
    p=strchr(s,':');
    if(p){
      *p=0;
      if(!strcmp(s,field)){
        p++;
        fclose(f);
        return atol(p);
      }
    }
  }
  fclose(f);
  return -1;
}

int main(int argc, char **argv, char **env){
  int p[2],n;
  unsigned long l,l1;
  long swapfree,swapfreemin;
  char *p0,*p1,*p2;
  pid_t pid;
  
  printf("Platform: pointer is %ld bits, int is %ld bits, long is %ld bits\n",
         (long)(sizeof(void*)*8),(long)(sizeof(int)*8),(long)(sizeof(long)*8));
  if(pipe(p)){
    perror("pipe");
    return 1;
  }
  if((pid=fork())<0){
    perror("fork");
    return 1;
  }
  if(pid==0){
    close(p[0]);
#ifdef USE_SBRK
    p0=(char*)sbrk(0);
    p1=p0-1;
    l=0; 
    while ((long)(p2=(char*)sbrk(4096))!=-1L){
      p1=p2+4096;
    }
#else
    p0=malloc(1);
    if(!p0) return 1;
    unsigned long s=0;
    while((p2=realloc(p0,s+4096))){
      s+=4096;
      p0=p2;
      p1=p2+s;
    }
#endif
    if(p1>p0) l=((unsigned long)(p1-p0))/1024UL;
    write(p[1],&l,sizeof(unsigned long));
    for(p2=p0;p2<p1;p2+=4096){
      (*p2)++;
      l=((unsigned long)(p2-p0))/1024UL;
      write(p[1],&l,sizeof(unsigned long));
    }
    return 0;
  }else{
    close(p[1]);
    if((read(p[0],&l,sizeof(unsigned long))==sizeof(unsigned long))){
      swapfree=getvalue("/proc/meminfo","SwapFree");
      swapfreemin=swapfree;
      if(swapfree<0){
        printf("Allocated %luK, can't get free swap value\n",l);
      }else{
        printf("Allocated %luK, free swap %ldK\n",l,swapfree);
      }
      while((n=(read(p[0],&l1,sizeof(unsigned long))==sizeof(unsigned long)))){
        if(n) l=l1;
        swapfree=getvalue("/proc/meminfo","SwapFree");
        if(swapfree<0){
          printf("\rAccessing %luK, can't get free swap value... \x1b[K",l);
        }else{
          if(swapfree<swapfreemin) swapfreemin=swapfree;
          printf("\rAccessing %luK, free swap %ldK... \x1b[K",l,swapfree);
        }
      }
    }
    wait(&n);
    printf("\r\x1b[K");
    if(WIFEXITED(n)){
      printf("Exited with status %d, ",WEXITSTATUS(n));
    }else{
      if(WIFSIGNALED(n)){
        printf("Received signal %d, ",WTERMSIG(n));
      }else{
        printf("Exited with unknown cause, ");
      }
    }
    swapfree=getvalue("/proc/meminfo","SwapFree");
    if(swapfree<0){
      printf("accessed %luK, can't get swap value\n",l);
    }else{
      printf("accessed %luK, min free swap %ldK, free swap now %ldK\n",l,swapfreemin,swapfree);
    }
    return 0;
  }
}