setrlimit + RLIMIT_AS + malloc
 

#include <sys/time.h>
#include <sys/resource.h>
#include <iostream.h>
#include <unistd.h>
#include <stdlib.h>

int main()

{
struct rlimit rlim;

int result = getrlimit(RLIMIT_AS, &rlim);
int *a1 =(int *)malloc(20*sizeof(int));
if(a1 != NULL)
cout<<"Memory allocated\n";
else
cout<<"Memory allocation failed for the first time\n";


rlim.rlim_cur = 8;
rlim.rlim_max = 8;
result = setrlimit(RLIMIT_AS, &rlim);
cout<<"\nRLIMIT_AS: ";
cout<<"\n\tResult: "<<result;
cout<<"\n\tSoft Limit: "<<rlim.rlim_cur;
cout<<"\n\tHard Limit: "<<rlim.rlim_max<<endl;

int *b1 =(int *)malloc(8*sizeof(int));
if(b1 != NULL)
cout<<"Memory allocated\n";
else
cout<<"Memory allocation failed for the first time\n";

free(a1);
free(b1);
return 0;
}


Expected Output:
Memory allocated
RLIMIT_AS:
0
8
8
Memory allocation failed for the first time


Observed o/p:
Memory allocated
RLIMIT_AS:
0
8
8
Memory allocated



Why this discrepancy???
Why the second time malloc didnt fail?

Regards
Shivali

The above program gives the expected o/p if i remove the first malloc from the program. why so???

i.e if the program is the one given below it works.

#include <sys/time.h>
#include <sys/resource.h>
#include <iostream.h>
#include <unistd.h>
#include <stdlib.h>

int main()

{
struct rlimit rlim;

int result = getrlimit(RLIMIT_AS, &rlim);
rlim.rlim_cur = 8;
rlim.rlim_max = 8;
result = setrlimit(RLIMIT_AS, &rlim);
cout<<"\nRLIMIT_AS: ";
cout<<"\n\tResult: "<<result;
cout<<"\n\tSoft Limit: "<<rlim.rlim_cur;
cout<<"\n\tHard Limit: "<<rlim.rlim_max<<endl;

int *b1 =(int *)malloc(8*sizeof(int));
if(b1 != NULL)
cout<<"Memory allocated\n";
else
cout<<"Memory allocation failed for the first time\n";

free(a1);
free(b1);
return 0;
}