I'd like to make `malloc()` fail by limiting the memory available.

```
$ ulimit -v 1000
$ ./main.exe 10000000
0x102bfb000

```

But even with ulimit, the following program still finishes correctly. Does anybody know how to make `malloc()` fail? Thanks.

```
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
    size_t size = atoi(argv[1]);
    void *ptr = NULL;

    if((ptr = malloc(size)) == NULL) {
        perror("malloc()");
        exit(1);
    }

    printf("%p\n", ptr);
    free(ptr);
    return 0;
}

```

EDIT: The above is on Mac OS X.

On Linux, I got segmentation fault. Why `malloc()` can cause segmentation fault? How to make `malloc()` return a NULL pointer?