C - 在 SIGINT 上免费分配 memory

Question

I want to write a program which will fill the computer's memory with 0's until malloc() fails. However, I wasn't sure if killing the program with Ctrl + C would free this memory. I added some signal-handling code, so that when the program receives SIGINT , the allocated memory is freed and the program is killed.

My code appears to work, but I want to know if this method of freeing memory on SIGINT makes sense, or if there is a better way to do it.

My code:

#include <stdlib.h>
#include <signal.h>

int *ptr;

void inthandler(int dummy) { /* what does this argument do? */
   extern int *ptr;
   free(ptr);
   exit(-1);
}

int main(void) {
   signal(SIGINT, inthandler);
   extern int *ptr;
   while ((ptr = malloc(sizeof *ptr)) != NULL) {
         *ptr = 0;
   }
}

Answer 1

However, I wasn't sure if killing the program with Ctrl+C would free this memory.

On any modern OS, it will.

My code appears to work, but I want to know if this method of freeing memory on SIGINT makes sense, or if there is a better way to do it.

Your code is deeply flawed (in addition to being pointless).

malloc and free are not async-signal safe. Calling them from a signal handler invokes undefined behavior, and your program may crash at random times.

Finally, your inthandler() is never actually called -- you need to call signal() or sigaction() to actually set the inthandler as a SIGINT handler.