scanf loop, and signal handler

Question

Just learned about sigacation, also implemented another timer to make it more interesting.

#include 
#include  
#include 

        

Answer 1

A (pedantically) correct signal handler can do very few things: notably setting a volatile sig_atomic_t variable (this is some integer type), and perhaps calling siglongjmp [I'm not even sure for siglongjmp].

So declare first

volatile sig_atomic_t gotsignal;

then your signal handler is simply

void handler (void)
{
  gotsignal = 1;
}

and your loop is

while(!gotsignal && x < y){
    printf("Insert a value: \n");
    scanf("%d", &value);
    x+=value;
}

Don't forget that asynchronous signals happen at any time (any machine instruction!!!), including inside malloc or printf. Never call these functions from inside a handler.

Bugs related to bad signal handling are hard to debug: they are not reproducible!

Consider perhaps using sigaction.