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#include <signal.h>

sig_atomic_t i;

void handler(int signum) {
  i = 0;
}

int main(void) {
  i = 1;
  signal(SIGINT, handler);
  while (i) {
   /* do something */
  }
  return 0;
}

Compliant Solution

By adding the volatile qualifier, i is guaranteed to be accessed from its original address for every iteration of the while loop.

#include <signal.h>

volatile sig_atomic_t i;

void handler(int signum) {
  i = 0;
}

int main(void) {
  i = 1;
  signal(SIGINT, handler);
  while (i) {
   /* do something */
  }
  return 0;
}

The sig_atomic_t type is the integer type of an object that can be accessed as an atomic entity, even in the presence of asynchronous interrupts. The type of sig_atomic_t is implementation-defined, although there are constraints. Only assign integer values from 0 through 127 to a variable of type sig_atomic_t to be fully portable.

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