C example interrupt.c does not match with the description

[franzhollerer]

According the description in section Handling Interrupt Signals the signal handler sets the global variable s_interrupted.

The program provides s_catch_signals(), which traps Ctrl-C (SIGINT) and SIGTERM. When either
of these signals arrive, the s_catch_signals() handler sets the global variable s_interrupted.
Thanks to your signal handler, your application will not die automatically. Instead, you have a
chance to clean up and exit gracefully. 

However, the C example implements a different approach. It uses a pipe instead of the global variable.

From interrupt.c:

//  Shows how to handle Ctrl-C

#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>

#include <zmq.h>

//  Signal handling
//
//  Create a self-pipe and call s_catch_signals(pipe's writefd) in your application
//  at startup, and then exit your main loop if your pipe contains any data.
//  Works especially well with zmq_poll.

#define S_NOTIFY_MSG " "
#define S_ERROR_MSG "Error while writing to self-pipe.\n"
static int s_fd;
static void s_signal_handler (int signal_value)
{
    int rc = write (s_fd, S_NOTIFY_MSG, sizeof(S_NOTIFY_MSG));
    if (rc != sizeof(S_NOTIFY_MSG)) {
        write (STDOUT_FILENO, S_ERROR_MSG, sizeof(S_ERROR_MSG)-1);
        exit(1);
    }
}
...