root/sigchain.c

DEFINITIONS

1. check_signum
2. sigchain_push
3. sigchain_pop
4. sigchain_push_common

#include "cache.h"
#include "sigchain.h"

#define SIGCHAIN_MAX_SIGNALS 32

struct sigchain_signal {
        sigchain_fun *old;
        int n;
        int alloc;
};
static struct sigchain_signal signals[SIGCHAIN_MAX_SIGNALS];

static void check_signum(int sig)
{
        if (sig < 1 || sig >= SIGCHAIN_MAX_SIGNALS)
                die("BUG: signal out of range: %d", sig);
}

int sigchain_push(int sig, sigchain_fun f)
{
        struct sigchain_signal *s = signals + sig;
        check_signum(sig);

        ALLOC_GROW(s->old, s->n + 1, s->alloc);
        s->old[s->n] = signal(sig, f);
        if (s->old[s->n] == SIG_ERR)
                return -1;
        s->n++;
        return 0;
}

int sigchain_pop(int sig)
{
        struct sigchain_signal *s = signals + sig;
        check_signum(sig);
        if (s->n < 1)
                return 0;

        if (signal(sig, s->old[s->n - 1]) == SIG_ERR)
                return -1;
        s->n--;
        return 0;
}

void sigchain_push_common(sigchain_fun f)
{
        sigchain_push(SIGINT, f);
        sigchain_push(SIGHUP, f);
        sigchain_push(SIGTERM, f);
        sigchain_push(SIGQUIT, f);
        sigchain_push(SIGPIPE, f);
}