sigchain.c

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#include "sigchain.h"
#include "cache.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);
}

static 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);
}