LXR linux/tools/lib/subcmd/sigchain.c

   1#include <signal.h>
   2#include "subcmd-util.h"
   3#include "sigchain.h"
   4
   5#define SIGCHAIN_MAX_SIGNALS 32
   6
   7struct sigchain_signal {
   8        sigchain_fun *old;
   9        int n;
  10        int alloc;
  11};
  12static struct sigchain_signal signals[SIGCHAIN_MAX_SIGNALS];
  13
  14static void check_signum(int sig)
  15{
  16        if (sig < 1 || sig >= SIGCHAIN_MAX_SIGNALS)
  17                die("BUG: signal out of range: %d", sig);
  18}
  19
  20static int sigchain_push(int sig, sigchain_fun f)
  21{
  22        struct sigchain_signal *s = signals + sig;
  23        check_signum(sig);
  24
  25        ALLOC_GROW(s->old, s->n + 1, s->alloc);
  26        s->old[s->n] = signal(sig, f);
  27        if (s->old[s->n] == SIG_ERR)
  28                return -1;
  29        s->n++;
  30        return 0;
  31}
  32
  33int sigchain_pop(int sig)
  34{
  35        struct sigchain_signal *s = signals + sig;
  36        check_signum(sig);
  37        if (s->n < 1)
  38                return 0;
  39
  40        if (signal(sig, s->old[s->n - 1]) == SIG_ERR)
  41                return -1;
  42        s->n--;
  43        return 0;
  44}
  45
  46void sigchain_push_common(sigchain_fun f)
  47{
  48        sigchain_push(SIGINT, f);
  49        sigchain_push(SIGHUP, f);
  50        sigchain_push(SIGTERM, f);
  51        sigchain_push(SIGQUIT, f);
  52        sigchain_push(SIGPIPE, f);
  53}
  54