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
   7 struct sigchain_signal {
   8         sigchain_fun *old;
   9         int n;
  10         int alloc;
  11 };
  12 static struct sigchain_signal signals[SIGCHAIN_MAX_SIGNALS];
  13
  14 static 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
  20 static 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
  33 int 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
  46 void 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 }