tools/lib/subcmd/sigchain.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <signal.h>
   3 #include "subcmd-util.h"
   4 #include "sigchain.h"
   5
   6 #define SIGCHAIN_MAX_SIGNALS 32
   7
   8 struct sigchain_signal {
   9         sigchain_fun *old;
  10         int n;
  11         int alloc;
  12 };
  13 static struct sigchain_signal signals[SIGCHAIN_MAX_SIGNALS];
  14
  15 static void check_signum(int sig)
  16 {
  17         if (sig < 1 || sig >= SIGCHAIN_MAX_SIGNALS)
  18                 die("BUG: signal out of range: %d", sig);
  19 }
  20
  21 static int sigchain_push(int sig, sigchain_fun f)
  22 {
  23         struct sigchain_signal *s = signals + sig;
  24         check_signum(sig);
  25
  26         ALLOC_GROW(s->old, s->n + 1, s->alloc);
  27         s->old[s->n] = signal(sig, f);
  28         if (s->old[s->n] == SIG_ERR)
  29                 return -1;
  30         s->n++;
  31         return 0;
  32 }
  33
  34 int sigchain_pop(int sig)
  35 {
  36         struct sigchain_signal *s = signals + sig;
  37         check_signum(sig);
  38         if (s->n < 1)
  39                 return 0;
  40
  41         if (signal(sig, s->old[s->n - 1]) == SIG_ERR)
  42                 return -1;
  43         s->n--;
  44         return 0;
  45 }
  46
  47 void sigchain_push_common(sigchain_fun f)
  48 {
  49         sigchain_push(SIGINT, f);
  50         sigchain_push(SIGHUP, f);
  51         sigchain_push(SIGTERM, f);
  52         sigchain_push(SIGQUIT, f);
  53         sigchain_push(SIGPIPE, f);
  54 }