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 
check_signum(int sig)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 
sigchain_push(int sig,sigchain_fun f)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 
sigchain_pop(int sig)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 
sigchain_push_common(sigchain_fun f)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 }
55