lib/subcmd/sigchain.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <signal.h>
0003 #include "subcmd-util.h"
0004 #include "sigchain.h"
0005
0006 #define SIGCHAIN_MAX_SIGNALS 32
0007
0008 struct sigchain_signal {
0009     sigchain_fun *old;
0010     int n;
0011     int alloc;
0012 };
0013 static struct sigchain_signal signals[SIGCHAIN_MAX_SIGNALS];
0014
0015 static void check_signum(int sig)
0016 {
0017     if (sig < 1 || sig >= SIGCHAIN_MAX_SIGNALS)
0018         die("BUG: signal out of range: %d", sig);
0019 }
0020
0021 static int sigchain_push(int sig, sigchain_fun f)
0022 {
0023     struct sigchain_signal *s = signals + sig;
0024     check_signum(sig);
0025
0026     ALLOC_GROW(s->old, s->n + 1, s->alloc);
0027     s->old[s->n] = signal(sig, f);
0028     if (s->old[s->n] == SIG_ERR)
0029         return -1;
0030     s->n++;
0031     return 0;
0032 }
0033
0034 int sigchain_pop(int sig)
0035 {
0036     struct sigchain_signal *s = signals + sig;
0037     check_signum(sig);
0038     if (s->n < 1)
0039         return 0;
0040
0041     if (signal(sig, s->old[s->n - 1]) == SIG_ERR)
0042         return -1;
0043     s->n--;
0044     return 0;
0045 }
0046
0047 void sigchain_push_common(sigchain_fun f)
0048 {
0049     sigchain_push(SIGINT, f);
0050     sigchain_push(SIGHUP, f);
0051     sigchain_push(SIGTERM, f);
0052     sigchain_push(SIGQUIT, f);
0053     sigchain_push(SIGPIPE, f);
0054 }