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Diffstat (limited to 'examples/dte/signals.c')
| -rw-r--r-- | examples/dte/signals.c | 169 |
1 files changed, 0 insertions, 169 deletions
diff --git a/examples/dte/signals.c b/examples/dte/signals.c deleted file mode 100644 index e1a7155..0000000 --- a/examples/dte/signals.c +++ /dev/null @@ -1,169 +0,0 @@ -#include "compat.h" -#include <errno.h> -#include <string.h> -#include <unistd.h> -#include "signals.h" -#include "util/debug.h" -#include "util/exitcode.h" -#include "util/log.h" -#include "util/macros.h" - -volatile sig_atomic_t resized = 0; - -static const int ignored_signals[] = { - SIGINT, // Terminal interrupt (see: VINTR in termios(3)) - SIGQUIT, // Terminal quit (see: VQUIT in termios(3)) - SIGTSTP, // Terminal stop (see: VSUSP in termios(3)) - SIGXFSZ, // File size limit exceeded (see: RLIMIT_FSIZE in getrlimit(3)) - SIGPIPE, // Broken pipe (see: EPIPE error in write(3)) - SIGUSR1, // User signal 1 (terminates by default, for no good reason) - SIGUSR2, // User signal 2 (as above) -}; - -static const int default_signals[] = { - SIGABRT, // Terminate (cleanup already done) - SIGCHLD, // Ignore (see: wait(3)) - SIGURG, // Ignore - SIGTTIN, // Stop - SIGTTOU, // Stop - SIGCONT, // Continue -}; - -static const int fatal_signals[] = { - SIGBUS, - SIGFPE, - SIGILL, - SIGSEGV, - SIGSYS, - SIGTRAP, - SIGXCPU, - SIGALRM, - SIGVTALRM, - SIGHUP, - SIGTERM, -#ifdef SIGPROF - SIGPROF, -#endif -#ifdef SIGEMT - SIGEMT, -#endif -}; - -void handle_sigwinch(int UNUSED_ARG(signum)) -{ - resized = 1; -} - -static noreturn COLD void handle_fatal_signal(int signum) -{ - LOG_CRITICAL("received signal %d (%s)", signum, strsignal(signum)); - - // If `signum` is SIGHUP, there's no point in trying to clean up the - // state of the (disconnected) terminal - if (signum != SIGHUP) { - fatal_error_cleanup(); - } - - // Restore and unblock `signum` and then re-raise it, to ensure the - // termination status (as seen by e.g. waitpid(3) in the parent) is - // set appropriately - struct sigaction sa = {.sa_handler = SIG_DFL}; - if ( - sigemptyset(&sa.sa_mask) == 0 - && sigaction(signum, &sa, NULL) == 0 - && sigaddset(&sa.sa_mask, signum) == 0 - && sigprocmask(SIG_UNBLOCK, &sa.sa_mask, NULL) == 0 - ) { - raise(signum); - } - - // This is here just to make extra certain the handler never returns. - // If everything is working correctly, this code should be unreachable. - raise(SIGKILL); - _exit(EX_OSERR); -} - -// strsignal(3) is fine in situations where a signal is being reported -// as terminating a process, but it tends to be confusing in most other -// circumstances, where the signal name (not description) is usually -// clearer -static const char *signum_to_str(int signum) -{ -#if HAVE_SIG2STR - static char buf[SIG2STR_MAX + 3]; - if (sig2str(signum, buf + 3) == 0) { - return memcpy(buf, "SIG", 3); - } -#elif HAVE_SIGABBREV_NP - static char buf[16]; - const char *abbr = sigabbrev_np(signum); - if (abbr && memccpy(buf + 3, abbr, '\0', sizeof(buf) - 3)) { - return memcpy(buf, "SIG", 3); - } -#endif - - const char *str = strsignal(signum); - return likely(str) ? str : "??"; -} - -static void do_sigaction(int sig, const struct sigaction *action) -{ - struct sigaction old_action; - if (unlikely(sigaction(sig, action, &old_action) != 0)) { - const char *err = strerror(errno); - LOG_ERROR("failed to set disposition for signal %d: %s", sig, err); - return; - } - if (unlikely(old_action.sa_handler == SIG_IGN)) { - const char *str = signum_to_str(sig); - LOG_WARNING("ignored signal was inherited: %d (%s)", sig, str); - } -} - -/* - * "A program that uses these functions should be written to catch all - * signals and take other appropriate actions to ensure that when the - * program terminates, whether planned or not, the terminal device's - * state is restored to its original state." - * - * (https://pubs.opengroup.org/onlinepubs/9699919799/functions/tcgetattr.html) - */ -void set_signal_handlers(void) -{ - struct sigaction action = {.sa_handler = handle_fatal_signal}; - sigfillset(&action.sa_mask); - for (size_t i = 0; i < ARRAYLEN(fatal_signals); i++) { - do_sigaction(fatal_signals[i], &action); - } - - // "The default actions for the realtime signals in the range SIGRTMIN - // to SIGRTMAX shall be to terminate the process abnormally." - // (POSIX.1-2017 ยง2.4.3) -#if defined(SIGRTMIN) && defined(SIGRTMAX) - for (int s = SIGRTMIN, max = SIGRTMAX; s <= max; s++) { - do_sigaction(s, &action); - } -#endif - - action.sa_handler = SIG_IGN; - for (size_t i = 0; i < ARRAYLEN(ignored_signals); i++) { - do_sigaction(ignored_signals[i], &action); - } - - action.sa_handler = SIG_DFL; - for (size_t i = 0; i < ARRAYLEN(default_signals); i++) { - do_sigaction(default_signals[i], &action); - } - -#if defined(SIGWINCH) - LOG_INFO("setting SIGWINCH handler"); - action.sa_handler = handle_sigwinch; - do_sigaction(SIGWINCH, &action); -#endif - - // Set signal mask explicitly, to avoid any possibility of - // inheriting blocked signals - sigset_t mask; - sigemptyset(&mask); - sigprocmask(SIG_SETMASK, &mask, NULL); -} |