1 ///////////////////////////////////////////////////////////////////////////////
4 /// \brief Handling signals to abort operation
6 // Author: Lasse Collin
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
11 ///////////////////////////////////////////////////////////////////////////////
16 volatile sig_atomic_t user_abort = false;
19 #if !(defined(_WIN32) && !defined(__CYGWIN__))
21 /// If we were interrupted by a signal, we store the signal number so that
22 /// we can raise that signal to kill the program when all cleanups have
24 static volatile sig_atomic_t exit_signal = 0;
26 /// Mask of signals for which have have established a signal handler to set
27 /// user_abort to true.
28 static sigset_t hooked_signals;
30 /// True once signals_init() has finished. This is used to skip blocking
31 /// signals (with uninitialized hooked_signals) if signals_block() and
32 /// signals_unblock() are called before signals_init() has been called.
33 static bool signals_are_initialized = false;
35 /// signals_block() and signals_unblock() can be called recursively.
36 static size_t signals_block_count = 0;
40 signal_handler(int sig)
51 // List of signals for which we establish the signal handler.
52 static const int sigs[] = {
69 // Mask of the signals for which we have established a signal handler.
70 sigemptyset(&hooked_signals);
71 for (size_t i = 0; i < ARRAY_SIZE(sigs); ++i)
72 sigaddset(&hooked_signals, sigs[i]);
76 // All the signals that we handle we also blocked while the signal
78 sa.sa_mask = hooked_signals;
80 // Don't set SA_RESTART, because we want EINTR so that we can check
81 // for user_abort and cleanup before exiting. We block the signals
82 // for which we have established a handler when we don't want EINTR.
84 sa.sa_handler = &signal_handler;
86 for (size_t i = 0; i < ARRAY_SIZE(sigs); ++i) {
87 // If the parent process has left some signals ignored,
88 // we don't unignore them.
90 if (sigaction(sigs[i], NULL, &old) == 0
91 && old.sa_handler == SIG_IGN)
94 // Establish the signal handler.
95 if (sigaction(sigs[i], &sa, NULL))
96 message_signal_handler();
99 signals_are_initialized = true;
109 if (signals_are_initialized) {
110 if (signals_block_count++ == 0) {
111 const int saved_errno = errno;
112 mythread_sigmask(SIG_BLOCK, &hooked_signals, NULL);
122 signals_unblock(void)
124 if (signals_are_initialized) {
125 assert(signals_block_count > 0);
127 if (--signals_block_count == 0) {
128 const int saved_errno = errno;
129 mythread_sigmask(SIG_UNBLOCK, &hooked_signals, NULL);
142 const int sig = exit_signal;
146 sa.sa_handler = SIG_DFL;
147 sigfillset(&sa.sa_mask);
149 sigaction(sig, &sa, NULL);
158 // While Windows has some very basic signal handling functions as required
159 // by C89, they are not really used, and e.g. SIGINT doesn't work exactly
160 // the way it does on POSIX (Windows creates a new thread for the signal
161 // handler). Instead, we use SetConsoleCtrlHandler() to catch user
162 // pressing C-c, because that seems to be the recommended way to do it.
164 // NOTE: This doesn't work under MSYS. Trying with SIGINT doesn't work
165 // either even if it appeared to work at first. So test using Windows
169 signal_handler(DWORD type lzma_attribute((unused)))
171 // Since we don't get a signal number which we could raise() at
172 // signals_exit() like on POSIX, just set the exit status to
173 // indicate an error, so that we cannot return with zero exit status.
174 set_exit_status(E_ERROR);
183 if (!SetConsoleCtrlHandler(&signal_handler, TRUE))
184 message_signal_handler();