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+/* Emergency actions in case of a fatal signal.
+ Copyright (C) 2003-2004, 2009-2022 Free Software Foundation, Inc.
+ Written by Bruno Haible <bruno@clisp.org>, 2003.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+
+#ifndef _FATAL_SIGNAL_H
+#define _FATAL_SIGNAL_H
+
+#include <signal.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/* It is often useful to do some cleanup action when a usually fatal signal
+ terminates the process, like removing a temporary file or killing a
+ subprocess that may be stuck waiting for a device, pipe or network input.
+ Such signals are SIGHUP, SIGINT, SIGPIPE, SIGTERM, and possibly others.
+ The limitation of this facility is that it cannot work for SIGKILL.
+
+ Signals with a SIG_IGN handler are considered to be non-fatal. The
+ functions in this file assume that when a SIG_IGN handler is installed
+ for a signal, it was installed before any functions in this file were
+ called and it stays so for the whole lifetime of the process. */
+
+/* Register a cleanup function to be executed when a catchable fatal signal
+ occurs.
+
+ Restrictions for the cleanup function:
+ - The cleanup function can do all kinds of system calls. It may also
+ modify (clobber) errno.
+ - It can also access application dependent memory locations and data
+ structures provided they are in a consistent state. One way to ensure
+ this is through block_fatal_signals()/unblock_fatal_signals(), see
+ below. Another - more tricky - way to ensure this is the careful use
+ of 'volatile'.
+ However,
+ - malloc() and similarly complex facilities are not safe to be called
+ because they are not guaranteed to be in a consistent state.
+ - Also, the cleanup function must not block the catchable fatal signals
+ and leave them blocked upon return.
+
+ The cleanup function is executed asynchronously. It is unspecified
+ whether during its execution the catchable fatal signals are blocked
+ or not.
+
+ Return 0 upon success, or -1 if there was a memory allocation problem. */
+extern int at_fatal_signal (_GL_ASYNC_SAFE void (*function) (int sig));
+
+
+/* Sometimes it is necessary to block the usually fatal signals while the
+ data structures being accessed by the cleanup action are being built or
+ reorganized. This is the case, for example, when a temporary file or
+ directory is created through mkstemp() or mkdtemp(), because these
+ functions create the temporary file or directory _before_ returning its
+ name to the application. */
+
+/* Temporarily delay the catchable fatal signals.
+ The signals will be blocked (= delayed) until the next call to
+ unblock_fatal_signals(). If the signals are already blocked, a further
+ call to block_fatal_signals() has no effect. */
+extern void block_fatal_signals (void);
+
+/* Stop delaying the catchable fatal signals. */
+extern void unblock_fatal_signals (void);
+
+
+/* Return the list of signals that block_fatal_signals/unblock_fatal_signals
+ would block or unblock.
+ Fills signals[0..count-1] and returns count. */
+extern unsigned int get_fatal_signals (int signals[64]);
+
+/* Return the list of signals that block_fatal_signals/unblock_fatal_signals
+ would block or unblock. */
+extern const sigset_t * get_fatal_signal_set (void);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _FATAL_SIGNAL_H */