1 /* Emergency actions in case of a fatal signal.
2 Copyright (C) 2003 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2003.
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2, or (at your option)
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
25 /* It is often useful to do some cleanup action when a usually fatal signal
26 terminates the process, like removing a temporary file or killing a
27 subprocess that may be stuck waiting for a device, pipe or network input.
28 Such signals are SIGHUP, SIGINT, SIGPIPE, SIGTERM, and possibly others.
29 The limitation of this facility is that it cannot work for SIGKILL. */
31 /* Register a cleanup function to be executed when a catchable fatal signal
34 Restrictions for the cleanup function:
35 - The cleanup function can do all kinds of system calls.
36 - It can also access application dependent memory locations and data
37 structures provided they are in a consistent state. One way to ensure
38 this is through block_fatal_signals()/unblock_fatal_signals(), see
39 below. Another - more tricky - way to ensure this is the careful use
42 - malloc() and similarly complex facilities are not safe to be called
43 because they are not guaranteed to be in a consistent state.
44 - Also, the cleanup function must not block the catchable fatal signals
45 and leave them blocked upon return.
47 The cleanup function is executed asynchronously. It is unspecified
48 whether during its execution the catchable fatal signals are blocked
50 extern void at_fatal_signal (void (*function) (void));
53 /* Sometimes it is necessary to block the usually fatal signals while the
54 data structures being accessed by the cleanup action are being built or
55 reorganized. This is the case, for example, when a temporary file or
56 directory is created through mkstemp() or mkdtemp(), because these
57 functions create the temporary file or directory _before_ returning its
58 name to the application. */
60 /* Temporarily delay the catchable fatal signals.
61 The signals will be blocked (= delayed) until the next call to
62 unblock_fatal_signals(). If the signals are already blocked, a further
63 call to block_fatal_signals() has no effect. */
64 extern void block_fatal_signals (void);
66 /* Stop delaying the catchable fatal signals. */
67 extern void unblock_fatal_signals (void);