/* Emergency actions in case of a fatal signal. Copyright (C) 2003-2004, 2009-2012 Free Software Foundation, Inc. Written by Bruno Haible <bruno@clisp.org>, 2003. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #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 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. */ extern void at_fatal_signal (void (*function) (void)); /* 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); #ifdef __cplusplus } #endif