/* Emergency actions in case of a fatal signal.
- Copyright (C) 2003 Free Software Foundation, Inc.
+ Copyright (C) 2003-2004 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2003.
- This program is free software; you can redistribute it and/or modify
+ 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 2, or (at your option)
- any later version.
+ 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
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, write to the Free Software Foundation,
- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifdef __cplusplus
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. */
+ 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. */
+ 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));
functions create the temporary file or directory _before_ returning its
name to the application. */
-/* Temporarily delay the catchable fatal signals. */
+/* 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. */