mirror of https://gitee.com/openkylin/wget.git
102 lines
4.0 KiB
C
102 lines
4.0 KiB
C
/* Emergency actions in case of a fatal signal.
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Copyright (C) 2003-2004, 2009-2023 Free Software Foundation, Inc.
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Written by Bruno Haible <bruno@clisp.org>, 2003.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#ifndef _FATAL_SIGNAL_H
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#define _FATAL_SIGNAL_H
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/* This file uses _GL_ASYNC_SAFE. */
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#if !_GL_CONFIG_H_INCLUDED
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#error "Please include config.h first."
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#endif
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#include <signal.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* It is often useful to do some cleanup action when a usually fatal signal
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terminates the process, like removing a temporary file or killing a
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subprocess that may be stuck waiting for a device, pipe or network input.
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Such signals are SIGHUP, SIGINT, SIGPIPE, SIGTERM, and possibly others.
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The limitation of this facility is that it cannot work for SIGKILL.
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Signals with a SIG_IGN handler are considered to be non-fatal. The
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functions in this file assume that when a SIG_IGN handler is installed
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for a signal, it was installed before any functions in this file were
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called and it stays so for the whole lifetime of the process. */
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/* Register a cleanup function to be executed when a catchable fatal signal
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occurs.
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Restrictions for the cleanup function:
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- The cleanup function can do all kinds of system calls. It may also
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modify (clobber) errno.
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- It can also access application dependent memory locations and data
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structures provided they are in a consistent state. One way to ensure
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this is through block_fatal_signals()/unblock_fatal_signals(), see
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below. Another - more tricky - way to ensure this is the careful use
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of 'volatile'.
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However,
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- malloc() and similarly complex facilities are not safe to be called
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because they are not guaranteed to be in a consistent state.
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- Also, the cleanup function must not block the catchable fatal signals
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and leave them blocked upon return.
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The cleanup function is executed asynchronously. It is unspecified
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whether during its execution the catchable fatal signals are blocked
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or not.
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Return 0 upon success, or -1 if there was a memory allocation problem. */
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extern int at_fatal_signal (_GL_ASYNC_SAFE void (*function) (int sig));
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/* Sometimes it is necessary to block the usually fatal signals while the
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data structures being accessed by the cleanup action are being built or
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reorganized. This is the case, for example, when a temporary file or
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directory is created through mkstemp() or mkdtemp(), because these
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functions create the temporary file or directory _before_ returning its
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name to the application. */
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/* Temporarily delay the catchable fatal signals.
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The signals will be blocked (= delayed) until the next call to
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unblock_fatal_signals(). If the signals are already blocked, a further
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call to block_fatal_signals() has no effect. */
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extern void block_fatal_signals (void);
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/* Stop delaying the catchable fatal signals. */
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extern void unblock_fatal_signals (void);
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/* Return the list of signals that block_fatal_signals/unblock_fatal_signals
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would block or unblock.
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Fills signals[0..count-1] and returns count. */
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extern unsigned int get_fatal_signals (int signals[64]);
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/* Return the list of signals that block_fatal_signals/unblock_fatal_signals
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would block or unblock. */
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extern const sigset_t * get_fatal_signal_set (void);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _FATAL_SIGNAL_H */
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