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3cfa137ca5
This patch is motivated by the wait function for the record-full target, that would install a custom signal handler for SIGINT, but could throw an exception and never reset the SIGINT handler. This is clearly a bad idea, so this patch introduces the class scoped_signal_handler in a new .h file. The file is added to gdbsupport, even though only gdb code is using it, because it feels like an addition that would be useful for more than just directly gdb. The implementation of the RAII class is based on the implementation on gdb/utils.c. That is, it uses preprocessor ifdefs to probe for sigaction support, and uses it if possible, defaulting to a raw call to signal only if sigaction isn't supported. sigaction is preferred based on the "portability" section of the manual page for the signal function. There are 3 places where this class can just be dropped in, gdb/record-full.c, gdb/utils.c and gdb/extension.c. This third place already had a specialized RAII signal handler setter, but it is substituted for the new general purpose one. Approved-By: Tom Tromey <tom@tromey.com>
74 lines
2.2 KiB
C++
74 lines
2.2 KiB
C++
/* RAII class to install a separate handler for a given signal
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Copyright (C) 2024 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program 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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef SCOPED_SIGNAL_HANDLER_H
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#define SCOPED_SIGNAL_HANDLER_H
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#include <signal.h>
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#undef HAVE_SIGACTION
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/* RAII class to set a signal handler for a scope, that will take care of
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unsetting the handler when the scope is left.
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This class will try to use sigaction whenever available, following the
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recommendation on the man page for signal, and only fallback to signal
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if necessary. */
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template <int SIG>
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class scoped_signal_handler
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{
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public:
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scoped_signal_handler (sighandler_t handler)
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{
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#if defined (HAVE_SIGACTION)
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struct sigaction act;
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act.sa_handler = handler;
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sigemptyset (&act.sa_mask);
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act.sa_flags = 0;
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sigaction (SIG, &act, &m_prev_handler);
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#else
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/* The return of the function call is the previous signal handler, or
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SIG_ERR if the function doesn't succeed. */
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m_prev_handler = signal (SIG, handler);
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/* According to the GNU libc manual, the only way signal fails is if
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the signum given is invalid, so we should be safe to assert. */
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gdb_assert (m_prev_handler != SIG_ERR);
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#endif
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}
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~scoped_signal_handler ()
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{
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#if defined (HAVE_SIGACTION)
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sigaction (SIG, &m_prev_handler, nullptr);
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#else
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signal (SIG, m_prev_handler);
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#endif
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}
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DISABLE_COPY_AND_ASSIGN (scoped_signal_handler);
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private:
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#if defined (HAVE_SIGACTION)
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struct sigaction m_prev_handler;
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#else
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sighandler_t m_prev_handler;
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#endif
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};
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#endif /* SCOPED_SIGNAL_HANDLER_H */
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