138 lines
4.4 KiB
C++
138 lines
4.4 KiB
C++
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// Copyright 2010 Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// * Neither the name of Google Inc. nor the names of its contributors
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// may be used to endorse or promote products derived from this software
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// without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "utils/signals/programmer.hpp"
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extern "C" {
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#include <signal.h>
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}
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#include <cerrno>
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#include "utils/format/macros.hpp"
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#include "utils/logging/macros.hpp"
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#include "utils/sanity.hpp"
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#include "utils/signals/exceptions.hpp"
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namespace utils {
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namespace signals {
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/// Internal implementation for the signals::programmer class.
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struct programmer::impl {
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/// The number of the signal managed by this programmer.
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int signo;
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/// Whether the signal is currently programmed by us or not.
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bool programmed;
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/// The signal handler that we replaced; to be restored on unprogramming.
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struct ::sigaction old_sa;
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/// Initializes the internal implementation of the programmer.
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///
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/// \param signo_ The signal number.
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impl(const int signo_) :
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signo(signo_),
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programmed(false)
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{
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}
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};
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} // namespace signals
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} // namespace utils
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namespace signals = utils::signals;
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/// Programs a signal handler.
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///
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/// \param signo The signal for which to install the handler.
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/// \param handler The handler to install.
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///
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/// \throw signals::system_error If there is an error programming the signal.
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signals::programmer::programmer(const int signo, const handler_type handler) :
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_pimpl(new impl(signo))
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{
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struct ::sigaction sa;
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sa.sa_handler = handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_RESTART;
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if (::sigaction(_pimpl->signo, &sa, &_pimpl->old_sa) == -1) {
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const int original_errno = errno;
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throw system_error(F("Could not install handler for signal %s") %
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_pimpl->signo, original_errno);
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} else
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_pimpl->programmed = true;
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}
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/// Destructor; unprograms the signal handler if still programmed.
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///
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/// Given that this is a destructor and it can't report errors back to the
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/// caller, the caller must attempt to call unprogram() on its own.
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signals::programmer::~programmer(void)
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{
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if (_pimpl->programmed) {
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LW("Destroying still-programmed signals::programmer object");
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try {
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unprogram();
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} catch (const system_error& e) {
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UNREACHABLE;
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}
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}
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}
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/// Unprograms the signal handler.
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///
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/// \pre The signal handler is programmed (i.e. this can only be called once).
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///
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/// \throw system_error If unprogramming the signal failed. If this happens,
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/// the signal is left programmed, this object forgets about the signal and
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/// therefore there is no way to restore the original handler.
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void
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signals::programmer::unprogram(void)
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{
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PRE(_pimpl->programmed);
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// If we fail, we don't want the destructor to attempt to unprogram the
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// handler again, as it would result in a crash.
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_pimpl->programmed = false;
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if (::sigaction(_pimpl->signo, &_pimpl->old_sa, NULL) == -1) {
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const int original_errno = errno;
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throw system_error(F("Could not reset handler for signal %s") %
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_pimpl->signo, original_errno);
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}
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}
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