268 lines
8.4 KiB
C++
268 lines
8.4 KiB
C++
// Copyright 2012 Google Inc.
|
|
// All rights reserved.
|
|
//
|
|
// Redistribution and use in source and binary forms, with or without
|
|
// modification, are permitted provided that the following conditions are
|
|
// met:
|
|
//
|
|
// * Redistributions of source code must retain the above copyright
|
|
// notice, this list of conditions and the following disclaimer.
|
|
// * Redistributions in binary form must reproduce the above copyright
|
|
// notice, this list of conditions and the following disclaimer in the
|
|
// documentation and/or other materials provided with the distribution.
|
|
// * Neither the name of Google Inc. nor the names of its contributors
|
|
// may be used to endorse or promote products derived from this software
|
|
// without specific prior written permission.
|
|
//
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
#include "utils/signals/interrupts.hpp"
|
|
|
|
extern "C" {
|
|
#include <signal.h>
|
|
#include <unistd.h>
|
|
}
|
|
|
|
#include <cstdlib>
|
|
#include <cstring>
|
|
#include <set>
|
|
|
|
#include "utils/sanity.hpp"
|
|
#include "utils/signals/exceptions.hpp"
|
|
#include "utils/signals/programmer.hpp"
|
|
|
|
namespace signals = utils::signals;
|
|
|
|
|
|
namespace {
|
|
|
|
|
|
/// The interrupt signal that fired, or -1 if none.
|
|
static volatile int fired_signal = -1;
|
|
|
|
|
|
/// Collection of PIDs.
|
|
typedef std::set< pid_t > pids_set;
|
|
|
|
|
|
/// List of processes to kill upon reception of a signal.
|
|
static pids_set pids_to_kill;
|
|
|
|
|
|
/// Programmer status for the SIGHUP signal.
|
|
static std::auto_ptr< signals::programmer > sighup_handler;
|
|
/// Programmer status for the SIGINT signal.
|
|
static std::auto_ptr< signals::programmer > sigint_handler;
|
|
/// Programmer status for the SIGTERM signal.
|
|
static std::auto_ptr< signals::programmer > sigterm_handler;
|
|
|
|
|
|
/// Signal mask to restore after exiting a signal inhibited section.
|
|
static sigset_t old_sigmask;
|
|
|
|
|
|
/// Whether there is an interrupts_handler object in existence or not.
|
|
bool interrupts_handler_active = false;
|
|
|
|
|
|
/// Whether there is an interrupts_inhibiter object in existence or not.
|
|
bool interrupts_inhibiter_active = false;
|
|
|
|
|
|
/// Generic handler to capture interrupt signals.
|
|
///
|
|
/// From this handler, we record that an interrupt has happened so that
|
|
/// check_interrupt() can know whether there execution has to be stopped or not.
|
|
/// We also terminate any of our child processes (started by the
|
|
/// utils::process::children class) so that any ongoing wait(2) system calls
|
|
/// terminate.
|
|
///
|
|
/// \param signo The signal that caused this handler to be called.
|
|
static void
|
|
signal_handler(const int signo)
|
|
{
|
|
static const char* message = "[-- Signal caught; please wait for "
|
|
"cleanup --]\n";
|
|
if (::write(STDERR_FILENO, message, std::strlen(message)) == -1) {
|
|
// We are exiting: the message printed here is only for informational
|
|
// purposes. If we fail to print it (which probably means something
|
|
// is really bad), there is not much we can do within the signal
|
|
// handler, so just ignore this.
|
|
}
|
|
|
|
fired_signal = signo;
|
|
|
|
for (pids_set::const_iterator iter = pids_to_kill.begin();
|
|
iter != pids_to_kill.end(); ++iter) {
|
|
// Redirecting the interrupt signal to our child processes does NOT
|
|
// guarantee that they also terminate. For that to happen, we'd need to
|
|
// SIGKILL them.
|
|
//
|
|
// *However*, because we use this code to invoke the kyua-testers only,
|
|
// and because we assume that such processes are well-behaved and
|
|
// terminate according to our expectations, we do it this way, which
|
|
// allows the testers to know which specific signal made them terminate.
|
|
(void)::kill(*iter, signo);
|
|
}
|
|
}
|
|
|
|
|
|
/// Installs signal handlers for potential interrupts.
|
|
///
|
|
/// \pre Must not have been called before.
|
|
/// \post The various sig*_handler global variables are atomically updated.
|
|
static void
|
|
setup_handlers(void)
|
|
{
|
|
PRE(sighup_handler.get() == NULL);
|
|
PRE(sigint_handler.get() == NULL);
|
|
PRE(sigterm_handler.get() == NULL);
|
|
|
|
// Create the handlers on the stack first so that, if any of them fails, the
|
|
// stack unwinding cleans things up.
|
|
std::auto_ptr< signals::programmer > tmp_sighup_handler(
|
|
new signals::programmer(SIGHUP, signal_handler));
|
|
std::auto_ptr< signals::programmer > tmp_sigint_handler(
|
|
new signals::programmer(SIGINT, signal_handler));
|
|
std::auto_ptr< signals::programmer > tmp_sigterm_handler(
|
|
new signals::programmer(SIGTERM, signal_handler));
|
|
|
|
// Now, update the global pointers, which is an operation that cannot fail.
|
|
sighup_handler = tmp_sighup_handler;
|
|
sigint_handler = tmp_sigint_handler;
|
|
sigterm_handler = tmp_sigterm_handler;
|
|
}
|
|
|
|
|
|
/// Uninstalls the signal handlers installed by setup_handlers().
|
|
static void
|
|
cleanup_handlers(void)
|
|
{
|
|
sighup_handler->unprogram(); sighup_handler.reset(NULL);
|
|
sigint_handler->unprogram(); sigint_handler.reset(NULL);
|
|
sigterm_handler->unprogram(); sigterm_handler.reset(NULL);
|
|
}
|
|
|
|
|
|
|
|
/// Masks the signals installed by setup_handlers().
|
|
static void
|
|
mask_signals(void)
|
|
{
|
|
sigset_t mask;
|
|
sigemptyset(&mask);
|
|
sigaddset(&mask, SIGHUP);
|
|
sigaddset(&mask, SIGINT);
|
|
sigaddset(&mask, SIGTERM);
|
|
#if defined(__minix) && !defined(NDEBUG)
|
|
const int ret =
|
|
#endif /* defined(__minix) && !defined(NDEBUG) */
|
|
::sigprocmask(SIG_BLOCK, &mask, &old_sigmask);
|
|
INV(ret != -1);
|
|
}
|
|
|
|
|
|
/// Resets the signal masking put in place by mask_signals().
|
|
static void
|
|
unmask_signals(void)
|
|
{
|
|
#if defined(__minix) && !defined(NDEBUG)
|
|
const int ret =
|
|
#endif /* defined(__minix) && !defined(NDEBUG) */
|
|
::sigprocmask(SIG_SETMASK, &old_sigmask, NULL);
|
|
INV(ret != -1);
|
|
}
|
|
|
|
|
|
} // anonymous namespace
|
|
|
|
|
|
/// Constructor that sets up the signal handlers.
|
|
signals::interrupts_handler::interrupts_handler(void)
|
|
{
|
|
PRE(!interrupts_handler_active);
|
|
setup_handlers();
|
|
interrupts_handler_active = true;
|
|
}
|
|
|
|
|
|
/// Destructor that removes the signal handlers.
|
|
signals::interrupts_handler::~interrupts_handler(void)
|
|
{
|
|
cleanup_handlers();
|
|
interrupts_handler_active = false;
|
|
}
|
|
|
|
|
|
/// Constructor that sets up signal masking.
|
|
signals::interrupts_inhibiter::interrupts_inhibiter(void)
|
|
{
|
|
PRE(!interrupts_inhibiter_active);
|
|
mask_signals();
|
|
interrupts_inhibiter_active = true;
|
|
}
|
|
|
|
|
|
/// Destructor that removes signal masking.
|
|
signals::interrupts_inhibiter::~interrupts_inhibiter(void)
|
|
{
|
|
unmask_signals();
|
|
interrupts_inhibiter_active = false;
|
|
}
|
|
|
|
|
|
/// Checks if an interrupt has fired.
|
|
///
|
|
/// Calls to this function should be sprinkled in strategic places through the
|
|
/// code protected by an interrupts_handler object.
|
|
///
|
|
/// \throw interrupted_error If there has been an interrupt.
|
|
void
|
|
signals::check_interrupt(void)
|
|
{
|
|
if (fired_signal != -1)
|
|
throw interrupted_error(fired_signal);
|
|
}
|
|
|
|
|
|
/// Registers a child process to be killed upon reception of an interrupt.
|
|
///
|
|
/// \pre Must be called with interrupts being inhibited. The caller must ensure
|
|
/// that the call call to fork() and the addition of the PID happen atomically.
|
|
///
|
|
/// \param pid The PID of the child process. Must not have been yet regsitered.
|
|
void
|
|
signals::add_pid_to_kill(const pid_t pid)
|
|
{
|
|
PRE(interrupts_inhibiter_active);
|
|
PRE(pids_to_kill.find(pid) == pids_to_kill.end());
|
|
pids_to_kill.insert(pid);
|
|
}
|
|
|
|
|
|
/// Unregisters a child process previously registered via add_pid_to_kill().
|
|
///
|
|
/// \pre Must be called with interrupts being inhibited. This is not necessary,
|
|
/// but pushing this to the caller simplifies our logic and provides consistency
|
|
/// with the add_pid_to_kill() call.
|
|
///
|
|
/// \param pid The PID of the child process. Must have been registered
|
|
/// previously, and the process must have already been awaited for.
|
|
void
|
|
signals::remove_pid_to_kill(const pid_t pid)
|
|
{
|
|
PRE(interrupts_inhibiter_active);
|
|
PRE(pids_to_kill.find(pid) != pids_to_kill.end());
|
|
pids_to_kill.erase(pid);
|
|
}
|