Watchdog.cxx

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/*
 * Copyright (c) 2001-2004 MUSIC TECHNOLOGY GROUP (MTG)
 *                         UNIVERSITAT POMPEU FABRA
 *
 *
 * 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 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
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * 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
 *
 */

#include "Watchdog.hxx"

#include <pthread.h>
#include <unistd.h>
#include <cstdio>
#include <cstdlib>

namespace CLAM {


        sig_atomic_t Watchdog::mBeat = 0;
        unsigned int Watchdog::mQuantumTime = 5;
        bool         Watchdog::mStarted = false;
        bool         Watchdog::mVerbose = false;

        void *Watchdog::BeatThread(void*)
        {
                setuid(getuid());

                while(1)
                {
                        sleep(mQuantumTime);
                        if (mBeat != 1)
                        {
                                mBeat = 1;
                        }
                        if (mVerbose)
                        {
                                putchar('-');
                                fflush(stdout);
                        }
                }
        }


        void *Watchdog::WatchdogThread(void*)
        {
                setuid(getuid());

                if (mVerbose) puts("WatchdogThread: Started.");

                while(1)
                {
                        sleep(2*mQuantumTime);

                        if (mBeat == 1)
                        {
                                mBeat = 0;
                        }
                        else
                        {
                                puts("WatchdogThread: CPU exhaustion detected. Exiting.");
                                exit(1);
                        }
                }
                return 0;
        }


        bool Watchdog::Start(unsigned int quantum, bool verbose)
        {
                if (mStarted)
                        return true;

                if (quantum < 1)
                {
                        puts("Watchdog::Start(): Time quantum must be at least 1 second.");
                        return false;
                }

                mVerbose = verbose;

                pthread_t          beat_thread;
                pthread_attr_t     beat_attrs;

                pthread_attr_init(&beat_attrs);

                if (pthread_create(&beat_thread,
                                                   &beat_attrs,
                                                   &BeatThread, 0) != 0)
                {
                        puts("Watchdog::Start(): Failed to create beat thread (you need to be root).");
                        perror("pthread_create()");
                        return false;
                }

                pthread_t          watchdog_thread;
                pthread_attr_t     watchdog_attrs;
                struct sched_param watchdog_param;

                watchdog_param.sched_priority = 99;

                pthread_attr_init(&watchdog_attrs);
                pthread_attr_setschedpolicy(&watchdog_attrs,SCHED_FIFO);
                pthread_attr_setschedparam(&watchdog_attrs,&watchdog_param);

                if (pthread_create(&watchdog_thread,
                                                   &watchdog_attrs,
                                                   &WatchdogThread, 0) != 0)
                {
                        puts("Watchdog::Start(): Failed to create watchdog thread (you need to be root).");
                        perror("pthread_create()");
                        return false;
                }

                mStarted = true;

                return true;
        }

}

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