SDaemonFramework.h

Go to the documentation of this file.

//
// Date:      19 May 2003
//            11 August 2003
//            27 November 2005
//            2  December 2005  umask(0) added
//                              sigwait() instead of handlers
//
// Copyright (c) Sergey Satskiy 2003
//               <sergesatsky@yahoo.com>
//
// Permission to copy, use, modify, sell and distribute this software 
// is granted provided this copyright notice appears in all copies. 
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//



#ifndef SDAEMONFRAMEWORK_H
#define SDAEMONFRAMEWORK_H

#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/stat.h>


    // Anonymous namespace gives ability compiled with no problems
    // even if the file is included into many .cpp files
namespace
{

    inline void SignalOK( void );
    inline void SignalFailed( void );

    inline void SignalOK( void )
    {
        #if DAEMON == 1
        kill( getppid(), SIGUSR1 );
        #endif
    }

    inline void SignalFailed( void )
    {
        #if DAEMON == 1
        kill( getppid(), SIGUSR2 );
        #endif
    }

     /*template <typename Fake>*/
    inline void Daemonise( void )
    {

         #if DAEMON == 1
         if ( getppid() != 1 )
         {
            sigset_t           Feedback;    // Mask to wait for feedback
            sigset_t           Storage;     // Old mask - used to restore

            sigemptyset( &Feedback );
            sigaddset( &Feedback, SIGUSR1 );
            sigaddset( &Feedback, SIGUSR2 );
            sigprocmask( SIG_BLOCK, &Feedback, &Storage );

            signal( SIGTTOU, SIG_IGN );
            signal( SIGTTIN, SIG_IGN );
            signal( SIGTSTP, SIG_IGN );
    
                // Become a daemon
            if ( fork() != 0 )
            {
                int     SignalNumber( -1 );

                if ( sigwait( &Feedback, &SignalNumber ) != 0 )
                {
                        // Error waiting for the signal
                    exit( 2 );
                }

                exit( SignalNumber != SIGUSR1 );
            }

                // Child process - restore the signals mask
                // and set a new leader of the session
            if ( (sigprocmask( SIG_SETMASK, &Storage, NULL ) != 0) ||
                 ( setsid() == -1 ) )
            {
                SignalFailed();
                exit( 1 );
            }
        }

            // Close file descriptors of stdin, stdout and stderr
        if ( ttyname( 0 ) != NULL ) close( 0 );
        if ( ttyname( 1 ) != NULL ) close( 1 );
        if ( ttyname( 2 ) != NULL ) close( 2 );
        

        #ifdef HOME
        chdir( HOME );              // To be sure not staying nowhere
        setenv( "HOME", HOME, 1 );  
        #else
        chdir( "/" );
        setenv( "HOME", "/", 1 );
        #endif                      // #ifdef HOME
        
        #endif      // #if DAEMON == 1
    
            // Daemon should not inherit the files mask
            // To make the non-daemon process behaviour uniform do it 
            //    in any case
        umask( 0 );

        return;
    }


}   // End of anonymous namespace


#endif

---