// Copyright (c) 1999-2002 David Muse
// See the COPYING file for more information.

#ifndef RUDIMENTS_DAEMONPROCESS_H
#define RUDIMENTS_DAEMONPROCESS_H

#include <rudiments/private/daemonprocessincludes.h>

// Daemons are long running processes which often detach themselves from
// the controlling terminal and run in the background.  They are frequently
// started at boot time and run until the machine is shut down.
//
// Daemons typically perform "housecleaning" tasks or serve data to client
// programs.  See the server class.

class daemonprocess {
        public:
                                daemonprocess();
                        virtual ~daemonprocess();

                        int     checkForPidFile(const char *filename) const;
                                // Checks for filename "filename" and reads the
                                // process id out of it, if it exists.  Returns
                                // the process id on success or -1 on failure.
                        bool    createPidFile(const char *filename,
                                                mode_t permissions) const;
                                // Create's file "filename" with permissions
                                // "permissions" and puts the current process
                                // id in it.  Note that when you delete this
                                // file during shutdown you must use the full
                                // pathname since the detach() method below
                                // changes directories to "/".  Returns true on
                                // success and false on failure.

                        void    detach() const;
                                // Detach from the controlling terminal and
                                // process and run in the background.  Also
                                // change directories to "/" and set the file
                                // creation mask such that all files are 
                                // created -rw-rw-rw and all directories 
                                // drwxrwxrwx.

                        // These methods allow the daemon to run as a different
                        // user or group than the one that started the process.
                        // They have no effect unless the process is started
                        // by the root user.
                        //
                        // These methods return 1 on success, 0 on failure and
                        // -1 on error.
                        int     runAsUser(const char *username) const;
                                // Note that runAsUser() uses the passwdentry
                                // class.  If you are using this method in a
                                // multithreaded application, you may need to
                                // supply the passwdentry classes a mutex.
                                // See passwdentry.h for more detail.
                        int     runAsGroup(const char *groupname) const;
                                // Note that runAsGroup() uses the groupentry
                                // class.  If you are using this method in a
                                // multithreaded application, you may need to
                                // supply the groupentry classes a mutex.
                                // See groupentry.h for more detail.
                        int     runAsUserId(uid_t uid) const;
                        int     runAsGroupId(gid_t gid) const;

                static  void    handleShutDown(void *shutdownfunction);
                                // This method allows you to designate a
                                // function to run when the daemon is killed.

                static  void    handleCrash(void *crashfunction);
                                // This method allows you to designate a
                                // function to run if the daemon crashes.

                static  void    waitForChildren();
                                // This method causes the daemon to wait
                                // on child processes which have exited,
                                // preventing so-called "zombie" processes
                                // from occurring.  This method is called
                                // in the constructor and is thus the default
                                // behavior of this class.
                static  void    dontWaitForChildren();
                                // This method causes the daemon not to
                                // wait on child processes which have exited.
                                // Ordinarily, you'd want to wait on child
                                // processes, but this interferes with the
                                // behavior of WEXITSTATUS() after a call to
                                // system() (and possibly other calls).  This
                                // method allows you to disable waiting on
                                // child processes.

        #include <rudiments/private/daemonprocess.h>

};

#endif