/*
** openMosix lock/unlock test
**
** Copyright (C) 2004  Moreno 'baro' Baricevic
**                                      <baro AT democritos DOT it>
** This  file may be used subject to the terms and conditions of the
** GNU Library General Public License as published by the Free Soft-
** ware Foundation; either version 2 of the License, or (at your op-
** tion) any later version.
**
** This file is distributed in the hope that it will be useful,  but
** WITHOUT  ANY  WARRANTY; without even the implied warranty of MER-
** CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Li-
** brary General Public License for more details.
*/

/**************************************************
 * Author: Moreno "Baro" Baricevic                *
 * Contact: baro@democritos.it                    *
 * Date:   21-02-2004                             *
 * Title:  sguscio.c                              *
 *================================================*
 * Prev Modified: 21-02-2004                      *
 * Last Modified: 06-06-2004                      *
 **************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>

char p_lock[32];

#define LOCKED		'1'
#define UNLOCKED	'0'

/*************************************************************************
 *_____________________________  OM_SETLOCK _____________________________*
 *************************************************************************/
// adapted from omprocps-X.Y.Z proc/ominfo.c and lock/*
/*
** om_unlock(): always success
** om_lock():   - always success if already locked (...);
**              - always works on caller self process pid;
**              - can't lock any unlocked process, write() returns -1
**                and sets errno to EINVAL.
*/
int __om_setlock( const char * lockfile , char lk )
{
   int w = -1 , r = -1;
   int fd = -1;
   char c = 0x00;

   fd = open( lockfile , O_RDWR | O_TRUNC );
   if ( fd < 0 )
   {
      fprintf( stderr , "*** cannot open lock file '%s': [%d] %m\n"
                      , p_lock , errno );
      return -1;
   }

   w = write( fd , &lk , 1 );
   if ( w != 1 )
   {
      fprintf( stderr , "*** cannot %slock myself: [%d] %m\n"
                      , lk == UNLOCKED ? "un" : "" , errno );
      close( fd );
      return -1;
   }

   (void)lseek( fd , 0L , SEEK_SET );
   r = read( fd , &c , 1 );
   if ( r != w )
   {
      fprintf( stderr , "*** cannot read lock status: [%d] %m\n" , errno );
      close( fd );
      return -1;
   }
   else if ( c != lk )
   {
      fprintf( stderr , "*** %slock failed: wrote 0x%02x - read 0x%02x\n"
                      , lk == UNLOCKED ? "un" : ""  , lk , c );
      close( fd );
      return -1;
   }

   close( fd );
   return 0;

} /* __om_setlock */



void lock( int signo )
{
   __om_setlock( p_lock , LOCKED );
}

void unlock( int signo )
{
   __om_setlock( p_lock , UNLOCKED );
}


int main ( int argc , char * argv[] )
{
   long long int lli;
   pid_t pid = getpid();
   const char * basename = strrchr( argv[0] , '/' );
   if ( basename && *basename && *(basename+1) )
     ++basename;
   else
     basename = argv[0];

   snprintf( p_lock , sizeof( p_lock ) , "/proc/%u/lock" , pid );

   printf( "Some tips:\n" );
   printf( "name  %s\n" , basename );
   printf( "pid   %u\n" , pid      );
   printf( "lock  %s\n" , p_lock   );

#define CMD( SIGNAL )			\
	"ompsinfo -C %s ; "		\
	"kill -" SIGNAL " %u && "	\
	"usleep 0 ; "			\
	"ompsinfo -h -C %s"		\

   printf( CMD( "SIGUSR1" ) "\t# lock\n"   , basename , pid , basename );
   printf( CMD( "SIGUSR2" ) "\t# unlock\n" , basename , pid , basename );

//   printf( "migrate %u SOMENODE && ompsinfo -C %s\n" , pid , basename );

   signal( SIGUSR1 , lock );
   signal( SIGUSR2 , unlock );

   for(lli=0;;lli++);

   exit( 0 );

}

//EOF