/* System V Semaphores and pthreads. */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/sem.h>

#include "nya/array.h"

#define massert( cond, msg )             \
   if( cond ) {                          \
      perror( msg );                     \
      exit(-1);                          \
   }

#define set_semop_( _sem, _op, _num  )                   \
   _sem.sem_num = _num;                                  \
   _sem.sem_op  = _op;                                   \
   _sem.sem_flg = SEM_UNDO;                              \


#define PATH   "/tmp/tmp_191944_s/d"

char buf[] = "abcdefghijklmnopqrstuvwsyz";
int sem_id = 0;
struct sembuf lock_m, unlock_m,
              lock_i, unlock_i,
              lock_r, unlock_r;


void clear_sem( ) {
   massert( semctl( sem_id, 0, IPC_RMID, 0) == -1, "semctl");
   exit(0);
}

void *inv( ) {
   int len = strlen(buf);
   while( 1 ) {
      massert( semop( sem_id, &lock_i, 1) < 0, "semop");
         inverse(buf, len);
      massert( semop( sem_id, &unlock_m, 1) < 0, "semop");
   }
}
void *rev( ) {
   int len = strlen(buf);
   while( 1 ) {
      massert( semop( sem_id, &lock_r, 1) < 0, "semop");
         reverse(buf, len);
      massert( semop( sem_id, &unlock_m, 1) < 0, "semop");
   }
}  

int main( int argc, char* argv[] ) {
   
   pthread_t inv_pthread, rev_pthread;
   key_t key;
   struct sembuf lock, unlock ;
   set_semop_( lock_m, -1, 0);
   set_semop_( unlock_m, 1, 0);
   set_semop_( lock_i, -1, 1);
   set_semop_( unlock_i, 1, 1);
   set_semop_( lock_r, -1, 2);
   set_semop_( unlock_r, 1, 2);

   massert((key = ftok( PATH, 'd' )) < 0, "ftok" );

   massert((sem_id = semget(key, 3, 0666|IPC_CREAT )) < 0, "semget");
   
   massert(pthread_create( &inv_pthread, NULL, inv, NULL ) != 0, "pthread" );
   massert(pthread_create( &rev_pthread, NULL, rev, NULL ) != 0, "pthread" );
   signal( SIGINT, clear_sem );
   while(1) {
      massert( semop( sem_id, &unlock_i, 1) < 0, "semop");
      massert( semop( sem_id, &lock_m, 1) < 0, "semop");
        puts(buf);
        sleep( 1 );
      massert( semop( sem_id, &unlock_r, 1) < 0, "semop");
      massert( semop( sem_id, &lock_m, 1) < 0, "semop");
         puts(buf);
         sleep( 1 );
   }

   return 0;
}