ТВПиС лабораторная работа 2 / lab02 / Lab02

#include <linux/sem.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <signal.h>

int start = 0;

#define LEN 20

pid_t chpid [2];

int main (int argc, char *argv [])
{
    struct timeval c_time;
    void c_action (int);
    static struct sigaction pact, cact;
    char str [LEN];
    id_t pid;
	// создаем общий файл
    unlink("temp");
    int fd = open("temp",O_CREAT|O_RDWR);
    char* map = mmap(0,1000*LEN,PROT_READ | PROT_WRITE, MAP_SHARED, fd,0);
    if(map == MAP_FAILED){
    		perror("mmap");
    		return 1;}
	// создаем семафор
    int j,n,i=0;
    key_t key;
    if((key = ftok("temp",3)) < 0){
      perror("Can\'t generate key");
      return 1;
    }

    int semid = semget(key, 4, 0666 | IPC_CREAT );
    if (semid < 0){
		perror("semget");
        	return 1;}

    struct sembuf s_red[2] = {0, -1, IPC_NOWAIT, 1, 1, IPC_NOWAIT};
    struct sembuf s_green[2] = {0, 1, IPC_NOWAIT, 1, -1, IPC_NOWAIT}; 
    struct sembuf s_wait[2] = {0, 0, 0, 1, 0, 0}; 
    struct sembuf s_readed = {2, 0, 0}; 
    struct sembuf s_lock = {2, 1, IPC_NOWAIT}; 
    struct sembuf s_unlock = {2, -1, IPC_NOWAIT}; 

    union semun arg;

    arg.val = 0;
    semctl(semid, 0, SETVAL, arg);
    arg.val = 1;
    semctl(semid, 1, SETVAL, arg);
    arg.val = 0;
    semctl(semid, 2, SETVAL, arg);


	// создаем два процесса
    for (j=0; j<2; j++) {
	switch (chpid [j] = fork ()) {
	case -1:
	    printf ("Fork call error\n");
	    return 1;
	case 0:
	    //child
		cact.sa_flags = SA_SIGINFO;
		cact.sa_sigaction = (void *) c_action;
      		sigaction (SIGUSR1, &cact, NULL);
		printf("child #%d\n",getpid());
	    while (i <= 1000) {
		  // ожидаем разрешения
		   
		    if ((start)&&
			(semop( semid, &s_readed, 1)==0)&&
			(semop( semid, &s_wait[j], 1)==0))
			{ 
   			lseek (fd, 0, SEEK_END);
			i = semctl(semid, 3, GETVAL);
			if (i==1000)break;
			for (n=0;n<100;n++){			
				gettimeofday(&c_time,NULL);
				sprintf (str,"%4d #%5d :%6d\n", i+n+1, 
					getpid (), c_time.tv_usec);
				write(fd,str,LEN);
			}
			i+=n;
    			arg.val = i;
    			semctl(semid, 3, SETVAL, arg);
			// переключаем поток
			if (j==0) semop( semid, &s_green, 2);
			else semop( semid, &s_red, 2);	

		    }
	    } 		
	    return 0;
	}
    }
    printf("father #%d\n",getpid());
    //father
	kill (chpid [0], SIGUSR1);
	kill (chpid [1], SIGUSR1);
	i=0;
	    while (i < 1000) {
		    sleep(1);
		    // ожидаем разрешения
			j=semctl(semid, 3, GETVAL);
		    if( (j>i+75)||(j==1000))
			{
		    // блокируем
		        semop( semid, &s_lock, 1);		
		    // читаем	
			lseek (fd, i*LEN, SEEK_SET);

			for (n=0;n<75;n++){
				if (i+n ==1000) break;
				read(fd,str,LEN);
				printf ("%s", str);			
			}
		        i+=n; 
		    // разблокируем	
		        semop( semid, &s_unlock, 1);
		    }		    
	    }
    close(fd);
    semctl(semid, 0, IPC_RMID);
    return 0;
}

void c_action (int sig)
    {
      start = 1;
      printf("action #%d\n",getpid());
    }