test2.c

1。创建一共享内存。a进程对共享内存中的某个整型不断加一

#include <stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/sem.h>
#include<sys/types.h>
#include"shm_com2.h"
static int semaphore_p(int);
static int semaphore_v(int);
static int set_semvalue(int);
static int del_semvalue(int);
//static int sem_id;
int main(int argc, char *argv[])
{
	pid_t pid;
	int sem_id;
	int sem_id1;
	srand((unsigned)getpid());
	sem_id=semget((key_t)1243,1,0666|IPC_CREAT);
	sem_id1=semget((key_t)12435,1,0666|IPC_CREAT);
	if(sem_id==-1)
	{
		fprintf(stderr,"semget error");
		exit(EXIT_FAILURE);
	}
	if (!set_semvalue(sem_id)) {
            fprintf(stderr, "Failed to initialize semaphore\n");
            exit(EXIT_FAILURE);
        }

	pid=fork();
	switch(pid)
	{
		case -1:
			perror("fork failed");
			exit(1);
		case 0:
		{
			if (!semaphore_p(sem_id1)) exit(EXIT_FAILURE);
				printf("bbbb\n");
				fflush(stdout);   
				 
			if (!semaphore_v(sem_id)) exit(EXIT_FAILURE); 
			if (!semaphore_p(sem_id1)) exit(EXIT_FAILURE); 
			
			//if (!semaphore_p(sem_id)) exit(EXIT_FAILURE);
				printf("dddd\n");
				fflush(stdout);   				//sleep(1);            
				
			
			break;
		}
		default:
		{
			
		
				printf("aaaa\n");
				fflush(stdout); 
			if(!set_semvalue(sem_id1))
			{
			fprintf(stderr,"Failure to initialize semaphore\n");
			exit(EXIT_FAILURE);
			} 
			if (!semaphore_v(sem_id1)) exit(EXIT_FAILURE); 
				//sleep(1);      
			//if (!semaphore_p()) exit(EXIT_FAILURE);
			
		if (!semaphore_p(sem_id)) exit(EXIT_FAILURE); 
			
				printf("cccc\n");
				fflush(stdout);   
				//sleep(1);            
		if (!semaphore_v(sem_id1)) exit(EXIT_FAILURE);				
			wait(0);
				break;
			
		}
	del_semvalue(sem_id);
	del_semvalue(sem_id1);
		
	}
}
static int semaphore_p(int sem_id)
{
	struct sembuf sem_b;
	sem_b.sem_num=0;
	sem_b.sem_op=-1;
	sem_b.sem_flg=SEM_UNDO;
	if(semop(sem_id,&sem_b,1)==-1)
	{
		fprintf(stderr,"semmaphore_p is error\n");
		return (0);
	}
	
	return(1);
	
}
static int semaphore_v(int sem_id)
{
	struct sembuf sem_b;
	sem_b.sem_num=0;
	sem_b.sem_op=1;
	sem_b.sem_flg=SEM_UNDO;
	if(semop(sem_id,&sem_b,1)==-1)
	{
		fprintf(stderr,"semmaphore_v is error\n");
		return(0);
	}
	return(1);
}
static int set_semvalue(int sem_id)
{
    union semun sem_union;
    sem_union.val = 0;
    if (semctl(sem_id, 0, SETVAL, sem_union) == -1) return(0);
    return(1);
}
static int del_semvalue(int sem_id)
{
	union semun sem_union;
	sem_union.val=0;
	if(semctl(sem_id,0,SETVAL,sem_union)==-1)
	{
		return(0);
	}
}