8.4嵌入式作业（进程间通信、信号捕获）

• 作业内容
• • 1. A、B进程间通信
  • • 进程A代码部分
    • 进程B代码部分
    • 运行结果
  • 2.捕获信号
  • • 代码部分
    • 运行结果

1. 要求AB进程做通信：
   A进程发送一句话，B进程接收打印
   然后B进程发送给A进程一句话，A进程接收打印
   重复1,2步骤，直到A进程或者B进程收到quit，退出AB进程；
2. 捕获2号、3号、20号信号

#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main(int argc, const char *argv[])
{
	//创建有名管道
	if(mkfifo("./myfifo1",0777) < 0)
	{
		if(errno != EEXIST)
		{
			perror("mkfifo1");
			return -1;
		}
	}
	if(mkfifo("./myfifo2",0777) < 0)
	{
		if(errno != EEXIST)
		{
			perror("mkfifo2");
			return -1;
		}
	}

	//打开管道
	int fd1 = open("./myfifo1",O_WRONLY);
	if(fd1 < 0)
	{
		perror("open");
		return -1;
	}
	int fd2 = open("./myfifo2",O_RDONLY);
	if(fd2 < 0)
	{
		perror("open");
		return -1;
	}

	char buf1[128] = "";
	char buf2[128] = "";
	ssize_t res = 0;
	
	while(1)
	{
		//将内容写入管道文件中
		printf("A is writing: ");
		fgets(buf1,sizeof(buf1),stdin);
		buf1[strlen(buf1)-1] = 0;

		if(write(fd1,buf1,sizeof(buf1)) < 0)
		{
			perror("write");
			return -1;
		}
		if(strcasecmp(buf1,"quit") == 0)
			break;

		//读取管道文件内容
		bzero(buf2,sizeof(buf2));
		res = read(fd2,buf2,sizeof(buf2));
		if(res < 0)
		{
			perror("read");
			return -1;
		}
		else if(0 == res)
		{
			printf("B has exitedn");
			break;
		}
		printf("A receive a message from B: %sn",buf2);
	}

	//关闭文件描述符
	close(fd1);
	close(fd2);

	return 0;
}

#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main(int argc, const char *argv[])
{
	//创建有名管道
	if(mkfifo("./myfifo1",0777) < 0)
	{
		if(errno != EEXIST)
		{
			perror("mkfifo1");
			return -1;
		}
	}
	if(mkfifo("./myfifo2",0777) < 0)
	{
		if(errno != EEXIST)
		{
			perror("mkfifo2");
			return -1;
		}
	}

	//打开管道文件
	int fd1 = open("./myfifo1",O_RDONLY);
	if(fd1 < 0)
	{
		perror("open");
		return -1;
	}
	int fd2 = open("./myfifo2",O_WRONLY);
	if(fd2 < 0)
	{
		perror("open");
		return -1;
	}

	char buf1[128] = "";
	char buf2[128] = "";
	ssize_t res = 0;

	while(1)
	{
		//读取管道文件内容
		bzero(buf1,sizeof(buf1));
		res = read(fd1,buf1,sizeof(buf1));
		if(res < 0)
		{
			perror("read");
			return -1;
		}
		else if(0 == res)
		{
			printf("A has exitedn");
			break;
		}
		printf("B receive a message from A: %sn",buf1);

		//将内容写入管道文件中
		printf("B is writing: ");
		fgets(buf2,sizeof(buf2),stdin);
		buf2[strlen(buf2)-1] = 0;

		if(write(fd2,buf2,sizeof(buf2)) < 0)
		{
			perror("write");
			return -1;
		}
		if(strcasecmp(buf2,"quit") == 0)
			break;
	}

	//关闭文件描述符
	close(fd1);
	close(fd2);

	return 0;
}

#include 
#include 
#include 

typedef void (*sighandler_t)(int);

//新的处理函数
void handler_2(int sig)
{
	printf("This is SIGINT: %dn",sig);
}
void handler_3(int sig)
{
	printf("This is SIGQUIT: %dn",sig);
}
void handler_20(int sig)
{
	printf("This is SIGTSTP: %dn",sig);
}

int main(int argc, const char *argv[])
{
	//捕获2号信号SIGINT
	sighandler_t s1 = signal(2,handler_2);
	if(SIG_ERR == s1)
	{
		perror("signal");
		return -1;
	}
	//捕获3号信号SIGQUIT
	sighandler_t s2 = signal(3,handler_3);
	if(SIG_ERR == s2)
	{
		perror("signal");
		return -1;
	}
	//捕获20号信号SIGTSTP
	sighandler_t s3 = signal(20,handler_20);
	if(SIG_ERR == s3)
	{
		perror("signal");
		return -1;
	}

	while(1);

	return 0;
}