Homework 8.4 Interprocess Communication Pipes and Signals

题目一：要求ABprocess to communicate

1.AThe process sends a sentence,BThe process receives the print
2.然后B进程发送给AProcess in a word,AThe process receives the print
3.重复1,2步骤,直到A进程或者B进程收到quit,退出AB进程;

实现代码

进程A

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>

int main(int argc, const char *argv[])
{
    
	umask(0);
	//创建有名管道1
	if(mkfifo( "./myfifo1",0777) < 0)
	{
    
		//printf( "errno = %d\n",errno);
		if(errno != 17)
		{
    
			//如果errno==17Indicates that the pipeline file already exists,is a legitimate error not handled
			perror( "mkfifo");
			return -1;
		}
	}
	printf( "mkfifo1 success\n" );

	//创建有名管道2
	if(mkfifo( "./myfifo2",0777) < 0)
	{
    
		//printf( "errno = %d\n",errno);
		if(errno != 17)
		{
    
			//如果errno==17Indicates that the pipeline file already exists,is a legitimate error not handled
			perror( "mkfifo");
			return -1;
		}
	}
	printf( "mkfifo2 success\n" );
	//Open the named pipe file for write only1
	int fd1 = open( "./myfifo1",O_WRONLY);
	if(fd1 < 0)
	{
    
		perror( "open" );
		return -1;
	}
	//Open the named pipe file as read-only2
	int fd2 = open( "./myfifo2",O_RDONLY);
	if(fd2 < 0)
	{
    
		perror( "open" );
		return -1;
	}
	printf( "open readonly success\n");

	char buf1[128]="";
	char buf2[128]="";
	ssize_t res=0;
	while(1)
	{
    
		bzero(buf1,sizeof(buf1));
		printf("请输入>>>");
		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;
		printf("write success\n");
		bzero(buf2,sizeof(buf2));
		res=read(fd2,buf2,sizeof(buf2));
		if(strcasecmp(buf2, "quit") == 0)
			break;
		if(res<0)
		{
    
			perror("read");
			return -1;
		}
		else if(0==res)
		{
    
			printf("The other process exits\n");
			break;
		}
		printf("read success:%s\n",buf2);
	}

	//关闭文件描述符
	close(fd1);
	close(fd2);

	return 0;
}

进程B

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
int main(int argc, const char *argv[])
{
    
	umask(0);
	//创建有名管道1
	if(mkfifo( "./myfifo1",0777) < 0)
	{
    
		//printf( "errno = %d\n",errno);
		if(errno != 17)
		{
    
			//如果errno==17Indicates that the pipeline file already exists,is a legitimate error not handled
			perror( "mkfifo");
			return -1;
		}
	}
	printf( "mkfifo1 success\n" );
	//创建有名管道2
	if(mkfifo( "./myfifo2",0777) < 0)
	{
    
		//printf( "errno = %d\n",errno);
		if(errno != 17)
		{
    
			//如果errno==17Indicates that the pipeline file already exists,is a legitimate error not handled
			perror( "mkfifo");
			return -1;
		}
	}
	printf( "mkfifo2 success\n" );

	//Open the named pipe file as read-only1
	int fd1 = open( "./myfifo1",O_RDONLY);
	if(fd1 < 0)
	{
    
		perror( "open" );
		return -1;
	}
	//Open the named pipe file for write only2
	int fd2 = open( "./myfifo2",O_WRONLY);
	if(fd2 < 0)
	{
    
		perror( "open" );
		return -1;
	}
	printf( "open readonly success\n");

	char buf1[128]="";
	char buf2[128]="";
	ssize_t res=0;
	while(1)
	{
    
		bzero(buf1,sizeof(buf1));
		res=read(fd1,buf1,sizeof(buf1));
		if(strcasecmp(buf1, "quit") == 0)
			break;
		if(res<0)
		{
    
			perror("read");
			return -1;
		}
		else if(0==res)
		{
    
			printf("The other process exits\n");
			break;
		}
		printf("read success:%s\n",buf1);
		bzero(buf2,sizeof(buf2));
		printf("请输入>>>");
		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;
		printf("write success\n");
	}

	//关闭文件描述符
	close(fd1);
	close(fd2);

	return 0;
}

运行结果

题目二：捕获2）3）20）号信号

实现代码

#include <stdio.h>
#include <signal.h>
#include <unistd.h>

typedef void (*sighandler_t)(int);


//New handler function
void handler_1(int sig)
{
    
	printf("this is handler_1 \n");
	printf("成功捕获%d号信号\n", sig);
}

void handler_2(int sig)
{
    
	printf("this is handler_2\n");
	printf("成功捕获%d号信号\n", sig);
}
void handler_3(int sig)
{
    
	printf("this is handler_3 \n");
	printf("成功捕获%d号信号\n", sig);
}


int main(int argc, const char *argv[])
{
    
	//捕获2号信号SIGINT
	sighandler_t s = signal(2, handler_1);
	if(SIG_ERR == s)
	{
    
		perror("signal");
		return -1;
	}

	//捕获3号信号SIGINT
	s = signal(3, handler_2);
	if(SIG_ERR == s)
	{
    
		perror("signal");
		return -1;
	}

	//捕获20号信号SIGINT
	s = signal(20, handler_3);
	if(SIG_ERR == s)
	{
    
		perror("signal");
		return -1;
	}
	while(1)
	{
    
		printf("this is main\n");
		sleep(1);
	}

	return 0;
}

运行结果