10-12.c

提供了许多进程间通信的实例程序。用linux下的C语言实现。

#include  <sys/types.h>
#include <sys/Socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <netinet/in.h>
int main()
{
	Int rcd ;
	struct sockaddr_un	server_sockaddr ;
	int backlog ;
	ushort	 ci ;
	int watch_fd_list[3] ;
	fd_set	 catch_fd_set ;
	fd_set	 watchset ;
	int new_cli_fd ;
	int maxfd;
	int socklen ,server_len;
	struct sockaddr_un	cli_sockaddr ;
	struct {
		char	module_id ;	/* Module ID		*/
		int	cli_sock_fd ;	/* Socket ID		*/
	} cli_info_t[2] ;
	
	for (ci=0;ci<=1;ci++)
		cli_info_t[ci].cli_sock_fd=－1;
		
	for (ci=0;ci<=2;ci++)
		watch_fd_list[ci]=－1;	
		
	int server_sockfd,client_sockfd;
	
	server_sockfd = Socket( AF_UNIX, SOCK_STREAM, 0 ) ;
	server_sockaddr.sun_family = AF_UNIX ;
	strcpy( server_sockaddr.sun_path, "server_Socket" ) ;
	server_len=sizeof(server_sockaddr);
	rcd = bind( server_sockfd, ( struct sockaddr * )&server_sockaddr, server_len ) ;
	
	backlog = 5 ;
	rcd = listen( server_sockfd, backlog ) ;
	printf("SERVER::Server is  waitting on Socket=%d \n",server_sockfd);

	watch_fd_list[0]=server_sockfd;
	FD_ZERO( &watchset ) ;
	FD_SET( server_sockfd, &watchset ) ;
	maxfd=watch_fd_list[0];
/*
在上面的程序中，Server生成listening Socket（server_sockfd）,初始化Socket监视集合（watchset），并将listening Socket放入Socket监视集合中。
	*/	
while (1){
		char ch;
		int fd;
		int nread;
		
		catch_fd_set=watchset;
		rcd = select( maxfd+1, &catch_fd_set, NULL, NULL, (struct timeval *)0 ) ;
	/*	
在上面的程序中，Server运用系统调用函数 select来实时检查是否有数据到达Socket监视集合中的任何一个Socket。
  */	
			if ( rcd < 0 ) {
			printf("SERVER::Server 5 \n");
			exit(1);
		}

		if ( FD_ISSET( server_sockfd, &catch_fd_set ) ) {
			socklen = sizeof( cli_sockaddr ) ;
			new_cli_fd = accept( server_sockfd, ( struct sockaddr * )&( cli_sockaddr ), &socklen ) ;
			printf(" SERVER::open communication with  Client %s on Socket %d\n", cli_sockaddr.sun_path,new_cli_fd);	
	
			for (ci=1;ci<=2;ci++){
				if(watch_fd_list[ci] != －1) continue;
				else{	
					watch_fd_list[ci] = new_cli_fd;
					break;
				}	
			}	
			FD_SET(new_cli_fd , &watchset ) ;
			if ( maxfd < new_cli_fd ) {
				maxfd = new_cli_fd ;
			}
			
			for ( ci=0;ci<=1;ci++){
				if(cli_info_t[ci].cli_sock_fd == －1) {
					cli_info_t[ci].module_id=cli_sockaddr.sun_path[0];
					cli_info_t[ci].cli_sock_fd=new_cli_fd;
					break;
				}		
			}
				
			continue;	
		}
	for ( ci = 1; ci<=2 ; ci++ ) {
			int dst_fd = －1 ;
			char dst_module_id;
			char src_module_id;
			int i;

			if (watch_fd_list[ ci ]==－1) continue;
			if ( !FD_ISSET( watch_fd_list[ ci ], &catch_fd_set ) ) {
				continue ;
			}
			ioctl(watch_fd_list[ ci ],FIONREAD,&nread);
			if (nread==0){
				continue;
			}	
			read( watch_fd_list[ ci ], &dst_module_id, 1 ) ;
			for (i=0;i<=1;i++){
				if(cli_info_t[i].module_id == dst_module_id) 
					dst_fd=	cli_info_t[i].cli_sock_fd;	
				 if(cli_info_t[i].cli_sock_fd==watch_fd_list[ ci ]) 
				src_module_id=	cli_info_t[i].module_id;		
			}
			read( watch_fd_list[ ci ], &ch, 1 ) ;
			printf("SERVER::char=%c to  Client %c on Socket%d\n",ch, dst_module_id,dst_fd);	
			write(dst_fd,&src_module_id, 1 ) ;
			write(dst_fd,&ch, 1 ) ;

		}
	}	
}