0707 父子进程之间传递文件描述符

  1 /*************************************************************************
  2     > File Name: pass_fd.c
  3     > Author:Monica
  4     > Mail:liling222@126.com 
  5     > Created Time: Mon 07 Jul 2014 09:52:49 PM CST
  6  ************************************************************************/
  7 
  8 #include <stdio.h>
  9 #include <sys/types.h>
 10 #include <sys/socket.h>
 11 #include <strings.h>
 12 #include <stdlib.h>
 13 #include <unistd.h>
 14 #include <signal.h>
 15 #include <sys/stat.h>
 16 #include <fcntl.h>
 17 #include <string.h>
 18 
 19 void my_handler(int signum)
 20 {
 21     wait(NULL);
 22     exit(0);
 23 }
 24 void send_n(int fd_socket, int fd_to_send);
 25 void recv_n(int fd_socket, int* fd_to_recv);
 26 
 27 int main(int argc, char* argv[])    //exe  filename
 28 {
 29     int fd_socket[2];
 30     int fd_file;
 31     if(socketpair(AF_LOCAL, SOCK_STREAM, 0, fd_socket) == -1)
 32     {
 33         perror("socketpair");
 34         exit(-1);
 35     }
 36     if(fork()>0)    //parent fd[0]
 37     {
 38         close(fd_socket[1]);
 39         signal(SIGCHLD, my_handler);
 40         fd_file = open(argv[1], O_RDONLY);
 41         if(fd_file == -1)
 42         {
 43             perror("open");
 44             close(fd_socket[0]);
 45             close(fd_socket[1]);
 46             exit(-1);
 47         }
 48         send_n(fd_socket[0], fd_file);
 49         printf("parent fd_file:%d
", fd_file);
 50         close(fd_file);
 51         close(fd_socket[0]);
 52         return;
 53     }
 54     else    //child fd[1]
 55     {
 56         int fd_to_recv;
 57         char buf[1024];
 58         close(fd_socket[0]);
 59         recv_n(fd_socket[1], &fd_to_recv);
 60         printf("child recv fd:%d
", fd_to_recv);
 61         FILE* fp = fdopen(fd_to_recv, "r");
 62         while(bzero(buf, 1024), fgets(buf, 1024, fp) != NULL)
 63         {
 64             printf("%s", buf);
 65         }
 66         fclose(fp);
 67         close(fd_to_recv);
 68         close(fd_socket[1]);
 69     }
 70     return 0;
 71 }
 72 void send_n(int fd_socket, int fd_to_send)
 73 {
 74     struct msghdr send_msg;
 75     struct iovec  bufs[1];
 76     struct cmsghdr *pcmsg;
 77     char buffer[]="hello world";
 78     int cmsglen = CMSG_LEN(sizeof(int));
 79     send_msg.msg_name = NULL;
 80     send_msg.msg_namelen = 0;
 81     send_msg.msg_flags = 0;
 82     bufs[0].iov_base = buffer;
 83     bufs[0].iov_len = strlen(buffer);
 84     send_msg.msg_iov = bufs;
 85     send_msg.msg_iovlen = 1;
 86     pcmsg = (struct cmsghdr*)calloc(1, cmsglen);
 87     pcmsg->cmsg_len = cmsglen;
 88     pcmsg->cmsg_level = SOL_SOCKET;
 89     pcmsg->cmsg_type = SCM_RIGHTS;
 90     *(int*)CMSG_DATA(pcmsg) = fd_to_send;
 91     send_msg.msg_control = pcmsg;
 92     send_msg.msg_controllen = cmsglen;
 93     sendmsg(fd_socket, &send_msg, 0);
 94 }
 95 
 96 void recv_n(int fd_socket, int* fd_to_recv)
 97 {
 98     struct msghdr recv_msg;
 99     struct iovec  bufs[1];
100     struct cmsghdr*  pcmsg;
101     char buffer[1024]="";
102     int cmsglen = CMSG_LEN(sizeof(int));
103     pcmsg = (struct cmsghdr*)calloc(1,cmsglen );
104     bufs[0].iov_base = buffer;
105     bufs[0].iov_len = 1024;
106     recv_msg.msg_iov = bufs;
107     recv_msg.msg_iovlen = 1;
108     recv_msg.msg_control = pcmsg;
109     recv_msg.msg_controllen = cmsglen;
110     recvmsg(fd_socket, &recv_msg, 0);
111     printf("buf:%s
", buffer);
112     *fd_to_recv = *(int*)CMSG_DATA(pcmsg);
113 }