test/debug/fdpassing.c

   1
   2 /*
   3  * cc -Wall fdpassing.c -o /tmp/fdp
   4  */
   5 #include <sys/types.h>
   6 #include <sys/socket.h>
   7 #include <sys/wait.h>
   8 #include <sys/uio.h>
   9 #include <sys/stat.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <unistd.h>
  13 #include <string.h>
  14 #include <fcntl.h>
  15 #include <errno.h>
  16
  17 void sendfd(int s, int fd);
  18 int recvfd(int s);
  19
  20 int
  21 main(int ac, char **av)
  22 {
  23     struct stat st;
  24     int fds[2];
  25     int fd;
  26     int i;
  27     int dummy;
  28
  29     if (socketpair(PF_LOCAL, SOCK_STREAM, 0, fds) < 0) {
  30         perror("socketpair");
  31         exit(1);
  32     }
  33     fcntl(fds[0], F_SETFL, 0);
  34     fcntl(fds[1], F_SETFL, 0);
  35     if (fork() == 0) {
  36         close(fds[1]);
  37         while ((fd = recvfd(fds[0])) >= 0) {
  38                 fflush(stdout);
  39                 usleep(1000000 / 10);
  40                 if (fstat(fd, &st) < 0)
  41                     printf("B");
  42                 else if (read(fd, &dummy, sizeof(dummy)) != sizeof(dummy))
  43                     printf("b");
  44                 else
  45                     printf("r");
  46                 close(fd);
  47                 usleep(1000000 / 10);
  48         }
  49         printf("X\n");
  50         _exit(0);
  51     }
  52     close(fds[0]);
  53
  54     for (;;) {
  55         for (i = 1; i < ac; ++i) {
  56             if ((fd = open(av[i], O_RDONLY, 0666)) < 0) {
  57                 fprintf(stderr, "unable to open %s\n", av[i]);
  58             } else {
  59                 sendfd(fds[1], fd);
  60                 printf("w");
  61                 fflush(stdout);
  62                 close(fd);
  63             }
  64         }
  65         usleep(1000000 / 5 - 10000);
  66     }
  67     printf("DONE\n");
  68     close(fds[1]);
  69     while (wait(NULL) < 0)
  70         ;
  71     return(0);
  72 }
  73
  74 void
  75 sendfd(int s, int fd)
  76 {
  77     struct msghdr msg;
  78     struct {
  79         struct cmsghdr cmsg;
  80         int fd;
  81     } cmsg;
  82     struct iovec iov;
  83
  84     bzero(&msg, sizeof(msg));
  85     bzero(&cmsg, sizeof(cmsg));
  86
  87     iov.iov_base = NULL;
  88     iov.iov_len = 0;
  89
  90     msg.msg_iov = &iov;
  91     msg.msg_iovlen = 1;
  92     msg.msg_control = (caddr_t)&cmsg;
  93     msg.msg_controllen = sizeof(cmsg);
  94
  95     cmsg.cmsg.cmsg_level = SOL_SOCKET;
  96     cmsg.cmsg.cmsg_type = SCM_RIGHTS;
  97     cmsg.cmsg.cmsg_len = sizeof(cmsg);
  98     cmsg.fd = fd;
  99
 100     if (sendmsg(s, &msg, 0) < 0) {
 101         printf("sendfd: failed %s\n", strerror(errno));
 102         exit(1);
 103     }
 104 }
 105
 106 int
 107 recvfd(int s)
 108 {
 109     struct msghdr msg;
 110     struct {
 111         struct cmsghdr cmsg;
 112         int fd;
 113     } cmsg;
 114     struct iovec iov;
 115     int r;
 116     int dummy;
 117
 118     bzero(&msg, sizeof(msg));
 119     bzero(&cmsg, sizeof(cmsg));
 120
 121     iov.iov_base = &dummy;
 122     iov.iov_len = sizeof(dummy);
 123
 124     msg.msg_iov = &iov;
 125     msg.msg_iovlen = 1;
 126     msg.msg_control = (caddr_t)&cmsg;
 127     msg.msg_controllen = sizeof(cmsg);
 128
 129 #if 0
 130     cmsg.cmsg.cmsg_level = SOL_SOCKET;
 131     cmsg.cmsg.cmsg_type = SCM_RIGHTS;
 132 #endif
 133     cmsg.cmsg.cmsg_len = sizeof(cmsg);
 134     cmsg.fd = -1;
 135
 136     if ((r = recvmsg(s, &msg, MSG_EOR)) < 0) {
 137         printf("recvmsg: failed %s\n", strerror(errno));
 138         return(-1);
 139     }
 140     return(cmsg.fd);
 141 }