external/ibm-public/postfix/dist/src/util/select_bug.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      select_bug 1
   6 /* SUMMARY
   7 /*      select test program
   8 /* SYNOPSIS
   9 /*      select_bug
  10 /* DESCRIPTION
  11 /*      select_bug forks child processes that perform select()
  12 /*      on a shared socket, and sees if a wakeup affects other
  13 /*      processes selecting on a different socket or stdin.
  14 /* DIAGNOSTICS
  15 /*      Problems are reported to the standard error stream.
  16 /* LICENSE
  17 /* .ad
  18 /* .fi
  19 /*      The Secure Mailer license must be distributed with this software.
  20 /* AUTHOR(S)
  21 /*      Wietse Venema
  22 /*      IBM T.J. Watson Research
  23 /*      P.O. Box 704
  24 /*      Yorktown Heights, NY 10598, USA
  25 /*--*/
  26
  27 /* System library. */
  28
  29 #include <sys_defs.h>
  30 #include <sys/time.h>
  31 #include <sys/socket.h>
  32 #include <sys/wait.h>
  33 #include <unistd.h>
  34 #include <stdlib.h>
  35 #include <string.h>                     /* bzero() prototype for 44BSD */
  36
  37 /* Utility library. */
  38
  39 #include <msg.h>
  40 #include <vstream.h>
  41 #include <msg_vstream.h>
  42
  43 static pid_t fork_and_read_select(const char *what, int delay, int fd)
  44 {
  45     struct timeval tv;
  46     pid_t   pid;
  47     fd_set  readfds;
  48
  49     switch (pid = fork()) {
  50     case -1:
  51         msg_fatal("fork: %m");
  52     case 0:
  53         tv.tv_sec = delay;
  54         tv.tv_usec = 0;
  55         FD_ZERO(&readfds);
  56         FD_SET(fd, &readfds);
  57         switch (select(fd + 1, &readfds, (fd_set *) 0, &readfds, &tv)) {
  58         case -1:
  59             msg_fatal("select: %m");
  60         case 0:
  61             msg_info("%s select timed out", what);
  62             exit(0);
  63         default:
  64             msg_info("%s select wakeup", what);
  65             exit(0);
  66         }
  67     default:
  68         return (pid);
  69     }
  70 }
  71
  72 int     main(int argc, char **argv)
  73 {
  74     int     pair1[2];
  75     int     pair2[2];
  76
  77     msg_vstream_init(argv[0], VSTREAM_ERR);
  78
  79 #define DELAY 1
  80
  81     if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair1) < 0)
  82         msg_fatal("socketpair: %m");
  83     if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair2) < 0)
  84         msg_fatal("socketpair: %m");
  85
  86     vstream_printf("Doing multiple select on socket1, then write to it...\n");
  87     vstream_fflush(VSTREAM_OUT);
  88     fork_and_read_select("socket1", DELAY, pair1[0]);   /* one */
  89     fork_and_read_select("socket1", DELAY, pair1[0]);   /* two */
  90     fork_and_read_select("socket2", DELAY, pair2[0]);
  91     fork_and_read_select("stdin", DELAY, 0);
  92     if (write(pair1[1], "", 1) != 1)
  93         msg_fatal("write: %m");
  94     while (wait((int *) 0) >= 0)
  95          /* void */ ;
  96     return (0);
  97 }