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

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      fifo_rdonly_bug 1
   6 /* SUMMARY
   7 /*      fifo server test program
   8 /* SYNOPSIS
   9 /*      fifo_rdonly_bug
  10 /* DESCRIPTION
  11 /*      fifo_rdonly_bug creates a FIFO and opens it read only. It
  12 /*      then opens the FIFO for writing, writes one byte, and closes
  13 /*      the writing end. On Linux Redhat 4.2 and 5.0, and HP-UX 9.05
  14 /*      and 10.20, select() will report that the FIFO remains readable
  15 /*      even after multiple read operations.
  16 /* DIAGNOSTICS
  17 /*      Problems are reported to the standard error stream.
  18 /* LICENSE
  19 /* .ad
  20 /* .fi
  21 /*      The Secure Mailer license must be distributed with this software.
  22 /* AUTHOR(S)
  23 /*      Wietse Venema
  24 /*      IBM T.J. Watson Research
  25 /*      P.O. Box 704
  26 /*      Yorktown Heights, NY 10598, USA
  27 /*--*/
  28
  29 #include <sys_defs.h>
  30 #include <sys/stat.h>
  31 #include <sys/time.h>
  32 #include <stdio.h>
  33 #include <unistd.h>
  34 #include <stdlib.h>
  35 #include <fcntl.h>
  36 #include <string.h>
  37
  38 #define FIFO_PATH       "test-fifo"
  39 #define TRIGGER_DELAY   5
  40
  41 #define perrorexit(s)   { perror(s); exit(1); }
  42
  43 static void cleanup(void)
  44 {
  45     printf("Removing fifo %s...\n", FIFO_PATH);
  46     if (unlink(FIFO_PATH))
  47         perrorexit("unlink");
  48     printf("Done.\n");
  49 }
  50
  51 static void perrorcleanup(char *str)
  52 {
  53     perror(str);
  54     cleanup();
  55     exit(0);
  56 }
  57
  58 static void readable_event(int fd)
  59 {
  60     char    ch;
  61     static int count = 0;
  62
  63     if (read(fd, &ch, 1) < 0) {
  64         perror("read");
  65         sleep(1);
  66     }
  67     if (count++ > 5) {
  68         printf("FIFO remains readable after multiple reads.\n");
  69         cleanup();
  70         exit(1);
  71     }
  72 }
  73
  74 int     main(int unused_argc, char **unused_argv)
  75 {
  76     struct timeval tv;
  77     fd_set  read_fds;
  78     fd_set  except_fds;
  79     int     fd;
  80     int     fd2;
  81
  82     (void) unlink(FIFO_PATH);
  83
  84     printf("Create fifo %s...\n", FIFO_PATH);
  85     if (mkfifo(FIFO_PATH, 0600) < 0)
  86         perrorexit("mkfifo");
  87
  88     printf("Open fifo %s, read-only mode...\n", FIFO_PATH);
  89     if ((fd = open(FIFO_PATH, O_RDONLY | O_NONBLOCK, 0)) < 0)
  90         perrorcleanup("open");
  91
  92     printf("Write one byte to the fifo, then close it...\n");
  93     if ((fd2 = open(FIFO_PATH, O_WRONLY, 0)) < 0)
  94         perrorcleanup("open fifo O_WRONLY");
  95     if (write(fd2, "", 1) < 1)
  96         perrorcleanup("write one byte to fifo");
  97     if (close(fd2) < 0)
  98         perrorcleanup("close fifo");
  99
 100     printf("Selecting the fifo for readability...\n");
 101
 102     for (;;) {
 103         FD_ZERO(&read_fds);
 104         FD_SET(fd, &read_fds);
 105         FD_ZERO(&except_fds);
 106         FD_SET(fd, &except_fds);
 107         tv.tv_sec = 1;
 108         tv.tv_usec = 0;
 109
 110         switch (select(fd + 1, &read_fds, (fd_set *) 0, &except_fds, &tv)) {
 111         case -1:
 112             perrorexit("select");
 113         default:
 114             if (FD_ISSET(fd, &except_fds)) {
 115                 printf("Exceptional fifo condition! You are not normal!\n");
 116                 readable_event(fd);
 117             } else if (FD_ISSET(fd, &read_fds)) {
 118                 printf("Readable fifo condition\n");
 119                 readable_event(fd);
 120             }
 121             break;
 122         case 0:
 123             printf("The fifo is not readable. You're normal.\n");
 124             cleanup();
 125             exit(0);
 126             break;
 127         }
 128     }
 129 }