1/*	$NetBSD$	*/
2
3/*++
4/* NAME
5/*	fifo_rdwr_bug 1
6/* SUMMARY
7/*	fifo server test program
8/* SYNOPSIS
9/*	fifo_rdwr_bug
10/* DESCRIPTION
11/*	fifo_rdwr_bug creates a FIFO and opens it read-write mode.
12/*	On BSD/OS 3.1 select() will report that the FIFO is readable
13/*	even before any data is written to it. Doing an actual read
14/*	causes the read to block; a non-blocking read fails.
15/* DIAGNOSTICS
16/*	Problems are reported to the standard error stream.
17/* LICENSE
18/* .ad
19/* .fi
20/*	The Secure Mailer license must be distributed with this software.
21/* AUTHOR(S)
22/*	Wietse Venema
23/*	IBM T.J. Watson Research
24/*	P.O. Box 704
25/*	Yorktown Heights, NY 10598, USA
26/*--*/
27
28#include <sys_defs.h>
29#include <sys/time.h>
30#include <sys/param.h>
31#include <sys/stat.h>
32#include <stdio.h>
33#include <fcntl.h>
34#include <signal.h>
35#include <unistd.h>
36#include <stdlib.h>
37#include <string.h>
38
39#define FIFO_PATH       "test-fifo"
40#define perrorexit(s)   { perror(s); exit(1); }
41
42static void cleanup(void)
43{
44    printf("Removing fifo %s...\n", FIFO_PATH);
45    if (unlink(FIFO_PATH))
46	perrorexit("unlink");
47    printf("Done.\n");
48}
49
50int     main(int unused_argc, char **unused_argv)
51{
52    struct timeval tv;
53    fd_set  read_fds;
54    fd_set  except_fds;
55    int     fd;
56
57    (void) unlink(FIFO_PATH);
58
59    printf("Creating fifo %s...\n", FIFO_PATH);
60    if (mkfifo(FIFO_PATH, 0600) < 0)
61	perrorexit("mkfifo");
62
63    printf("Opening fifo %s, read-write mode...\n", FIFO_PATH);
64    if ((fd = open(FIFO_PATH, O_RDWR, 0)) < 0) {
65	perror("open");
66	cleanup();
67	exit(1);
68    }
69    printf("Selecting the fifo for readability...\n");
70    FD_ZERO(&read_fds);
71    FD_SET(fd, &read_fds);
72    FD_ZERO(&except_fds);
73    FD_SET(fd, &except_fds);
74    tv.tv_sec = 1;
75    tv.tv_usec = 0;
76
77    switch (select(fd + 1, &read_fds, (fd_set *) 0, &except_fds, &tv)) {
78    case -1:
79	perrorexit("select");
80    default:
81	if (FD_ISSET(fd, &read_fds)) {
82	    printf("Opening a fifo read-write makes it readable!!\n");
83	    break;
84	}
85    case 0:
86	printf("The fifo is not readable, as it should be.\n");
87	break;
88    }
89    cleanup();
90    exit(0);
91}
92