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/*++
/* NAME
/* fifo_rdonly_bug 1
/* SUMMARY
/* fifo server test program
/* SYNOPSIS
/* fifo_rdonly_bug
/* DESCRIPTION
/* fifo_rdonly_bug creates a FIFO and opens it read only. It
/* then opens the FIFO for writing, writes one byte, and closes
/* the writing end. On Linux Redhat 4.2 and 5.0, and HP-UX 9.05
/* and 10.20, select() will report that the FIFO remains readable
/* even after multiple read operations.
/* DIAGNOSTICS
/* Problems are reported to the standard error stream.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
#include <sys_defs.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#define FIFO_PATH "test-fifo"
#define TRIGGER_DELAY 5
#define perrorexit(s) { perror(s); exit(1); }
static void cleanup(void)
{
printf("Removing fifo %s...\n", FIFO_PATH);
if (unlink(FIFO_PATH))
perrorexit("unlink");
printf("Done.\n");
}
static void perrorcleanup(char *str)
{
perror(str);
cleanup();
exit(0);
}
static void readable_event(int fd)
{
char ch;
static int count = 0;
if (read(fd, &ch, 1) < 0) {
perror("read");
sleep(1);
}
if (count++ > 5) {
printf("FIFO remains readable after multiple reads.\n");
cleanup();
exit(1);
}
}
int main(int unused_argc, char **unused_argv)
{
struct timeval tv;
fd_set read_fds;
fd_set except_fds;
int fd;
int fd2;
(void) unlink(FIFO_PATH);
printf("Create fifo %s...\n", FIFO_PATH);
if (mkfifo(FIFO_PATH, 0600) < 0)
perrorexit("mkfifo");
printf("Open fifo %s, read-only mode...\n", FIFO_PATH);
if ((fd = open(FIFO_PATH, O_RDONLY | O_NONBLOCK, 0)) < 0)
perrorcleanup("open");
printf("Write one byte to the fifo, then close it...\n");
if ((fd2 = open(FIFO_PATH, O_WRONLY, 0)) < 0)
perrorcleanup("open fifo O_WRONLY");
if (write(fd2, "", 1) < 1)
perrorcleanup("write one byte to fifo");
if (close(fd2) < 0)
perrorcleanup("close fifo");
printf("Selecting the fifo for readability...\n");
for (;;) {
FD_ZERO(&read_fds);
FD_SET(fd, &read_fds);
FD_ZERO(&except_fds);
FD_SET(fd, &except_fds);
tv.tv_sec = 1;
tv.tv_usec = 0;
switch (select(fd + 1, &read_fds, (fd_set *) 0, &except_fds, &tv)) {
case -1:
perrorexit("select");
default:
if (FD_ISSET(fd, &except_fds)) {
printf("Exceptional fifo condition! You are not normal!\n");
readable_event(fd);
} else if (FD_ISSET(fd, &read_fds)) {
printf("Readable fifo condition\n");
readable_event(fd);
}
break;
case 0:
printf("The fifo is not readable. You're normal.\n");
cleanup();
exit(0);
break;
}
}
}
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