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