1 /* $OpenBSD: instr.c,v 1.14 2016/01/10 13:35:09 mestre Exp $ */
2 /* $NetBSD: instr.c,v 1.5 1997/07/10 06:47:30 mikel Exp $ */
3
4 /*-
5 * Copyright (c) 1990, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <sys/wait.h>
34
35 #include <err.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <paths.h>
39 #include <stdlib.h>
40 #include <unistd.h>
41
42 #include "pathnames.h"
43
44 void
instructions(void)45 instructions(void)
46 {
47 int pstat;
48 int fd;
49 pid_t pid;
50 const char *pager;
51
52 if ((fd = open(_PATH_INSTR, O_RDONLY)) == - 1)
53 errx(1, "can't open %s", _PATH_INSTR);
54
55 switch (pid = vfork()) {
56 case -1:
57 err(1, "vfork");
58 case 0:
59 if (!isatty(1))
60 pager = "/bin/cat";
61 else {
62 if (!(pager = getenv("PAGER")) || (*pager == 0))
63 pager = _PATH_MORE;
64 }
65 if (dup2(fd, 0) == -1)
66 err(1, "dup2");
67 execl(_PATH_BSHELL, "sh", "-c", pager, (char *)NULL);
68 err(1, "exec sh -c %s", pager);
69 default:
70 do {
71 pid = waitpid(pid, &pstat, 0);
72 } while (pid == -1 && errno == EINTR);
73 close(fd);
74 if (pid == -1 || WEXITSTATUS(pstat))
75 exit(1);
76 break;
77 }
78 }
79