1 /* $OpenBSD: lockspool.c,v 1.23 2023/03/08 04:43:05 guenther Exp $ */
2
3 /*
4 * Copyright (c) 1998 Theo de Raadt <deraadt@theos.com>
5 * Copyright (c) 1998 Todd C. Miller <millert@openbsd.org>
6 * 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 *
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
19 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
20 * THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
21 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
22 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
23 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
25 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
26 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <signal.h>
30 #include <pwd.h>
31 #include <syslog.h>
32 #include <unistd.h>
33 #include <errno.h>
34 #include <stdio.h>
35 #include <paths.h>
36 #include <stdlib.h>
37 #include <poll.h>
38 #include <err.h>
39
40 #include "mail.local.h"
41
42 void unhold(int);
43 void usage(void);
44
45 extern char *__progname;
46
47 int
main(int argc,char * argv[])48 main(int argc, char *argv[])
49 {
50 struct passwd *pw;
51 struct pollfd pfd;
52 ssize_t nread;
53 char *from, c;
54 int holdfd;
55
56 if (unveil(_PATH_MAILDIR, "rwc") == -1)
57 err(1, "unveil %s", _PATH_MAILDIR);
58 if (pledge("stdio rpath wpath getpw cpath fattr", NULL) == -1)
59 err(1, "pledge");
60
61 openlog(__progname, LOG_PERROR, LOG_MAIL);
62
63 if (argc != 1 && argc != 2)
64 usage();
65 if (argc == 2 && getuid() != 0)
66 merr(1, "you must be root to lock someone else's spool");
67
68 signal(SIGTERM, unhold);
69 signal(SIGINT, unhold);
70 signal(SIGHUP, unhold);
71 signal(SIGPIPE, unhold);
72
73 if (argc == 2)
74 pw = getpwnam(argv[1]);
75 else
76 pw = getpwuid(getuid());
77 if (pw == NULL)
78 exit (1);
79 from = pw->pw_name;
80
81 holdfd = getlock(from, pw);
82 if (holdfd == -1) {
83 write(STDOUT_FILENO, "0\n", 2);
84 exit (1);
85 }
86 write(STDOUT_FILENO, "1\n", 2);
87
88 /* wait for the other end of the pipe to close, then release the lock */
89 pfd.fd = STDIN_FILENO;
90 pfd.events = POLLIN;
91 do {
92 if (poll(&pfd, 1, INFTIM) == -1) {
93 if (errno != EINTR)
94 break;
95 }
96 do {
97 nread = read(STDIN_FILENO, &c, 1);
98 } while (nread == 1 || (nread == -1 && errno == EINTR));
99 } while (nread == -1 && errno == EAGAIN);
100 rellock();
101 exit (0);
102 }
103
104 void
unhold(int signo)105 unhold(int signo)
106 {
107
108 rellock();
109 _exit(0);
110 }
111
112 void
usage(void)113 usage(void)
114 {
115
116 merr(1, "usage: %s [username]", __progname);
117 }
118