1/*++
2/* NAME
3/*	fifo_trigger 3
4/* SUMMARY
5/*	wakeup fifo server
6/* SYNOPSIS
7/*	#include <trigger.h>
8/*
9/*	int	fifo_trigger(service, buf, len, timeout)
10/*	const char *service;
11/*	const char *buf;
12/*	ssize_t	len;
13/*	int	timeout;
14/* DESCRIPTION
15/*	fifo_trigger() wakes up the named fifo server by writing
16/*	the contents of the specified buffer to the fifo. There is
17/*	no guarantee that the written data will actually be received.
18/*
19/*	Arguments:
20/* .IP service
21/*	Name of the communication endpoint.
22/* .IP buf
23/*	Address of data to be written.
24/* .IP len
25/*	Amount of data to be written.
26/* .IP timeout
27/*	Deadline in seconds. Specify a value <= 0 to disable
28/*	the time limit.
29/* DIAGNOSTICS
30/*	The result is zero when the fifo could be opened, -1 otherwise.
31/* BUGS
32/* LICENSE
33/* .ad
34/* .fi
35/*	The Secure Mailer license must be distributed with this software.
36/* AUTHOR(S)
37/*	Wietse Venema
38/*	IBM T.J. Watson Research
39/*	P.O. Box 704
40/*	Yorktown Heights, NY 10598, USA
41/*--*/
42
43/* System library. */
44
45#include <sys_defs.h>
46#include <fcntl.h>
47#include <unistd.h>
48
49/* Utility library. */
50
51#include <msg.h>
52#include <iostuff.h>
53#include <safe_open.h>
54#include <trigger.h>
55
56/* fifo_trigger - wakeup fifo server */
57
58int     fifo_trigger(const char *service, const char *buf, ssize_t len, int timeout)
59{
60    static VSTRING *why;
61    const char *myname = "fifo_trigger";
62    VSTREAM *fp;
63    int     fd;
64
65    if (why == 0)
66	why = vstring_alloc(1);
67
68    /*
69     * Write the request to the service fifo. According to POSIX, the open
70     * shall always return immediately, and shall return an error when no
71     * process is reading from the FIFO.
72     *
73     * Use safe_open() so that we don't follow symlinks, and so that we don't
74     * open files with multiple hard links. We're not (yet) going to bother
75     * the caller with safe_open() specific quirks such as the why argument.
76     */
77    if ((fp = safe_open(service, O_WRONLY | O_NONBLOCK, 0,
78			(struct stat *) 0, -1, -1, why)) == 0) {
79	if (msg_verbose)
80	    msg_info("%s: open %s: %s", myname, service, vstring_str(why));
81	return (-1);
82    }
83    fd = vstream_fileno(fp);
84
85    /*
86     * Write the request...
87     */
88    non_blocking(fd, timeout > 0 ? NON_BLOCKING : BLOCKING);
89    if (write_buf(fd, buf, len, timeout) < 0)
90	if (msg_verbose)
91	    msg_warn("%s: write %s: %m", myname, service);
92
93    /*
94     * Disconnect.
95     */
96    if (vstream_fclose(fp))
97	if (msg_verbose)
98	    msg_warn("%s: close %s: %m", myname, service);
99    return (0);
100}
101
102#ifdef TEST
103
104 /*
105  * Set up a FIFO listener, and keep triggering until the listener becomes
106  * idle, which should never happen.
107  */
108#include <signal.h>
109#include <stdlib.h>
110
111#include "events.h"
112#include "listen.h"
113
114#define TEST_FIFO	"test-fifo"
115
116int     trig_count;
117int     wakeup_count;
118
119static void cleanup(void)
120{
121    unlink(TEST_FIFO);
122    exit(1);
123}
124
125static void handler(int sig)
126{
127    msg_fatal("got signal %d after %d triggers %d wakeups",
128	      sig, trig_count, wakeup_count);
129}
130
131static void read_event(int unused_event, char *context)
132{
133    int     fd = CAST_CHAR_PTR_TO_INT(context);
134    char    ch;
135
136    wakeup_count++;
137
138    if (read(fd, &ch, 1) != 1)
139	msg_fatal("read %s: %m", TEST_FIFO);
140}
141
142int     main(int unused_argc, char **unused_argv)
143{
144    int     listen_fd;
145
146    listen_fd = fifo_listen(TEST_FIFO, 0600, NON_BLOCKING);
147    msg_cleanup(cleanup);
148    event_enable_read(listen_fd, read_event, CAST_INT_TO_CHAR_PTR(listen_fd));
149    signal(SIGINT, handler);
150    signal(SIGALRM, handler);
151    for (;;) {
152	alarm(10);
153	if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
154	    msg_fatal("trigger %s: %m", TEST_FIFO);
155	trig_count++;
156	if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
157	    msg_fatal("trigger %s: %m", TEST_FIFO);
158	trig_count++;
159	if (fifo_trigger(TEST_FIFO, "", 1, 0) < 0)
160	    msg_fatal("trigger %s: %m", TEST_FIFO);
161	trig_count++;
162	event_loop(-1);
163	event_loop(-1);
164	event_loop(-1);
165    }
166}
167
168#endif
169