refclock_shm.c revision 132451 
1/*
2 * refclock_shm - clock driver for utc via shared memory
3 * - under construction -
4 * To add new modes: Extend or union the shmTime-struct. Do not
5 * extend/shrink size, because otherwise existing implementations
6 * will specify wrong size of shared memory-segment
7 * PB 18.3.97
8 */
9
10#ifdef HAVE_CONFIG_H
11# include <config.h>
12#endif
13
14#if defined(REFCLOCK) && defined(CLOCK_SHM)
15
16#include "ntpd.h"
17#undef fileno
18#include "ntp_io.h"
19#undef fileno
20#include "ntp_refclock.h"
21#undef fileno
22#include "ntp_unixtime.h"
23#undef fileno
24#include "ntp_stdlib.h"
25
26#undef fileno
27#include <ctype.h>
28#undef fileno
29
30#ifndef SYS_WINNT
31# include <sys/ipc.h>
32# include <sys/shm.h>
33# include <assert.h>
34# include <unistd.h>
35# include <stdio.h>
36#endif
37
38/*
39 * This driver supports a reference clock attached thru shared memory
40 */
41
42/*
43 * SHM interface definitions
44 */
45#define PRECISION       (-1)    /* precision assumed (0.5 s) */
46#define REFID           "SHM"   /* reference ID */
47#define DESCRIPTION     "SHM/Shared memory interface"
48
49#define NSAMPLES        3       /* stages of median filter */
50
51/*
52 * Function prototypes
53 */
54static  int     shm_start       (int, struct peer *);
55static  void    shm_shutdown    (int, struct peer *);
56static  void    shm_poll        (int unit, struct peer *);
57
58/*
59 * Transfer vector
60 */
61struct  refclock refclock_shm = {
62	shm_start,              /* start up driver */
63	shm_shutdown,           /* shut down driver */
64	shm_poll,               /* transmit poll message */
65	noentry,                /* not used */
66	noentry,                /* initialize driver (not used) */
67	noentry,                /* not used */
68	NOFLAGS                 /* not used */
69};
70struct shmTime {
71	int    mode; /* 0 - if valid set
72		      *       use values,
73		      *       clear valid
74		      * 1 - if valid set
75		      *       if count before and after read of values is equal,
76		      *         use values
77		      *       clear valid
78		      */
79	int    count;
80	time_t clockTimeStampSec;
81	int    clockTimeStampUSec;
82	time_t receiveTimeStampSec;
83	int    receiveTimeStampUSec;
84	int    leap;
85	int    precision;
86	int    nsamples;
87	int    valid;
88	int    dummy[10];
89};
90
91struct shmTime *getShmTime(int);
92
93struct shmTime *getShmTime (int unit) {
94#ifndef SYS_WINNT
95	int shmid=0;
96
97	assert (unit<10); /* MAXUNIT is 4, so should never happen */
98	shmid=shmget (0x4e545030+unit, sizeof (struct shmTime),
99		      IPC_CREAT|(unit<2?0700:0777));
100	if (shmid==-1) { /*error */
101		msyslog(LOG_ERR,"SHM shmget (unit %d): %s",unit,strerror(errno));
102		return 0;
103	}
104	else { /* no error  */
105		struct shmTime *p=(struct shmTime *)shmat (shmid, 0, 0);
106		if ((int)(long)p==-1) { /* error */
107			msyslog(LOG_ERR,"SHM shmat (unit %d): %s",unit,strerror(errno));
108			return 0;
109		}
110		return p;
111	}
112#else
113	char buf[10];
114	LPSECURITY_ATTRIBUTES psec=0;
115	HANDLE shmid=0;
116	SECURITY_DESCRIPTOR sd;
117	SECURITY_ATTRIBUTES sa;
118	sprintf (buf,"NTP%d",unit);
119	if (unit>=2) { /* world access */
120		if (!InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION)) {
121			msyslog(LOG_ERR,"SHM InitializeSecurityDescriptor (unit %d): %m",unit);
122			return 0;
123		}
124		if (!SetSecurityDescriptorDacl(&sd,1,0,0)) {
125			msyslog(LOG_ERR,"SHM SetSecurityDescriptorDacl (unit %d): %m",unit);
126			return 0;
127		}
128		sa.nLength=sizeof (SECURITY_ATTRIBUTES);
129		sa.lpSecurityDescriptor=&sd;
130		sa.bInheritHandle=0;
131		psec=&sa;
132	}
133	shmid=CreateFileMapping ((HANDLE)0xffffffff, psec, PAGE_READWRITE,
134				 0, sizeof (struct shmTime),buf);
135	if (!shmid) { /*error*/
136		char buf[1000];
137		FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM,
138			       0, GetLastError (), 0, buf, sizeof (buf), 0);
139		msyslog(LOG_ERR,"SHM CreateFileMapping (unit %d): %s",unit,buf);
140		return 0;
141	}
142	else {
143		struct shmTime *p=(struct shmTime *) MapViewOfFile (shmid,
144								    FILE_MAP_WRITE, 0, 0, sizeof (struct shmTime));
145		if (p==0) { /*error*/
146			char buf[1000];
147			FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM,
148				       0, GetLastError (), 0, buf, sizeof (buf), 0);
149			msyslog(LOG_ERR,"SHM MapViewOfFile (unit %d): %s",unit,buf);
150			return 0;
151		}
152		return p;
153	}
154#endif
155}
156/*
157 * shm_start - attach to shared memory
158 */
159static int
160shm_start(
161	int unit,
162	struct peer *peer
163	)
164{
165	struct refclockproc *pp;
166	pp = peer->procptr;
167	pp->io.clock_recv = noentry;
168	pp->io.srcclock = (caddr_t)peer;
169	pp->io.datalen = 0;
170	pp->io.fd = -1;
171	pp->unitptr = (caddr_t)getShmTime(unit);
172
173	/*
174	 * Initialize miscellaneous peer variables
175	 */
176	memcpy((char *)&pp->refid, REFID, 4);
177	if (pp->unitptr!=0) {
178		((struct shmTime*)pp->unitptr)->precision=PRECISION;
179		peer->precision = ((struct shmTime*)pp->unitptr)->precision;
180		((struct shmTime*)pp->unitptr)->valid=0;
181		((struct shmTime*)pp->unitptr)->nsamples=NSAMPLES;
182		pp->clockdesc = DESCRIPTION;
183		return (1);
184	}
185	else {
186		return 0;
187	}
188}
189
190
191/*
192 * shm_shutdown - shut down the clock
193 */
194static void
195shm_shutdown(
196	int unit,
197	struct peer *peer
198	)
199{
200	register struct shmTime *up;
201	struct refclockproc *pp;
202
203	pp = peer->procptr;
204	up = (struct shmTime *)pp->unitptr;
205#ifndef SYS_WINNT
206	/* HMS: shmdt()wants char* or const void * */
207	(void) shmdt (up);
208#else
209	UnmapViewOfFile (up);
210#endif
211}
212
213
214/*
215 * shm_poll - called by the transmit procedure
216 */
217static void
218shm_poll(
219	int unit,
220	struct peer *peer
221	)
222{
223	register struct shmTime *up;
224	struct refclockproc *pp;
225
226	/*
227	 * This is the main routine. It snatches the time from the shm
228	 * board and tacks on a local timestamp.
229	 */
230	pp = peer->procptr;
231	up = (struct shmTime*)pp->unitptr;
232	if (up==0) { /* try to map again - this may succeed if meanwhile some-
233			body has ipcrm'ed the old (unaccessible) shared mem
234			segment  */
235		pp->unitptr = (caddr_t)getShmTime(unit);
236		up = (struct shmTime*)pp->unitptr;
237	}
238	if (up==0) {
239		refclock_report(peer, CEVNT_FAULT);
240		return;
241	}
242	if (up->valid) {
243		struct timeval tvr;
244		struct timeval tvt;
245		struct tm *t;
246		int ok=1;
247		switch (up->mode) {
248		    case 0: {
249			    tvr.tv_sec=up->receiveTimeStampSec;
250			    tvr.tv_usec=up->receiveTimeStampUSec;
251			    tvt.tv_sec=up->clockTimeStampSec;
252			    tvt.tv_usec=up->clockTimeStampUSec;
253		    }
254		    break;
255		    case 1: {
256			    int cnt=up->count;
257			    tvr.tv_sec=up->receiveTimeStampSec;
258			    tvr.tv_usec=up->receiveTimeStampUSec;
259			    tvt.tv_sec=up->clockTimeStampSec;
260			    tvt.tv_usec=up->clockTimeStampUSec;
261			    ok=(cnt==up->count);
262		    }
263		    break;
264		    default:
265			msyslog (LOG_ERR, "SHM: bad mode found in shared memory: %d",up->mode);
266		}
267		up->valid=0;
268		if (ok) {
269			TVTOTS(&tvr,&pp->lastrec);
270			pp->lastrec.l_ui += JAN_1970;
271			/* pp->lasttime = current_time; */
272			pp->polls++;
273			t=gmtime (&tvt.tv_sec);
274			pp->day=t->tm_yday+1;
275			pp->hour=t->tm_hour;
276			pp->minute=t->tm_min;
277			pp->second=t->tm_sec;
278			pp->nsec=tvt.tv_usec * 1000;
279			peer->precision=up->precision;
280			pp->leap=up->leap;
281		}
282		else {
283			refclock_report(peer, CEVNT_FAULT);
284			msyslog (LOG_NOTICE, "SHM: access clash in shared memory");
285			return;
286		}
287	}
288	else {
289		refclock_report(peer, CEVNT_TIMEOUT);
290		/*
291		msyslog (LOG_NOTICE, "SHM: no new value found in shared memory");
292		*/
293		return;
294	}
295	if (!refclock_process(pp)) {
296		refclock_report(peer, CEVNT_BADTIME);
297		return;
298	}
299	pp->lastref = pp->lastrec;
300	refclock_receive(peer);
301}
302
303#else
304int refclock_shm_bs;
305#endif /* REFCLOCK */
306