Begin factoring out ntplib.

All knowledge of the ntpd SHM format is now confined to the three
files ntpshm.h, ntpshmread.c, and ntpshmwrite.c.

No logic changes.  All regression tests pass.  PPS works on GR-601W.

1 files changed, 16 insertions, 434 deletions

diff --git a/ntpshmwrite.c b/ntpshmwrite.c
index f03b152a..f001d9ea 100644
--- a/ntpshmwrite.c
+++ b/ntpshmwrite.c
@@ -1,11 +1,5 @@
 /*
- * ntpshmwrite.c - put time information in SHM segment for xntpd, or to chrony
- *
- * struct shmTime and getShmTime from file in the xntp distribution:
- *	sht.c - Testprogram for shared memory refclock
- *
- * Note that for easy debugging all logging from this file is prefixed
- * with PPS or NTP.
+ * ntpshmwrite.c - put time information in SHM segment for ntpd
  *
  * This file is Copyright (c) 2010 by the GPSD project BSD terms apply:
  * see the file COPYING in the distribution root for details.
@@ -24,235 +18,13 @@
 #include <unistd.h>
 #endif /* S_SPLINT_S */
 
-#include "gpsd.h"
-
-#ifdef NTPSHM_ENABLE
 #include "ntpshm.h"
+#include "compiler.h"
 
-/* Note: you can start gpsd as non-root, and have it work with ntpd.
- * However, it will then only use the ntpshm segments 2 3, and higher.
- *
- * Ntpd always runs as root (to be able to control the system clock).
- * After that it often (depending on its host configuration) drops to run as
- * user ntpd and group ntpd.
- * 
- * As of February 2015 its rules for the creation of ntpshm segments are:
- *
- * Segments 0 and 1: permissions 0600, i.e. other programs can only
- *                   read and write as root.
- *
- * Segments 2, 3, and higher: 
- *                   permissions 0666, i.e. other programs can read
- *                   and write as any user.  I.e.: if ntpd has been
- *                   configured to use these segments, any
- *                   unprivileged user is allowed to provide data
- *                   for synchronisation.
- *
- * By default ntpd creates 0 segments (though the documentation is
- * written in such a way as to suggest it creates 4).  It can be
- * configured to create up to 217.  gpsd creates two segments for each
- * device it can drive; by default this is 8 segments for 4
- * devices,but can be higher if it was compiled with a larger value of
- * MAX_DEVICES.
- *
- * Started as root, gpsd does as ntpd when attaching (creating) the
- * segments.  In contrast to ntpd, which only attaches (creates)
- * configured segments, gpsd creates all segments.  Thus a gpsd will
- * by default create eight segments 0-7 that an ntpd with default
- * configuration does not watch.
- *
- * Started as non-root, gpsd will only attach (create) segments 2 and
- * above, with permissions 0666.  As the permissions are for any user,
- * the creator does not matter.
- *
- * For each GPS module gpsd controls, it will use the attached ntpshm
- * segments in pairs (for coarse clock and pps source, respectively)
- * starting from the first found segments.  I.e. started as root, one
- * GPS will deliver data on all segments including 0 and 1; started as
- * non-root, gpsd will be deliver data only on segments 2 and higher.
- *
- * Segments are allocated to activated devices on a first-come-first-served
- * basis. A device's segment is marked unused when the device is closed and
- * may be re-used by devices connected later.
- *
- * To debug, try looking at the live segments this way:
- *
- *  ipcs -m
- * 
- * results  should look like this:
- * ------ Shared Memory Segments --------
- *  key        shmid      owner      perms      bytes      nattch     status
- *  0x4e545030 0          root       700        96         2
- *  0x4e545031 32769      root       700        96         2
- *  0x4e545032 163842     root       666        96         1
- *  0x4e545033 196611     root       666        96         1
- *  0x4e545034 253555     root       666        96         1
- *  0x4e545035 367311     root       666        96         1
- *
- * For a bit more data try this:
- *  cat /proc/sysvipc/shm
- *
- * If gpsd can not open the segments be sure you are not running SELinux
- * or apparmor.
- *
- * if you see the shared segments (keys 1314148400 -- 1314148405), and
- * no gpsd or ntpd is running, you can remove them like this:
- *
- * ipcrm  -M 0x4e545030
- * ipcrm  -M 0x4e545031
- * ipcrm  -M 0x4e545032
- * ipcrm  -M 0x4e545033
- * ipcrm  -M 0x4e545034
- * ipcrm  -M 0x4e545035
- *
- * Removing these segments is usually not necessary, as the operating system 
- * garbage-collects them when they have no attached processes.
- */
-
-#define PPS_MIN_FIXES	3	/* # fixes to wait for before shipping PPS */
-
-static /*@null@*/ volatile struct shmTime *getShmTime(struct gps_context_t *context, int unit)
-{
-    int shmid;
-    unsigned int perms;
-    volatile struct shmTime *p;
-    // set the SHM perms the way ntpd does
-    if (unit < 2) {
-	// we are root, be careful
-	perms = 0600;
-    } else {
-	// we are not root, try to work anyway
-	perms = 0666;
-    }
-
-    /*
-     * Note: this call requires root under BSD, and possibly on
-     * well-secured Linux systems.  This is why ntpshmwrite.context_init() has to be
-     * called before privilege-dropping.
-     */
-    shmid = shmget((key_t) (NTPD_BASE + unit),
-		   sizeof(struct shmTime), (int)(IPC_CREAT | perms));
-    if (shmid == -1) {
-	gpsd_report(&context->errout, LOG_ERROR,
-		    "NTPD shmget(%ld, %zd, %o) fail: %s\n",
-		    (long int)(NTPD_BASE + unit), sizeof(struct shmTime),
-		    (int)perms, strerror(errno));
-	return NULL;
-    }
-    p = (struct shmTime *)shmat(shmid, 0, 0);
-    /*@ -mustfreefresh */
-    if ((int)(long)p == -1) {
-	gpsd_report(&context->errout, LOG_ERROR,
-		    "NTPD shmat failed: %s\n",
-		    strerror(errno));
-	return NULL;
-    }
-    gpsd_report(&context->errout, LOG_PROG,
-		"NTPD shmat(%d,0,0) succeeded, segment %d\n",
-		shmid, unit);
-    return p;
-    /*@ +mustfreefresh */
-}
-
-void ntpshm_context_init(struct gps_context_t *context)
-/* Attach all NTP SHM segments. Called once at startup, while still root. */
-{
-    int i;
-
-    for (i = 0; i < NTPSHMSEGS; i++) {
-	// Only grab the first two when running as root.
-	if (2 <= i || 0 == getuid()) {
-	    context->shmTime[i] = getShmTime(context, i);
-	}
-    }
-    memset(context->shmTimeInuse, 0, sizeof(context->shmTimeInuse));
-}
-
-/*@-unqualifiedtrans@*/
-static /*@null@*/ volatile struct shmTime *ntpshm_alloc(struct gps_context_t *context)
-/* allocate NTP SHM segment.  return its segment number, or -1 */
-{
-    int i;
-
-    for (i = 0; i < NTPSHMSEGS; i++)
-	if (context->shmTime[i] != NULL && !context->shmTimeInuse[i]) {
-	    context->shmTimeInuse[i] = true;
-
-	    /*
-	     * In case this segment gets sent to ntpd before an
-	     * ephemeris is available, the LEAP_NOTINSYNC value will
-	     * tell ntpd that this source is in a "clock alarm" state
-	     * and should be ignored.  The goal is to prevent ntpd
-	     * from declaring the GPS a falseticker before it gets
-	     * all its marbles together.
-	     */
-	    memset((void *)context->shmTime[i], 0, sizeof(struct shmTime));
-	    context->shmTime[i]->mode = 1;
-	    context->shmTime[i]->leap = LEAP_NOTINSYNC;
-	    context->shmTime[i]->precision = -1;	/* initially 0.5 sec */
-	    context->shmTime[i]->nsamples = 3;	/* stages of median filter */
-
-	    return context->shmTime[i];
-	}
-
-    return NULL;
-}
-/*@+unqualifiedtrans@*/
-
-static bool ntpshm_free(struct gps_context_t * context, volatile struct shmTime *s)
-/* free NTP SHM segment */
-{
-    int i;
-
-    for (i = 0; i < NTPSHMSEGS; i++)
-	if (s == context->shmTime[i]) {
-	    context->shmTimeInuse[i] = false;
-	    return true;
-	}
-
-    return false;
-}
-
-void ntpshm_session_init(struct gps_device_t *session)
-{
-    /*@-mustfreeonly@*/
-#ifdef NTPSHM_ENABLE
-    /* mark NTPD shared memory segments as unused */
-    session->shm_clock = NULL;
-#endif /* NTPSHM_ENABLE */
-#ifdef PPS_ENABLE
-    session->shm_pps = NULL;
-#endif	/* PPS_ENABLE */
-    /*@+mustfreeonly@*/
-}
-
-int ntpshm_put(struct gps_device_t *session, volatile struct shmTime *shmseg, struct timedelta_t *td)
+void ntp_write(volatile struct shmTime *shmseg, 
+	       struct timedelta_t *td, int precision, int leap_notify)
 /* put a received fix time into shared memory for NTP */
 {
-    char real_str[TIMESPEC_LEN];
-    char clock_str[TIMESPEC_LEN];
-    /*
-     * shmTime is volatile to try to prevent C compiler from reordering
-     * writes, or optimizing some 'dead code'.  but CPU cache may still
-     * write out of order if memory_barrier() is a no-op (our implementation 
-     * isn't portable).
-     */
-    volatile struct shmTime *shmTime = shmseg;
-    /* Any NMEA will be about -1 or -2. Garmin GPS-18/USB is around -6 or -7. */
-    int precision = -1; /* default precision */
-
-    if (shmTime == NULL) {
-	gpsd_report(&session->context->errout, LOG_RAW, "NTPD missing shm\n");
-	return 0;
-    }
-
-#ifdef PPS_ENABLE
-    /* ntpd sets -20 for PPS refclocks, thus -20 precision */
-    /* TODO: if PPS over USB 1.1, then precision = -10 */
-    if (shmTime == session->shm_pps)
-	precision = -20;
-#endif	/* PPS_ENABLE */
-
     /* we use the shmTime mode 1 protocol
      *
      * ntpd does this:
@@ -268,214 +40,24 @@ int ntpshm_put(struct gps_device_t *session, volatile struct shmTime *shmseg, st
      *
      */
 
-    shmTime->valid = 0;
-    shmTime->count++;
+    shmseg->valid = 0;
+    shmseg->count++;
     /* We need a memory barrier here to prevent write reordering by
      * the compiler or CPU cache */
     memory_barrier();
     /*@-type@*/ /* splint is confused about struct timespec */
-    shmTime->clockTimeStampSec = (time_t)td->real.tv_sec;
-    shmTime->clockTimeStampUSec = (int)(td->real.tv_nsec/1000);
-    shmTime->clockTimeStampNSec = (unsigned)td->real.tv_nsec;
-    shmTime->receiveTimeStampSec = (time_t)td->clock.tv_sec;
-    shmTime->receiveTimeStampUSec = (int)(td->clock.tv_nsec/1000);
-    shmTime->receiveTimeStampNSec = (unsigned)td->clock.tv_nsec;
+    shmseg->clockTimeStampSec = (time_t)td->real.tv_sec;
+    shmseg->clockTimeStampUSec = (int)(td->real.tv_nsec/1000);
+    shmseg->clockTimeStampNSec = (unsigned)td->real.tv_nsec;
+    shmseg->receiveTimeStampSec = (time_t)td->clock.tv_sec;
+    shmseg->receiveTimeStampUSec = (int)(td->clock.tv_nsec/1000);
+    shmseg->receiveTimeStampNSec = (unsigned)td->clock.tv_nsec;
     /*@+type@*/
-    shmTime->leap = session->context->leap_notify;
-    shmTime->precision = precision;
+    shmseg->leap = leap_notify;
+    shmseg->precision = precision;
     memory_barrier();
-    shmTime->count++;
-    shmTime->valid = 1;
-
-    /*@-type@*/ /* splint is confused about struct timespec */
-    timespec_str( &td->real, real_str, sizeof(real_str) );
-    timespec_str( &td->clock, clock_str, sizeof(clock_str) );
-    gpsd_report(&session->context->errout, LOG_RAW,
-		"NTP ntpshm_put(%s %s) %s @ %s\n",
-		session->gpsdata.dev.path,
-		(precision == -20) ? "pps" : "clock", 
-		real_str, clock_str);
-    /*@+type@*/
-
-    return 1;
-}
-
-#ifdef PPS_ENABLE
-#define SOCK_MAGIC 0x534f434b
-struct sock_sample {
-    struct timeval tv;
-    double offset;
-    int pulse;
-    int leap;
-    // cppcheck-suppress unusedStructMember
-    int _pad;
-    int magic;      /* must be SOCK_MAGIC */
-};
-
-/*@-mustfreefresh@*/
-static void init_hook(struct gps_device_t *session)
-/* for chrony SOCK interface, which allows nSec timekeeping */
-{
-    /* open the chrony socket */
-    char chrony_path[GPS_PATH_MAX];
-
-    session->chronyfd = -1;
-    if ( 0 == getuid() ) {
-	/* this case will fire on command-line devices;
-	 * they're opened before priv-dropping.  Matters because
-         * only root can use /var/run.
-	 */
-	(void)snprintf(chrony_path, sizeof (chrony_path),
-		"/var/run/chrony.%s.sock", basename(session->gpsdata.dev.path));
-    } else {
-	(void)snprintf(chrony_path, sizeof (chrony_path),
-		"/tmp/chrony.%s.sock", 	basename(session->gpsdata.dev.path));
-    }
-
-    if (access(chrony_path, F_OK) != 0) {
-	gpsd_report(&session->context->errout, LOG_PROG,
-		    "PPS chrony socket %s doesn't exist\n", chrony_path);
-    } else {
-	session->chronyfd = netlib_localsocket(chrony_path, SOCK_DGRAM);
-	if (session->chronyfd < 0)
-	    gpsd_report(&session->context->errout, LOG_PROG,
-		"PPS connect chrony socket failed: %s, error: %d, errno: %d/%s\n",
-		chrony_path, session->chronyfd, errno, strerror(errno));
-	else
-	    gpsd_report(&session->context->errout, LOG_RAW,
-			"PPS using chrony socket: %s\n", chrony_path);
-    }
-}
-/*@+mustfreefresh@*/
-
-
-/* td is the real time and clock time of the edge */
-/* offset is actual_ts - clock_ts */
-static void chrony_send(struct gps_device_t *session, struct timedelta_t *td)
-{
-    char real_str[TIMESPEC_LEN];
-    char clock_str[TIMESPEC_LEN];
-    struct timespec offset;
-    struct sock_sample sample;
-
-    /* chrony expects tv-sec since Jan 1970 */
-    sample.pulse = 0;
-    sample.leap = session->context->leap_notify;
-    sample.magic = SOCK_MAGIC;
-    /*@-compdef@*/
-    /*@-type@*//* splint is confused about struct timespec */
-    /* chronyd wants a timeval, not a timspec, not to worry, it is
-     * just the top of the second */
-    TSTOTV(&sample.tv, &td->clock);
-    /* calculate the offset as a timespec to not lose precision */
-    TS_SUB( &offset, &td->real, &td->clock);
-    /* if tv_sec greater than 2 then tv_nsec loses precision, but
-     * not a big deal as slewing will bbe required */
-    sample.offset = TSTONS( &offset );
-    /*@+compdef@*/
-    sample._pad = 0;
-    /*@+type@*/
-
-    /*@-type@*/ /* splint is confused about struct timespec */
-    timespec_str( &td->real, real_str, sizeof(real_str) );
-    timespec_str( &td->clock, clock_str, sizeof(clock_str) );
-    gpsd_report(&session->context->errout, LOG_RAW,
-		"PPS chrony_send %s @ %s Offset: %0.9f\n",
-		real_str, clock_str, sample.offset);
-    /*@+type@*/
-    (void)send(session->chronyfd, &sample, sizeof (sample), 0);
-}
-
-static void wrap_hook(struct gps_device_t *session)
-{
-    if (session->chronyfd != -1)
-	(void)close(session->chronyfd);
-}
-
-static /*@observer@*/ char *report_hook(struct gps_device_t *session,
-					struct timedelta_t *td)
-/* ship the time of a PPS event to ntpd and/or chrony */
-{
-    char *log1;
-
-    if (!session->ship_to_ntpd)
-	return "skipped ship_to_ntp=0";
-
-    /*
-     * Only listen to PPS after several consecutive fixes,
-     * otherwise time may be inaccurate.  (We know this is
-     * required on all Garmin and u-blox; safest to do it 
-     * for all cases as we have no other general way to know 
-     * if PPS is good.
-     *
-     * Not sure yet how to handle u-blox UBX_MODE_TMONLY
-     */
-    if (session->fixcnt <= PPS_MIN_FIXES)
-	return "no fix";
-
-    log1 = "accepted";
-    if ( 0 <= session->chronyfd ) {
-	log1 = "accepted chrony sock";
-	chrony_send(session, td);
-    }
-    if (session->shm_pps != NULL)
-	(void)ntpshm_put(session, session->shm_pps, td);
-
-    return log1;
-}
-#endif	/* PPS_ENABLE */
-
-/*@-mustfreeonly@*/
-void ntpshm_link_deactivate(struct gps_device_t *session)
-/* release ntpshm storage for a session */
-{
-    if (session->shm_clock != NULL) {
-	(void)ntpshm_free(session->context, session->shm_clock);
-	session->shm_clock = NULL;
-    }
-#if defined(PPS_ENABLE)
-    if (session->shm_pps != NULL) {
-	pps_thread_deactivate(session);
-	(void)ntpshm_free(session->context, session->shm_pps);
-	session->shm_pps = NULL;
-    }
-#endif	/* PPS_ENABLE */
-}
-/*@+mustfreeonly@*/
-
-/*@-mustfreeonly@*/
-void ntpshm_link_activate(struct gps_device_t *session)
-/* set up ntpshm storage for a session */
-{
-    /* don't talk to NTP when we're running inside the test harness */
-    if (session->sourcetype == source_pty)
-	return;
-
-    /* allocate a shared-memory segment for "NMEA" time data */
-    session->shm_clock = ntpshm_alloc(session->context);
-
-    if (session->shm_clock == NULL) {
-	gpsd_report(&session->context->errout, LOG_INF, 
-                    "NTPD ntpshm_alloc() failed\n");
-#if defined(PPS_ENABLE)
-    } else if (session->sourcetype == source_usb || session->sourcetype == source_rs232) {
-	/* We also have the 1pps capability, allocate a shared-memory segment
-	 * for the 1pps time data and launch a thread to capture the 1pps
-	 * transitions
-	 */
-	if ((session->shm_pps = ntpshm_alloc(session->context)) == NULL) {
-	    gpsd_report(&session->context->errout, LOG_INF, 
-                        "NTPD ntpshm_alloc(1) failed\n");
-	} else {
-	    init_hook(session);
-	    session->thread_report_hook = report_hook;
-	    session->thread_wrap_hook = wrap_hook;
-	    pps_thread_activate(session);
-	}
-#endif /* PPS_ENABLE */
-    }
+    shmseg->count++;
+    shmseg->valid = 1;
 }
-/*@+mustfreeonly@*/
 
-#endif /* NTPSHM_ENABLE */
 /* end */