Attempt to support /dev/pps devices.

For these devices:

1. The hunt loop is disabled.

2. When emitting a PPS report, all other (non-/dev/pps) devices are
checked for in-band time.  If no time is found the report is not
emitted. If time is ound its seconds field is incremented by 1 and it
is used

Every PPS from a device resets its online time, which should prevent
/dev/pps devices from timing out too often.

Not yet tested with a /dev/pps device.  All regression tests oass.

1 files changed, 6 insertions, 0 deletions

diff --git a/serial.c b/serial.c
index 282d009c..28f65b2e 100644
--- a/serial.c
+++ b/serial.c
@@ -54,6 +54,8 @@ static sourcetype_t gpsd_classify(const char *path)
     /* OS-independent check for ptys using Unix98 naming convention */
     else if (strncmp(path, "/dev/pts/", 9) == 0)
 	return source_pty;
+    else if (strncmp(path, "/dev/pps", 8) == 0)
+	return source_pps;
     else if (S_ISCHR(sb.st_mode)) {
 	sourcetype_t devtype = source_rs232;
 #ifdef __linux__
@@ -637,6 +639,10 @@ bool gpsd_next_hunt_setting(struct gps_device_t * session)
     if (isatty(session->gpsdata.gps_fd) == 0)
 	return false;
 
+    /* ...or if it's nominally a tty but delivers only PPS and no data */
+    if (session->sourcetype == source_pps)
+	return false;
+
     if (session->lexer.retry_counter++ >= SNIFF_RETRIES) {
 #ifdef FIXED_PORT_SPEED
 	return false;