From 3816992ad8285d40eb1f8ab1338c84fcc1e911b6 Mon Sep 17 00:00:00 2001
From: Harsh Sharma <harsh.sharma@multitech.com>
Date: Mon, 29 Nov 2021 15:21:41 -0600
Subject: Fixed gps not updating on internal concentrator time difference being
 larger than 1.5. Added getting leap seconds from gpspipe

---
 libloragw/inc/loragw_gps.h |  7 ++++++
 libloragw/src/loragw_gps.c | 53 ++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/libloragw/inc/loragw_gps.h b/libloragw/inc/loragw_gps.h
index 94d1d2a..0714974 100644
--- a/libloragw/inc/loragw_gps.h
+++ b/libloragw/inc/loragw_gps.h
@@ -116,6 +116,13 @@ int lgw_gps_enable(struct gps_data_t *gpsdata, struct fixsource_t *source);
 */
 int lgw_gps_disable(struct gps_data_t *gpsdata);
 
+/**
+@brief Get updated leap seconds
+
+@return success if the function was able to get the new leap seconds
+*/
+int lgw_get_leap_seconds();
+
 /**
 @brief Parse messages coming from the GPS system (or other GNSS)
 
diff --git a/libloragw/src/loragw_gps.c b/libloragw/src/loragw_gps.c
index 329827e..68a65ac 100644
--- a/libloragw/src/loragw_gps.c
+++ b/libloragw/src/loragw_gps.c
@@ -89,6 +89,9 @@ static bool gps_lock_ok = false;
 static char gps_mod = 'N'; /* GPS mode (N no fix, A autonomous, D differential) */
 static short gps_sat = 0; /* number of satellites used for fix */
 
+static uint32_t leap_seconds = 18; /* Adjustment that is applied to Coordinated Universal Time,
+ to accommodate the difference between precise time and imprecise observed solar time */
+
 /* -------------------------------------------------------------------------- */
 /* --- PRIVATE FUNCTIONS DECLARATION ---------------------------------------- */
 
@@ -255,6 +258,14 @@ int lgw_gps_enable(struct gps_data_t *gpsdata, struct fixsource_t *source) {
     unsigned int flags = WATCH_ENABLE| WATCH_JSON;
     gpsd_source_spec(NULL, source);
 
+    /* Update leap seconds from gpspipe */
+    if (lgw_get_leap_seconds() != LGW_GPS_SUCCESS) {
+        DEBUG_MSG("WARNING: Could not update leap seconds, using default value: %d\n", leap_seconds);
+    } else {
+        DEBUG_MSG("Updated leap seconds to: %d\n", leap_seconds);
+    }
+
+
     if (gps_open(source->server, source->port, gpsdata) != 0) {
         DEBUG_MSG("gpspipe: could not connect to gpsd %s:%s, %s(%d)\n",
               source->server, source->port, gps_errstr(errno), errno);
@@ -293,6 +304,40 @@ int lgw_gps_disable(struct gps_data_t *gpsdata) {
 
 /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
 
+int lgw_get_leap_seconds() {
+
+    FILE *fp;
+    char path[1035];
+    uint32_t result = 0;
+    /* Open the command for reading. */
+    fp = popen("/usr/bin/gpspipe -w -n 4 | grep leapsec | jsparser --path leapseconds", "r");
+    if (fp == NULL) {
+        DEBUG_MSG("ERROR: Failed to run command\n" );
+        return LGW_GPS_ERROR;
+    }
+
+
+    if (fgets(path, sizeof(path), fp) == NULL) {
+        DEBUG_MSG("ERROR: Unable to get leap seconds\n");
+        pclose(fp);
+        return LGW_GPS_ERROR;
+    }
+
+    pclose(fp);
+
+    result = atoi(path);
+
+    if (result == 0) {
+        DEBUG_MSG("ERROR: Invalid leap second value\n");
+        return LGW_GPS_ERROR;
+    } else {
+        leap_seconds = result;
+        return LGW_GPS_SUCCESS;
+    }
+}
+
+/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
+
 enum gps_msg lgw_parse_ubx(const char *serial_buff, size_t buff_size, size_t *msg_size) {
     bool valid = 0;    /* iTOW, fTOW and week validity */
     unsigned int payload_length;
@@ -599,11 +644,7 @@ int lgw_gps_sync(struct tref *ref, uint32_t count_us, struct timespec gps_time)
            slope = 0.0;
         }
 
-        if (cnt_diff > 1.5) {
-           update = true;
-        }
-
-        update = (slope >= MINUS_10PPM && slope <= PLUS_10PPM);
+        update = ((slope >= MINUS_10PPM && slope <= PLUS_10PPM) || cnt_diff > 1.5);
 
         if (!calibrating && utc_diff < 10.0) {
             return LGW_GPS_ERROR;
@@ -626,7 +667,7 @@ int lgw_gps_sync(struct tref *ref, uint32_t count_us, struct timespec gps_time)
         ref->utc.tv_sec = gps_time.tv_sec - timezone;
         ref->utc.tv_nsec = gps_time.tv_nsec;
         // ref->gps.tv_sec = gps_time.tv_sec;
-        ref->gps.tv_sec = gps_time.tv_sec + 18 - 315964800;
+        ref->gps.tv_sec = gps_time.tv_sec + leap_seconds - 315964800;
         ref->gps.tv_nsec = gps_time.tv_nsec;
         ref->xtal_err = slope;
         return LGW_GPS_SUCCESS;
-- 
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