gpsutils: fix rounding error in unix_to_iso8601(), add/fix tests.

1541766896.999512 became "2018-11-09T12:34:56.000Z".  Which sould
be :57.  The fractional seconds got rounded up, but the seconds did
not get incremented to match.

Added regression tests for unix_to_iso8601().

Reported by Peter Liu <greendice@me.com>.

3 files changed, 59 insertions, 15 deletions

diff --git a/gpsutils.c b/gpsutils.c
index 3070ca59..4d276626 100644
--- a/gpsutils.c
+++ b/gpsutils.c
@@ -499,11 +499,9 @@ timestamp_t iso8601_to_unix(char *isotime)
 #endif /* __clang_analyzer__ */
 }
 
-/* *INDENT-OFF* */
-char *unix_to_iso8601(timestamp_t fixtime,
-				     char isotime[], size_t len)
 /* Unix UTC time to ISO8601, no timezone adjustment */
 /* example: 2007-12-11T23:38:51.033Z */
+char *unix_to_iso8601(timestamp_t fixtime, char isotime[], size_t len)
 {
     struct tm when;
     double integral, fractional;
@@ -512,6 +510,13 @@ char *unix_to_iso8601(timestamp_t fixtime,
     char fractstr[10];
 
     fractional = modf(fixtime, &integral);
+    /* snprintf rounding of %3f can get ugly, so pre-round */
+    if ( 0.999499999 < fractional) {
+        /* round up */
+        integral++;
+        /* give the fraction a nudge to ensure rounding */
+        fractional += 0.0005;
+    }
     intfixtime = (time_t) integral;
 #ifdef HAVE_GMTIME_R
     (void)gmtime_r(&intfixtime, &when);
@@ -531,7 +536,6 @@ char *unix_to_iso8601(timestamp_t fixtime,
     (void)snprintf(isotime, len, "%s%sZ",timestr, strchr(fractstr,'.'));
     return isotime;
 }
-/* *INDENT-ON* */
 
 #define Deg2Rad(n)	((n) * DEG_2_RAD)
 
diff --git a/test/daemon/superstar2.log.chk b/test/daemon/superstar2.log.chk
index bd6bd50f..7da40722 100644
--- a/test/daemon/superstar2.log.chk
+++ b/test/daemon/superstar2.log.chk
@@ -7,7 +7,7 @@ $GPGGA,055054,5333.7867,N,11326.3743,W,1,05,3.10,631.80,M,,,*29
 $GPRMC,055054,A,5333.7867,N,11326.3743,W,0.0000,0.000,040709,,*38

 $GPGSA,A,3,29,11,1,3,28,,,,,,,,5.2,3.1,3.3*34

 $GPGBS,055054,31.47,M,35.54,M,75.90,M*02

-{"class":"TPV","mode":3,"time":"2009-07-04T05:50:54.000Z","ept":0.005,"lat":53.563112132,"lon":-113.439571599,"alt":631.801,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000}

+{"class":"TPV","mode":3,"time":"2009-07-04T05:50:55.000Z","ept":0.005,"lat":53.563112132,"lon":-113.439571599,"alt":631.801,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000}

 $GPGSV,3,1,12,01,76,110,50,11,67,212,50,29,55,030,39,03,41,063,36*7C

 $GPGSV,3,2,12,28,22,023,37,09,18,156,00,30,15,073,00,23,14,223,00*72

 $GPGSV,3,3,12,22,06,031,00,08,01,208,00,137,28,172,00,134,26,203,00*75

@@ -17,7 +17,7 @@ $GPGGA,055055,5333.7867,N,11326.3743,W,1,05,3.10,631.87,M,,,*2F
 $GPRMC,055055,A,5333.7867,N,11326.3743,W,0.0000,0.000,040709,,*39

 $GPGSA,A,3,1,11,29,3,28,,,,,,,,5.2,3.1,3.3*34

 $GPGBS,055055,31.47,M,35.54,M,75.90,M*03

-{"class":"TPV","mode":3,"time":"2009-07-04T05:50:55.000Z","ept":0.005,"lat":53.563111922,"lon":-113.439572138,"alt":631.867,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

+{"class":"TPV","mode":3,"time":"2009-07-04T05:50:56.000Z","ept":0.005,"lat":53.563111922,"lon":-113.439572138,"alt":631.867,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

 $GPGSV,3,1,12,01,76,110,50,11,67,212,50,29,55,030,39,03,41,063,36*7C

 $GPGSV,3,2,12,28,22,023,37,09,18,156,00,30,15,073,00,23,14,223,00*72

 $GPGSV,3,3,12,22,06,031,00,08,01,208,00,137,28,172,00,134,26,203,00*75

@@ -27,7 +27,7 @@ $GPGGA,055056,5333.7867,N,11326.3744,W,1,05,3.10,631.94,M,,,*29
 $GPRMC,055056,A,5333.7867,N,11326.3744,W,0.0000,0.000,040709,,*3D

 $GPGSA,A,3,1,11,29,3,28,,,,,,,,5.2,3.1,3.3*34

 $GPGBS,055056,31.47,M,35.54,M,75.90,M*00

-{"class":"TPV","mode":3,"time":"2009-07-04T05:50:56.000Z","ept":0.005,"lat":53.563111644,"lon":-113.439572583,"alt":631.943,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

+{"class":"TPV","mode":3,"time":"2009-07-04T05:50:57.000Z","ept":0.005,"lat":53.563111644,"lon":-113.439572583,"alt":631.943,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

 $GPGSV,3,1,12,01,76,110,50,11,67,212,50,29,55,030,40,03,41,063,36*72

 $GPGSV,3,2,12,28,22,023,37,09,18,156,00,30,15,073,00,23,14,223,00*72

 $GPGSV,3,3,12,22,06,031,00,08,01,208,00,137,28,172,00,134,26,203,00*75

@@ -37,7 +37,7 @@ $GPGGA,055057,5333.7867,N,11326.3744,W,1,05,3.10,632.00,M,,,*26
 $GPRMC,055057,A,5333.7867,N,11326.3744,W,0.0000,0.000,040709,,*3C

 $GPGSA,A,3,1,11,29,3,28,,,,,,,,5.2,3.1,3.3*34

 $GPGBS,055057,31.47,M,35.54,M,75.90,M*01

-{"class":"TPV","mode":3,"time":"2009-07-04T05:50:57.000Z","ept":0.005,"lat":53.563111100,"lon":-113.439573094,"alt":632.002,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

+{"class":"TPV","mode":3,"time":"2009-07-04T05:50:58.000Z","ept":0.005,"lat":53.563111100,"lon":-113.439573094,"alt":632.002,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

 $GPGSV,3,1,12,01,76,110,50,11,67,212,50,29,55,030,40,03,41,063,36*72

 $GPGSV,3,2,12,28,22,023,36,09,18,156,00,30,15,073,00,23,14,223,00*73

 $GPGSV,3,3,12,22,06,031,00,08,01,208,00,137,28,172,00,134,26,203,00*75

@@ -47,7 +47,7 @@ $GPGGA,055058,5333.7866,N,11326.3744,W,1,05,3.10,632.09,M,,,*21
 $GPRMC,055058,A,5333.7866,N,11326.3744,W,0.0000,0.000,040709,,*32

 $GPGSA,A,3,1,11,29,3,28,,,,,,,,5.2,3.1,3.3*34

 $GPGBS,055058,31.47,M,35.54,M,75.90,M*0E

-{"class":"TPV","mode":3,"time":"2009-07-04T05:50:58.000Z","ept":0.005,"lat":53.563110659,"lon":-113.439573808,"alt":632.093,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

+{"class":"TPV","mode":3,"time":"2009-07-04T05:50:59.000Z","ept":0.005,"lat":53.563110659,"lon":-113.439573808,"alt":632.093,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

 $GPGSV,3,1,12,01,76,110,50,11,67,212,50,29,55,030,39,03,41,063,36*7C

 $GPGSV,3,2,12,28,22,023,37,09,18,156,00,30,15,073,00,23,14,223,00*72

 $GPGSV,3,3,12,22,06,031,00,08,01,208,00,137,28,172,00,134,26,203,00*75

@@ -57,7 +57,7 @@ $GPGGA,055059,5333.7866,N,11326.3745,W,1,05,3.10,632.20,M,,,*2A
 $GPRMC,055059,A,5333.7866,N,11326.3745,W,0.0000,0.000,040709,,*32

 $GPGSA,A,3,1,11,29,3,28,,,,,,,,5.2,3.1,3.3*34

 $GPGBS,055059,31.47,M,35.54,M,75.90,M*0F

-{"class":"TPV","mode":3,"time":"2009-07-04T05:50:59.000Z","ept":0.005,"lat":53.563110309,"lon":-113.439574638,"alt":632.204,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

+{"class":"TPV","mode":3,"time":"2009-07-04T05:51:00.000Z","ept":0.005,"lat":53.563110309,"lon":-113.439574638,"alt":632.204,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

 $GPGSV,3,1,12,01,76,110,50,11,67,212,50,29,55,030,40,03,41,063,36*72

 $GPGSV,3,2,12,28,22,023,36,09,18,156,00,30,15,073,00,23,14,223,00*73

 $GPGSV,3,3,12,22,06,031,00,08,01,208,00,137,28,172,00,134,26,203,00*75

@@ -67,7 +67,7 @@ $GPGGA,055100,5333.7866,N,11326.3745,W,1,05,3.10,632.27,M,,,*20
 $GPRMC,055100,A,5333.7866,N,11326.3745,W,0.0000,0.000,040709,,*3F

 $GPGSA,A,3,1,11,29,3,28,,,,,,,,5.2,3.1,3.3*34

 $GPGBS,055100,31.47,M,35.54,M,75.90,M*02

-{"class":"TPV","mode":3,"time":"2009-07-04T05:51:00.000Z","ept":0.005,"lat":53.563109836,"lon":-113.439575270,"alt":632.266,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

+{"class":"TPV","mode":3,"time":"2009-07-04T05:51:01.000Z","ept":0.005,"lat":53.563109836,"lon":-113.439575270,"alt":632.266,"epx":31.470,"epy":35.543,"epv":75.900,"track":0.0000,"speed":0.000,"climb":0.000,"eps":71.09,"epc":151.80}

 $GPGSV,3,1,12,01,76,110,50,11,67,212,50,29,55,030,40,03,41,063,36*72

 $GPGSV,3,2,12,28,22,023,36,09,18,156,00,30,15,073,00,23,14,223,00*73

 $GPGSV,3,3,12,22,06,031,00,08,01,208,00,137,28,172,00,134,26,203,00*75

diff --git a/test_mktime.c b/test_mktime.c
index 59890532..cfe0a53e 100644
--- a/test_mktime.c
+++ b/test_mktime.c
@@ -1,10 +1,13 @@
 /*
+ * tests for mktime() and unix_to_iso8601().
+ *
  * This file is Copyright (c) 2010 by the GPSD project
  * SPDX-License-Identifier: BSD-2-clause
  */
-#include <stdlib.h>
-#include <stdio.h>
 #include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <time.h>
 
 #include "gps.h"
@@ -82,6 +85,30 @@ static struct
 };
 
 
+/* tests for unit_to_iso8601() */
+static struct
+{
+    timestamp_t unixtime;   /* unix time */
+    char *iso8601;        /* iso8601 result */
+} tests1[] = {
+    /* time zero */
+    {(timestamp_t)0, "1970-01-01T00:00:00.000Z"},
+
+    /* before/after leap second end of 2008, notice no :60! */
+    {(timestamp_t)1230767999.01, "2008-12-31T23:59:59.010Z"},
+    {(timestamp_t)1230768000.02, "2009-01-01T00:00:00.020Z"},
+
+    /* test for rounding at %.3f */
+    {(timestamp_t)1541766896.999412, "2018-11-09T12:34:56.999Z"},
+    {(timestamp_t)1541766896.999499, "2018-11-09T12:34:56.999Z"},
+    {(timestamp_t)1541766896.999500, "2018-11-09T12:34:57.000Z"},
+    {(timestamp_t)1541766896.999501, "2018-11-09T12:34:57.000Z"},
+
+    /* the end of time: 2038 */
+    {(timestamp_t)2147483647.123456, "2038-01-19T03:14:07.123Z"},
+    {(timestamp_t)2147483648.123456, "2038-01-19T03:14:08.123Z"},
+};
+
 int main(int argc UNUSED, char *argv[] UNUSED)
 {
     int i;
@@ -90,17 +117,30 @@ int main(int argc UNUSED, char *argv[] UNUSED)
 
     (void)setenv("TZ", "GMT", 1);
 
+
     for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) {
 	time_t ts = mktime(&tests[i].t);
 	if (ts != tests[i].result) {
 	    failed = true;
 	    (void)strftime(tbuf, sizeof(tbuf), "%F %T", &tests[i].t);
-	    (void)printf("test %2d failed. "
-			 "Time returned from: %s should be %lu (but was: %lu)\n",
+	    (void)printf("test_mktime: test %2d failed.\n"
+			 "  Time returned from: %s should be %lu "
+                         " (but was: %lu)\n",
 			 i, tbuf, (unsigned long)tests[i].result,
 			 (unsigned long)ts);
 	}
     }
+
+    /* test unix_to_iso8601() */
+    for (i = 0; i < (int)(sizeof(tests1) / sizeof(tests1[0])); i++) {
+	unix_to_iso8601(tests1[i].unixtime, tbuf, sizeof(tbuf));
+        if (0 != strcmp(tests1[i].iso8601, tbuf)) {
+	    failed = true;
+	    (void)printf("test_mktime: test1 %f failed.\n  Got %s, s/b %s\n",
+                         tests1[i].unixtime, tbuf, tests1[i].iso8601);
+        }
+    }
+
     return (int)failed;
 }