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grib: fix NullPointerException for legacy NOAA RAP models
Attempting to load a [legacy] NOAA Rapid Refresh GRIB2 file fails with a NullPointerException. java -jar netcdfAll-5.10.0-SNAPSHOT.jar \ rap_130_20170720_0000_000.grb2 This file loads correctly in netcdf-java 4.6, but it has a quirk: it contains at least one PDS that does not define a time range. grib_dump -O -p section_4 \ -w section4Length=58,numberOfTimeRange=0 \ rap_130_20170720_0000_000.grb2 6bef2fb (Fix for issue #606, version 5., 2021-02-26) corrects time calculations for GRIB2 PDS which have incompatible units for **time intervals** and related time quantities. The above patch introduces a `TimeIntervalAndUnits` parser for PDS times. If a PDS does not define *any* time intervals, the previous version of Grib2Tables.getForecastTimeInterval(Grib2Record) returns a duration of zero—i.e., no elapsed time. This is likely the correct interpretation if no time intervals are present. After 6bef2fb, this method raises a NullPointerException instead. This is because the inner function Grib2Tables.getForecastTimeInterval(Grib2Pds.PdsInterval) returns an invalid `TimeIntervalAndUnits` when it ought to return a zero duration instead. The calling functions do not treat this data type as fallible and may use it in conversions that return null. If the PDS does not contain any time intervals, return a "zero hour" duration instead. This restores the previous behavior. * In legacy and modern RAP models, PDS which *do* define time intervals define them as zero. The interpretation of the "quirky" PDS remains consistent with its brethren. * This quirk is not present in more [recent] RAP model runs, so this bug is unlikely to affect current RAP data. [legacy]: https://www.ncei.noaa.gov/oa/prod-model/rapid-refresh/access/historical/analysis/201707/20170720/rap_130_20170720_0000_000.grb2 [recent]: https://www.ncei.noaa.gov/oa/prod-model/rapid-refresh/access/rap-130-13km/analysis/202504/20250401/rap_130_20250401_0000_000.grb2
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‎grib/src/main/java/ucar/nc2/grib/grib2/table/Grib2Tables.java‎

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@@ -607,6 +607,10 @@ private TimeIntervalAndUnits getForecastTimeInterval(Grib2Pds.PdsInterval pdsInt
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range += ti.timeIncrement;
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}
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}
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if (timeUnitIntv < 0) {
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range = 0;
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timeUnitIntv = 1; /* hours */
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}
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return new TimeIntervalAndUnits(timeUnitIntv, range);
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}
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‎grib/src/test/data/index/example_pds_8_quirks.grib2.gbx9‎

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‎grib/src/test/java/ucar/nc2/grib/grib2/TestPds8.java‎

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package ucar.nc2.grib.grib2;
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import org.junit.Before;
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import org.junit.Test;
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import java.io.IOException;
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import org.junit.runner.RunWith;
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import org.junit.runners.JUnit4;
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import ucar.nc2.grib.coord.TimeCoordIntvDateValue;
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import ucar.nc2.grib.grib2.table.Grib2Tables;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertTrue;
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@RunWith(JUnit4.class)
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public class TestPds8 {
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@Before
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public void openTestFile() throws IOException {
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String testfile = "../grib/src/test/data/index/example_pds_8_quirks.grib2.gbx9";
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Grib2Index gi = new Grib2Index();
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boolean success = gi.readIndex(testfile, -1);
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assertTrue(success);
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assertEquals(gi.getRecords().size(), 2);
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quirky = gi.getRecords().get(0);
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normal = gi.getRecords().get(1);
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}
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@Test
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public void testForQuirkyRecord() {
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Grib2Pds normal_pds = normal.getPDS();
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Grib2Pds quirky_pds = quirky.getPDS();
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assertEquals(normal_pds.getRawLength(), 58);
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assertEquals(quirky_pds.getRawLength(), 58);
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// byte 41 is numberOfTimeRange, which is generally 1 for
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// this type of GRIB2 record. For the quirk, it is zero.
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assertEquals(normal_pds.getOctet(42), 1);
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assertEquals(quirky_pds.getOctet(42), 0);
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}
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@Test
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public void testPds8ReadBasic() {
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Grib2Pds pds8 = quirky.getPDS();
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assertEquals(pds8.getTemplateNumber(), 8);
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assertEquals(pds8.getParameterCategory(), 1);
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assertEquals(pds8.getParameterNumber(), 29);
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assertEquals(pds8.getGenProcessType(), 2);
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assertEquals(pds8.getGenProcessId(), 105);
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assertEquals(pds8.getBackProcessId(), 0);
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assertEquals(pds8.getTimeUnit(), 1);
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assertEquals(pds8.getForecastTime(), 0);
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}
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@Test
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public void testPds8CanGetNormalTime() {
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Grib2Tables tbl = Grib2Tables.factory(normal);
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TimeCoordIntvDateValue tc = tbl.getForecastTimeInterval(normal);
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// start and end times are the same
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assertEquals(tc.getStart().getMillis(), tc.getEnd().getMillis());
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assertEquals(tc.getStart().getMillis(), 1500508800000L);
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}
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@Test
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public void testPds8CanStillGetQuirkyTime() {
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Grib2Tables tbl = Grib2Tables.factory(quirky);
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TimeCoordIntvDateValue tc = tbl.getForecastTimeInterval(quirky);
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// start and end times are the same
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assertEquals(tc.getStart().getMillis(), tc.getEnd().getMillis());
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assertEquals(tc.getStart().getMillis(), 1500508800000L);
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}
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/*
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* ====================== SECTION_4 ( length=58, padding=0 ) ======================
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* 1-4 section4Length = 58
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* 5 numberOfSection = 4
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* 6-7 NV = 0
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* 8-9 productDefinitionTemplateNumber = 8 [Average, accumulation, extreme values or other statistically processed
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* values at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval
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* (grib2/tables/2/4.0.table) ]
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* 10 parameterCategory = 1 [Moisture (grib2/tables/2/4.1.0.table) ]
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* 11 parameterNumber = 8 [Total precipitation (kg m-2) (grib2/tables/2/4.2.0.1.table) ]
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* 12 typeOfGeneratingProcess = 2 [Forecast (grib2/tables/2/4.3.table) ]
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* 13 backgroundProcess = 0
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* 14 generatingProcessIdentifier = 105
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* 15-16 hoursAfterDataCutoff = 0
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* 17 minutesAfterDataCutoff = 0
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* 18 indicatorOfUnitOfTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
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* 19-22 forecastTime = 0
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* 23 typeOfFirstFixedSurface = 1 [Ground or water surface (grib2/tables/2/4.5.table ,
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* grib2/tables/local/kwbc/1/4.5.table) ]
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* 24 scaleFactorOfFirstFixedSurface = 0
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* 25-28 scaledValueOfFirstFixedSurface = 0
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* 29 typeOfSecondFixedSurface = 255 [Missing (grib2/tables/2/4.5.table , grib2/tables/local/kwbc/1/4.5.table) ]
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* 30 scaleFactorOfSecondFixedSurface = 0
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* 31-34 scaledValueOfSecondFixedSurface = 0
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* 35-36 yearOfEndOfOverallTimeInterval = 2017
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* 37 monthOfEndOfOverallTimeInterval = 7
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* 38 dayOfEndOfOverallTimeInterval = 20
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* 39 hourOfEndOfOverallTimeInterval = 0
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* 40 minuteOfEndOfOverallTimeInterval = 0
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* 41 secondOfEndOfOverallTimeInterval = 0
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* 42 numberOfTimeRange = 1
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* 43-46 numberOfMissingInStatisticalProcess = 0
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* 47 typeOfStatisticalProcessing = 1 [Accumulation (grib2/tables/2/4.10.table) ]
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* 48 typeOfTimeIncrement = 2 [Successive times processed have same start time of forecast, forecast time is
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* incremented (grib2/tables/2/4.11.table) ]
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* 49 indicatorOfUnitForTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
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* 50-53 lengthOfTimeRange = 0
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* 54 indicatorOfUnitForTimeIncrement = 255 [Missing (grib2/tables/2/4.4.table) ]
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* 55-58 timeIncrement = 0
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*/
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private Grib2Record quirky;
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/*
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* ====================== SECTION_4 ( length=58, padding=0 ) ======================
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* 1-4 section4Length = 58
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* 5 numberOfSection = 4
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* 6-7 NV = 0
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* 8-9 productDefinitionTemplateNumber = 8 [Average, accumulation, extreme values or other statistically processed
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* values at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval
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* (grib2/tables/2/4.0.table) ]
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* 10 parameterCategory = 1 [Moisture (grib2/tables/2/4.1.0.table) ]
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* 11 parameterNumber = 8 [Total precipitation (kg m-2) (grib2/tables/2/4.2.0.1.table) ]
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* 12 typeOfGeneratingProcess = 2 [Forecast (grib2/tables/2/4.3.table) ]
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* 13 backgroundProcess = 0
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* 14 generatingProcessIdentifier = 105
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* 15-16 hoursAfterDataCutoff = 0
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* 17 minutesAfterDataCutoff = 0
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* 18 indicatorOfUnitOfTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
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* 19-22 forecastTime = 0
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* 23 typeOfFirstFixedSurface = 1 [Ground or water surface (grib2/tables/2/4.5.table ,
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* grib2/tables/local/kwbc/1/4.5.table) ]
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* 24 scaleFactorOfFirstFixedSurface = 0
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* 25-28 scaledValueOfFirstFixedSurface = 0
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* 29 typeOfSecondFixedSurface = 255 [Missing (grib2/tables/2/4.5.table , grib2/tables/local/kwbc/1/4.5.table) ]
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* 30 scaleFactorOfSecondFixedSurface = 0
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* 31-34 scaledValueOfSecondFixedSurface = 0
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* 35-36 yearOfEndOfOverallTimeInterval = 2017
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* 37 monthOfEndOfOverallTimeInterval = 7
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* 38 dayOfEndOfOverallTimeInterval = 20
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* 39 hourOfEndOfOverallTimeInterval = 0
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* 40 minuteOfEndOfOverallTimeInterval = 0
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* 41 secondOfEndOfOverallTimeInterval = 0
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* 42 numberOfTimeRange = 1
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* 43-46 numberOfMissingInStatisticalProcess = 0
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* 47 typeOfStatisticalProcessing = 1 [Accumulation (grib2/tables/2/4.10.table) ]
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* 48 typeOfTimeIncrement = 2 [Successive times processed have same start time of forecast, forecast time is
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* incremented (grib2/tables/2/4.11.table) ]
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* 49 indicatorOfUnitForTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
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* 50-53 lengthOfTimeRange = 0
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* 54 indicatorOfUnitForTimeIncrement = 255 [Missing (grib2/tables/2/4.4.table) ]
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* 55-58 timeIncrement = 0
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*/
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private Grib2Record normal;
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}
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/*
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* # steps to reproduce test data
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*
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* baseurl='www.ncei.noaa.gov/oa/prod-model/rapid-refresh/access/historical/analysis'
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* curl -O "https://${baseurl}/201707/20170720/rap_130_20170720_0000_000.grb2"
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*
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* codes_split_file -1 rap_130_20170720_0000_000.grb2
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*
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* # quirky
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* grib_dump -O -p section_4 \
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* -w section4Length=58,numberOfTimeRange=0 \
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* rap_130_20170720_0000_000.grb2_199
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*
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* # normal
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* grib_dump -O -p section_4 \
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* -w section4Length=58,numberOfTimeRange=1 \
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* rap_130_20170720_0000_000.grb2_212
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*
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* cat \
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* rap_130_20170720_0000_000.grb2_199 \
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* rap_130_20170720_0000_000.grb2_212 \
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* >example_pds_8_quirks.grib2
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*
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* # index
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* java -jar netcdfAll-5.10.0-SNAPSHOT.jar \
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* example_pds_8_quirks.grib2
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*
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* # generates example_pds_8_quirks.grib2.gbx9
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*/

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