From c8020f6c8eb617fd21b45483f0381f99ac985579 Mon Sep 17 00:00:00 2001
From: Colin S <3526918+cbs228@users.noreply.github.com>
Date: Thu, 6 Nov 2025 21:34:19 -0600
Subject: [PATCH] grib: fix NullPointerException for legacy NOAA RAP models
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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

6bef2fb9f5 (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
6bef2fb9f5, 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
---
 .../nc2/grib/grib2/table/Grib2Tables.java     |   4 +
 .../index/example_pds_8_quirks.grib2.gbx9     | Bin 0 -> 376 bytes
 .../java/ucar/nc2/grib/grib2/TestPds8.java    | 186 ++++++++++++++++++
 3 files changed, 190 insertions(+)
 create mode 100644 grib/src/test/data/index/example_pds_8_quirks.grib2.gbx9
 create mode 100644 grib/src/test/java/ucar/nc2/grib/grib2/TestPds8.java

diff --git a/grib/src/main/java/ucar/nc2/grib/grib2/table/Grib2Tables.java b/grib/src/main/java/ucar/nc2/grib/grib2/table/Grib2Tables.java
index 63afb2e4fe..2e2d46aae7 100644
--- a/grib/src/main/java/ucar/nc2/grib/grib2/table/Grib2Tables.java
+++ b/grib/src/main/java/ucar/nc2/grib/grib2/table/Grib2Tables.java
@@ -607,6 +607,10 @@ private TimeIntervalAndUnits getForecastTimeInterval(Grib2Pds.PdsInterval pdsInt
         range += ti.timeIncrement;
       }
     }
+    if (timeUnitIntv < 0) {
+      range = 0;
+      timeUnitIntv = 1; /* hours */
+    }
     return new TimeIntervalAndUnits(timeUnitIntv, range);
   }
 
diff --git a/grib/src/test/data/index/example_pds_8_quirks.grib2.gbx9 b/grib/src/test/data/index/example_pds_8_quirks.grib2.gbx9
new file mode 100644
index 0000000000000000000000000000000000000000..a501fe6c3eed35c3e983105e7b2c45a1331ec580
GIT binary patch
literal 376
zcmZ=S%1koy%u7kFV0+EPC6!u{m|KvO8efo79B&a{SejXsU96W5QX>>B6v)895Xj8H
zz!bO{$dY3N5~zUjFarZ)Aj6N`6}%sc3oICGD;)SwPjO&4w@w3$9Y7)=4AUl6&BY)v
zk6nU6Nt}aSfI)&ufl-6ei2Wfyy9iK;1%m^l0fUtlkZHvNBsdslnHVyG3`QV^5Dfo8
zOa}IcU=3h4BNJE}Ea9+$(L*C(^J313<BSRa88gl@7Mx|RU}#`u=wNgJTYim^Xv;b9
cTMls)vgPMEpq4-709pQ;qky$y9y`Qx0G-)H0RR91

literal 0
HcmV?d00001

diff --git a/grib/src/test/java/ucar/nc2/grib/grib2/TestPds8.java b/grib/src/test/java/ucar/nc2/grib/grib2/TestPds8.java
new file mode 100644
index 0000000000..6f08632ab7
--- /dev/null
+++ b/grib/src/test/java/ucar/nc2/grib/grib2/TestPds8.java
@@ -0,0 +1,186 @@
+package ucar.nc2.grib.grib2;
+
+import org.junit.Before;
+import org.junit.Test;
+import java.io.IOException;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import ucar.nc2.grib.coord.TimeCoordIntvDateValue;
+import ucar.nc2.grib.grib2.table.Grib2Tables;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+@RunWith(JUnit4.class)
+public class TestPds8 {
+  @Before
+  public void openTestFile() throws IOException {
+    String testfile = "../grib/src/test/data/index/example_pds_8_quirks.grib2.gbx9";
+
+    Grib2Index gi = new Grib2Index();
+    boolean success = gi.readIndex(testfile, -1);
+    assertTrue(success);
+    assertEquals(gi.getRecords().size(), 2);
+    quirky = gi.getRecords().get(0);
+    normal = gi.getRecords().get(1);
+  }
+
+  @Test
+  public void testForQuirkyRecord() {
+    Grib2Pds normal_pds = normal.getPDS();
+    Grib2Pds quirky_pds = quirky.getPDS();
+
+    assertEquals(normal_pds.getRawLength(), 58);
+    assertEquals(quirky_pds.getRawLength(), 58);
+
+    // byte 41 is numberOfTimeRange, which is generally 1 for
+    // this type of GRIB2 record. For the quirk, it is zero.
+    assertEquals(normal_pds.getOctet(42), 1);
+    assertEquals(quirky_pds.getOctet(42), 0);
+  }
+
+  @Test
+  public void testPds8ReadBasic() {
+    Grib2Pds pds8 = quirky.getPDS();
+    assertEquals(pds8.getTemplateNumber(), 8);
+    assertEquals(pds8.getParameterCategory(), 1);
+    assertEquals(pds8.getParameterNumber(), 29);
+    assertEquals(pds8.getGenProcessType(), 2);
+    assertEquals(pds8.getGenProcessId(), 105);
+    assertEquals(pds8.getBackProcessId(), 0);
+    assertEquals(pds8.getTimeUnit(), 1);
+    assertEquals(pds8.getForecastTime(), 0);
+  }
+
+  @Test
+  public void testPds8CanGetNormalTime() {
+    Grib2Tables tbl = Grib2Tables.factory(normal);
+    TimeCoordIntvDateValue tc = tbl.getForecastTimeInterval(normal);
+    // start and end times are the same
+    assertEquals(tc.getStart().getMillis(), tc.getEnd().getMillis());
+    assertEquals(tc.getStart().getMillis(), 1500508800000L);
+  }
+
+  @Test
+  public void testPds8CanStillGetQuirkyTime() {
+    Grib2Tables tbl = Grib2Tables.factory(quirky);
+    TimeCoordIntvDateValue tc = tbl.getForecastTimeInterval(quirky);
+    // start and end times are the same
+    assertEquals(tc.getStart().getMillis(), tc.getEnd().getMillis());
+    assertEquals(tc.getStart().getMillis(), 1500508800000L);
+  }
+
+  /*
+   * ====================== SECTION_4 ( length=58, padding=0 ) ======================
+   * 1-4 section4Length = 58
+   * 5 numberOfSection = 4
+   * 6-7 NV = 0
+   * 8-9 productDefinitionTemplateNumber = 8 [Average, accumulation, extreme values or other statistically processed
+   * values at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval
+   * (grib2/tables/2/4.0.table) ]
+   * 10 parameterCategory = 1 [Moisture (grib2/tables/2/4.1.0.table) ]
+   * 11 parameterNumber = 8 [Total precipitation (kg m-2) (grib2/tables/2/4.2.0.1.table) ]
+   * 12 typeOfGeneratingProcess = 2 [Forecast (grib2/tables/2/4.3.table) ]
+   * 13 backgroundProcess = 0
+   * 14 generatingProcessIdentifier = 105
+   * 15-16 hoursAfterDataCutoff = 0
+   * 17 minutesAfterDataCutoff = 0
+   * 18 indicatorOfUnitOfTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
+   * 19-22 forecastTime = 0
+   * 23 typeOfFirstFixedSurface = 1 [Ground or water surface (grib2/tables/2/4.5.table ,
+   * grib2/tables/local/kwbc/1/4.5.table) ]
+   * 24 scaleFactorOfFirstFixedSurface = 0
+   * 25-28 scaledValueOfFirstFixedSurface = 0
+   * 29 typeOfSecondFixedSurface = 255 [Missing (grib2/tables/2/4.5.table , grib2/tables/local/kwbc/1/4.5.table) ]
+   * 30 scaleFactorOfSecondFixedSurface = 0
+   * 31-34 scaledValueOfSecondFixedSurface = 0
+   * 35-36 yearOfEndOfOverallTimeInterval = 2017
+   * 37 monthOfEndOfOverallTimeInterval = 7
+   * 38 dayOfEndOfOverallTimeInterval = 20
+   * 39 hourOfEndOfOverallTimeInterval = 0
+   * 40 minuteOfEndOfOverallTimeInterval = 0
+   * 41 secondOfEndOfOverallTimeInterval = 0
+   * 42 numberOfTimeRange = 1
+   * 43-46 numberOfMissingInStatisticalProcess = 0
+   * 47 typeOfStatisticalProcessing = 1 [Accumulation (grib2/tables/2/4.10.table) ]
+   * 48 typeOfTimeIncrement = 2 [Successive times processed have same start time of forecast, forecast time is
+   * incremented (grib2/tables/2/4.11.table) ]
+   * 49 indicatorOfUnitForTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
+   * 50-53 lengthOfTimeRange = 0
+   * 54 indicatorOfUnitForTimeIncrement = 255 [Missing (grib2/tables/2/4.4.table) ]
+   * 55-58 timeIncrement = 0
+   */
+  private Grib2Record quirky;
+
+  /*
+   * ====================== SECTION_4 ( length=58, padding=0 ) ======================
+   * 1-4 section4Length = 58
+   * 5 numberOfSection = 4
+   * 6-7 NV = 0
+   * 8-9 productDefinitionTemplateNumber = 8 [Average, accumulation, extreme values or other statistically processed
+   * values at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval
+   * (grib2/tables/2/4.0.table) ]
+   * 10 parameterCategory = 1 [Moisture (grib2/tables/2/4.1.0.table) ]
+   * 11 parameterNumber = 8 [Total precipitation (kg m-2) (grib2/tables/2/4.2.0.1.table) ]
+   * 12 typeOfGeneratingProcess = 2 [Forecast (grib2/tables/2/4.3.table) ]
+   * 13 backgroundProcess = 0
+   * 14 generatingProcessIdentifier = 105
+   * 15-16 hoursAfterDataCutoff = 0
+   * 17 minutesAfterDataCutoff = 0
+   * 18 indicatorOfUnitOfTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
+   * 19-22 forecastTime = 0
+   * 23 typeOfFirstFixedSurface = 1 [Ground or water surface (grib2/tables/2/4.5.table ,
+   * grib2/tables/local/kwbc/1/4.5.table) ]
+   * 24 scaleFactorOfFirstFixedSurface = 0
+   * 25-28 scaledValueOfFirstFixedSurface = 0
+   * 29 typeOfSecondFixedSurface = 255 [Missing (grib2/tables/2/4.5.table , grib2/tables/local/kwbc/1/4.5.table) ]
+   * 30 scaleFactorOfSecondFixedSurface = 0
+   * 31-34 scaledValueOfSecondFixedSurface = 0
+   * 35-36 yearOfEndOfOverallTimeInterval = 2017
+   * 37 monthOfEndOfOverallTimeInterval = 7
+   * 38 dayOfEndOfOverallTimeInterval = 20
+   * 39 hourOfEndOfOverallTimeInterval = 0
+   * 40 minuteOfEndOfOverallTimeInterval = 0
+   * 41 secondOfEndOfOverallTimeInterval = 0
+   * 42 numberOfTimeRange = 1
+   * 43-46 numberOfMissingInStatisticalProcess = 0
+   * 47 typeOfStatisticalProcessing = 1 [Accumulation (grib2/tables/2/4.10.table) ]
+   * 48 typeOfTimeIncrement = 2 [Successive times processed have same start time of forecast, forecast time is
+   * incremented (grib2/tables/2/4.11.table) ]
+   * 49 indicatorOfUnitForTimeRange = 1 [Hour (grib2/tables/2/4.4.table) ]
+   * 50-53 lengthOfTimeRange = 0
+   * 54 indicatorOfUnitForTimeIncrement = 255 [Missing (grib2/tables/2/4.4.table) ]
+   * 55-58 timeIncrement = 0
+   */
+  private Grib2Record normal;
+}
+
+/*
+ * # steps to reproduce test data
+ *
+ * baseurl='www.ncei.noaa.gov/oa/prod-model/rapid-refresh/access/historical/analysis'
+ * curl -O "https://${baseurl}/201707/20170720/rap_130_20170720_0000_000.grb2"
+ *
+ * codes_split_file -1 rap_130_20170720_0000_000.grb2
+ *
+ * # quirky
+ * grib_dump -O -p section_4 \
+ * -w section4Length=58,numberOfTimeRange=0 \
+ * rap_130_20170720_0000_000.grb2_199
+ *
+ * # normal
+ * grib_dump -O -p section_4 \
+ * -w section4Length=58,numberOfTimeRange=1 \
+ * rap_130_20170720_0000_000.grb2_212
+ *
+ * cat \
+ * rap_130_20170720_0000_000.grb2_199 \
+ * rap_130_20170720_0000_000.grb2_212 \
+ * >example_pds_8_quirks.grib2
+ *
+ * # index
+ * java -jar netcdfAll-5.10.0-SNAPSHOT.jar \
+ * example_pds_8_quirks.grib2
+ *
+ * # generates example_pds_8_quirks.grib2.gbx9
+ */