Crash when there is just y-part of the vector dataset in gdal (#80)

fix #79 Crash when there is just y-part of the vector dataset in gdal

mdal/frmts/mdal_gdal.cpp

@@ -259,6 +259,60 @@ void MDAL::DriverGdal::parseRasterBands( const MDAL::GdalDataset *cfGDALDataset
   }
 }
 
+void MDAL::DriverGdal::fixRasterBands()
+{
+  // go through all bands and find out if both x and y dataset are valid
+  // if such pair if found, make the group scalar by removal of null band pointer
+  // this can happen is parseBandInfo() returns false-positive in vector detection
+  for ( data_hash::iterator band = mBands.begin(); band != mBands.end(); band++ )
+  {
+    if ( band->second.empty() )
+      continue;
+
+    // scalars are always ok
+    bool is_scalar = ( band->second.begin()->second.size() == 1 );
+    if ( is_scalar )
+      continue;
+
+    // check if we have some null bands
+    int needs_fix = false;
+    for ( timestep_map::const_iterator time_step = band->second.begin(); time_step != band->second.end(); time_step++ )
+    {
+      std::vector<GDALRasterBandH> raster_bands = time_step->second;
+
+      if ( !raster_bands[0] )
+      {
+        needs_fix = true;
+        break;
+      }
+      if ( !raster_bands[1] )
+      {
+        needs_fix = true;
+        break;
+      }
+    }
+
+    // convert this vector to scalar
+    if ( needs_fix )
+    {
+      for ( timestep_map::iterator time_step = band->second.begin(); time_step != band->second.end(); time_step++ )
+      {
+        std::vector<GDALRasterBandH> &raster_bands = time_step->second;
+
+        if ( !raster_bands[0] )
+        {
+          raster_bands[0] = raster_bands[1];
+        }
+        // get rid of y-coord
+        raster_bands.resize( 1 );
+
+        // not we should have only 1 band and valid
+        assert( raster_bands[0] );
+      }
+    }
+  }
+}
+
 void MDAL::DriverGdal::addDataToOutput( GDALRasterBandH raster_band, std::shared_ptr<MemoryDataset> tos, bool is_vector, bool is_x )
 {
   assert( raster_band );
@@ -552,6 +606,12 @@ std::unique_ptr<MDAL::Mesh> MDAL::DriverGdal::load( const std::string &fileName,
       }
     }
 
+    // Fix consistency of groups
+    // It can happen that we thought that the
+    // group is vector based on name, but it could be just coicidence
+    // or clash in naming
+    fixRasterBands();
+
     // Create MDAL datasets
     addDatasetGroups();
   }

mdal/frmts/mdal_gdal.hpp

@@ -94,6 +94,7 @@ namespace MDAL
       void addDatasetGroups();
       void createMesh();
       void parseRasterBands( const GdalDataset *cfGDALDataset );
+      void fixRasterBands();
 
       std::string mFileName;
       const std::string mGdalDriverName; /* GDAL driver name */

scripts/ci/windows/install.bash

@@ -3,5 +3,5 @@ set -e
 
 echo "Installing qgis with choco"
 
-choco install qgis --version 3.4.2 -y --verbose
+choco install qgis --version 3.4.3 -y --verbose
 mv  "C:/Program Files/QGIS 3.4" "C:/OSGeo4W64"

tests/test_gdal_grib.cpp

@@ -98,6 +98,49 @@ TEST( MeshGdalGribTest, VectorFile )
   MDAL_CloseMesh( m );
 }
 
+TEST( MeshGdalGribTest, ScalarFileWithUComponent )
+{
+  // https://github.com/lutraconsulting/MDAL/issues/79
+  std::string path = test_file( "/grib/wind_only_u_component.grib" );
+  MeshH m = MDAL_LoadMesh( path.c_str() );
+  ASSERT_NE( m, nullptr );
+  MDAL_Status s = MDAL_LastStatus();
+  EXPECT_EQ( MDAL_Status::None, s );
+  ASSERT_EQ( 1, MDAL_M_datasetGroupCount( m ) );
+
+  DatasetGroupH g = MDAL_M_datasetGroup( m, 0 );
+  ASSERT_NE( g, nullptr );
+
+  int meta_count = MDAL_G_metadataCount( g );
+  ASSERT_EQ( 1, meta_count );
+
+  const char *name = MDAL_G_name( g );
+  EXPECT_EQ( std::string( "10 metre wind [m/s]" ), std::string( name ) );
+
+  bool scalar = MDAL_G_hasScalarData( g );
+  EXPECT_EQ( true, scalar );
+
+  bool onVertices = MDAL_G_isOnVertices( g );
+  EXPECT_EQ( true, onVertices );
+
+  ASSERT_EQ( 2, MDAL_G_datasetCount( g ) );
+  DatasetH ds = MDAL_G_dataset( g, 0 );
+  ASSERT_NE( ds, nullptr );
+
+  bool valid = MDAL_D_isValid( ds );
+  EXPECT_EQ( true, valid );
+
+  bool active = getActive( ds, 0 );
+  EXPECT_EQ( true, active );
+
+  int count = MDAL_D_valueCount( ds );
+  ASSERT_EQ( 115680, count );
+
+  double value = getValue( ds, 1600 );
+  EXPECT_DOUBLE_EQ( -0.818756103515625, value );
+
+  MDAL_CloseMesh( m );
+}
 
 int main( int argc, char **argv )
 {