Merge pull request #4867 from rouault/fix_4847

GDALPamRasterBand::CloneInfo(): deal correctly with NaN nodata to avoid generating useless .aux.xml file (fixes #4847)
OSGeo · Nov 22, 2021 · cae6bfc · cae6bfc
2 parents 5bb3cf6 + ac80057
commit cae6bfc
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Showing 2 changed files with 25 additions and 4 deletions.
diff --git a/autotest/gcore/pam.py b/autotest/gcore/pam.py
@@ -537,6 +537,19 @@ def test_pam_metadata_coordinate_epoch():
 
     gdal.GetDriverByName('PNM').Delete(tmpfilename)
 
+###############################################################################
+# Check that PAM handles correctly equality of NaN nodata values (#4847)
+
+def test_pam_nodata_nan():
+
+    outfilename = '/vsimem/test_pam_nodata_nan.tif'
+    src_ds = gdal.GetDriverByName('MEM').Create('', 1, 1, 1, gdal.GDT_Float32)
+    src_ds.GetRasterBand(1).SetNoDataValue(float('nan'))
+    gdal.GetDriverByName('GTiff').CreateCopy(outfilename, src_ds)
+    # Check that no PAM file is generated
+    assert gdal.VSIStatL(outfilename + '.aux.xml') is None
+    gdal.GetDriverByName('GTiff').Delete(outfilename)
+
 ###############################################################################
 # Cleanup.
 

diff --git a/gcore/gdalpamrasterband.cpp b/gcore/gdalpamrasterband.cpp
@@ -564,15 +564,23 @@ CPLErr GDALPamRasterBand::CloneInfo( GDALRasterBand *poSrcBand,
 /* -------------------------------------------------------------------- */
     if( nCloneFlags & GCIF_NODATA )
     {
-        int bSuccess = FALSE;  // TODO(schwehr): int -> bool.
+        int bSuccess = FALSE;
         const double dfNoData = poSrcBand->GetNoDataValue( &bSuccess );
 
         if( bSuccess )
         {
-            if( !bOnlyIfMissing
-                || GetNoDataValue( &bSuccess ) != dfNoData
-                || !bSuccess )
+            if( !bOnlyIfMissing )
                 GDALPamRasterBand::SetNoDataValue( dfNoData );
+            else
+            {
+                const double dfExistingNoData = GetNoDataValue( &bSuccess );
+                if( !bSuccess ||
+                    !((std::isnan(dfExistingNoData) && std::isnan(dfNoData)) ||
+                      dfExistingNoData == dfNoData) )
+                {
+                    GDALPamRasterBand::SetNoDataValue( dfNoData );
+                }
+            }
         }
     }