GTiff: fix retrieving mask band of overview band when the mask is ext…

…ernal. Fixes -co COPY_SRC_OVERVIEWS=YES of such datasets (fixes #754)
OSGeo · Jul 14, 2018 · fde9dea · fde9dea
1 parent 12e52bc
commit fde9dea
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diff --git a/autotest/gcore/tiff_read.py b/autotest/gcore/tiff_read.py
@@ -3748,6 +3748,40 @@ def tiff_read_zstd_corrupted2():
     with gdaltest.error_handler():
         return ut.testOpen()
 
+
+###############################################################################
+
+
+def tiff_read_overview_of_external_mask():
+
+    filename = '/vsimem/tiff_read_overview_of_external_mask.tif'
+    gdal.Translate(filename, 'data/byte.tif', options='-b 1 -mask 1')
+    ds = gdal.Open(filename, gdal.GA_Update)
+    ds.BuildOverviews('CUBIC', overviewlist=[2])
+    ds = None
+    ds = gdal.Open(filename + '.msk', gdal.GA_Update)
+    ds.BuildOverviews('NEAREST', overviewlist=[2])
+    ds = None
+    ds = gdal.Open(filename)
+    cs1 = ds.GetRasterBand(1).GetOverview(0).GetMaskBand().Checksum()
+    cs2 = ds.GetRasterBand(1).GetMaskBand().GetOverview(0).Checksum()
+    flags1 = ds.GetRasterBand(1).GetOverview(0).GetMaskFlags()
+    ds = None
+
+    gdal.Unlink(filename)
+    gdal.Unlink(filename + '.msk')
+
+    if cs1 != cs2:
+        gdaltest.post_reason('fail')
+        print(cs1, cs2)
+        return 'fail'
+    if flags1 != gdal.GMF_PER_DATASET:
+        gdaltest.post_reason('fail')
+        print(flags1)
+        return 'fail'
+
+    return 'success'
+
 ###############################################################################
 
 
@@ -3876,6 +3910,7 @@ def tiff_read_zstd_corrupted2():
 gdaltest_list.append((tiff_read_zstd))
 gdaltest_list.append((tiff_read_zstd_corrupted))
 gdaltest_list.append((tiff_read_zstd_corrupted2))
+gdaltest_list.append((tiff_read_overview_of_external_mask))
 
 gdaltest_list.append((tiff_read_online_1))
 gdaltest_list.append((tiff_read_online_2))

diff --git a/gdal/frmts/gtiff/geotiff.cpp b/gdal/frmts/gtiff/geotiff.cpp
@@ -382,6 +382,7 @@ class GTiffDataset final : public GDALPamDataset
 
     GTiffDataset* poMaskDS;
     GTiffDataset* poBaseDS;
+    bool          bIsOverview_ = false;
 
     CPLString    osFilename;
 
@@ -5594,6 +5595,11 @@ int GTiffRasterBand::GetMaskFlags()
         return 0;
     }
 
+    if( poGDS->bIsOverview_ )
+    {
+        return poGDS->poBaseDS->GetRasterBand(nBand)->GetMaskFlags();
+    }
+
     return GDALPamRasterBand::GetMaskFlags();
 }
 
@@ -5613,6 +5619,26 @@ GDALRasterBand *GTiffRasterBand::GetMaskBand()
         return poGDS->poMaskDS->GetRasterBand(nBand);
     }
 
+    if( poGDS->bIsOverview_ )
+    {
+        GDALRasterBand* poBaseMask =
+            poGDS->poBaseDS->GetRasterBand(nBand)->GetMaskBand();
+        if( poBaseMask )
+        {
+            const int nOverviews = poBaseMask->GetOverviewCount();
+            for( int i = 0; i < nOverviews; i++ )
+            {
+                GDALRasterBand* poOvr = poBaseMask->GetOverview(i);
+                if( poOvr &&
+                    poOvr->GetXSize() == GetXSize() &&
+                    poOvr->GetYSize() == GetYSize() )
+                {
+                    return poOvr;
+                }
+            }
+        }
+    }
+
     return GDALPamRasterBand::GetMaskBand();
 }
 
@@ -9954,6 +9980,7 @@ CPLErr GTiffDataset::RegisterNewOverviewDataset(toff_t nOverviewOffset,
                     nOverviewCount * (sizeof(void*))) );
     papoOverviewDS[nOverviewCount-1] = poODS;
     poODS->poBaseDS = this;
+    poODS->bIsOverview_ = true;
     return CE_None;
 }
 
@@ -14718,6 +14745,7 @@ void GTiffDataset::ScanDirectories()
                                nOverviewCount * (sizeof(void*))) );
                 papoOverviewDS[nOverviewCount-1] = poODS;
                 poODS->poBaseDS = this;
+                poODS->bIsOverview_ = true;
             }
         }
         // Embedded mask of the main image.