gdaladdo: validate values of decimation factors

Author: rouault

apps/gdaladdo.cpp

@@ -692,7 +692,23 @@ MAIN_START(nArgc, papszArgv)
     {
         for (const auto &level : *levels)
         {
+            if (CPLGetValueType(level.c_str()) != CPL_VALUE_INTEGER)
+            {
+                CPLError(
+                    CE_Failure, CPLE_IllegalArg,
+                    "Value '%s' is not a positive integer subsampling factor",
+                    level.c_str());
+                std::exit(1);
+            }
             anLevels.push_back(atoi(level.c_str()));
+            if (anLevels.back() <= 0)
+            {
+                CPLError(
+                    CE_Failure, CPLE_IllegalArg,
+                    "Value '%s' is not a positive integer subsampling factor",
+                    level.c_str());
+                std::exit(1);
+            }
             if (anLevels.back() == 1)
             {
                 printf(

autotest/utilities/test_gdaladdo.py

@@ -455,3 +455,33 @@ def test_gdaladdo_partial_refresh_from_source_timestamp_gti(gdaladdo_path, tmp_p
             ovr_data_refreshed[idx] = ovr_data_ori[idx]
     assert ovr_data_refreshed == ovr_data_ori
     ds = None
+
+
+###############################################################################
+#
+
+
+def test_gdaladdo_illegal_factor(gdaladdo_path, tmp_path):
+
+    shutil.copyfile("../gcore/data/byte.tif", f"{tmp_path}/byte.tif")
+
+    _, err = gdaltest.runexternal_out_and_err(
+        f"{gdaladdo_path} -r average {tmp_path}/byte.tif invalid"
+    )
+    assert "Value 'invalid' is not a positive integer subsampling factor" in err
+    with gdal.Open(f"{tmp_path}/byte.tif") as ds:
+        assert ds.GetRasterBand(1).GetOverviewCount() == 0
+
+    _, err = gdaltest.runexternal_out_and_err(
+        f"{gdaladdo_path} -r average {tmp_path}/byte.tif 0"
+    )
+    assert "Value '0' is not a positive integer subsampling factor" in err
+    with gdal.Open(f"{tmp_path}/byte.tif") as ds:
+        assert ds.GetRasterBand(1).GetOverviewCount() == 0
+
+    _, err = gdaltest.runexternal_out_and_err(
+        f"{gdaladdo_path} -r average {tmp_path}/byte.tif -1"
+    )
+    assert "Value '-1' is not a positive integer subsampling factor" in err
+    with gdal.Open(f"{tmp_path}/byte.tif") as ds:
+        assert ds.GetRasterBand(1).GetOverviewCount() == 0