i.maxlik: fix crash when classification result is NULL (OSGeo#2724)

If any input cell from imagery group is NULL, the result of classification is also NULL. The implementation of original cat restoration (79f9500) did not check for this corner case and thus caused an out of bounds value access.
ninsbl · Feb 17, 2023 · f0acd20 · f0acd20
1 parent 1a65d93
commit f0acd20
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Showing 2 changed files with 3 additions and 2 deletions.
diff --git a/imagery/i.maxlik/main.c b/imagery/i.maxlik/main.c
@@ -124,7 +124,8 @@ int main(int argc, char *argv[])
             for (int col = 0; col < ncols; col++) {
                 /* Predicted classes start at 1 but signature array is 0 based
                  */
-                class_cell[col] = S.sig[class_cell[col] - 1].oclass;
+                if (Rast_is_c_null_value(&class_cell[col]) == 0)
+                    class_cell[col] = S.sig[class_cell[col] - 1].oclass;
             }
         }
         Rast_put_row(class_fd, class_cell, CELL_TYPE);

diff --git a/imagery/i.maxlik/testsuite/test_i_maxlik.py b/imagery/i.maxlik/testsuite/test_i_maxlik.py
@@ -66,7 +66,7 @@ def setUpClass(cls):
         )
         cls.runModule(
             "r.mapcalc",
-            expression=f"{cls.b2}=5.0+rand(-1.0,1.0)",
+            expression=f"{cls.b2}=if(row() == 3 && col() == 3, null(), 5.0+rand(-1.0,1.0))",
             flags="s",
             quiet=True,
         )