Ensure nullptr checks come before dereferences

src/mesh/impls/bout/boutmesh.cxx

@@ -50,11 +50,7 @@
 /// MPI type of BoutReal for communications
 #define PVEC_REAL_MPI_TYPE MPI_DOUBLE
 
-BoutMesh::BoutMesh(GridDataSource *s, Options *options) : Mesh(s, options) {
-  if (options == NULL) {
-    options = Options::getRoot()->getSection("mesh");
-  }
-
+BoutMesh::BoutMesh(GridDataSource *s, Options *opt) : Mesh(s, opt) {
   OPTION(options, symmetricGlobalX, true);
   if (!options->isSet("symmetricGlobalY")) {
     std::string optionfile;

src/mesh/mesh.cxx

@@ -26,6 +26,10 @@ Mesh::Mesh(GridDataSource *s, Options* opt) : source(s), coords(0), options(opt)
   if(s == NULL)
     throw BoutException("GridDataSource passed to Mesh::Mesh() is NULL");
 
+  if (options == nullptr) {
+    options = Options::getRoot()->getSection("mesh");
+  }
+
   /// Get mesh options
   OPTION(options, StaggerGrids,   false); // Stagger grids
   OPTION(options, maxregionblocksize, MAXREGIONBLOCKSIZE);

src/solver/solver.cxx

@@ -339,6 +339,11 @@ void Solver::add(Vector3D &v, const char* name) {
  **************************************************************************/
 
 void Solver::constraint(Field2D &v, Field2D &C_v, const char* name) {
+
+  if (name == nullptr) {
+    throw BoutException("ERROR: Constraint requested for variable with NULL name\n");
+  }
+
   TRACE("Constrain 2D scalar: Solver::constraint(%s)", name);
 
 #if CHECK > 0  
@@ -352,9 +357,6 @@ void Solver::constraint(Field2D &v, Field2D &C_v, const char* name) {
   if(initialised)
     throw BoutException("Error: Cannot add constraints to solver after initialisation\n");
 
-  if(name == NULL)
-    throw BoutException("WARNING: Constraint requested for variable with NULL name\n");
-
   VarStr<Field2D> d;
 
   d.constraint = true;
@@ -366,6 +368,11 @@ void Solver::constraint(Field2D &v, Field2D &C_v, const char* name) {
 }
 
 void Solver::constraint(Field3D &v, Field3D &C_v, const char* name) {
+
+  if (name == nullptr) {
+    throw BoutException("ERROR: Constraint requested for variable with NULL name\n");
+  }
+
   TRACE("Constrain 3D scalar: Solver::constraint(%s)", name);
 
 #if CHECK > 0
@@ -379,9 +386,6 @@ void Solver::constraint(Field3D &v, Field3D &C_v, const char* name) {
   if(initialised)
     throw BoutException("Error: Cannot add constraints to solver after initialisation\n");
 
-  if(name == NULL)
-    throw BoutException("WARNING: Constraint requested for variable with NULL name\n");
-
   VarStr<Field3D> d;
 
   d.constraint = true;
@@ -394,6 +398,11 @@ void Solver::constraint(Field3D &v, Field3D &C_v, const char* name) {
 }
 
 void Solver::constraint(Vector2D &v, Vector2D &C_v, const char* name) {
+
+  if (name == nullptr) {
+    throw BoutException("ERROR: Constraint requested for variable with NULL name\n");
+  }
+
   TRACE("Constrain 2D vector: Solver::constraint(%s)", name);
 
 #if CHECK > 0  
@@ -407,9 +416,6 @@ void Solver::constraint(Vector2D &v, Vector2D &C_v, const char* name) {
   if(initialised)
     throw BoutException("Error: Cannot add constraints to solver after initialisation\n");
 
-  if(name == NULL)
-    throw BoutException("WARNING: Constraint requested for variable with NULL name\n");
-
   VarStr<Vector2D> d;
 
   d.constraint = true;
@@ -433,6 +439,11 @@ void Solver::constraint(Vector2D &v, Vector2D &C_v, const char* name) {
 }
 
 void Solver::constraint(Vector3D &v, Vector3D &C_v, const char* name) {
+
+  if (name == nullptr) {
+    throw BoutException("ERROR: Constraint requested for variable with NULL name\n");
+  }
+
   TRACE("Constrain 3D vector: Solver::constraint(%s)", name);
 
 #if CHECK > 0  
@@ -446,9 +457,6 @@ void Solver::constraint(Vector3D &v, Vector3D &C_v, const char* name) {
   if(initialised)
     throw BoutException("Error: Cannot add constraints to solver after initialisation\n");
 
-  if(name == NULL)
-    throw BoutException("WARNING: Constraint requested for variable with NULL name\n");
-
   VarStr<Vector3D> d;
 
   d.constraint = true;

src/sys/comm_group.cxx

@@ -204,14 +204,14 @@ namespace comm_group {
 
     return (root == handle->myrank);
   }
-
-
-  bool Comm_wait(Comm_handle_t *handle)
-  {
-    TRACE("Comm_gather_wait(%d)", handle->root);
 
-    if(handle == NULL)
+  bool Comm_wait(Comm_handle_t *handle) {
+    if (handle == nullptr) {
       return false;
+    }
+
+    TRACE("Comm_gather_wait(%d)", handle->root);
+
     if(!handle->current)
       return false;
 

tests/unit/mesh/test_boutmesh.cxx

@@ -0,0 +1,46 @@
+#include "gtest/gtest.h"
+
+#include "../src/mesh/impls/bout/boutmesh.hxx"
+#include "bout/mesh.hxx"
+#include "output.hxx"
+#include "unused.hxx"
+
+class FakeGridDataSource : public GridDataSource {
+public:
+  FakeGridDataSource(){};
+  ~FakeGridDataSource(){};
+  bool hasVar(const string &UNUSED(name)) { return false; };
+  bool get(Mesh *UNUSED(m), int &UNUSED(ival), const string &UNUSED(name)) {
+    return true;
+  };
+  bool get(Mesh *UNUSED(m), BoutReal &UNUSED(rval), const string &UNUSED(name)) {
+    return true;
+  }
+  bool get(Mesh *UNUSED(m), Field2D &UNUSED(var), const string &UNUSED(name),
+           BoutReal UNUSED(def) = 0.0) {
+    return true;
+  }
+  bool get(Mesh *UNUSED(m), Field3D &UNUSED(var), const string &UNUSED(name),
+           BoutReal UNUSED(def) = 0.0) {
+    return true;
+  }
+  bool get(Mesh *UNUSED(m), vector<int> &UNUSED(var), const string &UNUSED(name),
+           int UNUSED(len), int UNUSED(offset) = 0,
+           Direction UNUSED(dir) = GridDataSource::X) {
+    return true;
+  }
+  bool get(Mesh *UNUSED(m), vector<BoutReal> &UNUSED(var), const string &UNUSED(name),
+           int UNUSED(len), int UNUSED(offset) = 0,
+           Direction UNUSED(dir) = GridDataSource::X) {
+    return true;
+  }
+};
+
+TEST(BoutMeshTest, NullOptionsCheck) {
+  // Temporarily turn off outputs to make test quiet
+  output_info.disable();
+  output_warn.disable();
+  EXPECT_NO_THROW(BoutMesh mesh(new FakeGridDataSource, nullptr));
+  output_info.enable();
+  output_warn.enable();
+}