add some null pointer checks

does no harm and aids static analyzers

src/ASM/DomainDecomposition.C

@@ -126,6 +126,9 @@ OrientIterator::OrientIterator(const ASMbase* pch,
 DomainDecomposition::
 OrientIterator::OrientIterator(const ASMbase* pch, int orient, int lIdx)
 {
+  if (!pch)
+    return;
+
   const ASMstruct* spch = dynamic_cast<const ASMstruct*>(pch);
   if (!spch) {
     nodes.resize(pch->getNoBoundaryElms(lIdx, pch->getNoSpaceDim()-1));
@@ -453,6 +456,9 @@ void DomainDecomposition::setupNodeNumbers(int basis, IntVec& lNodes,
                                            const ASMbase* pch,
                                            int dim, int lidx, int thick, int orient)
 {
+  if (!pch)
+    return;
+
   if (basis != 0) // specified base
     cbasis = utl::getDigits(basis);
   else if (dim == 0 || (dim == 1 && pch->getNoSpaceDim() == 3))

src/LinAlg/PETScMatrix.C

@@ -587,6 +587,9 @@ bool PETScMatrix::solveDirect(PETScVector& B)
 
   // Set correct number of rows and columns for matrix.
   size_t nrow = IA.size()-1;
+  if (nrow == 0 || IA.empty())
+    return false;
+
   MatSetSizes(pA, nrow, nrow, PETSC_DECIDE, PETSC_DECIDE);
   MatSetFromOptions(pA);
   PetscInt max = 0;

src/LinAlg/SAM.C

@@ -208,7 +208,7 @@ bool SAM::initSystemEquations ()
   std::cout <<"SAM::initSystemEquations()"<< std::endl;
 #endif
   if (!msc && ndof > 0) return false;
-  if (!mpmceq && nceq > 0) return false;
+  if ((!msc || !mpmceq) && nceq > 0) return false;
 
   // Initialize the DOF-to-equation connectivity array
   int i, j, ierr = 0;

src/Utility/Functions.C

@@ -730,7 +730,7 @@ static const ScalarFunc* parseFunction (const char* type, char* cline, Real C)
     if (cline) IFEM::cout <<"*"<< scale;
     return new LinearFunc(fname,colum,scale);
   }
-  else if (strncasecmp(type,"Constant",8) == 0)
+  else if (strncasecmp(type,"Constant",8) == 0 && cline)
   {
     Real value = atof(cline);
     IFEM::cout << value;
@@ -738,7 +738,12 @@ static const ScalarFunc* parseFunction (const char* type, char* cline, Real C)
   }
   else // linear in time
   {
-    Real scale = atof(strncasecmp(type,"Lin",3) == 0 ? cline : type);
+    Real scale;
+    if (type && cline)
+      scale = atof(strncasecmp(type,"Lin",3) == 0 ? cline : type);
+    else
+      scale = 1.0;
+
     IFEM::cout << scale <<"*t";
     return new LinearFunc(C*scale);
   }

src/Utility/HDF5Writer.C

@@ -353,6 +353,9 @@ void HDF5Writer::writeSIM (int level, const DataEntry& entry,
     {
       Vector psol;
       ASMbase* pch = sim->getPatch(loc);
+      if (!pch)
+        continue;
+
       if (results & DataExporter::PRIMARY && !sol->empty()) {
         size_t ndof1 = sim->extractPatchSolution(*sol,psol,pch,entry.second.ncmps,
                                                  usedescription ? 1 : 0);