add utility function for verifying simulator output directory

use this in fvbaseproblem.hh. allows to encapsulate some includes

opm/models/discretization/common/fvbaseproblem.hh

@@ -44,9 +44,6 @@
 #include <limits>
 #include <string>
 
-#include <sys/stat.h>
-#include <unistd.h>
-
 namespace Opm::Properties {
 
 template <class TypeTag, class MyTypeTag>
@@ -208,23 +205,7 @@ public:
      */
     std::string outputDir() const
     {
-        std::string outputDir = Parameters::Get<Parameters::OutputDir>();
+        return simulatorOutputDir();
-
-        if (outputDir.empty())
-            outputDir = ".";
-
-        // TODO: replace this by std::filesystem once we require c++-2017
-        struct stat st;
-        if (::stat(outputDir.c_str(), &st) != 0)
-            throw std::runtime_error("Could not access output directory '"+outputDir+"':"
-                                     +strerror(errno));
-        if (!S_ISDIR(st.st_mode))
-            throw std::runtime_error("Path to output directory '"+outputDir+"' exists but is not a directory");
-
-        if (access(outputDir.c_str(), W_OK) != 0)
-            throw std::runtime_error("Output directory '"+outputDir+"' exists but is not writeable");
-
-        return outputDir;
     }
 
     /*!

opm/models/utils/simulatorutils.cpp

@@ -24,10 +24,16 @@
 #include <config.h>
 #include <opm/models/utils/simulatorutils.hpp>
 
+#include <opm/models/discretization/common/fvbaseparameters.hh>
+
+#include <opm/models/utils/parametersystem.hpp>
+
 #include <cmath>
 #include <fstream>
 #include <iomanip>
 #include <sstream>
+#include <sys/stat.h>
+#include <unistd.h>
 #include <vector>
 
 #if HAVE_QUAD
@@ -110,6 +116,32 @@ std::string humanReadableTime(double timeInSeconds, bool isAmendment)
     return oss.str();
 }
 
+std::string simulatorOutputDir()
+{
+    std::string outputDir = Parameters::Get<Parameters::OutputDir>();
+
+    if (outputDir.empty()) {
+        outputDir = ".";
+    }
+
+    // TODO: replace this by std::filesystem once we require c++-2017
+    struct stat st;
+    if (::stat(outputDir.c_str(), &st) != 0)
+        throw std::runtime_error("Could not access output directory '" + outputDir + "':" +
+                                 strerror(errno));
+    if (!S_ISDIR(st.st_mode)) {
+        throw std::runtime_error("Path to output directory '" +outputDir +
+                                 "' exists but is not a directory");
+    }
+
+    if (access(outputDir.c_str(), W_OK) != 0) {
+        throw std::runtime_error("Output directory '" + outputDir +
+                                 "' exists but is not writeable");
+    }
+
+    return outputDir;
+}
+
 template<class Scalar>
 std::vector<Scalar> readTimeStepFile(const std::string& file)
 {

opm/models/utils/simulatorutils.hpp

@@ -37,6 +37,11 @@ namespace Opm {
 */
 std::string humanReadableTime(double timeInSeconds, bool isAmendment = true);
 
+/*!
+ * \brief Determine and check the configured directory for simulation output.
+ */
+std::string simulatorOutputDir();
+
 /*!
  * \brief Read explicitly defined time steps from file.
  * \param file File to read