FEM: Restore path functions of run module

The functions getTempDir, getBesideDir and getBesideBase where moved to
femutils, modified and made public in the past. This breaks the solver
framework under certain circumstances. These folders are only intended
for the solver. Using it for other puroses may result in unexpected
behaviour (including crashes). This commit restores the original
functions for the solver module. The problem that other modules of the
workbench use those folders should be resolved at some point.

src/Mod/Fem/femsolver/run.py

@@ -37,6 +37,7 @@ import os
 import os.path
 # import threading  # not used ATM
 import shutil
+import tempfile
 
 import FreeCAD as App
 import femtools.femutils as femutils
@@ -176,7 +177,7 @@ def _isPathValid(m, path):
     if setting == settings.DirSetting.BESIDE:
         if t == settings.DirSetting.BESIDE:
             base = os.path.split(m.directory.rstrip("/"))[0]
-            return base == femutils.get_beside_base(m.solver)
+            return base == _getBesideBase(m.solver)
         return False
     if setting == settings.DirSetting.TEMPORARY:
         return t == settings.DirSetting.TEMPORARY
@@ -184,7 +185,7 @@ def _isPathValid(m, path):
         if t == settings.DirSetting.CUSTOM:
             firstBase = os.path.split(m.directory.rstrip("/"))[0]
             customBase = os.path.split(firstBase)[0]
-            return customBase == femutils.get_custom_base(m.solver)
+            return customBase == _getCustomBase(m.solver)
         return False
 
 
@@ -193,15 +194,15 @@ def _createMachine(solver, path, testmode):
     setting = settings.get_dir_setting()
     if path is not None:
         _dirTypes[path] = None
-    elif setting == settings.BESIDE:
-        path = femutils.get_beside_dir(solver)
-        _dirTypes[path] = settings.BESIDE
-    elif setting == settings.TEMPORARY:
-        path = femutils.get_temp_dir(solver)
-        _dirTypes[path] = settings.TEMPORARY
-    elif setting == settings.CUSTOM:
-        path = femutils.get_custom_dir(solver)
-        _dirTypes[path] = settings.CUSTOM
+    elif setting == settings.DirSetting.BESIDE:
+        path = _getBesideDir(solver)
+        _dirTypes[path] = settings.DirSetting.BESIDE
+    elif setting == settings.DirSetting.TEMPORARY:
+        path = _getTempDir(solver)
+        _dirTypes[path] = settings.DirSetting.TEMPORARY
+    elif setting == settings.DirSetting.CUSTOM:
+        path = _getCustomDir(solver)
+        _dirTypes[path] = settings.DirSetting.CUSTOM
     m = solver.Proxy.createMachine(solver, path, testmode)
     oldMachine = _machines.get(solver)
     if oldMachine is not None and _dirTypes.get(oldMachine.directory) is not None:
@@ -210,6 +211,63 @@ def _createMachine(solver, path, testmode):
     return m
 
 
+def _getTempDir(solver):
+    return tempfile.mkdtemp(prefix="fem")
+
+
+def _getBesideDir(solver):
+    base = _getBesideBase(solver)
+    specificPath = os.path.join(base, solver.Label)
+    specificPath = _getUniquePath(specificPath)
+    if not os.path.isdir(specificPath):
+        os.makedirs(specificPath)
+    return specificPath
+
+
+def _getBesideBase(solver):
+    path = femutils.get_doc_dir(solver.Document)
+    if path is None:
+        error_message = (
+            "Please save the file before executing the solver. "
+            "This must be done because the location of the working "
+            "directory is set to \"Beside *.FCStd File\"."
+        )
+        App.Console.PrintError(error_message + "\n")
+        if App.GuiUp:
+            QtGui.QMessageBox.critical(
+                FreeCADGui.getMainWindow(),
+                "Can't start Solver",
+                error_message
+            )
+        raise MustSaveError()
+    return path
+
+
+def _getCustomDir(solver):
+    base = _getCustomBase(solver)
+    specificPath = os.path.join(
+        base, solver.Document.Name, solver.Label)
+    specificPath = _getUniquePath(specificPath)
+    if not os.path.isdir(specificPath):
+        os.makedirs(specificPath)
+    return specificPath
+
+
+def _getCustomBase(solver):
+    path = settings.get_custom_dir()
+    if not os.path.isdir(path):
+        error_message = "Selected working directory doesn't exist."
+        App.Console.PrintError(error_message + "\n")
+        if App.GuiUp:
+            QtGui.QMessageBox.critical(
+                FreeCADGui.getMainWindow(),
+                "Can't start Solver",
+                error_message
+            )
+        raise DirectoryDoesNotExistError("Invalid path")
+    return path
+
+
 def _getUniquePath(path):
     postfix = 1
     if path in _dirTypes: