BUG: questionable findInstance handling of constant (related to #1112)

- when searching for a file that may not actually exist,
  the short-cut optimization could lead to the 'constant' directory
  being ignored.

STYLE: simplify logic in points0MotionSolver::points0IO

src/OpenFOAM/global/fileOperations/fileOperation/fileOperation.C

@@ -757,8 +757,8 @@ Foam::IOobject Foam::fileOperation::findInstance
         return io;
     }
 
-    // Search back through the time directories to find the time
-    // closest to and lower than current time
+    // Search back through the time directories to find the first time
+    // that is less than or equal to the current time
 
     instantList ts = time.times();
     label instanceI = ts.size()-1;
@@ -771,20 +771,21 @@ Foam::IOobject Foam::fileOperation::findInstance
         }
     }
 
-    // Continue searching from here
+    // Found the time, continue from here
     for (; instanceI >= 0; --instanceI)
     {
+        io.instance() = ts[instanceI].name();
+
         // Shortcut: if actual directory is the timeName we've already tested it
         if
         (
-            ts[instanceI].name() == startIO.instance()
-         && ts[instanceI].name() != stopInstance
+            io.instance() == startIO.instance()
+         && io.instance() != stopInstance
         )
         {
             continue;
         }
 
-        io.instance() = ts[instanceI].name();
         if (exists(io))
         {
             DebugInFunction
@@ -796,7 +797,7 @@ Foam::IOobject Foam::fileOperation::findInstance
         }
 
         // Check if hit minimum instance
-        if (ts[instanceI].name() == stopInstance)
+        if (io.instance() == stopInstance)
         {
             DebugInFunction
                 << "Hit stopInstance " << stopInstance << endl;

src/dynamicMesh/motionSolvers/displacement/points0/points0MotionSolver.C

@@ -48,26 +48,6 @@ Foam::IOobject Foam::points0MotionSolver::points0IO(const polyMesh& mesh)
             IOobject::READ_IF_PRESENT
         );
 
-    if (instance != mesh.time().constant())
-    {
-        // points0 written to a time folder
-
-        return
-            IOobject
-            (
-                "points0",
-                instance,
-                polyMesh::meshSubDir,
-                mesh,
-                IOobject::MUST_READ,
-                IOobject::NO_WRITE,
-                false
-            );
-    }
-    else
-    {
-        // Check that points0 are actually in constant directory
-
     IOobject io
     (
         "points0",
@@ -79,27 +59,18 @@ Foam::IOobject Foam::points0MotionSolver::points0IO(const polyMesh& mesh)
         false
     );
 
-        if (io.typeHeaderOk<pointIOField>())
-        {
-            return io;
-        }
-        else
-        {
-            // Copy of original mesh points
-
-            return
-                IOobject
+    // If points0 are located in constant directory, verify their existence
+    // or fallback to a copy of the original mesh points
+    if
     (
-                    "points",
-                    instance,
-                    polyMesh::meshSubDir,
-                    mesh,
-                    IOobject::MUST_READ,
-                    IOobject::NO_WRITE,
-                    false
-                );
-        }
+        instance == mesh.time().constant()
+     && !io.typeHeaderOk<pointIOField>()
+    )
+    {
+        io.rename("points");
     }
+
+    return io;
 }