add testing for the error case where the grid is smaller than the molecule

(before this would access memory off the end of the grid
==> core dump on some platforms, eg alphas)


git-svn-id: http://svn.cactuscode.org/arrangements/CactusBase/LocalInterp/trunk@122 df1f8a13-aa1d-4dd4-9681-27ded5b42416

3 files changed, 53 insertions, 19 deletions

diff --git a/src/GeneralizedPolynomial-Uniform/InterpLocalUniform.h b/src/GeneralizedPolynomial-Uniform/InterpLocalUniform.h
index 24be556..d2990df 100644
--- a/src/GeneralizedPolynomial-Uniform/InterpLocalUniform.h
+++ b/src/GeneralizedPolynomial-Uniform/InterpLocalUniform.h
@@ -20,16 +20,16 @@ typedef int bool;
 /******************************************************************************/
 
 /* number of integers in the range [x,y] inclusive */
-#define how_many_in_range(x,y)  ((y) - (x) + 1)
+#define HOW_MANY_IN_RANGE(x,y)  ((y) - (x) + 1)
 
 /* is the integer x even/odd? */
-#define is_even(x)	(((x) & 0x1) == 0)
-#define is_odd (x)	(((x) & 0x1) != 0)
+#define IS_EVEN(x)	(((x) & 0x1) == 0)
+#define IS_ODD (x)	(((x) & 0x1) != 0)
 
 /* round floating-point value to nearest integer */
 /* ... result is expressed as floating point! */
 /* ... needs <math.h> for floor() */
-#define jt_round(x)	floor((x) + 0.5)
+#define JT_ROUND(x)	floor((x) + 0.5)
 
 /******************************************************************************/
 
@@ -149,6 +149,25 @@ struct	Jacobian_info
 	CCTK_INT Jacobian_part_stride;
 	};
 
+/**************************************/
+
+/*
+ * error codes for LocalInterp_molecule_posn()
+ * ... these are defined in terms of INT_MIN from <limits.h>
+ */
+
+/* x < minimum allowable x in grid */
+#define MOLECULE_POSN_ERROR_X_LT_MIN	(INT_MIN + 0)
+
+/* x > maximum allowable x in grid */
+#define MOLECULE_POSN_ERROR_X_GT_MAX	(INT_MIN + 1)
+
+/* grid is smaller than molecule */
+#define MOLECULE_POSN_ERROR_GRID_TINY	(INT_MIN + 2)
+
+/* is a given integer an error code? */
+#define IS_MOLECULE_POSN_ERROR_CODE(x)	(x <= MOLECULE_POSN_ERROR_GRID_TINY)
+
 /******************************************************************************/
 
 /*
diff --git a/src/GeneralizedPolynomial-Uniform/molecule_posn.c b/src/GeneralizedPolynomial-Uniform/molecule_posn.c
index 44e78fc..e007396 100644
--- a/src/GeneralizedPolynomial-Uniform/molecule_posn.c
+++ b/src/GeneralizedPolynomial-Uniform/molecule_posn.c
@@ -140,12 +140,16 @@ static const char *rcsid = "$Header$";
  @returntype	int
  @returndesc
 	This function returns the integer coordinate i_center at which
-	the molecule should be centered, or one of the error codes
-	(from <limits.h>)
-	INT_MIN  if  x  is out-of-range on the min end of the grid
-		 (i.e. x < the minimum allowable x)
-	INT_MAX  if  x  is out-of-range on the max end of the grid
-		 (i.e. x > the maximum allowable x)
+	the molecule should be centered, or one of the error codes defined
+	in "InterpLocalUniform.h":
+	MOLECULE_POSN_ERROR_X_LT_MIN
+		if  x  is out-of-range on the min end of the grid
+		(i.e. x < the minimum allowable x)
+	MOLECULE_POSN_ERROR_X_GT_MAX
+		if  x  is out-of-range on the max end of the grid
+		(i.e. x > the maximum allowable x)
+	MOLECULE_POSN_ERROR_GRID_TINY
+		if the grid is smaller than the molecule
  @endreturndesc
  @@*/
 int LocalInterp_molecule_posn(fp grid_origin, fp grid_delta,
@@ -184,7 +188,7 @@ if (out_of_range_tolerance_max >= 0.0)
 /* (see diagram in header comment for explanation) */
 /* ... as a floating-point number */
   {
-const fp fp_i_center = is_even(molecule_size) ? floor(fp_i) : jt_round(fp_i);
+const fp fp_i_center = IS_EVEN(molecule_size) ? floor(fp_i) : JT_ROUND(fp_i);
 /* ... as an integer */
 int i_center = (int) fp_i_center;
 
@@ -194,13 +198,15 @@ const int centered_i_max = i_center + m_max;
 
 /* check if off-centered molecules are forbidden? */
 if ((out_of_range_tolerance_min == -1.0) && (centered_i_min < grid_i_min))
-   then return INT_MIN;					/*** ERROR RETURN ***/
+   then return MOLECULE_POSN_ERROR_X_LT_MIN;		/*** ERROR RETURN ***/
 if ((out_of_range_tolerance_max == -1.0) && (centered_i_max > grid_i_max))
-   then return INT_MAX;					/*** ERROR RETURN ***/
+   then return MOLECULE_POSN_ERROR_X_GT_MAX;		/*** ERROR RETURN ***/
 
 /* off-center as needed if we're close to the edge of the grid */
   {
 int shift = 0;
+if (molecule_size > HOW_MANY_IN_RANGE(grid_i_min,grid_i_max))
+   then return MOLECULE_POSN_ERROR_GRID_TINY;		/*** ERROR RETURN ***/
 if (centered_i_min < grid_i_min)
    then shift = grid_i_min - centered_i_min;	/* a positive number */
 if (centered_i_max > grid_i_max)
diff --git a/src/GeneralizedPolynomial-Uniform/template.c b/src/GeneralizedPolynomial-Uniform/template.c
index ac1d98e..0bb409b 100644
--- a/src/GeneralizedPolynomial-Uniform/template.c
+++ b/src/GeneralizedPolynomial-Uniform/template.c
@@ -945,37 +945,46 @@ int pt;
 
     /* is the interpolation point out-of-range? */
     #if (N_DIMS >= 1)
-      if ((center_i == INT_MIN) || (center_i == INT_MAX))
+      if (IS_MOLECULE_POSN_ERROR_CODE(center_i))
 	 then {
+	      if (center_i == MOLECULE_POSN_ERROR_GRID_TINY)
+		 then return CCTK_ERROR_INTERP_GRID_TOO_TINY;
 	      if (error_flags != NULL)
 		 then {
 		      error_flags->error_pt = pt;
 		      error_flags->error_axis = X_AXIS;
-		      error_flags->error_end = (center_i > 0) ? +1 : -1;
+		      error_flags->error_end
+			 = (center_i == MOLECULE_POSN_ERROR_X_GT_MAX) ? +1 : -1;
 		      }
 	      return CCTK_ERROR_INTERP_POINT_X_RANGE; /*** ERROR RETURN ***/
 	      }
     #endif
     #if (N_DIMS >= 2)
-      if ((center_j == INT_MIN) || (center_j == INT_MAX))
+      if (IS_MOLECULE_POSN_ERROR_CODE(center_j))
 	 then {
+	      if (center_j == MOLECULE_POSN_ERROR_GRID_TINY)
+		 then return CCTK_ERROR_INTERP_GRID_TOO_TINY;
 	      if (error_flags != NULL)
 		 then {
 		      error_flags->error_pt = pt;
 		      error_flags->error_axis = Y_AXIS;
-		      error_flags->error_end = (center_j > 0) ? +1 : -1;
+		      error_flags->error_end
+			 = (center_j == MOLECULE_POSN_ERROR_X_GT_MAX) ? +1 : -1;
 		      }
 	      return CCTK_ERROR_INTERP_POINT_X_RANGE; /*** ERROR RETURN ***/
 	      }
     #endif
     #if (N_DIMS >= 3)
-      if ((center_k == INT_MIN) || (center_k == INT_MAX))
+      if (IS_MOLECULE_POSN_ERROR_CODE(center_k))
 	 then {
+	      if (center_k == MOLECULE_POSN_ERROR_GRID_TINY)
+		 then return CCTK_ERROR_INTERP_GRID_TOO_TINY;
 	      if (error_flags != NULL)
 		 then {
 		      error_flags->error_pt = pt;
 		      error_flags->error_axis = Z_AXIS;
-		      error_flags->error_end = (center_k > 0) ? +1 : -1;
+		      error_flags->error_end
+			 = (center_k == MOLECULE_POSN_ERROR_X_GT_MAX) ? +1 : -1;
 		      }
 	      return CCTK_ERROR_INTERP_POINT_X_RANGE; /*** ERROR RETURN ***/
 	      }