Fix for bug #31236: Inconsistent division by zero behavior for

                    floating point numbers

Some math functions did not check if the result is a valid number
(i.e. neither of +-inf or nan).

Fixed by validating the result where necessary and returning NULL in
case of invalid result.


BitKeeper/deleted/.del-matherr.c:
  Rename: sql/matherr.c -> BitKeeper/deleted/.del-matherr.c
configure.in:
  Removed DONT_USE_FINITE, it is not used anywhere.
include/my_global.h:
  isfinite() is a C99 macro which absoletes finite(). First try to use
  it, then fall back to finite() if the target platform has it,
  otherwise use our own implementation.
mysql-test/r/func_math.result:
  Added a test case for bug #31236.
mysql-test/r/strict.result:
  Fixed a test case which relied on old behavior.
mysql-test/t/func_math.test:
  Added a test case for bug #31236.
mysql-test/t/strict.test:
  Fixed a test case which relied on old behavior.
sql/field.cc:
  No need to check if the finite() or its equivalent is available.
sql/item_func.cc:
  Use fix_result() wherever the result can be one of +-inf or nan, 
  assuming the function arguments are valid numbers.
  Removed fix_result() from functions that are defined for all possible
  input numbers.
sql/item_func.h:
  Moved fix_result() from Item_dec_func to Item_func which is a common
  ancestor for Item_dec_func and Item_num_op.
sql/unireg.h:
  Removed POSTFIX_ERROR because no code returns it.

1 files changed, 11 insertions, 11 deletions

diff --git a/sql/item_func.cc b/sql/item_func.cc
index 8fd6f0966ad..3d6ed590f81 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -1104,7 +1104,7 @@ double Item_func_plus::real_op()
   double value= args[0]->val_real() + args[1]->val_real();
   if ((null_value=args[0]->null_value || args[1]->null_value))
     return 0.0;
-  return value;
+  return fix_result(value);
 }
 
 
@@ -1186,7 +1186,7 @@ double Item_func_minus::real_op()
   double value= args[0]->val_real() - args[1]->val_real();
   if ((null_value=args[0]->null_value || args[1]->null_value))
     return 0.0;
-  return value;
+  return fix_result(value);
 }
 
 
@@ -1224,7 +1224,7 @@ double Item_func_mul::real_op()
   double value= args[0]->val_real() * args[1]->val_real();
   if ((null_value=args[0]->null_value || args[1]->null_value))
     return 0.0;
-  return value;
+  return fix_result(value);
 }
 
 
@@ -1282,7 +1282,7 @@ double Item_func_div::real_op()
     signal_divide_by_null();
     return 0.0;
   }
-  return value/val2;
+  return fix_result(value/val2);
 }
 
 
@@ -1655,7 +1655,7 @@ double Item_func_exp::val_real()
   double value= args[0]->val_real();
   if ((null_value=args[0]->null_value))
     return 0.0; /* purecov: inspected */
-  return exp(value);
+  return fix_result(exp(value));
 }
 
 double Item_func_sqrt::val_real()
@@ -1674,7 +1674,7 @@ double Item_func_pow::val_real()
   double val2= args[1]->val_real();
   if ((null_value=(args[0]->null_value || args[1]->null_value)))
     return 0.0; /* purecov: inspected */
-  return pow(value,val2);
+  return fix_result(pow(value,val2));
 }
 
 // Trigonometric functions
@@ -1686,7 +1686,7 @@ double Item_func_acos::val_real()
   volatile double value= args[0]->val_real();
   if ((null_value=(args[0]->null_value || (value < -1.0 || value > 1.0))))
     return 0.0;
-  return fix_result(acos(value));
+  return acos(value);
 }
 
 double Item_func_asin::val_real()
@@ -1696,7 +1696,7 @@ double Item_func_asin::val_real()
   volatile double value= args[0]->val_real();
   if ((null_value=(args[0]->null_value || (value < -1.0 || value > 1.0))))
     return 0.0;
-  return fix_result(asin(value));
+  return asin(value);
 }
 
 double Item_func_atan::val_real()
@@ -1712,7 +1712,7 @@ double Item_func_atan::val_real()
       return 0.0;
     return fix_result(atan2(value,val2));
   }
-  return fix_result(atan(value));
+  return atan(value);
 }
 
 double Item_func_cos::val_real()
@@ -1721,7 +1721,7 @@ double Item_func_cos::val_real()
   double value= args[0]->val_real();
   if ((null_value=args[0]->null_value))
     return 0.0;
-  return fix_result(cos(value));
+  return cos(value);
 }
 
 double Item_func_sin::val_real()
@@ -1730,7 +1730,7 @@ double Item_func_sin::val_real()
   double value= args[0]->val_real();
   if ((null_value=args[0]->null_value))
     return 0.0;
-  return fix_result(sin(value));
+  return sin(value);
 }
 
 double Item_func_tan::val_real()