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.

configure.in

@@ -991,8 +991,8 @@ case $SYSTEM_TYPE in
     ;;
   *hpux11.*)
     AC_MSG_WARN([Enabling workarounds for hpux 11])
-    CFLAGS="$CFLAGS -DHPUX11  -DSNPRINTF_RETURN_TRUNC -DHAVE_BROKEN_PREAD -DDONT_USE_FINITE -DHAVE_BROKEN_GETPASS -DNO_FCNTL_NONBLOCK -DDO_NOT_REMOVE_THREAD_WRAPPERS -DHAVE_BROKEN_PTHREAD_COND_TIMEDWAIT"
-    CXXFLAGS="$CXXFLAGS -DHPUX11  -DSNPRINTF_RETURN_TRUNC -DHAVE_BROKEN_PREAD -DDONT_USE_FINITE -D_INCLUDE_LONGLONG -DNO_FCNTL_NONBLOCK -DDO_NOT_REMOVE_THREAD_WRAPPERS -DHAVE_BROKEN_PTHREAD_COND_TIMEDWAIT"
+    CFLAGS="$CFLAGS -DHPUX11  -DSNPRINTF_RETURN_TRUNC -DHAVE_BROKEN_PREAD -DHAVE_BROKEN_GETPASS -DNO_FCNTL_NONBLOCK -DDO_NOT_REMOVE_THREAD_WRAPPERS -DHAVE_BROKEN_PTHREAD_COND_TIMEDWAIT"
+    CXXFLAGS="$CXXFLAGS -DHPUX11  -DSNPRINTF_RETURN_TRUNC -DHAVE_BROKEN_PREAD -D_INCLUDE_LONGLONG -DNO_FCNTL_NONBLOCK -DDO_NOT_REMOVE_THREAD_WRAPPERS -DHAVE_BROKEN_PTHREAD_COND_TIMEDWAIT"
     if test "$with_named_thread" = "no"
     then 
       AC_MSG_WARN([Using --with-named-thread=-lpthread])

include/my_global.h

@@ -486,9 +486,6 @@ C_MODE_END
 #include <sys/stream.h>		/* HPUX 10.20 defines ulong here. UGLY !!! */
 #define HAVE_ULONG
 #endif
-#ifdef DONT_USE_FINITE		/* HPUX 11.x has is_finite() */
-#undef HAVE_FINITE
-#endif
 #if defined(HPUX10) && defined(_LARGEFILE64_SOURCE) && defined(THREAD)
 /* Fix bug in setrlimit */
 #undef setrlimit
@@ -858,9 +855,13 @@ typedef SOCKET_SIZE_TYPE size_socket;
 #define SIZE_T_MAX ~((size_t) 0)
 #endif
 
-#ifndef HAVE_FINITE
+#ifndef isfinite
+#ifdef HAVE_FINITE
+#define isfinite(x) finite(x)
+#else
 #define finite(x) (1.0 / fabs(x) > 0.0)
-#endif
+#endif /* HAVE_FINITE */
+#endif /* isfinite */
 
 #ifndef HAVE_ISNAN
 #define isnan(x) ((x) != (x))
@@ -870,7 +871,7 @@ typedef SOCKET_SIZE_TYPE size_socket;
 /* isinf() can be used in both C and C++ code */
 #define my_isinf(X) isinf(X)
 #else
-#define my_isinf(X) (!finite(X) && !isnan(X))
+#define my_isinf(X) (!isfinite(X) && !isnan(X))
 #endif
 
 /* Define missing math constants. */

mysql-test/r/func_math.result

@@ -408,3 +408,22 @@ a DIV 2
 0
 DROP TABLE t1;
 End of 5.0 tests
+SELECT 1e308 + 1e308;
+1e308 + 1e308
+NULL
+SELECT -1e308 - 1e308;
+-1e308 - 1e308
+NULL
+SELECT 1e300 * 1e300;
+1e300 * 1e300
+NULL
+SELECT 1e300 / 1e-300;
+1e300 / 1e-300
+NULL
+SELECT EXP(750);
+EXP(750)
+NULL
+SELECT POW(10, 309);
+POW(10, 309)
+NULL
+End of 5.1 tests

mysql-test/r/strict.result

@@ -895,7 +895,6 @@ ERROR 22003: Out of range value for column 'col1' at row 1
 INSERT INTO t1 (col2) VALUES ('-1.2E-3');
 ERROR 22003: Out of range value for column 'col2' at row 1
 UPDATE t1 SET col1 =col1 * 5000 WHERE col1 > 0;
-ERROR 22003: Out of range value for column 'col1' at row 3
 UPDATE t1 SET col2 =col2 / 0 WHERE col2 > 0;
 ERROR 22012: Division by 0
 UPDATE t1 SET col2= MOD(col2,0) WHERE col2 > 0;
@@ -923,10 +922,10 @@ SELECT * FROM t1;
 col1	col2
 -2.2e-307	0
 1e-303	0
-1.7e+308	1.7e+308
+NULL	1.7e+308
 -2.2e-307	0
 -2e-307	0
-1.7e+308	1.7e+308
+NULL	1.7e+308
 0	NULL
 2	NULL
 NULL	NULL

mysql-test/t/func_math.test

@@ -248,5 +248,17 @@ INSERT INTO t1 VALUES ('a');
 SELECT a DIV 2 FROM t1 UNION SELECT a DIV 2 FROM t1;
 DROP TABLE t1;
 
-
 --echo End of 5.0 tests
+
+#
+# Bug #31236: Inconsistent division by zero behavior for floating point numbers
+#
+
+SELECT 1e308 + 1e308;
+SELECT -1e308 - 1e308;
+SELECT 1e300 * 1e300;
+SELECT 1e300 / 1e-300;
+SELECT EXP(750);
+SELECT POW(10, 309);
+
+--echo End of 5.1 tests

mysql-test/t/strict.test

@@ -822,7 +822,6 @@ INSERT INTO t1 (col2) VALUES (-1.1E-3);
 INSERT INTO t1 (col1) VALUES ('+1.8E+309');
 --error 1264
 INSERT INTO t1 (col2) VALUES ('-1.2E-3');
---error 1264
 UPDATE t1 SET col1 =col1 * 5000 WHERE col1 > 0;
 --error 1365
 UPDATE t1 SET col2 =col2 / 0 WHERE col2 > 0;

sql/field.cc

@@ -2263,13 +2263,11 @@ int Field_decimal::store(double nr)
     return 1;
   }
   
-#ifdef HAVE_FINITE
-  if (!finite(nr)) // Handle infinity as special case
+  if (!isfinite(nr)) // Handle infinity as special case
   {
     overflow(nr < 0.0);
     return 1;
   }
-#endif
 
   reg4 uint i;
   size_t length;

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()

sql/item_func.h

@@ -192,6 +192,13 @@ class Item_func :public Item_result_field
                      void * arg, traverse_order order);
   bool is_expensive_processor(uchar *arg);
   virtual bool is_expensive() { return 0; }
+  inline double fix_result(double value)
+  {
+    if (isfinite(value))
+      return value;
+    null_value=1;
+    return 0.0;
+  }
 };
 
 
@@ -499,18 +506,6 @@ class Item_dec_func :public Item_real_func
     decimals=NOT_FIXED_DEC; max_length=float_length(decimals);
     maybe_null=1;
   }
-  inline double fix_result(double value)
-  {
-#ifndef HAVE_FINITE
-    return value;
-#else
-    /* The following should be safe, even if we compare doubles */
-    if (finite(value) && value != POSTFIX_ERROR)
-      return value;
-    null_value=1;
-    return 0.0;
-#endif
-  }
 };
 
 class Item_func_exp :public Item_dec_func

sql/matherr.c

-/* Copyright (C) 2000-2001 MySQL AB
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; version 2 of the License.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
-
-/* Fix that we got POSTFIX_ERROR when doing unreasonable math (not core) */
-
-#include <my_global.h>
-#include <errno.h>
-
-	/* Fix that we gets POSTFIX_ERROR when error in math */
-
-#if defined(HAVE_MATHERR)
-int matherr(struct exception *x)
-{
-  if (x->type != PLOSS)
-    x->retval=POSTFIX_ERROR;
-  switch (x->type) {
-  case DOMAIN:
-  case SING:
-    my_errno=EDOM;
-    break;
-  case OVERFLOW:
-  case UNDERFLOW:
-    my_errno=ERANGE;
-    break;
-  default:
-    break;
-  }
-  return(1);					/* Take no other action */
-}
-#endif

sql/unireg.h

@@ -108,7 +108,6 @@
 
 #define READ_RECORD_BUFFER	(uint) (IO_SIZE*8) /* Pointer_buffer_size */
 #define DISK_BUFFER_SIZE	(uint) (IO_SIZE*16) /* Size of diskbuffer */
-#define POSTFIX_ERROR		DBL_MAX
 
 #define ME_INFO (ME_HOLDTANG+ME_OLDWIN+ME_NOREFRESH)
 #define ME_ERROR (ME_BELL+ME_OLDWIN+ME_NOREFRESH)