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, 7 insertions, 6 deletions

diff --git a/include/my_global.h b/include/my_global.h
index 4b0786aa826..26412d4102e 100644
--- a/include/my_global.h
+++ b/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. */