Disable FP exceptions in H5T init code (#3837)

The H5T floating-point datatype initialization code can raise exceptions when handling signaling NaNs. This change disables FE_INVALID exceptions during initialization.

Also removes the -ieee=full change for NAG Fortran as that shouldn't be necessary anymore.

Fixes #3831

2 files changed, 37 insertions, 18 deletions

diff --git a/src/H5Tinit_float.c b/src/H5Tinit_float.c
index 3b9e127..3213f00 100644
--- a/src/H5Tinit_float.c
+++ b/src/H5Tinit_float.c
@@ -51,19 +51,23 @@
  * Function:    DETECT_F
  *
  * Purpose:     This macro takes a floating point type like `double' and
- *              a base name like `natd' and detects byte order, mantissa
- *              location, exponent location, sign bit location, presence or
- *              absence of implicit mantissa bit, and exponent bias and
- *              initializes a detected_t structure with those properties.
+ *              and detects byte order, mantissa location, exponent location,
+ *              sign bit location, presence or absence of implicit mantissa
+ *              bit, and exponent bias and initializes a detected_t structure
+ *              with those properties.
+ *
+ *              Note that these operations can raise floating-point
+ *              exceptions and building with some compiler options
+ *              (especially Fortran) can cause problems.
  *-------------------------------------------------------------------------
  */
-#define DETECT_F(TYPE, VAR, INFO)                                                                            \
+#define DETECT_F(TYPE, INFO)                                                                                 \
     do {                                                                                                     \
-        TYPE          _v1, _v2, _v3;                                                                         \
-        unsigned char _buf1[sizeof(TYPE)], _buf3[sizeof(TYPE)];                                              \
-        unsigned char _pad_mask[sizeof(TYPE)];                                                               \
-        unsigned char _byte_mask;                                                                            \
-        int           _i, _j, _last = (-1);                                                                  \
+        TYPE    _v1, _v2, _v3;                                                                               \
+        uint8_t _buf1[sizeof(TYPE)], _buf3[sizeof(TYPE)];                                                    \
+        uint8_t _pad_mask[sizeof(TYPE)];                                                                     \
+        uint8_t _byte_mask;                                                                                  \
+        int     _i, _j, _last = -1;                                                                          \
                                                                                                              \
         memset(&INFO, 0, sizeof(INFO));                                                                      \
         INFO.size = sizeof(TYPE);                                                                            \
@@ -81,7 +85,7 @@
         _v1 = (TYPE)4.0L;                                                                                    \
         H5MM_memcpy(_buf1, (const void *)&_v1, sizeof(TYPE));                                                \
         for (_i = 0; _i < (int)sizeof(TYPE); _i++)                                                           \
-            for (_byte_mask = (unsigned char)1; _byte_mask; _byte_mask = (unsigned char)(_byte_mask << 1)) { \
+            for (_byte_mask = (uint8_t)1; _byte_mask; _byte_mask = (uint8_t)(_byte_mask << 1)) {             \
                 _buf1[_i] ^= _byte_mask;                                                                     \
                 H5MM_memcpy((void *)&_v2, (const void *)_buf1, sizeof(TYPE));                                \
                 H5_GCC_CLANG_DIAG_OFF("float-equal")                                                         \
@@ -118,7 +122,7 @@
         _v1 = (TYPE)1.0L;                                                                                    \
         _v2 = (TYPE)-1.0L;                                                                                   \
         if (H5T__bit_cmp(sizeof(TYPE), INFO.perm, &_v1, &_v2, _pad_mask, &(INFO.sign)) < 0)                  \
-            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "failed to detect byte order");                    \
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "failed to determine sign bit");                   \
                                                                                                              \
         /* Mantissa */                                                                                       \
         INFO.mpos = 0;                                                                                       \
@@ -126,12 +130,11 @@
         _v1 = (TYPE)1.0L;                                                                                    \
         _v2 = (TYPE)1.5L;                                                                                    \
         if (H5T__bit_cmp(sizeof(TYPE), INFO.perm, &_v1, &_v2, _pad_mask, &(INFO.msize)) < 0)                 \
-            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "failed to detect byte order");                    \
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "failed to determine mantissa");                   \
         INFO.msize += 1 + (unsigned)(INFO.imp ? 0 : 1) - INFO.mpos;                                          \
                                                                                                              \
         /* Exponent */                                                                                       \
-        INFO.epos = INFO.mpos + INFO.msize;                                                                  \
-                                                                                                             \
+        INFO.epos  = INFO.mpos + INFO.msize;                                                                 \
         INFO.esize = INFO.sign - INFO.epos;                                                                  \
                                                                                                              \
         _v1        = (TYPE)1.0L;                                                                             \
@@ -456,17 +459,24 @@ H5T__set_precision(H5T_fpoint_det_t *d)
 herr_t H5_NO_UBSAN
 H5T__init_native_float_types(void)
 {
+    fenv_t           saved_fenv;
     H5T_fpoint_det_t det;
     H5T_t           *dt        = NULL;
     herr_t           ret_value = SUCCEED;
 
     FUNC_ENTER_PACKAGE
 
+    /* Turn off floating-point exceptions while initializing to avoid
+     * tripping over signaling NaNs while looking at "don't care" bits.
+     */
+    if (feholdexcept(&saved_fenv) != 0)
+        HSYS_GOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "can't save floating-point environment");
+
     /* H5T_NATIVE_FLOAT */
 
     /* Get the type's characteristics */
     memset(&det, 0, sizeof(H5T_fpoint_det_t));
-    DETECT_F(float, FLOAT, det);
+    DETECT_F(float, det);
 
     /* Allocate and fill type structure */
     if (NULL == (dt = H5T__alloc()))
@@ -497,7 +507,7 @@ H5T__init_native_float_types(void)
 
     /* Get the type's characteristics */
     memset(&det, 0, sizeof(H5T_fpoint_det_t));
-    DETECT_F(double, DOUBLE, det);
+    DETECT_F(double, det);
 
     /* Allocate and fill type structure */
     if (NULL == (dt = H5T__alloc()))
@@ -528,7 +538,7 @@ H5T__init_native_float_types(void)
 
     /* Get the type's characteristics */
     memset(&det, 0, sizeof(H5T_fpoint_det_t));
-    DETECT_F(long double, LDOUBLE, det);
+    DETECT_F(long double, det);
 
     /* Allocate and fill type structure */
     if (NULL == (dt = H5T__alloc()))
@@ -561,6 +571,14 @@ H5T__init_native_float_types(void)
     H5T_native_order_g = det.order;
 
 done:
+    /* Clear any FE_INVALID exceptions from NaN handling */
+    if (feclearexcept(FE_INVALID) != 0)
+        HSYS_GOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "can't clear floating-point exceptions");
+
+    /* Restore the original environment */
+    if (feupdateenv(&saved_fenv) != 0)
+        HSYS_GOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "can't restore floating-point environment");
+
     if (ret_value < 0) {
         if (dt != NULL) {
             dt->shared = H5FL_FREE(H5T_shared_t, dt->shared);
diff --git a/src/H5private.h b/src/H5private.h
index 14a0ac3..3aaa0d5 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -26,6 +26,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <fenv.h>
 #include <float.h>
 #include <math.h>
 #include <setjmp.h>