Ubsan fixes (#498)

* Fixed use of null pointer identified by UBSan

UBSan warned:
runtime error: member access within null pointer of type 'named_dt_t' (aka 'struct named_dt_t')

with these two tests:
H5REPACK-committed_dt_DFF
H5REPACK-committed_dt

Reformulated per @gnuoyd suggestion.

* Fixed undefined float -> unsigned char conversion in HL_test_image

* Removed dead skip_overflow_tests_g global

The global `skip_overflow_tests_g` was being set but never read.

* Don't treat 2d array as 1d array, fixing UBSan complaint in `CPP_testhdf5`

* Committing clang-format changes

* Remove extra ']' in line 730.

* Committing clang-format changes

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Larry Knox <lrknox@hdfgroup.org>

4 files changed, 19 insertions, 111 deletions

diff --git a/c++/test/ttypes.cpp b/c++/test/ttypes.cpp
index b633740..7d0337d 100644
--- a/c++/test/ttypes.cpp
+++ b/c++/test/ttypes.cpp
@@ -656,7 +656,6 @@ static void
 test_named()
 {
     static hsize_t ds_size[2] = {10, 20};
-    hsize_t        i;
     unsigned       attr_data[10][20];
     DataType *     ds_type = NULL;
 
@@ -726,8 +725,11 @@ test_named()
 
         // It should be possible to define an attribute for the named type
         Attribute attr1 = itype.createAttribute("attr1", PredType::NATIVE_UCHAR, space);
-        for (i = 0; i < ds_size[0] * ds_size[1]; i++)
-            attr_data[0][i] = (int)i; /*tricky*/
+        for (hsize_t i = 0; i < ds_size[0]; i++) {
+            for (hsize_t j = 0; j < ds_size[1]; j++) {
+                attr_data[i][j] = (unsigned)(i * ds_size[1] + j);
+            }
+        }
         attr1.write(PredType::NATIVE_UINT, attr_data);
         attr1.close();
 
diff --git a/hl/test/test_image.c b/hl/test/test_image.c
index 0c7d511..dc1be96 100644
--- a/hl/test/test_image.c
+++ b/hl/test/test_image.c
@@ -650,10 +650,10 @@ test_generate(void)
     HL_TESTING2("make indexed image from land data");
 
     for (i = 0; i < n_elements; i++) {
-        if (data[i] < 0)
+        if (data[i] < 0.0f)
             image_data[i] = 0;
         else
-            image_data[i] = (unsigned char)((255 * (data[i])) / xmax);
+            image_data[i] = (unsigned char)((255 * data[i]) / xmax);
     }
 
     /* make the image */
@@ -671,10 +671,11 @@ test_generate(void)
     HL_TESTING2("make indexed image from sea data");
 
     for (i = 0; i < n_elements; i++) {
-        if (data[i] > 0)
+        if (data[i] > 0.0f)
             image_data[i] = 0;
-        else
-            image_data[i] = (unsigned char)((255 * (data[i] - xmin)) / xmin);
+        else {
+            image_data[i] = (unsigned char)((255.0f * (data[i] - xmin)) / (xmax - xmin));
+        }
     }
 
     /* make the image */
diff --git a/test/dt_arith.c b/test/dt_arith.c
index f2bf6cf..ddc8814 100644
--- a/test/dt_arith.c
+++ b/test/dt_arith.c
@@ -74,9 +74,6 @@ typedef enum dtype_t {
     OTHER
 } dtype_t;
 
-/* Skip overflow tests if non-zero */
-static int skip_overflow_tests_g = 0;
-
 /*
  * Although we check whether a floating point overflow generates a SIGFPE and
  * turn off overflow tests in that case, it might still be possible for an
@@ -394,7 +391,6 @@ static int without_hardware_g = 0;
         HDfree(value);                                                                                       \
     }
 
-void           some_dummy_func(float x);
 static hbool_t overflows(unsigned char *origin_bits, hid_t src_id, size_t dst_num_bits);
 static int     my_isnan(dtype_t type, void *val);
 static int my_isinf(int endian, const unsigned char *val, size_t size, size_t mpos, size_t msize, size_t epos,
@@ -515,92 +511,6 @@ except_func(H5T_conv_except_t except_type, hid_t H5_ATTR_UNUSED src_id, hid_t H5
 }
 
 /*-------------------------------------------------------------------------
- * Function:    some_dummy_func
- *
- * Purpose:    A dummy function to help check for overflow.
- *
- * Note:    DO NOT DECLARE THIS FUNCTION STATIC OR THE COMPILER MIGHT
- *        PROMOTE ARGUMENT `x' TO DOUBLE AND DEFEAT THE OVERFLOW
- *        CHECKING.
- *
- * Return:    void
- *
- * Programmer:    Robb Matzke
- *              Tuesday, July 21, 1998
- *
- *-------------------------------------------------------------------------
- */
-void
-some_dummy_func(float x)
-{
-    char s[128];
-
-    HDsnprintf(s, sizeof(s), "%g", (double)x);
-}
-
-/*-------------------------------------------------------------------------
- * Function:    generates_sigfpe
- *
- * Purpose:    Determines if SIGFPE is generated from overflows.  We must be
- *        able to fork() and waitpid() in order for this test to work
- *        properly.  Sets skip_overflow_tests_g to non-zero if they
- *        would generate SIGBUS, zero otherwise.
- *
- * Programmer:    Robb Matzke
- *              Tuesday, July 21, 1998
- *
- * Modifications:
- *
- *-------------------------------------------------------------------------
- */
-static void
-generates_sigfpe(void)
-{
-#ifdef H5_HAVE_UNISTD_H
-    pid_t          pid;
-    int            status;
-    size_t         i, j;
-    double         d;
-    unsigned char *dp = (unsigned char *)&d;
-    float          f;
-
-    HDfflush(stdout);
-    HDfflush(stderr);
-    if ((pid = HDfork()) < 0) {
-        HDperror("fork");
-        HDexit(EXIT_FAILURE);
-    }
-    else if (0 == pid) {
-        for (i = 0; i < 2000; i++) {
-            for (j = 0; j < sizeof(double); j++)
-                dp[j] = (unsigned char)HDrand();
-            f = (float)d;
-            some_dummy_func((float)f);
-        }
-        HDexit(EXIT_SUCCESS);
-    }
-
-    while (pid != HDwaitpid(pid, &status, 0))
-        /*void*/;
-    if (WIFEXITED(status) && 0 == WEXITSTATUS(status)) {
-        HDputs("Floating-point overflow cases will be tested.");
-        skip_overflow_tests_g = FALSE;
-    }
-    else if (WIFSIGNALED(status) && SIGFPE == WTERMSIG(status)) {
-        HDputs("Floating-point overflow cases cannot be safely tested.");
-        skip_overflow_tests_g = TRUE;
-        /* delete the core dump file that SIGFPE may have created */
-        HDunlink("core");
-    }
-#else  /* H5_HAVE_UNISTD_H */
-    HDputs("Cannot determine if floating-point overflows generate a SIGFPE");
-    HDputs("due to a lack of fork(2) - assuming yes.");
-    HDputs("Overflow cases will not be tested.");
-    skip_overflow_tests_g = TRUE;
-#endif /* H5_HAVE_UNISTD_H */
-}
-
-/*-------------------------------------------------------------------------
  * Function:    test_hard_query
  *
  * Purpose:     Tests H5Tcompiler_conv() for querying whether a conversion is
@@ -5406,9 +5316,6 @@ main(void)
      * for user-defined integer types */
     nerrors += (unsigned long)test_derived_integer();
 
-    /* Does floating point overflow generate a SIGFPE? */
-    generates_sigfpe();
-
     /* Test degenerate cases */
     nerrors += (unsigned long)run_fp_tests("noop");
 
diff --git a/tools/src/h5repack/h5repack.c b/tools/src/h5repack/h5repack.c
index 7bcca8f..7cad36b 100644
--- a/tools/src/h5repack/h5repack.c
+++ b/tools/src/h5repack/h5repack.c
@@ -225,9 +225,9 @@ hid_t
 copy_named_datatype(hid_t type_in, hid_t fidout, named_dt_t **named_dt_head_p, trav_table_t *travt,
                     pack_opt_t *options)
 {
-    named_dt_t *dt     = *named_dt_head_p; /* Stack pointer */
-    named_dt_t *dt_ret = NULL;             /* Datatype to return */
-    H5O_info2_t oinfo;                     /* Object info of input dtype */
+    named_dt_t *dt     = NULL; /* Stack pointer */
+    named_dt_t *dt_ret = NULL; /* Datatype to return */
+    H5O_info2_t oinfo;         /* Object info of input dtype */
     int         token_cmp;
     hid_t       ret_value = H5I_INVALID_HID;
 
@@ -235,15 +235,13 @@ copy_named_datatype(hid_t type_in, hid_t fidout, named_dt_t **named_dt_head_p, t
         H5TOOLS_GOTO_ERROR(H5I_INVALID_HID, "H5Oget_info failed");
 
     if (*named_dt_head_p) {
-        if (H5Otoken_cmp(type_in, &dt->obj_token, &oinfo.token, &token_cmp) < 0)
-            H5TOOLS_GOTO_ERROR(H5I_INVALID_HID, "failed to compare object tokens");
-
-        /* Stack already exists, search for the datatype */
-        while (dt && token_cmp) {
-            dt = dt->next;
-
+        /* Search the stack for the datatype. */
+        for (dt = *named_dt_head_p; dt != NULL; dt = dt->next) {
             if (H5Otoken_cmp(type_in, &dt->obj_token, &oinfo.token, &token_cmp) < 0)
                 H5TOOLS_GOTO_ERROR(H5I_INVALID_HID, "failed to compare object tokens");
+
+            if (token_cmp == 0)
+                break; // found it!
         }
 
         dt_ret = dt;