Restore rand_r in a few parallel tests (#4749)

The t_pmulti_dset and t_select_io_dset tests rely on the behavior
of the previous private rand_r-like implementation to get the
correct sequence of random numbers to pass. This has been restored
using a fully private rand_r-like implementation that doesn't
rely on rand_r and will work on Windows and other platforms
where rand_r doesn't exist.

test/h5test.c

@@ -2563,3 +2563,24 @@ h5_driver_uses_multiple_files(const char *drv_name, unsigned flags)
 
  return ret_val;
 }
+
+/* Deterministic random number functions that don't modify the underlying
+ * C/POSIX library rand/random state, as this can cause spurious test failures.
+ *
+ * Adapted from the example code in the POSIX.1-2001 standard.
+ */
+
+static unsigned int next_g = 1;
+
+int
+h5_local_rand(void)
+{
+ next_g = next_g * 1103515245 + 12345;
+ return next_g & RAND_MAX;
+}
+
+void
+h5_local_srand(unsigned int seed)
+{
+ next_g = seed;
+}

test/h5test.h

@@ -319,6 +319,14 @@ H5TEST_DLL herr_t h5_using_parallel_driver(hid_t fapl_id, bool *driver_i
 H5TEST_DLL herr_t h5_driver_is_default_vfd_compatible(hid_t fapl_id, bool *default_vfd_compatible);
 H5TEST_DLL bool h5_driver_uses_multiple_files(const char *drv_name, unsigned flags);
 
+/* Random number functions that don't modify the underlying rand/random state.
+ * These use rand_r with a state pointer under the hood. The state is always
+ * initialized to the same value so that each process in the parallel tests
+ * always gets the same sequence.
+ */
+H5TEST_DLL int h5_local_rand(void);
+H5TEST_DLL void h5_local_srand(unsigned int seed);
+
 /* Functions that will replace components of a FAPL */
 H5TEST_DLL herr_t h5_get_vfd_fapl(hid_t fapl_id);
 H5TEST_DLL herr_t h5_get_libver_fapl(hid_t fapl_id);

testpar/t_pmulti_dset.c

@@ -267,7 +267,7 @@ test_pmdset(size_t niter, unsigned flags)
  for (i = 0; i < niter; i++) {
  /* Determine number of datasets */
  ndsets = (flags & MDSET_FLAG_MLAYOUT) ? 3
- : (flags & MDSET_FLAG_MDSET) ? (size_t)((size_t)rand() % max_dsets) + 1
+ : (flags & MDSET_FLAG_MDSET) ? (size_t)((size_t)h5_local_rand() % max_dsets) + 1
  : 1;
 
  /* Create file */
@@ -280,27 +280,27 @@ test_pmdset(size_t niter, unsigned flags)
  (flags & MDSET_FLAG_CHUNK) || ((flags & MDSET_FLAG_MLAYOUT) && (j == 1 || j == 2));
 
  /* Generate file dataspace */
- dset_dims[j][0] = (hsize_t)((rand() % MAX_DSET_X) + 1);
- dset_dims[j][1] = (hsize_t)((rand() % MAX_DSET_Y) + 1);
+ dset_dims[j][0] = (hsize_t)((h5_local_rand() % MAX_DSET_X) + 1);
+ dset_dims[j][1] = (hsize_t)((h5_local_rand() % MAX_DSET_Y) + 1);
  if ((file_space_ids[j] = H5Screate_simple(2, dset_dims[j], use_chunk ? max_dims : NULL)) < 0)
  T_PMD_ERROR;
 
  /* Generate chunk if called for by configuration (multi layout uses chunked for datasets
  * 1 and 2) */
  if (use_chunk) {
- chunk_dims[0] = (hsize_t)((rand() % MAX_CHUNK_X) + 1);
- chunk_dims[1] = (hsize_t)((rand() % MAX_CHUNK_Y) + 1);
+ chunk_dims[0] = (hsize_t)((h5_local_rand() % MAX_CHUNK_X) + 1);
+ chunk_dims[1] = (hsize_t)((h5_local_rand() % MAX_CHUNK_Y) + 1);
  if (H5Pset_chunk(dcpl_id[j], 2, chunk_dims) < 0)
  T_PMD_ERROR;
  } /* end if */
 
  /* Create dataset */
  /* If MDSET_FLAG_TCONV is set, use a different datatype with 50% probability, so
  * some datasets require type conversion and others do not */
- if ((dset_ids[j] =
- H5Dcreate2(file_id, dset_name[j],
- (flags & MDSET_FLAG_TCONV && rand() % 2) ? H5T_NATIVE_LONG : H5T_NATIVE_UINT,
- file_space_ids[j], H5P_DEFAULT, dcpl_id[j], H5P_DEFAULT)) < 0)
+ if ((dset_ids[j] = H5Dcreate2(file_id, dset_name[j],
+  (flags & MDSET_FLAG_TCONV && h5_local_rand() % 2) ? H5T_NATIVE_LONG
+   : H5T_NATIVE_UINT,
+  file_space_ids[j], H5P_DEFAULT, dcpl_id[j], H5P_DEFAULT)) < 0)
  T_PMD_ERROR;
  } /* end for */
 
@@ -325,7 +325,7 @@ test_pmdset(size_t niter, unsigned flags)
  /* Perform read/write operations */
  for (j = 0; j < OPS_PER_FILE; j++) {
  /* Decide whether to read or write */
- do_read = (bool)(rand() % 2);
+ do_read = (bool)(h5_local_rand() % 2);
 
  /* Barrier to ensure processes have finished the previous operation
  */
@@ -387,9 +387,9 @@ test_pmdset(size_t niter, unsigned flags)
  (int)((unsigned)max_dsets * MAX_DSET_X * MAX_DSET_Y) * ((int)l - (int)mpi_rank);
 
  /* Decide whether to do a hyperslab or point selection */
- if (rand() % 2) {
+ if (h5_local_rand() % 2) {
  /* Hyperslab */
- size_t nhs = (size_t)((rand() % MAX_HS) + 1); /* Number of hyperslabs */
+ size_t nhs = (size_t)((h5_local_rand() % MAX_HS) + 1); /* Number of hyperslabs */
  size_t max_hs_x = (MAX_HS_X <= dset_dims[k][0])
  ? MAX_HS_X
  : dset_dims[k][0]; /* Determine maximum hyperslab size in X */
@@ -401,14 +401,16 @@ test_pmdset(size_t niter, unsigned flags)
  overlap = true;
  for (n = 0; overlap && (n < MAX_SEL_RETRIES); n++) {
  /* Generate hyperslab */
- count[m][0] = (hsize_t)(((hsize_t)rand() % max_hs_x) + 1);
- count[m][1] = (hsize_t)(((hsize_t)rand() % max_hs_y) + 1);
- start[m][0] = (count[m][0] == dset_dims[k][0])
- ? 0
- : (hsize_t)rand() % (dset_dims[k][0] - count[m][0] + 1);
- start[m][1] = (count[m][1] == dset_dims[k][1])
- ? 0
- : (hsize_t)rand() % (dset_dims[k][1] - count[m][1] + 1);
+ count[m][0] = (hsize_t)(((hsize_t)h5_local_rand() % max_hs_x) + 1);
+ count[m][1] = (hsize_t)(((hsize_t)h5_local_rand() % max_hs_y) + 1);
+ start[m][0] =
+ (count[m][0] == dset_dims[k][0])
+ ? 0
+ : (hsize_t)h5_local_rand() % (dset_dims[k][0] - count[m][0] + 1);
+ start[m][1] =
+ (count[m][1] == dset_dims[k][1])
+ ? 0
+ : (hsize_t)h5_local_rand() % (dset_dims[k][1] - count[m][1] + 1);
 
  /* If writing, check for overlap with other processes */
  overlap = false;
@@ -460,7 +462,8 @@ test_pmdset(size_t niter, unsigned flags)
  } /* end if */
  else {
  /* Point selection */
- size_t npoints = (size_t)(((size_t)rand() % MAX_POINTS) + 1); /* Number of points */
+ size_t npoints =
+ (size_t)(((size_t)h5_local_rand() % MAX_POINTS) + 1); /* Number of points */
 
  /* Reset dataset usage array if reading, since in this case we don't care
  * about overlapping selections between processes */
@@ -472,8 +475,8 @@ test_pmdset(size_t niter, unsigned flags)
  overlap = true;
  for (n = 0; overlap && (n < MAX_SEL_RETRIES); n++) {
  /* Generate point */
- points[2 * m] = (unsigned)((hsize_t)rand() % dset_dims[k][0]);
- points[(2 * m) + 1] = (unsigned)((hsize_t)rand() % dset_dims[k][1]);
+ points[2 * m] = (unsigned)((hsize_t)h5_local_rand() % dset_dims[k][0]);
+ points[(2 * m) + 1] = (unsigned)((hsize_t)h5_local_rand() % dset_dims[k][1]);
 
  /* Check for overlap with other processes (write) or this process
  * (always) */
@@ -664,7 +667,7 @@ main(int argc, char *argv[])
 
  /* Seed random number generator with shared seed (so all ranks generate the
  * same sequence) */
- srand(seed);
+ h5_local_srand(seed);
 
  /* Fill dset_name array */
  for (i = 0; i < MAX_DSETS; i++) {

testpar/t_select_io_dset.c

@@ -1588,7 +1588,7 @@ test_multi_dsets_no_bkg(hid_t fid, unsigned chunked, unsigned dtrans, unsigned s
  mwbuf ? "mwbuf" : "nomwbuf");
 
  /* Flip a coin to see if we're doing type conversion */
- tconv = rand() % 2;
+ tconv = h5_local_rand() % 2;
  if (tconv)
  any_tconv = true;
 
@@ -2079,7 +2079,7 @@ test_multi_dsets_cmpd_with_bkg(hid_t fid, unsigned chunked, unsigned select, uns
  }
 
  /* Case c */
- mm = rand() % (int)ndsets;
+ mm = h5_local_rand() % (int)ndsets;
  if (!mm)
  mm++;
 
@@ -2719,9 +2719,9 @@ test_multi_dsets_conv_sel_empty(hid_t fid, unsigned chunked, unsigned dtrans, un
  P_TEST_ERROR;
  }
  else {
- if ((dset_dids[i] =
- H5Dcreate2(fid, dset_names[i], ((rand() % 2) ? H5T_NATIVE_LLONG : H5T_NATIVE_SHORT),
- file_sids[i], H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0)
+ if ((dset_dids[i] = H5Dcreate2(fid, dset_names[i],
+  ((h5_local_rand() % 2) ? H5T_NATIVE_LLONG : H5T_NATIVE_SHORT),
+  file_sids[i], H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0)
  P_TEST_ERROR;
  }
  }
@@ -2790,7 +2790,7 @@ test_multi_dsets_conv_sel_empty(hid_t fid, unsigned chunked, unsigned dtrans, un
  * process 0: get 0 row; other processes: hyperslab
  */
 
- mm = rand() % (int)ndsets;
+ mm = h5_local_rand() % (int)ndsets;
  if (mm == 0)
  mm++;
 
@@ -3169,7 +3169,7 @@ test_multi_dsets_all(int niter, hid_t fid, unsigned chunked, unsigned select, un
  if ((mem_sids[i] = H5Screate_simple(1, block, NULL)) < 0)
  P_TEST_ERROR;
 
- mm = rand() % (int)ndsets;
+ mm = h5_local_rand() % (int)ndsets;
  if (mm == 0) {
  dset_types[i] = DSET_WITH_NO_CONV;
  snprintf(dset_names[i], sizeof(dset_names[i]), "multi_all_nconv_dset%d_%s_%s_%s", i,