rest_vol_dataset: (fix) Write hyperslab (memory)

- Improved the function RV_dataset_write() such it makes use
  of the function H5Dgather() to gather the data needed
  for writing a hyperslab (memory) to a file. This approach
  is similar to the one found in the function RV_dataset_read().
- Adapted the hyperslab and point selection test.

src/rest_vol_dataset.c

@@ -829,6 +829,13 @@ RV_dataset_write(size_t count, void *dset[], hid_t mem_type_id[], hid_t mem_spac
             FUNC_GOTO_ERROR(H5E_DATATYPE, H5E_BADVALUE, FAIL, "memory datatype is invalid");
 
         write_body_len = (size_t)file_select_npoints * dtype_size;
+        if (NULL == (write_body = (char *)RV_malloc(write_body_len)))
+            FUNC_GOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL,
+                            "can't allocate space for the 'write_body' values");
+        if (H5Dgather(mem_space_id[0], buf[0], mem_type_id[0], write_body_len, write_body, NULL,
+                      write_body) < 0)
+            FUNC_GOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "can't gather data to write buffer");
+        buf[0] = write_body;
     } /* end if */
     else {
         if (H5T_STD_REF_OBJ == mem_type_id[0]) {

test/test_rest_vol.c

@@ -8539,6 +8539,7 @@ test_write_dataset_data_verification(void)
 {
     hssize_t space_npoints;
     hsize_t  dims[DATASET_DATA_VERIFY_WRITE_TEST_DSET_SPACE_RANK] = {10, 10, 10};
+    hsize_t  mdims[1];
     hsize_t  start[DATASET_DATA_VERIFY_WRITE_TEST_DSET_SPACE_RANK];
     hsize_t  stride[DATASET_DATA_VERIFY_WRITE_TEST_DSET_SPACE_RANK];
     hsize_t  count[DATASET_DATA_VERIFY_WRITE_TEST_DSET_SPACE_RANK];
@@ -8550,6 +8551,7 @@ test_write_dataset_data_verification(void)
     hid_t  container_group = -1;
     hid_t  dset_id         = -1;
     hid_t  fspace_id       = -1;
+    hid_t  mspace_id       = -1;
     void  *data            = NULL;
     void  *write_buf       = NULL;
     void  *read_buf        = NULL;
@@ -8697,23 +8699,34 @@ test_write_dataset_data_verification(void)
     }
 
     /* Write to first two rows of dataset */
+    mdims[0]  = dims[1] * 2;
+    start[0]  = 0;
+    stride[0] = 1;
+    count[0]  = dims[1] * 2;
+    block[0]  = 1;
+    if ((mspace_id = H5Screate_simple(1, mdims, NULL)) < 0)
+        TEST_ERROR
+    if (H5Sselect_hyperslab(mspace_id, H5S_SELECT_SET, start, stride, count, block) < 0)
+        TEST_ERROR
+
     start[0] = start[1] = start[2] = 0;
     stride[0] = stride[1] = stride[2] = 1;
     count[0]                          = 2;
     count[1]                          = dims[1];
     count[2]                          = 1;
     block[0] = block[1] = block[2] = 1;
-
     if (H5Sselect_hyperslab(fspace_id, H5S_SELECT_SET, start, stride, count, block) < 0)
         TEST_ERROR
 
-    if (H5Dwrite(dset_id, DATASET_DATA_VERIFY_WRITE_TEST_DSET_DTYPE, H5S_ALL, fspace_id, H5P_DEFAULT,
+    if (H5Dwrite(dset_id, DATASET_DATA_VERIFY_WRITE_TEST_DSET_DTYPE, mspace_id, fspace_id, H5P_DEFAULT,
                  write_buf) < 0) {
         H5_FAILED();
         printf("    couldn't write to dataset\n");
         goto error;
     }
 
+    if (H5Sclose(mspace_id) < 0)
+        TEST_ERROR
     if (H5Sclose(fspace_id) < 0)
         TEST_ERROR
     if (H5Dclose(dset_id) < 0)
@@ -8814,6 +8827,15 @@ test_write_dataset_data_verification(void)
     }
 
     /* Select a series of 10 points in the dataset */
+    mdims[0] = DATASET_DATA_VERIFY_WRITE_TEST_NUM_POINTS;
+    if ((mspace_id = H5Screate_simple(1, mdims, NULL)) < 0)
+        TEST_ERROR
+    for (i = 0; i < DATASET_DATA_VERIFY_WRITE_TEST_NUM_POINTS; i++) {
+        points[i] = i;
+    }
+    if (H5Sselect_elements(mspace_id, H5S_SELECT_SET, DATASET_DATA_VERIFY_WRITE_TEST_NUM_POINTS, points) < 0)
+        TEST_ERROR
+
     for (i = 0; i < DATASET_DATA_VERIFY_WRITE_TEST_NUM_POINTS; i++) {
         size_t j;
 
@@ -8824,13 +8846,15 @@ test_write_dataset_data_verification(void)
     if (H5Sselect_elements(fspace_id, H5S_SELECT_SET, DATASET_DATA_VERIFY_WRITE_TEST_NUM_POINTS, points) < 0)
         TEST_ERROR
 
-    if (H5Dwrite(dset_id, DATASET_DATA_VERIFY_WRITE_TEST_DSET_DTYPE, H5S_ALL, fspace_id, H5P_DEFAULT,
+    if (H5Dwrite(dset_id, DATASET_DATA_VERIFY_WRITE_TEST_DSET_DTYPE, mspace_id, fspace_id, H5P_DEFAULT,
                  write_buf) < 0) {
         H5_FAILED();
         printf("    couldn't write to dataset\n");
         goto error;
     }
 
+    if (H5Sclose(mspace_id) < 0)
+        TEST_ERROR
     if (H5Sclose(fspace_id) < 0)
         TEST_ERROR
     if (H5Dclose(dset_id) < 0)