[svn-r23237] Purpose: Implement H5Dscatter and H5Dgather

Description:
Adds 2 new API functions, H5Dscatter and H5Dgather.  H5Dscatter retrieves data
from a specified callback function and scatters it into a selection, defined by
a supplied dataspace, within a supplied memory buffer.  H5Dgather gathers data
from a selection within a supplied memory buffer and passes it in a contiguous
form to a supplied callback function.  Added tests for these functions

Tested: jam, ostrich, koala (h5committest); ummon

2 files changed, 24 insertions, 4 deletions

diff --git a/src/H5Dscatgath.c b/src/H5Dscatgath.c
index 74d6749..60a8800 100644
--- a/src/H5Dscatgath.c
+++ b/src/H5Dscatgath.c
@@ -1048,8 +1048,6 @@ H5Dgather(hid_t src_space_id, void *src_buf, hid_t type_id, size_t dst_buf_size,
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "destination buffer size is 0")
     if(dst_buf == NULL)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no destination buffer provided")
-    if(op == NULL)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid callback function pointer")
 
     /* Fill the DXPL cache values for later use */
     if(H5D__get_dxpl_cache(H5P_DATASET_XFER_DEFAULT, &dxpl_cache) < 0)
@@ -1068,6 +1066,11 @@ H5Dgather(hid_t src_space_id, void *src_buf, hid_t type_id, size_t dst_buf_size,
     if((nelmts = (hssize_t)H5S_GET_SELECT_NPOINTS(src_space)) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTCOUNT, FAIL, "unable to get number of elements in selection")
 
+    /* If dst_buf is not large enough to hold all the elements, make sure there
+     * is a callback */
+    if(((size_t)nelmts > dst_buf_nelmts) && (op == NULL))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no callback supplied and destination buffer too small")
+
     /* Initialize selection iterator */
     if(H5S_select_iter_init(&iter, src_space, type_size) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize selection iterator information")
@@ -1081,10 +1084,11 @@ H5Dgather(hid_t src_space_id, void *src_buf, hid_t type_id, size_t dst_buf_size,
         HDassert(nelmts_gathered == MIN(dst_buf_nelmts, (size_t)nelmts));
 
         /* Make callback to process dst_buf */
-        if(op(dst_buf, nelmts_gathered * type_size, op_data) < 0)
+        if(op && op(dst_buf, nelmts_gathered * type_size, op_data) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CALLBACK, FAIL, "callback operator returned failure")
 
         nelmts -= (hssize_t)nelmts_gathered;
+        HDassert(op || (nelmts == 0));
     } /* end while */
 
 done:
diff --git a/test/dsets.c b/test/dsets.c
index 7689a81..7abe818 100644
--- a/test/dsets.c
+++ b/test/dsets.c
@@ -8624,6 +8624,22 @@ test_gather(void)
         if(gather_info.expect_dst_buf - expect_dst_buf != 8) TEST_ERROR
     } /* end for */
 
+    /* Test without a callback */
+    /* Loop over buffer sizes */
+    for(dst_buf_size=8; dst_buf_size<=9; dst_buf_size++) {
+        /* Reset dst_buf */
+        (void)HDmemset(dst_buf, 0, sizeof(dst_buf));
+
+        /* Gather data */
+        if(H5Dgather(sid, src_buf, H5T_NATIVE_INT, dst_buf_size * sizeof(dst_buf[0]), dst_buf, NULL, NULL) < 0)
+            TEST_ERROR
+
+        /* Verify data */
+        for(i=0; i<(int)(sizeof(dst_buf)/sizeof(dst_buf[0])); i++)
+            if(dst_buf[i] != expect_dst_buf[i])
+                TEST_ERROR
+    } /* end for */
+
     /* Test with a dst_buf_size that is not a multiple of the datatype size */
     /* Reset dst_buf */
     dst_buf_size = 7;
@@ -9155,7 +9171,7 @@ test_gather_error(void)
     gather_info.expect_dst_buf = expect_dst_buf;
     gather_info.last_call = FALSE;
     H5E_BEGIN_TRY {
-        ret = H5Dgather(sid, src_buf, H5T_NATIVE_INT, 6 * sizeof(dst_buf[0]), dst_buf, NULL, &gather_info);
+        ret = H5Dgather(sid, src_buf, H5T_NATIVE_INT, 5 * sizeof(dst_buf[0]), dst_buf, NULL, &gather_info);
     } H5E_END_TRY
     if(ret >= 0) TEST_ERROR