From 9fc48a009786e78c1acf3ed7a5c74e1ef73e8b94 Mon Sep 17 00:00:00 2001
From: Quincey Koziol <koziol@hdfgroup.org>
Date: Wed, 22 Sep 2004 22:05:15 -0500
Subject: [svn-r9312] Purpose:     Bug fix.

Description:
    Allow I/O to occur on 0 element selections.

Platforms tested:
    h5committest
---
 src/H5Dio.c    | 12 ++++++------
 test/tselect.c |  7 +++++++
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/H5Dio.c b/src/H5Dio.c
index b7d9580..6c76b09 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -1134,9 +1134,8 @@ H5D_contig_read(hsize_t nelmts, H5D_t *dataset,
   	/* Sanity check dataset, then read it */
         assert(((dataset->layout.type==H5D_CONTIGUOUS && H5F_addr_defined(dataset->layout.u.contig.addr))
                 || (dataset->layout.type==H5D_CHUNKED && H5F_addr_defined(dataset->layout.u.chunk.addr)))
-            || dataset->efl.nused>0 || 
-            H5S_NULL == H5S_GET_EXTENT_TYPE(file_space) ||
-             dataset->layout.type==H5D_COMPACT);
+                || dataset->efl.nused>0 || 0 == nelmts
+                || dataset->layout.type==H5D_COMPACT);
         H5_CHECK_OVERFLOW(nelmts,hsize_t,size_t);
         status = (sconv->read)(dataset->ent.file, dxpl_cache, dxpl_id,
             dataset, (H5D_storage_t *)&(dataset->efl),
@@ -1243,8 +1242,8 @@ H5D_contig_read(hsize_t nelmts, H5D_t *dataset,
 	/* Sanity check that space is allocated, then read data from it */ 
         assert(((dataset->layout.type==H5D_CONTIGUOUS && H5F_addr_defined(dataset->layout.u.contig.addr))
                 || (dataset->layout.type==H5D_CHUNKED && H5F_addr_defined(dataset->layout.u.chunk.addr)))
-            || dataset->efl.nused>0 || 
-             dataset->layout.type==H5D_COMPACT);
+                || dataset->efl.nused>0 || 0 == nelmts
+                || dataset->layout.type==H5D_COMPACT);
         n = H5S_select_fgath(dataset->ent.file, dxpl_cache, dxpl_id,
             dataset, (H5D_storage_t *)&(dataset->efl),
             file_space, &file_iter, smine_nelmts,
@@ -1639,7 +1638,8 @@ H5D_chunk_read(hsize_t nelmts, H5D_t *dataset,
   	/* Sanity check dataset, then read it */
         assert(((dataset->layout.type==H5D_CONTIGUOUS && H5F_addr_defined(dataset->layout.u.contig.addr))
                 || (dataset->layout.type==H5D_CHUNKED && H5F_addr_defined(dataset->layout.u.chunk.addr)))
-            || dataset->efl.nused>0 || dataset->layout.type==H5D_COMPACT);
+                || dataset->efl.nused>0 || 0 == nelmts
+                || dataset->layout.type==H5D_COMPACT);
 
         /* Get first node in chunk tree */
         chunk_node=H5TB_first(fm.fsel->root);
diff --git a/test/tselect.c b/test/tselect.c
index c1d985f..c4090f8 100644
--- a/test/tselect.c
+++ b/test/tselect.c
@@ -5374,6 +5374,7 @@ test_select_none(void)
     hsize_t	dims1[] = {SPACE7_DIM1, SPACE7_DIM2};
     hsize_t	dims2[] = {SPACE7_DIM1, SPACE7_DIM2};
     uint8_t    *wbuf,           /* buffer to write to disk */
+               *rbuf,           /* buffer to read from disk */
                *tbuf;           /* temporary buffer pointer */
     int         i,j;            /* Counters */
     herr_t	ret;		/* Generic return value	*/
@@ -5383,6 +5384,7 @@ test_select_none(void)
 
     /* Allocate write & read buffers */
     wbuf=malloc(sizeof(uint8_t)*SPACE7_DIM1*SPACE7_DIM2);
+    rbuf=malloc(sizeof(uint8_t)*SPACE7_DIM1*SPACE7_DIM2);
 
     /* Initialize write buffer */
     for(i=0, tbuf=wbuf; i<SPACE7_DIM1; i++)
@@ -5412,6 +5414,10 @@ test_select_none(void)
     ret = H5Sselect_none(sid2);
     CHECK(ret, FAIL, "H5Sselect_none");
 
+    /* Attempt to read "nothing" from disk (before space is allocated) */
+    ret=H5Dread(dataset,H5T_NATIVE_UCHAR,sid2,sid1,H5P_DEFAULT,rbuf);
+    CHECK(ret, FAIL, "H5Dread");
+
     /* Write "nothing" to disk */
     ret=H5Dwrite(dataset,H5T_NATIVE_UCHAR,sid2,sid1,H5P_DEFAULT,wbuf);
     CHECK(ret, FAIL, "H5Dwrite");
@@ -5446,6 +5452,7 @@ test_select_none(void)
 
     /* Free memory buffers */
     free(wbuf);
+    free(rbuf);
 }   /* test_select_none() */
 
 /****************************************************************
-- 
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