[svn-r1210] Changed parameters for function calls which figure out the buffer size for

H5Dread/H5Dwrite to use to allow the I/O calls to break up a user's buffer into
pieces that are at least as large as the sequence of bytes being written in the
fastest changing dimension.

Also fixed a hard-to-find bug in the hyperslab I/O routines which could cause
data to be corrupted when writing out fields to compound datatype data with
background preservation turned on and hyperslabs which were large enough to
require two I/O passes on a hyperslab block.  A pretty obscure situation, but
it would be worthwhile for users to upgrade to this code in order to be certain
that correct data is being written.

1 files changed, 7 insertions, 5 deletions

diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index ff0a021..b01d9dc 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -78,11 +78,13 @@ typedef struct H5S_hyper_node_tag {
     hssize_t *end;      /* Pointer to a corner of a hyperslab furthest from the origin */
     struct {
         uintn cached;   /* Flag to indicate that the block is cached (during I/O only) */
-        size_t size;     /* Size of cached block (in elements) */
-        uintn left;     /* Elements left to access in block */
+        size_t size;    /* Size of cached block (in elements) */
+        uintn rleft;    /* Read elements left to access in block */
+        uintn wleft;    /* Write elements left to access in block */
         hid_t block_id; /* Temporary buffer ID */
         uint8_t *block; /* Pointer into temporary buffer for cache */
-        uint8_t *pos;   /* Pointer to current location within block */
+        uint8_t *rpos;  /* Pointer to current read location within block */
+        uint8_t *wpos;  /* Pointer to current write location within block */
     } cinfo;
     struct H5S_hyper_node_tag *next;  /* pointer to next hyperslab in list */
 } H5S_hyper_node_t;
@@ -182,7 +184,7 @@ typedef struct H5S_fconv_t {
     
     /* Initialize file element numbering information */
     herr_t (*init)(const struct H5O_layout_t *layout, const H5S_t *space,
-		   H5S_sel_iter_t *iter);
+		   H5S_sel_iter_t *iter, size_t *min_elem_out);
 
     /* Determine optimal number of elements to transfer */
     size_t (*avail)(const H5S_t *file_space, const H5S_sel_iter_t *file_iter,
@@ -214,7 +216,7 @@ typedef struct H5S_mconv_t {
     
     /* Initialize memory element numbering information */
     herr_t (*init)(const struct H5O_layout_t *layout, const H5S_t *space,
-		   H5S_sel_iter_t *iter);
+		   H5S_sel_iter_t *iter, size_t *min_elem_out);
 
     /* Gather elements from app buffer to type conversion buffer */
     size_t (*gath)(const void *buf, size_t elmt_size,