[svn-r9329]

Purpose:
Feature

Description:
Datatypes and groups now use H5FO "file object" code that was previously
only used by datasets.  These objects will hold a file open if the file
is closed but they have not yet been closed.  If these objects are unlinked
then relinked, they will not be destroyed.  If they are opened twice (even
by two different names), both IDs will "see" changes made to the object
using the other ID.
When an object is opened using two different names (e.g., if a dataset was
opened under one name, then mounted and opened under its new name), calling
H5Iget_name() on a given hid_t will return the name used to open that hid_t,
not the current name of the object (this is a feature, and a change from the
previous behavior of datasets).

Solution:
Used H5FO code that was already in place for datasets.  Broke H5D_t's, H5T_t's,
and H5G_t's into a "shared" struct and a private struct.  The shared structs
(H5D_shared_t, etc.) hold the object's information and are used by all IDs
that point to a given object in the file.  The private structs are pointed
to by the hid_t and contain the object's group entry information (including its
name) and a pointer to the shared struct for that object.
This changed the naming of structs throughout the library (e.g., datatype->size
is now datatype->shared->size).  I added an updated H5Tinit.c to windows.zip.

Platforms tested:
Visual Studio 7, sleipnir, arabica, verbena

Misc. update:

1 files changed, 11 insertions, 3 deletions

diff --git a/src/H5Dpkg.h b/src/H5Dpkg.h
index 8b88e92..293d869 100644
--- a/src/H5Dpkg.h
+++ b/src/H5Dpkg.h
@@ -74,10 +74,13 @@ typedef struct H5D_rdcdc_t {
 } H5D_rdcdc_t;
 
 /*
- * A dataset is the following struct.
+ * A dataset is made of two layers, an H5D_t struct that is unique to
+ * each instance of an opened datset, and a shared struct that is only
+ * created once for a given dataset.  Thus, if a dataset is opened twice,
+ * there will be two IDs and two H5D_t structs, both sharing one H5D_shared_t.
  */
-struct H5D_t {
-    H5G_entry_t         ent;            /* cached object header stuff   */
+typedef struct H5D_shared_t {
+    size_t              fo_count;       /* reference count */
     hid_t               type_id;        /* ID for dataset's datatype    */
     H5T_t              *type;           /* datatype of this dataset     */
     H5S_t              *space;          /* dataspace of this dataset    */
@@ -101,6 +104,11 @@ struct H5D_t {
                                          */
         H5D_rdcc_t      chunk;          /* Information about chunked data */
     }cache;
+} H5D_shared_t;
+
+struct H5D_t {
+    H5G_entry_t         ent;            /* cached object header stuff   */
+    H5D_shared_t        *shared;        /* cached information from file */
 };
 
 /* Enumerated type for allocating dataset's storage */