Creates and opens a new storage object on top of an ILockBytes
instance provided by the caller. The storage object uses the OLE-provided,
compound-file implementation for the IStorage
| ILockBytes * plkbyt,
||//Specifies the byte array object
| DWORD grfMode,
||//Specifies the access mode
| DWORD reserved,
||//Reserved; must be zero
| IStorage ** ppstgOpen
||//Points to location for returning the new storage object
Points to the underlying byte array object on which to create a compound file.
Specifies the access mode to use when opening the new compound file. For more
information, see the STGM
Reserved for future use; must be zero.
Points to the location where the new storage object is placed.
Indicates the compound file was successfully created.
Indicates the calling process does not have sufficient access. Attempt was
made to open an ILockBytes
object with permissions that conflict with another current opening of the
Indicates the compound file already exists and the grfMode
parameter is set to STGM_FAILIFTHERE.
Indicates the compound file was successfully converted. The original byte
array object was successfully converted to IStorage
Indicates the storage object was not created due to a lack of memory.
Indicates a bad pointer was in the pLkbyt
parameter or the ppStgOpen
Indicates a bad flag combination was in the grfMode
Indicates the storage object was not created due to a lack of file handles.
See also any file system errors for other error return values.
See also the ILockBytes
interface for other error return values.
This function creates a storage object on top of a byte array object using the
OLE-provided, compound-file implementation for the IStorage
interface. The StgCreateDocfileOnILockBytes
function can be used to store a document in a relational database. The byte
array indicated by the pLkbyt
parameter is used for the underlying storage in place of a disk file.
function has almost exactly the same semantics as the StgCreateDocfile
function. For more information, see the discussion of StgCreateDocfile
The newly created compound file is opened according to the access modes in the grfMode
parameter. For conversion purposes, the file is always considered to already
exist. As a result, it is not useful to use the STGM_FAILIFTHERE value, because
it always causes an error to be returned. However, STGM_CREATE and
STGM_CONVERT are both still useful.
The ability to build a compound file on top of a byte array object is provided
to support having the data (underneath an IStorage
tree structure) live in persistent space, space that does not ultimately
reside in the file system. Given this capability, there is nothing preventing a
document that is
stored in a file from using this facility. For example, a container might do
this to minimize the impact on its file format caused by adopting OLE. However,
it is recommended that OLE documents adopt the IStorage
interface for their own outer-level storage. This has the following
- The storage structure of the document is the same as its storage structure
when it is an embedded object, reducing the number of cases the application needs
- One can write tools to access the OLE embeddings and links within the document
without special knowledge of the document's file format. An example of such a
tool is a copy utility that copies all the documents included in a container
containing linked objects. A copy utility like this needs access to the contained
links to determine the extent of files to be copied.
- The IStorage instance addresses the problem of how to commit the changes to the file. An
application using the ILockBytes byte array must handle these issues itself.
- Future file systems will likely implement the IStorage and IStream interfaces as their native abstractions, rather than layer on top of a byte
array as is done in compound files. Such a file system could be built so
documents using the IStorage interface as their outer level containment structure would get an automatic
efficiency gain by having the layering flattened when files are saved on the new
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