IVssBackupComponents::GetWriterComponents method (vsbackup.h)

Article
10/13/2021

The GetWriterComponents method is used to return information about those components of a given writer that have been stored in a requester's Backup Components Document.

Syntax

HRESULT GetWriterComponents(
  [in]  UINT                    iWriter,
  [out] IVssWriterComponentsExt **ppWriter
);

Parameters

[in] iWriter

The index of the writer being queried. It is a number between 0 and n-1, where n is the value returned by IVssBackupComponents::GetWriterComponentsCount.

[out] ppWriter

Doubly indirect pointer to an IVssWriterComponentsExt interface object that will receive the returned component information.

Return value

The following are the valid return codes for this method.

Value	Meaning
S_OK	Successfully returned a pointer to an IVssWriterComponentsExt interface object.
E_INVALIDARG	One of the parameter values is not valid.
E_OUTOFMEMORY	The caller is out of memory or other system resources.
VSS_E_BAD_STATE	The backup components object is not initialized, this method has been called during a restore operation, or this method has not been called within the correct sequence.
VSS_E_OBJECT_NOT_FOUND	The specified shadow copy does not exist.
VSS_E_UNEXPECTED	Unexpected error. The error code is logged in the error log file. For more information, see Event and Error Handling Under VSS. Windows Server 2008, Windows Vista, Windows Server 2003 and Windows XP: This value is not supported until Windows Server 2008 R2 and Windows 7. E_UNEXPECTED is used instead.

Remarks

The caller of this method must call IUnknown::Release when it finishes accessing the component information.

GetWriterComponents retrieves component information for a component stored in the Backup Components Document by earlier calls to IVssBackupComponents::AddComponent.

The information in the components stored in the Backup Components Document is not static. If a writer updates a component during a restore, that change will be reflected in the component retrieved by GetWriterComponents. This is in contrast with component information found in the IVssWMComponent object returned by IVssExamineWriterMetadata::GetComponent. That information is read-only and comes from the Writer Metadata Document of a writer process.

The IVssWriterComponentsExt interface pointer that is returned in the pWriterComponents parameter should not be cached, because the following IVssBackupComponents methods cause the interface pointer that is returned by GetWriterComponents to be no longer valid:

IVssBackupComponents::PrepareForBackup IVssBackupComponents::DoSnapshotSet IVssBackupComponents::BackupComplete IVssBackupComponents::PreRestore IVssBackupComponents::PostRestore If you call one of these methods after you have retrieved an IVssWriterComponentsExt interface pointer by calling GetWriterComponents, you cannot reuse that pointer, because it is no longer valid. Instead, you must call GetWriterComponents again to retrieve a new IVssWriterComponentsExt interface pointer.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	vsbackup.h (include VsBackup.h, Vss.h, VsWriter.h)
Library	VssApi.lib