PRJ_NOTIFICATION_CB callback function (projectedfslib.h)

Article
02/22/2024

Delivers notifications to the provider about file system operations.

Syntax

PRJ_NOTIFICATION_CB PrjNotificationCb;

HRESULT PrjNotificationCb(
  [in]           const PRJ_CALLBACK_DATA *callbackData,
  [in]           BOOLEAN isDirectory,
  [in]           PRJ_NOTIFICATION notification,
  [in, optional] PCWSTR destinationFileName,
  [in, out]      PRJ_NOTIFICATION_PARAMETERS *operationParameters
)
{...}

Parameters

[in] callbackData

Information about the operation. The following callbackData members are necessary to implement this callback:

FilePathName Identifies the path for the file or directory to which the notification pertains.

The provider can access this buffer only while the callback is running. If it wishes to pend the operation and it requires data from this buffer, it must make its own copy of it.

[in] isDirectory

TRUE if the FilePathName field in callbackData refers to a directory, FALSE otherwise.

[in] notification

A PRJ_NOTIFICATION value specifying the notification.

[in, optional] destinationFileName

If notification is PRJ_NOTIFICATION_PRE_RENAME or PRJ_NOTIFICATION_PRE_SET_HARDLINK, this points to a null-terminated Unicode string specifying the path, relative to the virtualization root, of the target of the rename or set-hardlink operation.

[in, out] operationParameters

A pointer to a PRJ_NOTIFICATION_PARAMETERS union specifying extra parameters for certain values of notification:

PRJ_NOTIFICATION_FILE_OPENED, PRJ_NOTIFICATION_NEW_FILE_CREATED, or PRJ_NOTIFICATION_FILE_OVERWRITTEN

The fields of the PostCreate member are specified. These fields are:

NotificationMask

Upon return from the PRJ_NOTIFICATION_CB callback, the provider may specify a new set of notifications that it wishes to receive for the file here.

If the provider sets this value to 0, it is equivalent to specifying PRJ_NOTIFY_USE_EXISTING_MASK.

PRJ_NOTIFICATION_FILE_RENAMED

The fields of the FileRenamed member are specified. These fields are:

NotificationMask

Upon return from the PRJ_NOTIFICATION_CB callback, the provider may specify a new set of notifications that it wishes to receive for the file here.

If the provider sets this value to 0, it is equivalent to specifying PRJ_NOTIFY_USE_EXISTING_MASK.

PRJ_NOTIFICATION_FILE_HANDLE_CLOSED_FILE_DELETED

The fields of the FileDeletedOnHandleClose member are specified. These fields are:
NotificationMask

If the provider registered for PRJ_NOTIFY_FILE_HANDLE_CLOSED_FILE_MODIFIED as well as PRJ_NOTIFY_FILE_HANDLE_CLOSED_FILE_DELETED, this field is set to TRUE if the file was modified before it was deleted.

Return value

Return code	Description
S_OK	The provider successfully processed the notification.
HRESULT_FROM_WIN32(ERROR_IO_PENDING)	The provider wishes to complete the operation at a later time.

An appropriate HRESULT error code if the provider fails the operation. For pre-operation notifications (operations with "PRE" in their name), if the provider returns a failure code ProjFS will fail the corresponding operation with the provided error code.

Remarks

This callback is optional. If the provider does not supply an implementation of this callback, it will not receive notifications.

The provider registers for the notifications it wishes to receive when it calls PrjStartVirtualizing.

Requirements

Requirement	Value
Minimum supported client	Windows 10, version 1809 [desktop apps only]
Minimum supported server	Windows Server [desktop apps only]
Target Platform	Windows
Header	projectedfslib.h

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