FindFirstChangeNotification function

Creates a change notification handle and sets up initial change notification filter conditions. A wait on a notification handle succeeds when a change matching the filter conditions occurs in the specified directory or subtree. The function does not report changes to the specified directory itself.

This function does not indicate the change that satisfied the wait condition. To retrieve information about the specific change as part of the notification, use the ReadDirectoryChangesW function.

Syntax

HANDLE WINAPI FindFirstChangeNotification(
  _In_ LPCTSTR lpPathName,
  _In_ BOOL    bWatchSubtree,
  _In_ DWORD   dwNotifyFilter
);

Parameters

lpPathName [in]

The full path of the directory to be watched. This cannot be a relative path or an empty string.

In the ANSI version of this function, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, call the Unicode version of the function and prepend "\\?\" to the path. For more information, see Naming a File.

bWatchSubtree [in]

If this parameter is TRUE, the function monitors the directory tree rooted at the specified directory; if it is FALSE, it monitors only the specified directory.

dwNotifyFilter [in]

The filter conditions that satisfy a change notification wait. This parameter can be one or more of the following values.

Value	Meaning
FILE_NOTIFY_CHANGE_FILE_NAME 0x00000001	Any file name change in the watched directory or subtree causes a change notification wait operation to return. Changes include renaming, creating, or deleting a file name.
FILE_NOTIFY_CHANGE_DIR_NAME 0x00000002	Any directory-name change in the watched directory or subtree causes a change notification wait operation to return. Changes include creating or deleting a directory.
FILE_NOTIFY_CHANGE_ATTRIBUTES 0x00000004	Any attribute change in the watched directory or subtree causes a change notification wait operation to return.
FILE_NOTIFY_CHANGE_SIZE 0x00000008	Any file-size change in the watched directory or subtree causes a change notification wait operation to return. The operating system detects a change in file size only when the file is written to the disk. For operating systems that use extensive caching, detection occurs only when the cache is sufficiently flushed.
FILE_NOTIFY_CHANGE_LAST_WRITE 0x00000010	Any change to the last write-time of files in the watched directory or subtree causes a change notification wait operation to return. The operating system detects a change to the last write-time only when the file is written to the disk. For operating systems that use extensive caching, detection occurs only when the cache is sufficiently flushed.
FILE_NOTIFY_CHANGE_SECURITY 0x00000100	Any security-descriptor change in the watched directory or subtree causes a change notification wait operation to return.

 

Return value

If the function succeeds, the return value is a handle to a find change notification object.

If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.

Remarks

The wait functions can monitor the specified directory or subtree by using the handle returned by the FindFirstChangeNotification function. A wait is satisfied when one of the filter conditions occurs in the monitored directory or subtree.

After the wait has been satisfied, the application can respond to this condition and continue monitoring the directory by calling the FindNextChangeNotification function and the appropriate wait function. When the handle is no longer needed, it can be closed by using the FindCloseChangeNotification function.

Notifications may not be returned when calling FindFirstChangeNotification for a remote file system.

Symbolic link behavior—If the path points to a symbolic link, the notification handle is created for the target.

If an application has registered to receive change notifications for a directory that contains symbolic links, the application is only notified when the symbolic links have been changed, not the target files.

In Windows 8 and Windows Server 2012, this function is supported by the following technologies.

Application might experience false positives on CsvFs pause/resume.

Examples

For an example, see Obtaining Directory Change_Notifications.

Requirements

See also

Directory Management Functions

FindCloseChangeNotification

FindNextChangeNotification

ReadDirectoryChangesW