FindFirstChangeNotification
The 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.
HANDLE FindFirstChangeNotification(
|
LPCTSTR lpPathName, |
// pointer to name
of directory to watch |
|
BOOL bWatchSubtree, |
// flag for
monitoring directory or directory tree
|
|
DWORD dwNotifyFilter |
// filter
conditions to watch for |
|
); |
|
Parameters
lpPathName
Points to a
null-terminated string that specifies the path of the directory to watch.
bWatchSubtree
Specifies
whether the function will monitor the directory or the directory tree. 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
Specifies 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 |
|
|
|
Any
filename change in the watched directory or subtree causes a change
notification wait operation to return. Changes include renaming, creating, or
deleting a filename. |
|
FILE_NOTIFY_CHANGE_DIR_NAME |
|
|
|
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 |
|
|
|
Any
attribute change in the watched directory or subtree causes a change
notification wait operation to return. |
|
FILE_NOTIFY_CHANGE_SIZE |
|
|
|
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 |
|
|
|
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 |
|
|
|
Any
security-descriptor change in the watched directory or subtree causes a
change notification wait operation to return. |
Return Values
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.
See Also