This post is useful for developers only....
Sometime back, I was trying to look for a way to get Directory Change Notifications on Windows i.e. the same ones that dropbox or google drive any other file sync app would have used. The code would need to use FindFirstChangeNotification as well as WaitForMultipleObjects APIs:
MSDN Link -
http://msdn.microsoft.com/en-us/library/aa365261%28VS.85%29.aspx
-------------------
Sample code
-------------------
#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <tchar.h>
void RefreshDirectory(LPTSTR);
void RefreshTree(LPTSTR);
void WatchDirectory(LPTSTR);
void _tmain(int argc, TCHAR *argv[])
{
if(argc != 2)
{
_tprintf(TEXT("Usage: %s dir\n"), argv[0]);
return;
}
WatchDirectory(argv[1]);
}
void WatchDirectory(LPTSTR lpDir)
{
DWORD dwWaitStatus;
HANDLE dwChangeHandles[2];
TCHAR lpDrive[4];
TCHAR lpFile[_MAX_FNAME];
TCHAR lpExt[_MAX_EXT];
_tsplitpath_s(lpDir, lpDrive, 4, NULL, 0, lpFile, _MAX_FNAME, lpExt, _MAX_EXT);
lpDrive[2] = (TCHAR)'\\';
lpDrive[3] = (TCHAR)'\0';
// Watch the directory for file creation and deletion.
dwChangeHandles[0] = FindFirstChangeNotification(
lpDir, // directory to watch
FALSE, // do not watch subtree
FILE_NOTIFY_CHANGE_FILE_NAME); // watch file name changes
if (dwChangeHandles[0] == INVALID_HANDLE_VALUE)
{
printf("\n ERROR: FindFirstChangeNotification function failed.\n");
ExitProcess(GetLastError());
}
// Watch the subtree for directory creation and deletion.
dwChangeHandles[1] = FindFirstChangeNotification(
lpDrive, // directory to watch
TRUE, // watch the subtree
FILE_NOTIFY_CHANGE_DIR_NAME); // watch dir name changes
if (dwChangeHandles[1] == INVALID_HANDLE_VALUE)
{
printf("\n ERROR: FindFirstChangeNotification function failed.\n");
ExitProcess(GetLastError());
}
// Make a final validation check on our handles.
if ((dwChangeHandles[0] == NULL) (dwChangeHandles[1] == NULL))
{
printf("\n ERROR: Unexpected NULL from FindFirstChangeNotification.\n");
ExitProcess(GetLastError());
}
// Change notification is set. Now wait on both notification
// handles and refresh accordingly.
while (TRUE)
{
// Wait for notification.
printf("\nWaiting for notification...\n");
dwWaitStatus = WaitForMultipleObjects(2, dwChangeHandles,
FALSE, INFINITE);
switch (dwWaitStatus)
{
case WAIT_OBJECT_0:
// A file was created, renamed, or deleted in the directory.
// Refresh this directory and restart the notification.
RefreshDirectory(lpDir);
if ( FindNextChangeNotification(dwChangeHandles[0]) == FALSE )
{
printf("\n ERROR: FindNextChangeNotification function failed.\n");
ExitProcess(GetLastError());
}
break;
case WAIT_OBJECT_0 + 1:
// A directory was created, renamed, or deleted.
// Refresh the tree and restart the notification.
RefreshTree(lpDrive);
if (FindNextChangeNotification(dwChangeHandles[1]) == FALSE )
{
printf("\n ERROR: FindNextChangeNotification function failed.\n");
ExitProcess(GetLastError());
}
break;
case WAIT_TIMEOUT:
// A timeout occurred, this would happen if some value other
// than INFINITE is used in the Wait call and no changes occur.
// In a single-threaded environment you might not want an
// INFINITE wait.
printf("\nNo changes in the timeout period.\n");
break;
default:
printf("\n ERROR: Unhandled dwWaitStatus.\n");
ExitProcess(GetLastError());
break;
}
}
}
void RefreshDirectory(LPTSTR lpDir)
{
// This is where you might place code to refresh your
// directory listing, but not the subtree because it
// would not be necessary.
_tprintf(TEXT("Directory (%s) changed.\n"), lpDir);
}
void RefreshTree(LPTSTR lpDrive)
{
// This is where you might place code to refresh your
// directory listing, including the subtree.
_tprintf(TEXT("Directory tree (%s) changed.\n"), lpDrive);
}
Thanks to my colleague
+Abhijeet Singh for helping me with the above info.
