Added DirWatch

Author: RadAd

DirWatch.cpp

@@ -0,0 +1,122 @@
+//#define WIN32_LEAN_AND_MEAN
+#include <Windows.h>
+#include <tchar.h>
+
+#include <cstdlib>
+#include <cstdio>
+#include <memory>
+
+template <typename T, typename D>
+auto unique_resource(T* t, D&& d)
+{
+    return std::unique_ptr<T, D>(t, std::forward<D>(d));
+}
+
+inline const FILE_NOTIFY_INFORMATION* GetNext(const FILE_NOTIFY_INFORMATION* event)
+{
+    return event->NextEntryOffset ? (FILE_NOTIFY_INFORMATION*)((BYTE*)event + event->NextEntryOffset) : nullptr;
+}
+
+void OutputDirectoryChanges(HANDLE hDir, const BOOL bSubdir, const DWORD dwNotifyFilter)
+{
+    BYTE change_buf[1024];
+    DWORD bytes = 0;
+    if (!ReadDirectoryChangesW(hDir, change_buf, ARRAYSIZE(change_buf) * sizeof(change_buf[0]), bSubdir, dwNotifyFilter, &bytes, nullptr, nullptr))
+    {
+        _ftprintf(stderr, _T("Error ReadDirectoryChanges: 0x%08X\n"), GetLastError());
+    }
+    else
+    {
+        SYSTEMTIME time;
+        GetLocalTime(&time);
+        _tprintf(_T("%02u/%02u/%04u %02u:%02u:%02u.%03u"),
+            time.wDay, time.wMonth, time.wYear,
+            time.wHour, time.wMinute, time.wSecond, time.wMilliseconds);
+
+        for (const FILE_NOTIFY_INFORMATION* event = (FILE_NOTIFY_INFORMATION*) change_buf; event != nullptr; event = GetNext(event))
+        {
+            const DWORD name_len = event->FileNameLength / sizeof(wchar_t);
+            switch (event->Action)
+            {
+            case FILE_ACTION_ADDED:             wprintf(L"        Added: %.*s", name_len, event->FileName); break;
+            case FILE_ACTION_REMOVED:           wprintf(L"      Removed: %.*s", name_len, event->FileName); break;
+            case FILE_ACTION_MODIFIED:          wprintf(L"     Modified: %.*s", name_len, event->FileName); break;
+            case FILE_ACTION_RENAMED_OLD_NAME:  wprintf(L" Renamed from: %.*s", name_len, event->FileName); break;
+            case FILE_ACTION_RENAMED_NEW_NAME:  wprintf(L" to: %.*s", name_len, event->FileName); break;
+            default:                            _tprintf(_T("Unknown action!")); break;
+            }
+        }
+        _tprintf(_T("\n"));
+    }
+}
+
+int _tmain(const int argc, const LPCTSTR argv[])
+{
+    LPCTSTR sDir = nullptr;
+    BOOL bSubdir = FALSE;
+    const DWORD dwNotifyFilter = FILE_NOTIFY_CHANGE_FILE_NAME | FILE_NOTIFY_CHANGE_DIR_NAME | FILE_NOTIFY_CHANGE_LAST_WRITE;
+    for (int argi = 1; argi < argc; ++argi)
+    {
+        LPCTSTR arg = argv[argi];
+        if (_tcsicmp(arg, _T("/s")) == 0)
+            bSubdir = TRUE;
+        else if (sDir == nullptr)
+            sDir = arg;
+        else
+            _ftprintf(stderr, _T("Unknown argument: %s\n"), arg);
+    }
+
+    if (sDir == nullptr)
+    {
+        _tprintf(_T("Usage: DirWatch [/s] <directory>\n"));
+        return EXIT_SUCCESS;
+    }
+
+    auto hDir = unique_resource(CreateFile(sDir,
+        FILE_LIST_DIRECTORY,
+        FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+        NULL,
+        OPEN_EXISTING,
+        FILE_FLAG_BACKUP_SEMANTICS,
+        NULL),
+        [](HANDLE h) { CloseHandle(h); });
+    if (!hDir)
+    {
+        _ftprintf(stderr, _T("Error CreateFile: 0x%08X\n"), GetLastError());
+        return EXIT_FAILURE;
+    }
+
+#if 0
+    auto hWatch = unique_resource(FindFirstChangeNotification(sDir, bSubdir, dwNotifyFilter), [](HANDLE h) { FindCloseChangeNotification(h); });
+    if (!hWatch)
+    {
+        _ftprintf(stderr, _T("Error FindFirstChangeNotification: 0x%08X\n"), GetLastError());
+        return EXIT_FAILURE;
+    }
+
+    OutputDirectoryChanges(hDir.get(), bSubdir, dwNotifyFilter);
+
+    DWORD dwWait;
+    while ((dwWait = WaitForSingleObject(hWatch.get(), INFINITE)) == WAIT_OBJECT_0)
+    {
+        if (FindNextChangeNotification(hWatch.get()) == FALSE)
+        {
+            _ftprintf(stderr, _T("Error FindNextChangeNotification: 0x%08X\n"), GetLastError());
+            break;
+        }
+
+        OutputDirectoryChanges(hDir.get(), bSubdir, dwNotifyFilter);
+    }
+
+    if (dwWait != WAIT_OBJECT_0)
+    {
+        _ftprintf(stderr, _T("Error WaitForSingleObject: 0x%08X: 0x%08X\n"), dwWait, GetLastError());
+        return EXIT_FAILURE;
+    }
+#else
+    while (true)
+        OutputDirectoryChanges(hDir.get(), bSubdir, dwNotifyFilter);
+#endif
+
+    return EXIT_SUCCESS;
+}

README.md

@@ -33,6 +33,9 @@ Set the icon of the console window
 ## [CreateGuid](CreateGuid.cpp)
 Create a guid.
 
+## [DirWatch](DirWatch.cpp)
+Watch for changes in a direcory using [ReadDirectoryChanges](https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-readdirectorychangesw).
+
 ## [DragDrop](DragDrop.cpp)
 Simulates drag and dropping a file onto a window