installer: make sure we can delete files after killing processes

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Author: zx2c4

installer/customactions.c

@@ -366,6 +366,22 @@ __declspec(dllexport) UINT __stdcall EvaluateWireGuardComponents(MSIHANDLE insta
 	return ret == ERROR_SUCCESS ? ret : ERROR_INSTALL_FAILURE;
 }
 
+static bool can_open_for_deletion(const TCHAR *path)
+{
+	bool ret;
+	FILE_DISPOSITION_INFO di = { .DeleteFile = TRUE };
+	HANDLE file = CreateFile(path, DELETE, FILE_SHARE_DELETE, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, NULL);
+	if (file == INVALID_HANDLE_VALUE)
+		return GetLastError() == ERROR_FILE_NOT_FOUND || GetLastError() == ERROR_PATH_NOT_FOUND || GetLastError() == ERROR_INVALID_NAME;
+	ret = SetFileInformationByHandle(file, FileDispositionInfo, &di, sizeof(di));
+	if (ret) {
+		di.DeleteFile = FALSE;
+		SetFileInformationByHandle(file, FileDispositionInfo, &di, sizeof(di));
+	}
+	CloseHandle(file);
+	return ret;
+}
+
 struct file_id { DWORD volume, index_high, index_low; };
 
 static bool calculate_file_id(const TCHAR *path, struct file_id *id)
@@ -391,9 +407,9 @@ __declspec(dllexport) UINT __stdcall KillWireGuardProcesses(MSIHANDLE installer)
 {
 	HANDLE snapshot, process;
 	PROCESSENTRY32 entry = { .dwSize = sizeof(PROCESSENTRY32) };
-	TCHAR process_path[MAX_PATH], executable[MAX_PATH];
-	DWORD process_path_len = _countof(process_path);
-	struct file_id file_ids[3], file_id;
+	TCHAR process_path[MAX_PATH], executables[2][MAX_PATH];
+	DWORD process_path_len = _countof(process_path), tries = 0;
+	struct file_id file_ids[2], file_id;
 	size_t file_ids_len = 0;
 	bool is_com_initialized = SUCCEEDED(CoInitialize(NULL)), have_killed;
 	LSTATUS mret;
@@ -408,10 +424,13 @@ __declspec(dllexport) UINT __stdcall KillWireGuardProcesses(MSIHANDLE installer)
 
 	log_messagef(installer, LOG_LEVEL_INFO, TEXT("Detecting running processes"));
 
-	if (PathCombine(executable, process_path, TEXT("wg.exe")) && calculate_file_id(executable, &file_ids[file_ids_len]))
-		++file_ids_len;
-	if (PathCombine(executable, process_path, TEXT("wireguard.exe")) && calculate_file_id(executable, &file_ids[file_ids_len]))
-		++file_ids_len;
+	if (!PathCombine(executables[0], process_path, TEXT("wg.exe")) ||
+	    !PathCombine(executables[1], process_path, TEXT("wireguard.exe")))
+		goto out;
+	for (size_t i = 0; i < _countof(executables); ++i) {
+		if (calculate_file_id(executables[i], &file_ids[file_ids_len]))
+			++file_ids_len;
+	}
 	if (!file_ids_len)
 		goto out;
 
@@ -445,14 +464,25 @@ __declspec(dllexport) UINT __stdcall KillWireGuardProcesses(MSIHANDLE installer)
 			WaitForSingleObject(process, INFINITE);
 			log_messagef(installer, LOG_LEVEL_INFO, TEXT("Killed \"%1\" (pid %2!d!)"), process_path, entry.th32ProcessID);
 			have_killed = true;
-		}
+		} else
+			log_errorf(installer, LOG_LEVEL_WARN, GetLastError(), TEXT("Unable to kill \"%1\" (pid %2!d!)"), process_path, entry.th32ProcessID);
 	next:
 		CloseHandle(process);
 	}
 	CloseHandle(snapshot);
 	if (have_killed)
 		goto retry;
-
+	for (size_t i = 0; i < _countof(executables); ++i) {
+		if (!can_open_for_deletion(executables[i])) {
+			if (++tries > 50) {
+				log_messagef(installer, LOG_LEVEL_WARN, TEXT("File \"%1\" is still open"), executables[i]);
+				continue;
+			}
+			log_messagef(installer, LOG_LEVEL_INFO, TEXT("File \"%1\" is still open, sleeping and retrying"), executables[i]);
+			Sleep(100);
+			goto retry;
+		}
+	}
 out:
 	if (is_com_initialized)
 		CoUninitialize();