[GitHub] [nifi-minifi-cpp] lordgamez commented on a diff in pull request #1577: MINIFICPP-2020 - Protect MINIFI_HOME from mutual access

["lordgamez (via GitHub)" <gi...@apache.org>]

lordgamez commented on code in PR #1577:
URL: https://github.com/apache/nifi-minifi-cpp/pull/1577#discussion_r1223037064


##########
libminifi/src/utils/FileMutex.cpp:
##########


Review Comment:
   Just to consider: maybe it would look better to have separate files for Windows and Unix versions of the implementations instead of a single FileMutex.cpp



##########
libminifi/src/utils/FileMutex.cpp:
##########
@@ -0,0 +1,107 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "utils/FileMutex.h"
+
+#include "utils/gsl.h"
+
+template<typename T>
+static T& getOsHandle(std::array<std::byte, 24>& file_handle) {
+  void* ptr = reinterpret_cast<void*>(file_handle.data());
+  size_t size = file_handle.size();
+  void* result = std::align(alignof(T), sizeof(T), ptr, size);
+  gsl_Assert(result);
+  return *reinterpret_cast<T*>(result);
+}
+
+#ifdef WIN32
+#include <windows.h>
+#include "utils/OsUtils.h"
+
+namespace org::apache::nifi::minifi::utils {
+
+FileMutex::FileMutex(std::filesystem::path path): path_(std::move(path)) {}
+
+void FileMutex::lock() {
+  std::lock_guard guard(mtx_);
+  HANDLE handle = CreateFileA(path_.string().c_str(), (GENERIC_READ | GENERIC_WRITE), 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+
+  if (handle == INVALID_HANDLE_VALUE) {
+    throw std::runtime_error("Failed to open file '" + path_.string() + "' to be locked: " + utils::OsUtils::windowsErrorToErrorCode(GetLastError()).message());
+  }
+
+  getOsHandle<HANDLE>(file_handle_) = handle;
+}
+
+void FileMutex::unlock() {
+  std::lock_guard guard(mtx_);
+  CloseHandle(getOsHandle<HANDLE>(file_handle_));
+}
+
+}  // namespace org::apache::nifi::minifi::utils
+
+#else
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <cstring>
+
+namespace org::apache::nifi::minifi::utils {
+
+FileMutex::FileMutex(std::filesystem::path path): path_(std::move(path)) {}
+
+void FileMutex::lock() {
+  std::lock_guard guard(mtx_);
+  int flags = O_RDWR | O_CREAT;
+#ifdef O_CLOEXEC
+  flags |= O_CLOEXEC;
+#endif
+  int fd = open(path_.string().c_str(), flags, 0644);
+  if (fd < 0) {
+    throw std::runtime_error("Failed to open file '" + path_.string() + "' to be locked: " + std::strerror(errno));
+  }
+
+  errno = 0;
+  struct flock f{};
+  f.l_type = F_WRLCK;
+  int value = fcntl(fd, F_SETLK, &f);
+  if (value == -1) {
+    std::string err_str = "Failed to lock file '" + path_.string() + "': " + std::strerror(errno);
+    close(fd);
+    throw std::runtime_error(err_str);
+  }
+
+  getOsHandle<int>(file_handle_) = fd;
+}
+
+void FileMutex::unlock() {
+  std::lock_guard guard(mtx_);
+  errno = 0;
+  struct flock f{};
+  f.l_type = F_UNLCK;
+  int value = fcntl(getOsHandle<int>(file_handle_), F_SETLK, &f);
+  if (value == -1) {
+    std::string err_str = "Failed to unlock file '" + path_.string() + "': " + std::strerror(errno);
+    close(getOsHandle<int>(file_handle_));

Review Comment:
   Maybe this could be set in `gsl::finally` instead



##########
libminifi/src/utils/FileMutex.cpp:
##########
@@ -0,0 +1,107 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "utils/FileMutex.h"
+
+#include "utils/gsl.h"
+
+template<typename T>
+static T& getOsHandle(std::array<std::byte, 24>& file_handle) {
+  void* ptr = reinterpret_cast<void*>(file_handle.data());
+  size_t size = file_handle.size();
+  void* result = std::align(alignof(T), sizeof(T), ptr, size);
+  gsl_Assert(result);
+  return *reinterpret_cast<T*>(result);
+}
+
+#ifdef WIN32
+#include <windows.h>
+#include "utils/OsUtils.h"
+
+namespace org::apache::nifi::minifi::utils {
+
+FileMutex::FileMutex(std::filesystem::path path): path_(std::move(path)) {}
+
+void FileMutex::lock() {
+  std::lock_guard guard(mtx_);
+  HANDLE handle = CreateFileA(path_.string().c_str(), (GENERIC_READ | GENERIC_WRITE), 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
+
+  if (handle == INVALID_HANDLE_VALUE) {
+    throw std::runtime_error("Failed to open file '" + path_.string() + "' to be locked: " + utils::OsUtils::windowsErrorToErrorCode(GetLastError()).message());
+  }
+
+  getOsHandle<HANDLE>(file_handle_) = handle;
+}
+
+void FileMutex::unlock() {
+  std::lock_guard guard(mtx_);
+  CloseHandle(getOsHandle<HANDLE>(file_handle_));
+}
+
+}  // namespace org::apache::nifi::minifi::utils
+
+#else
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <cstring>
+
+namespace org::apache::nifi::minifi::utils {
+
+FileMutex::FileMutex(std::filesystem::path path): path_(std::move(path)) {}
+
+void FileMutex::lock() {
+  std::lock_guard guard(mtx_);
+  int flags = O_RDWR | O_CREAT;
+#ifdef O_CLOEXEC
+  flags |= O_CLOEXEC;
+#endif
+  int fd = open(path_.string().c_str(), flags, 0644);
+  if (fd < 0) {
+    throw std::runtime_error("Failed to open file '" + path_.string() + "' to be locked: " + std::strerror(errno));
+  }
+
+  errno = 0;
+  struct flock f{};

Review Comment:
   Please rename to something more descriptive



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