1 files changed, 129 insertions, 0 deletions
diff --git a/fcp/client/cache/temp_files.cc b/fcp/client/cache/temp_files.cc
new file mode 100644
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--- /dev/null
+++ b/fcp/client/cache/temp_files.cc
@@ -0,0 +1,129 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed 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 "fcp/client/cache/temp_files.h"
+
+#include <sys/file.h>
+#include <unistd.h>
+
+#include <cstdlib>
+#include <filesystem>
+#include <fstream>
+#include <memory>
+#include <string>
+#include <system_error>  // NOLINT
+
+#include "fcp/base/monitoring.h"
+#include "fcp/client/diag_codes.pb.h"
+
+namespace fcp {
+namespace client {
+namespace cache {
+namespace {
+
+absl::Status DeleteFilesInDirectory(const std::filesystem::path& directory) {
+  if (!std::filesystem::exists(directory)) {
+    return absl::InvalidArgumentError(
+        absl::StrCat("Directory does not exist: ", directory.string()));
+  }
+  absl::Status status = absl::OkStatus();
+  // Note this only iterates through the top level directory and will not
+  // traverse subdirectories.
+  for (auto& de : std::filesystem::directory_iterator(directory)) {
+    std::error_code error;
+    // Save the first error, but attempt to delete the other files.
+    if (!std::filesystem::remove(de.path(), error)) {
+      if (status.ok()) {
+        status = absl::InternalError(absl::StrCat(
+            "Failed to delete file with error code: ", error.value()));
+      }
+    }
+  }
+  return status;
+}
+
+}  // namespace
+
+absl::StatusOr<std::unique_ptr<TempFiles>> TempFiles::Create(
+    const std::string& cache_dir, LogManager* log_manager) {
+  std::filesystem::path root_path(cache_dir);
+  if (!root_path.is_absolute()) {
+    return absl::InvalidArgumentError(
+        absl::StrCat("The provided path: ", cache_dir,
+                     "is invalid. The path must start with \"/\""));
+  }
+
+  // Create fcp parent dir in the passed root dir.
+  std::filesystem::path fcp_base_dir = root_path / kParentDir;
+  std::error_code error;
+  std::filesystem::create_directories(fcp_base_dir, error);
+  if (error.value() != 0) {
+    return absl::InternalError(absl::StrCat(
+        "Failed to create TempFiles base directory ",
+        fcp_base_dir.generic_string(), " with error code ", error.value()));
+  }
+
+  // Create directory in parent dir for temporary files.
+  std::filesystem::path temp_files_dir = fcp_base_dir / kTempFilesDir;
+  std::filesystem::create_directories(temp_files_dir, error);
+  if (error.value() != 0) {
+    return absl::InternalError(
+        absl::StrCat("Failed to create TempFiles temp file directory ",
+                     temp_files_dir.generic_string()));
+  }
+
+  // We clean up the temp files dir on creation in case we failed to clean it up
+  // during a previous run (i.e. due to the training process getting killed
+  // etc.) and to make sure we don't end up in the pathological case where we
+  // are always crashing partway through training and stranding temp files
+  // because the TempFiles dtor never runs.
+  auto cleanup_status = DeleteFilesInDirectory(temp_files_dir);
+  if (!cleanup_status.ok()) {
+    log_manager->LogDiag(ProdDiagCode::TEMP_FILES_NATIVE_FAILED_TO_DELETE);
+    return cleanup_status;
+  }
+  return absl::WrapUnique(new TempFiles(temp_files_dir, log_manager));
+}
+
+absl::StatusOr<std::string> TempFiles::CreateTempFile(
+    const std::string& prefix, const std::string& suffix) {
+  std::filesystem::path candidate_path;
+  int fd;
+  do {
+    candidate_path = temp_files_dir_ /
+                     absl::StrCat(prefix, std::to_string(std::rand()), suffix);
+  } while ((fd = open(candidate_path.c_str(), O_CREAT | O_EXCL | O_RDWR,
+                      S_IRWXU)) == -1 &&
+           errno == EEXIST);
+  close(fd);
+  std::ofstream tmp_file(candidate_path);
+  if (!tmp_file) {
+    return absl::InvalidArgumentError(
+        absl::StrCat("could not create file ", candidate_path.string()));
+  }
+
+  return candidate_path.string();
+}
+
+TempFiles::~TempFiles() {
+  if (!DeleteFilesInDirectory(temp_files_dir_).ok()) {
+    log_manager_.LogDiag(ProdDiagCode::TEMP_FILES_NATIVE_FAILED_TO_DELETE);
+  }
+}
+
+}  // namespace cache
+}  // namespace client
+}  // namespace fcp