1 files changed, 70 insertions, 0 deletions
diff --git a/build/clang-plugin/mozsearch-plugin/FileOperations.h b/build/clang-plugin/mozsearch-plugin/FileOperations.h
new file mode 100644
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+++ b/build/clang-plugin/mozsearch-plugin/FileOperations.h
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef FileOperations_h
+#define FileOperations_h
+
+#include <stdio.h>
+#include <string>
+
+#if defined(_WIN32) || defined(_WIN64)
+#include <windows.h>
+#define PATHSEP_CHAR '\\'
+#define PATHSEP_STRING "\\"
+#else
+#define PATHSEP_CHAR '/'
+#define PATHSEP_STRING "/"
+#endif
+
+// Make sure that all directories on path exist, excluding the final element of
+// the path.
+void ensurePath(std::string Path);
+
+std::string getAbsolutePath(const std::string &Filename);
+
+// Used to synchronize access when writing to an analysis file, so that
+// concurrently running clang instances don't clobber each other's data.
+// On Windows, we use a named mutex. On POSIX platforms, we use flock on the
+// source files. flock is advisory locking, and doesn't interfere with clang's
+// own opening of the source files (i.e. to interfere, clang would have to be
+// using flock itself, which it does not).
+struct AutoLockFile {
+  // Absolute path to the analysis file
+  std::string Filename;
+
+#if defined(_WIN32) || defined(_WIN64)
+  // Handle for the named Mutex
+  HANDLE Handle = NULL;
+#else
+  // fd for the *source* file that corresponds to the analysis file. We use
+  // the source file because it doesn't change while the analysis file gets
+  // repeatedly replaced by a new version written to a separate tmp file.
+  // This fd is used when using flock to synchronize access.
+  int FileDescriptor = -1;
+#endif
+
+  // SrcFile should be the absolute path to the source code file, and DstFile
+  // the absolute path to the corresponding analysis file. This constructor
+  // will block until exclusive access has been obtained.
+  AutoLockFile(const std::string &SrcFile, const std::string &DstFile);
+  ~AutoLockFile();
+
+  // Check after constructing to ensure the mutex was properly set up.
+  bool success();
+
+  // There used to be an `openFile` method here but we switched to directly
+  // using a std::ifstream for the input file in able to take advantage of its
+  // support for variable length lines (as opposed to fgets which takes a fixed
+  // size buffer).
+
+  // Open a new tmp file for writing the new analysis data to. Caller is
+  // responsible for fclose'ing it.
+  FILE *openTmp();
+  // Replace the existing analysis file with the new "tmp" one that has the new
+  // data. Returns false on error.
+  bool moveTmp();
+};
+
+#endif