FileOperations.h - mozsearch

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/* -*- 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