xref: /third_party/ninja/src/disk_interface.h

// Copyright 2011 Google Inc. All Rights Reserved.
//
// 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.

#ifndef NINJA_DISK_INTERFACE_H_
#define NINJA_DISK_INTERFACE_H_

#include <map>
#include <string>

#include "timestamp.h"

/// Interface for reading files from disk.  See DiskInterface for details.
/// This base offers the minimum interface needed just to read files.
struct FileReader {
    virtual ~FileReader() {}

    /// Result of ReadFile.
    enum Status {
        Okay,
        NotFound,
        OtherError
    };

    /// Read and store in given string.  On success, return Okay.
    /// On error, return another Status and fill |err|.
    virtual Status ReadFile(const std::string& path, std::string* contents,
                                                    std::string* err) = 0;
};

/// Interface for accessing the disk.
///
/// Abstract so it can be mocked out for tests.  The real implementation
/// is RealDiskInterface.
struct DiskInterface: public FileReader {
    /// stat() a file, returning the mtime, or 0 if missing and -1 on
    /// other errors.
    virtual TimeStamp Stat(const std::string& path, std::string* err) const = 0;

    /// Create a directory, returning false on failure.
    virtual bool MakeDir(const std::string& path) = 0;

    /// Create a file, with the specified name and contents
    /// Returns true on success, false on failure
    virtual bool WriteFile(const std::string& path,
                                                  const std::string& contents) = 0;

    /// Remove the file named @a path. It behaves like 'rm -f path' so no errors
    /// are reported if it does not exists.
    /// @returns 0 if the file has been removed,
    ///          1 if the file does not exist, and
    ///          -1 if an error occurs.
    virtual int RemoveFile(const std::string& path) = 0;

    /// Create all the parent directories for path; like mkdir -p
    /// `basename path`.
    bool MakeDirs(const std::string& path);
};

/// Implementation of DiskInterface that actually hits the disk.
struct RealDiskInterface : public DiskInterface {
    RealDiskInterface();
    virtual ~RealDiskInterface() {}
    virtual TimeStamp Stat(const std::string& path, std::string* err) const;
    virtual bool MakeDir(const std::string& path);
    virtual bool WriteFile(const std::string& path, const std::string& contents);
    virtual Status ReadFile(const std::string& path, std::string* contents,
                                                    std::string* err);
    virtual int RemoveFile(const std::string& path);

    /// Whether stat information can be cached.  Only has an effect on Windows.
    void AllowStatCache(bool allow);

#ifdef _WIN32
    /// Whether long paths are enabled.  Only has an effect on Windows.
    bool AreLongPathsEnabled() const;
#endif

  private:
#ifdef _WIN32
    /// Whether stat information can be cached.
    bool use_cache_;

    /// Whether long paths are enabled.
    bool long_paths_enabled_;

    typedef std::map<std::string, TimeStamp> DirCache;
    // TODO: Neither a map nor a hashmap seems ideal here.  If the statcache
    // works out, come up with a better data structure.
    typedef std::map<std::string, DirCache> Cache;
    mutable Cache cache_;
#endif
};

#endif  // NINJA_DISK_INTERFACE_H_