1 // Copyright 2011 Google Inc. All Rights Reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #ifndef NINJA_DISK_INTERFACE_H_
16 #define NINJA_DISK_INTERFACE_H_
17 
18 #include <map>
19 #include <string>
20 
21 #include "timestamp.h"
22 
23 /// Interface for reading files from disk.  See DiskInterface for details.
24 /// This base offers the minimum interface needed just to read files.
25 struct FileReader {
~FileReaderFileReader26   virtual ~FileReader() {}
27 
28   /// Result of ReadFile.
29   enum Status {
30     Okay,
31     NotFound,
32     OtherError
33   };
34 
35   /// Read and store in given string.  On success, return Okay.
36   /// On error, return another Status and fill |err|.
37   virtual Status ReadFile(const std::string& path, std::string* contents,
38                           std::string* err) = 0;
39 };
40 
41 /// Interface for accessing the disk.
42 ///
43 /// Abstract so it can be mocked out for tests.  The real implementation
44 /// is RealDiskInterface.
45 struct DiskInterface: public FileReader {
46   /// stat() a file, returning the mtime, or 0 if missing and -1 on
47   /// other errors.
48   virtual TimeStamp Stat(const std::string& path, std::string* err) const = 0;
49 
50   /// Create a directory, returning false on failure.
51   virtual bool MakeDir(const std::string& path) = 0;
52 
53   /// Create a file, with the specified name and contents
54   /// Returns true on success, false on failure
55   virtual bool WriteFile(const std::string& path,
56                          const std::string& contents) = 0;
57 
58   /// Remove the file named @a path. It behaves like 'rm -f path' so no errors
59   /// are reported if it does not exists.
60   /// @returns 0 if the file has been removed,
61   ///          1 if the file does not exist, and
62   ///          -1 if an error occurs.
63   virtual int RemoveFile(const std::string& path) = 0;
64 
65   /// Create all the parent directories for path; like mkdir -p
66   /// `basename path`.
67   bool MakeDirs(const std::string& path);
68 };
69 
70 /// Implementation of DiskInterface that actually hits the disk.
71 struct RealDiskInterface : public DiskInterface {
RealDiskInterfaceRealDiskInterface72   RealDiskInterface()
73 #ifdef _WIN32
74                       : use_cache_(false)
75 #endif
76                       {}
~RealDiskInterfaceRealDiskInterface77   virtual ~RealDiskInterface() {}
78   virtual TimeStamp Stat(const std::string& path, std::string* err) const;
79   virtual bool MakeDir(const std::string& path);
80   virtual bool WriteFile(const std::string& path, const std::string& contents);
81   virtual Status ReadFile(const std::string& path, std::string* contents,
82                           std::string* err);
83   virtual int RemoveFile(const std::string& path);
84 
85   /// Whether stat information can be cached.  Only has an effect on Windows.
86   void AllowStatCache(bool allow);
87 
88  private:
89 #ifdef _WIN32
90   /// Whether stat information can be cached.
91   bool use_cache_;
92 
93   typedef std::map<std::string, TimeStamp> DirCache;
94   // TODO: Neither a map nor a hashmap seems ideal here.  If the statcache
95   // works out, come up with a better data structure.
96   typedef std::map<std::string, DirCache> Cache;
97   mutable Cache cache_;
98 #endif
99 };
100 
101 #endif  // NINJA_DISK_INTERFACE_H_
102