1    :  // Copyright 2011 Google Inc.
   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    :  // A few utility functions for determining if paths refer to the same file
  16    :  // or not.
  17    :  #ifndef SYZYGY_CORE_FILE_UTIL_H_
  18    :  #define SYZYGY_CORE_FILE_UTIL_H_
  19    :  
  20    :  #include "base/file_path.h"
  21    :  
  22  m :  namespace core {
  23    :  
  24    :  // Possible return values from this test.
  25  m :  enum FilePathCompareResult {
  26  m :    kFilePathCompareError,
  27    :  
  28    :    // This is returned of the two file paths are equivalent on this machine.
  29    :    // That is they both refer to the same file on disk, even if that is via
  30    :    // junctions or indirection.
  31  m :    kEquivalentFilePaths,
  32    :  
  33    :    // This is returned if the two file paths are guaranteed to refer to different
  34    :    // files on disk. It does not mean that they are both immediately creatable,
  35    :    // as there may be part of a directory hierarchy that also needs to be
  36    :    // created.
  37  m :    kDistinctFilePaths,
  38    :  
  39    :    // This is returned if *neither* of the file paths exist. That is, they
  40    :    // may very well refer to the same path via filesystem shenanigans, but there
  41    :    // is no way to know without creating at least one of them.
  42  m :    kUnableToCompareFilePaths,
  43  m :  };
  44    :  
  45    :  // Compares two paths, determining if they both refer to the same object.
  46    :  //
  47    :  // This test is read-only, and as such it is possible for the test to fail.
  48    :  // This can occur if neither of the paths exist, yet they do in fact refer to
  49    :  // the same file via some aliasing mechanism (junctions, mounts, etc). In that
  50    :  // case this will return kUnableToCompare. To attempt a comparison in this case
  51    :  // both paths will be converted to absolute paths using the current working
  52    :  // directory. If the paths are identical we can infer that the files will be
  53    :  // the same (but not vice versa). To get a solid answer at least one of the
  54    :  // paths must exist.
  55    :  //
  56    :  // @param path1 the first path to compare.
  57    :  // @param path2 the second path to compare.
  58    :  // @returns a FilePathCompareResult, described above.
  59  m :  FilePathCompareResult CompareFilePaths(const FilePath& path1,
  60  m :                                         const FilePath& path2);
  61    :  
  62  m :  }  // namespace core
  63    :  
  64    :  #endif  // SYZYGY_CORE_FILE_UTIL_H_