[PATCH] D54995: [MemoryBuffer] By default assume that all files are volatile to prevent unintended file locks

[Ivan Donchevskii via Phabricator via cfe-commits]

yvvan added a comment.

According to https://msdn.microsoft.com/en-us/2e9c3174-af48-4fa3-9f6a-fb62b23ed994 - "Unmapping a mapped view of a file invalidates the range occupied by the view in the address space of the process and makes the range available for other allocations".
Also as far as i understand from https://msdn.microsoft.com/en-us/library/ms810613.aspx mapped files can only be edited in other apps as mapped files opened with the same name (OpenFileMapping).

Simple example, I launch it and until i enter the number the test.h header remains locked and therefore i can't edit it in other apps.

  DWORD shareMode = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
  int accessRights = 0;
  accessRights |= GENERIC_READ;
  SECURITY_ATTRIBUTES securityAtts = { sizeof(SECURITY_ATTRIBUTES), NULL, FALSE };
  HANDLE fileHandle =
      CreateFile("D:\\test.h", accessRights, shareMode, &securityAtts,
                 OPEN_EXISTING,
                 FILE_FLAG_BACKUP_SEMANTICS,
                 NULL);
  
  HANDLE FileMappingHandle =
      CreateFileMappingA(fileHandle, 0, PAGE_READONLY, 0, 0, "D:_code_test.h");
  
  LPVOID Mapping = MapViewOfFile(FileMappingHandle, FILE_MAP_READ, 0, 0, 0);
  assert(Mapping);
  
  CloseHandle(FileMappingHandle);
  
  int i {0};
  std::cin >> i;
  UnmapViewOfFile(Mapping);
  
  CloseHandle(fileHandle);


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  https://reviews.llvm.org/D54995/new/

https://reviews.llvm.org/D54995