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c++filevisual-c++ntfssparse-file

Finding length of data block in sparse file

How can I find length of non-zero data block in sparse file starting from some offset? Do I have to make some file read or OS can read that information from some metadata which can be cached? I'm using Windows OS and Visual Studio C++.

Solution

  • You can use DeviceIoControl with FSCTL_QUERY_ALLOCATED_RANGES command.