rntviewer/src/rntuple.cpp

internal
String8 rntuple_description(Arena *arena, const RNTuple &anchor)
{
  String8 desc = push_str8f(arena, "version %u.%u.%u.%u", 
                            anchor.GetVersionEpoch(),
                            anchor.GetVersionMajor(),
                            anchor.GetVersionMinor(),
                            anchor.GetVersionPatch());
  return desc;
}

internal
RNTuple_Info get_rntuple_info(const char *fname, const char *ntpl_name)
{
  RNTuple_Info info = {};
  
  // Open the TFile
  TFile *tfile = TFile::Open(fname, "READ");
  if (!tfile) {
    fprintf(stderr, "Failed to open TFile.\n");
    return info;
  }
  defer { delete tfile; };

  // Get the RNTuple information
  const RNTuple *anchor = tfile->Get<RNTuple>(ntpl_name);
  if (anchor) {
    info.anchor = *anchor;
    info.rng_header.start = anchor->GetSeekHeader();
    info.rng_header.len = anchor->GetNBytesHeader();
    info.rng_footer.start = anchor->GetSeekFooter();
    info.rng_footer.len = anchor->GetNBytesFooter();
  } else {
    fprintf(stderr, "RNTuple '%s' not found in %s.\n", ntpl_name, fname);
  }

  // TODO: proper error handling
  auto raw_file = ROOT::Internal::RRawFile::Create(fname);
  if (raw_file) {
    PseudoMiniFileReader file_reader { raw_file.get() };
    auto file_info = file_reader.GetNTupleProper(ntpl_name).Unwrap();
    info.rng_anchor.start = file_info.anchor_seek;
    info.rng_anchor.len = file_info.anchor_nbytes;
    info.rng_anchor_key.start = file_info.anchor_key_seek;
    info.rng_anchor_key.len = file_info.anchor_key_nbytes;
    info.rblob_header_size = file_info.rblob_key_header_nbytes;
    info.root_file_header_size = file_info.tfile_header_nbytes;
  }

  return info;
}