Method open_file

cpp/dolfinx/io/HDF5Interface.cpp:55–117

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hid_t io::hdf5::open_file(MPI_Comm comm, const std::filesystem::path& filename,
                          const std::string& mode, bool use_mpi_io)
{
  // Set parallel access with communicator
  const hid_t plist_id = H5Pcreate(H5P_FILE_ACCESS);

  if (use_mpi_io)
  {
    MPI_Info info;
    MPI_Info_create(&info);
    if (H5Pset_fapl_mpio(plist_id, comm, info) < 0)
      throw std::runtime_error("Call to H5Pset_fapl_mpio unsuccessful");
    MPI_Info_free(&info);
  }

  hid_t file_id = -1;
  if (mode == "w") // Create file for write, overwriting any existing file
  {
    if (auto d = filename.parent_path(); !d.empty())
      std::filesystem::create_directories(d);
    file_id = H5Fcreate(filename.string().c_str(), H5F_ACC_TRUNC, H5P_DEFAULT,
                        plist_id);
    if (file_id < 0)
      throw std::runtime_error("Failed to create HDF5 file.");
  }
  else if (mode == "a") // Open file to append, creating if does not exist
  {
    if (std::filesystem::exists(filename))
      file_id = H5Fopen(filename.string().c_str(), H5F_ACC_RDWR, plist_id);
    else
    {
      if (auto d = filename.parent_path(); !d.empty())
        std::filesystem::create_directories(d);
      file_id = H5Fcreate(filename.string().c_str(), H5F_ACC_EXCL, H5P_DEFAULT,
                          plist_id);
    }

    if (file_id < 0)
    {
      throw std::runtime_error(
          "Failed to create/open HDF5 file (append mode).");
    }
  }
  else if (mode == "r") // Open file to read
  {
    if (std::filesystem::exists(filename))
    {
      file_id = H5Fopen(filename.string().c_str(), H5F_ACC_RDONLY, plist_id);
      if (file_id < 0)
        throw std::runtime_error("Failed to open HDF5 file.");
    }
    else
    {
      throw std::runtime_error("Unable to open HDF5 file. File "
                               + filename.string() + " does not exist.");
    }
  }