TrivialFileTransfer_service.cc

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#include "art/Framework/Services/FileServiceInterfaces/FileTransferStatus.h"
#include "art/Framework/Services/Optional/TrivialFileTransfer.h"

#include <algorithm>
#include <cerrno>
#include <cstdlib>
#include <fstream>
#include <iterator>

using namespace art;
using namespace std;
using fhicl::ParameterSet;

namespace {
  std::string const fileURI{"file://"};
}

art::TrivialFileTransfer::TrivialFileTransfer(
  TrivialFileTransfer::Parameters const&)
{}

int
art::TrivialFileTransfer::doTranslateToLocalFilename(std::string const& uri,
                                                     std::string& fileFQname)
{
  if (uri.substr(0, 7) != fileURI) {
    fileFQname = uri; // Unexpected protocol: pass through.
    return FileTransferStatus::SUCCESS;
  }

  FileTransferStatus stat = FileTransferStatus::PENDING;
  fileFQname = "";
  std::string inFileName;
  if (stripURI(uri, inFileName) != 0) {
    stat = FileTransferStatus::BAD_REQUEST;
    return stat;
  }

  ifstream infile{inFileName.c_str()};
  if (!infile) {
    stat = FileTransferStatus::NOT_FOUND;
    return stat;
  }
  fileFQname = inFileName;
  stat = FileTransferStatus::SUCCESS;
  return stat;
  // Implementation plan details -- alternatives not chosen:
  // x We could merely return the file name (the URI with file:// stripped off).
  //   Since the SAM developers may look at this file as a template for their
  //   real GeneralFileTransfer service, it is perhaps better to do the work of
  //   making a copy into a designated area.
  // x We  merely strip the file:// from the URI; this adhoc class is not beefed
  //   up to deal with genuine web access.
  // x An alternative would be to embed the last part of the file FQname into
  // the
  //   scratch file name, to try to maintain traceability in case things break.
}

int
art::TrivialFileTransfer::stripURI(std::string const& uri,
                                   std::string& inFileName) const
{
  if (uri.substr(0, 7) != fileURI) {
    inFileName = "";
    return 1;
  }
  inFileName = uri.substr(7);
  return 0;
}

int
art::TrivialFileTransfer::copyFile(std::ifstream& in, std::ofstream& out) const
{
  std::copy(std::istream_iterator<char>{in},
            std::istream_iterator<char>{},
            std::ostream_iterator<char>{out});
  return 0;
}

DEFINE_ART_SERVICE_INTERFACE_IMPL(art::TrivialFileTransfer, art::FileTransfer)