BESStreamResponseHandler.cc

// BESStreamResponseHandler.cc
 
// This file is part of bes, A C++ back-end server implementation framework
// for the OPeNDAP Data Access Protocol.
 
// Copyright (c) 2004-2009 University Corporation for Atmospheric Research
// Author: Patrick West <pwest@ucar.edu> and Jose Garcia <jgarcia@ucar.edu>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundatiion; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact University Corporation for Atmospheric Research at
// 3080 Center Green Drive, Boulder, CO 80301
 
// (c) COPYRIGHT University Corporation for Atmospheric Research 2004-2005
// Please read the full copyright statement in the file COPYRIGHT_UCAR.
//
// Authors:
//      pwest       Patrick West <pwest@ucar.edu>
//      jgarcia     Jose Garcia <jgarcia@ucar.edu>
 
#include <unistd.h>
 
#include <cerrno>
#include <iostream>
#include <fstream>
#include <string>
#include <cstring>
 
using std::ifstream;
using std::ios;
using std::endl;
using std::string;
using std::ostream;
 
#include "BESStreamResponseHandler.h"
#include "BESForbiddenError.h"
#include "BESNotFoundError.h"
#include "BESInternalError.h"
#include "BESContainer.h"
#include "BESDataHandlerInterface.h"
#include "BESUtil.h"
#include "RequestServiceTimer.h"
 
#define BES_STREAM_BUFFER_SIZE 4096
 
#define MODULE "bes"
#define prolog std::string("BESStreamResponseHandler::").append(__func__).append("() - ")

void BESStreamResponseHandler::execute(BESDataHandlerInterface &dhi)
{
    d_response_object = nullptr;
 
    // Verify the request hasn't exceeded bes_timeout, and disable timeout if allowed.
    RequestServiceTimer::TheTimer()->throw_if_timeout_expired(prolog + "ERROR: bes-timeout expired before transmit", __FILE__, __LINE__);
    BESUtil::conditional_timeout_cancel();
 
    // What if there is a special way to stream back a data file?
    // Should we pass this off to the request handlers and put
    // this code into a different class for reuse? For now
    // just keep it here. pcw 10/11/06
 
    // I thought about putting this in the transmit method below
    // but decided that this is like executing a non-buffered
    // request, so kept it here. Plus the idea expressed above
    // led me to leave the code in the execute method.
    // pcw 10/11/06
    if (dhi.containers.size() != 1) {
        throw BESInternalError("Unable to stream file: no container specified", __FILE__, __LINE__);
    }
 
    dhi.first_container();
    BESContainer *container = dhi.container;
    string filename = container->access();
    if (filename.empty()) {
        throw BESInternalError("Unable to stream file: filename not specified", __FILE__, __LINE__);
    }
 
    ifstream os;
    os.open(filename.c_str(), ios::in);
    int myerrno = errno;
    if (!os) {
        string serr = "Unable to stream file because it cannot be opened. file: '" + filename + "'  msg: ";
        char *err = strerror(myerrno);
        serr += err ? err: "Unknown error";
 
        // ENOENT means that the node wasn't found.
        // On some systems a file that doesn't exist returns ENOTDIR because: w.f.t?
        // Otherwise, access is being denied for some other reason
        if (myerrno == ENOENT || myerrno == ENOTDIR) {
            // On some systems a file that doesn't exist returns ENOTDIR because: w.f.t?
            throw BESNotFoundError(serr, __FILE__, __LINE__);
        }
        // Not a 404? Then we'll go with the forbidden fruit theory...
        throw BESForbiddenError(serr, __FILE__, __LINE__);
    }
 
    std::streamsize nbytes;
    char block[BES_STREAM_BUFFER_SIZE];
    os.read(block, sizeof block);   // read() returns the istream&
    nbytes = os.gcount();   // gcount() returns the number of chars read above
    while (nbytes) {
        dhi.get_output_stream().write((char*) block, nbytes);
        os.read(block, sizeof block);
        nbytes = os.gcount();
    }
 
    os.close();
}

void BESStreamResponseHandler::transmit(BESTransmitter */*transmitter*/, BESDataHandlerInterface &/*dhi*/)
{
    // The Data is transmitted when it is read, dumped to stdout, so there is nothing
    // to transmit here.
}

void BESStreamResponseHandler::dump(ostream &strm) const
{
    strm << BESIndent::LMarg << "BESStreamResponseHandler::dump - (" << (void *) this << ")" << endl;
    BESIndent::Indent();
    BESResponseHandler::dump(strm);
    BESIndent::UnIndent();
}
 
BESResponseHandler *
BESStreamResponseHandler::BESStreamResponseBuilder(const string &name)
{
    return new BESStreamResponseHandler(name);
}