XRootD to std::istream Adapter

XRdInputStreamBuf.cpp

//
// Created by Petr Mánek on 03.09.16.
//

#include "XRdInputStreamBuf.h"

using namespace std;
using namespace XrdCl;

XRdInputStreamBuf::XRdInputStreamBuf(string url) {
    buffer_ = new char[bufferSize_];
    offset_ = 0;

    file_ = new File();
    XRootDStatus result = file_->Open(url, OpenFlags::Read);

    if (!result.IsOK()) {
        LOG(ERROR) << "XRootD open operation failed: " << result.ToString();
    }
}

XRdInputStreamBuf::~XRdInputStreamBuf() {
    XRootDStatus result = file_->Close();
    if (!result.IsOK()) {
        LOG(ERROR) << "XRootD close operation failed: " << result.ToString();
    }

    delete file_;
    delete[] buffer_;
}

int XRdInputStreamBuf::underflow() {
    if (this->gptr() == this->egptr()) {
        // Not enough data buffered. Retrieve some more.
        uint32_t bytesRead = 0;
        XRootDStatus result = file_->Read(offset_, bufferSize_, (void *) buffer_, bytesRead);
        if (!result.IsOK()) {
            LOG(ERROR) << "XRootD read operation failed: " << result.ToString();
        }

        // Update underlying data structures.
        offset_ += bytesRead;
        this->setg(this->buffer_, this->buffer_, this->buffer_ + bytesRead);
    }

    // Read from underlying data structures.
    return this->gptr() == this->egptr()
           ? std::char_traits<char>::eof()
           : std::char_traits<char>::to_int_type(*this->gptr());
}

XRdInputStreamBuf.h

//
// Created by Petr Mánek on 03.09.16.
//

#ifndef CLSTRD_XRDINPUTSTREAMBUF_H
#define CLSTRD_XRDINPUTSTREAMBUF_H

#include <streambuf>

#include <glog/logging.h>
#include <XrdCl/XrdClFile.hh>

class XRdInputStreamBuf : public std::streambuf {
public:
    XRdInputStreamBuf(std::string url);

    virtual ~XRdInputStreamBuf();

protected:
    virtual int underflow() override;

private:
    XrdCl::File *file_;
    const size_t bufferSize_ = 1024;
    char *buffer_;
    uint64_t offset_;
};


#endif //CLSTRD_XRDINPUTSTREAMBUF_H