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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab ft=cpp
#ifndef RGW_B64_H
#define RGW_B64_H
#include <boost/archive/iterators/base64_from_binary.hpp>
#include <boost/archive/iterators/binary_from_base64.hpp>
#include <boost/archive/iterators/insert_linebreaks.hpp>
#include <boost/archive/iterators/transform_width.hpp>
#include <boost/archive/iterators/remove_whitespace.hpp>
#include <limits>
#include <string>
#include <string_view>
namespace rgw {
/*
* A header-only Base64 encoder built on boost::archive. The
* formula is based on a class poposed for inclusion in boost in
* 2011 by Denis Shevchenko (abandoned), updated slightly
* (e.g., uses std::string_view).
*
* Also, wrap_width added as template argument, based on
* feedback from Marcus.
*/
template<int wrap_width = std::numeric_limits<int>::max()>
inline std::string to_base64(std::string_view sview)
{
using namespace boost::archive::iterators;
// output must be =padded modulo 3
auto psize = sview.size();
while ((psize % 3) != 0) {
++psize;
}
/* RFC 2045 requires linebreaks to be present in the output
* sequence every at-most 76 characters (MIME-compliance),
* but we could likely omit it. */
typedef
insert_linebreaks<
base64_from_binary<
transform_width<
std::string_view::const_iterator
,6,8>
>
,wrap_width
> b64_iter;
std::string outstr(b64_iter(sview.data()),
b64_iter(sview.data() + sview.size()));
// pad outstr with '=' to a length that is a multiple of 3
for (size_t ix = 0; ix < (psize-sview.size()); ++ix)
outstr.push_back('=');
return outstr;
}
inline std::string from_base64(std::string_view sview)
{
using namespace boost::archive::iterators;
if (sview.empty())
return std::string();
/* MIME-compliant input will have line-breaks, so we have to
* filter WS */
typedef
transform_width<
binary_from_base64<
remove_whitespace<
std::string_view::const_iterator>>
,8,6
> b64_iter;
while (sview.back() == '=')
sview.remove_suffix(1);
std::string outstr(b64_iter(sview.data()),
b64_iter(sview.data() + sview.size()));
return outstr;
}
} /* namespace */
#endif /* RGW_B64_H */
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