text: /*
   zstream-cpp Library License:
   --------------------------
  
   The zlib/libpng License Copyright (c) 2003 Jonathan de Halleux.
  
   This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.
  
   Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
  
   1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
  
   2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
  
   3. This notice may not be removed or altered from any source distribution
  
   Author: Jonathan de Halleux, dehalleux@pelikhan.com, 2003
   Gero Mueller, post@geromueller.de, 2015
   */
  
  #ifndef INPUT_ZIP_STREAM_IMPL_HPP
  #define INPUT_ZIP_STREAM_IMPL_HPP
  
  #include "izstream.hpp"
  #include <sstream>
  #include <cstring>
  
  namespace zstream {
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  basic_unzip_streambuf<Elem, Tr, ElemA, ByteT, ByteAT>::basic_unzip_streambuf(
  		istream_reference istream_, size_t window_size_,
  		size_t read_buffer_size_, size_t input_buffer_size_) :
  		m_istream(istream_), m_input_buffer(input_buffer_size_), m_buffer(
  				read_buffer_size_), m_crc(0) {
  	// setting zalloc, zfree and opaque
  	m_zip_stream.zalloc = (alloc_func) 0;
  	m_zip_stream.zfree = (free_func) 0;
  
  	m_zip_stream.next_in = NULL;
  	m_zip_stream.avail_in = 0;
  	m_zip_stream.avail_out = 0;
  	m_zip_stream.next_out = NULL;
  
  	m_err = inflateInit2(&m_zip_stream, -static_cast<int>(window_size_));
  
  	this->setg(&(m_buffer[0]) + 4,     // beginning of putback area
  	&(m_buffer[0]) + 4,     // read position
  	&(m_buffer[0]) + 4);    // end position
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  size_t basic_unzip_streambuf<Elem, Tr, ElemA, ByteT, ByteAT>::fill_input_buffer() {
  	m_zip_stream.next_in = &(m_input_buffer[0]);
  	m_istream.read((char_type*) (&(m_input_buffer[0])),
  			static_cast<std::streamsize>(m_input_buffer.size()
  					/ sizeof(char_type)));
  	return m_zip_stream.avail_in = m_istream.gcount() * sizeof(char_type);
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  basic_unzip_streambuf<Elem, Tr, ElemA, ByteT, ByteAT>::~basic_unzip_streambuf() {
  	inflateEnd(&m_zip_stream);
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  typename basic_unzip_streambuf<Elem, Tr, ElemA, ByteT, ByteAT>::int_type basic_unzip_streambuf<
  		Elem, Tr, ElemA, ByteT, ByteAT>::underflow() {
  	if (this->gptr() && (this->gptr() < this->egptr()))
  		return *reinterpret_cast<unsigned char *>(this->gptr());
  
  	int n_putback = static_cast<int>(this->gptr() - this->eback());
  	if (n_putback > 4)
  		n_putback = 4;
  	memcpy(&(m_buffer[0]) + (4 - n_putback), this->gptr() - n_putback,
  			n_putback * sizeof(char_type));
  
  	int num = unzip_from_stream(&(m_buffer[0]) + 4,
  			static_cast<std::streamsize>((m_buffer.size() - 4)
  					* sizeof(char_type)));
  	if (num <= 0) // ERROR or EOF
  		return EOF;
  
  	// reset buffer pointers
  	this->setg(&(m_buffer[0]) + (4 - n_putback),   // beginning of putback area
  	&(m_buffer[0]) + 4,                 // read position
  	&(m_buffer[0]) + 4 + num);          // end of buffer
  
  	// return next character
  	return *reinterpret_cast<unsigned char *>(this->gptr());
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  std::streamsize basic_unzip_streambuf<Elem, Tr, ElemA, ByteT, ByteAT>::unzip_from_stream(
  		char_type* buffer_, std::streamsize buffer_size_) {
  	m_zip_stream.next_out = (byte_buffer_type) buffer_;
  	m_zip_stream.avail_out =
  			static_cast<uInt>(buffer_size_ * sizeof(char_type));
  	size_t count = m_zip_stream.avail_in;
  
  	do {
  		if (m_zip_stream.avail_in == 0)
  			count = fill_input_buffer();
  
  		if (m_zip_stream.avail_in) {
  			m_err = inflate(&m_zip_stream, Z_SYNC_FLUSH);
  		}
  	} while (m_err == Z_OK && m_zip_stream.avail_out != 0 && count != 0);
  
  	// updating crc
  	m_crc = crc32(m_crc, (byte_buffer_type) buffer_,
  			buffer_size_ - m_zip_stream.avail_out / sizeof(char_type));
  	std::streamsize n_read = buffer_size_
  			- m_zip_stream.avail_out / sizeof(char_type);
  
  	// check if it is the end
  	if (m_err == Z_STREAM_END)
  		put_back_from_zip_stream();
  
  	return n_read;
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  void basic_unzip_streambuf<Elem, Tr, ElemA, ByteT, ByteAT>::put_back_from_zip_stream() {
  	if (m_zip_stream.avail_in == 0)
  		return;
  
  	m_istream.clear(std::ios::goodbit);
  	m_istream.seekg(-static_cast<int>(m_zip_stream.avail_in),
  			std::ios_base::cur);
  
  	m_zip_stream.avail_in = 0;
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  int basic_gzip_istream<Elem, Tr, ElemA, ByteT, ByteAT>::check_header() {
  	int method; /* method byte */
  	int flags; /* flags byte */
  	uInt len;
  	int c;
  	int err = 0;
  	z_stream& zip_stream = this->rdbuf()->get_zip_stream();
  
  	/* Check the gzip magic header */
  	for (len = 0; len < 2; len++) {
  		c = (int) this->rdbuf()->get_istream().get();
  		if (c != detail::gz_magic[len]) {
  			if (len != 0)
  				this->rdbuf()->get_istream().unget();
  			if (c != EOF) {
  				this->rdbuf()->get_istream().unget();
  			}
  
  			err = zip_stream.avail_in != 0 ? Z_OK : Z_STREAM_END;
  			return err;
  		}
  	}
  
  	method = (int) this->rdbuf()->get_istream().get();
  	flags = (int) this->rdbuf()->get_istream().get();
  	if (method != Z_DEFLATED || (flags & detail::gz_reserved) != 0) {
  		err = Z_DATA_ERROR;
  		return err;
  	}
  
  	/* Discard time, xflags and OS code: */
  	for (len = 0; len < 6; len++)
  		this->rdbuf()->get_istream().get();
  
  	if ((flags & detail::gz_extra_field) != 0) {
  		/* skip the extra field */
  		len = (uInt) this->rdbuf()->get_istream().get();
  		len += ((uInt) this->rdbuf()->get_istream().get()) << 8;
  		/* len is garbage if EOF but the loop below will quit anyway */
  		while (len-- != 0 && this->rdbuf()->get_istream().get() != EOF)
  			;
  	}
  	if ((flags & detail::gz_orig_name) != 0) {
  		/* skip the original file name */
  		while ((c = this->rdbuf()->get_istream().get()) != 0 && c != EOF)
  			;
  	}
  	if ((flags & detail::gz_comment) != 0) {
  		/* skip the .gz file comment */
  		while ((c = this->rdbuf()->get_istream().get()) != 0 && c != EOF)
  			;
  	}
  	if ((flags & detail::gz_head_crc) != 0) { /* skip the header crc */
  		for (len = 0; len < 2; len++)
  			this->rdbuf()->get_istream().get();
  	}
  	err = this->rdbuf()->get_istream().eof() ? Z_DATA_ERROR : Z_OK;
  
  	return err;
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  void basic_gzip_istream<Elem, Tr, ElemA, ByteT, ByteAT>::read_footer() {
  	read_long(this->rdbuf()->get_istream(), m_gzip_crc);
  	read_long(this->rdbuf()->get_istream(), m_gzip_data_size);
  }
  
  template<typename Elem, typename Tr, typename ElemA, typename ByteT,
  		typename ByteAT>
  void basic_gzip_istream<Elem, Tr, ElemA, ByteT, ByteAT>::read_long(
  		istream_reference in_, unsigned int& x_) {
  	static const int size_ul = sizeof(unsigned int);
  	static const int size_c = sizeof(char_type);
  	static const int n_end = size_ul / size_c;
  	in_.read(reinterpret_cast<char*>(&x_), n_end);
  }
  
  } // zstream
  
  #endif
  