files.cpp

// files.cpp - written and placed in the public domain by Wei Dai

#include "pch.h"

#ifndef CRYPTOPP_IMPORTS

#include "files.h"

#include <limits>

NAMESPACE_BEGIN(CryptoPP)

using namespace std;

void Files_TestInstantiations()
{
        FileStore f0;
        FileSource f1;
        FileSink f2;
}

void FileStore::StoreInitialize(const NameValuePairs &parameters)
{
        m_file.reset(new std::ifstream);
        const char *fileName;
        if (parameters.GetValue(Name::InputFileName(), fileName))
        {
                ios::openmode binary = parameters.GetValueWithDefault(Name::InputBinaryMode(), true) ? ios::binary : ios::openmode(0);
                m_file->open(fileName, ios::in | binary);
                if (!*m_file)
                        throw OpenErr(fileName);
                m_stream = m_file.get();
        }
        else
        {
                m_stream = NULL;
                parameters.GetValue(Name::InputStreamPointer(), m_stream);
        }
        m_waiting = false;
}

lword FileStore::MaxRetrievable() const
{
        if (!m_stream)
                return 0;

        streampos current = m_stream->tellg();
        streampos end = m_stream->seekg(0, ios::end).tellg();
        m_stream->seekg(current);
        return end-current;
}

size_t FileStore::TransferTo2(BufferedTransformation &target, lword &transferBytes, const std::string &channel, bool blocking)
{
        if (!m_stream)
        {
                transferBytes = 0;
                return 0;
        }

        lword size=transferBytes;
        transferBytes = 0;

        if (m_waiting)
                goto output;

        while (size && m_stream->good())
        {
                {
                size_t spaceSize = 1024;
                m_space = HelpCreatePutSpace(target, channel, 1, UnsignedMin(size_t(0)-1, size), spaceSize);

                m_stream->read((char *)m_space, (unsigned int)STDMIN(size, (lword)spaceSize));
                }
                m_len = m_stream->gcount();
                size_t blockedBytes;
output:
                blockedBytes = target.ChannelPutModifiable2(channel, m_space, m_len, 0, blocking);
                m_waiting = blockedBytes > 0;
                if (m_waiting)
                        return blockedBytes;
                size -= m_len;
                transferBytes += m_len;
        }

        if (!m_stream->good() && !m_stream->eof())
                throw ReadErr();

        return 0;
}

size_t FileStore::CopyRangeTo2(BufferedTransformation &target, lword &begin, lword end, const std::string &channel, bool blocking) const
{
        if (!m_stream)
                return 0;

        if (begin == 0 && end == 1)
        {
                int result = m_stream->peek();
                if (result == char_traits<char>::eof())
                        return 0;
                else
                {
                        size_t blockedBytes = target.ChannelPut(channel, byte(result), blocking);
                        begin += 1-blockedBytes;
                        return blockedBytes;
                }
        }

        // TODO: figure out what happens on cin
        streampos current = m_stream->tellg();
        streampos endPosition = m_stream->seekg(0, ios::end).tellg();
        streampos newPosition = current + (streamoff)begin;

        if (newPosition >= endPosition)
        {
                m_stream->seekg(current);
                return 0;       // don't try to seek beyond the end of file
        }
        m_stream->seekg(newPosition);
        try
        {
                assert(!m_waiting);
                lword copyMax = end-begin;
                size_t blockedBytes = const_cast<FileStore *>(this)->TransferTo2(target, copyMax, channel, blocking);
                begin += copyMax;
                if (blockedBytes)
                {
                        const_cast<FileStore *>(this)->m_waiting = false;
                        return blockedBytes;
                }
        }
        catch(...)
        {
                m_stream->clear();
                m_stream->seekg(current);
                throw;
        }
        m_stream->clear();
        m_stream->seekg(current);

        return 0;
}

lword FileStore::Skip(lword skipMax)
{
        lword oldPos = m_stream->tellg();
        std::istream::off_type offset;
        if (!SafeConvert(skipMax, offset))
                throw InvalidArgument("FileStore: maximum seek offset exceeded");
        m_stream->seekg(offset, ios::cur);
        return (lword)m_stream->tellg() - oldPos;
}

void FileSink::IsolatedInitialize(const NameValuePairs &parameters)
{
        m_file.reset(new std::ofstream);
        const char *fileName;
        if (parameters.GetValue(Name::OutputFileName(), fileName))
        {
                ios::openmode binary = parameters.GetValueWithDefault(Name::OutputBinaryMode(), true) ? ios::binary : ios::openmode(0);
                m_file->open(fileName, ios::out | ios::trunc | binary);
                if (!*m_file)
                        throw OpenErr(fileName);
                m_stream = m_file.get();
        }
        else
        {
                m_stream = NULL;
                parameters.GetValue(Name::OutputStreamPointer(), m_stream);
        }
}

bool FileSink::IsolatedFlush(bool hardFlush, bool blocking)
{
        if (!m_stream)
                throw Err("FileSink: output stream not opened");

        m_stream->flush();
        if (!m_stream->good())
                throw WriteErr();

        return false;
}

size_t FileSink::Put2(const byte *inString, size_t length, int messageEnd, bool blocking)
{
        if (!m_stream)
                throw Err("FileSink: output stream not opened");

        while (length > 0)
        {
                std::streamsize size;
                if (!SafeConvert(length, size))
                        size = numeric_limits<std::streamsize>::max();
                m_stream->write((const char *)inString, size);
                inString += size;
                length -= size;
        }

        if (messageEnd)
                m_stream->flush();

        if (!m_stream->good())
                throw WriteErr();

        return 0;
}

NAMESPACE_END

#endif

---