fixing overrelease and out-of-bounds write, fixes #13725

[wxWidgets.git] / src / common / stdstream.cpp

/////////////////////////////////////////////////////////////////////////////
// Name:        src/common/stdstream.cpp
// Purpose:     Implementation of std::istream and std::ostream derived
//              wrappers for wxInputStream and wxOutputStream
// Author:      Jonathan Liu <net147@gmail.com>
// Created:     2009-05-02
// RCS-ID:      $Id$
// Copyright:   (c) 2009 Jonathan Liu
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

// ==========================================================================
// Declarations
// ==========================================================================

// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"

#ifdef __BORLANDC__
    #pragma hdrstop
#endif

#if wxUSE_STREAMS && wxUSE_STD_IOSTREAM

#ifndef WX_PRECOMP
#endif

#include "wx/stdstream.h"

#include <ios>
#include <istream>
#include <ostream>
#include <streambuf>

// ==========================================================================
// Helpers
// ==========================================================================

namespace
{

bool
IosSeekDirToWxSeekMode(std::ios_base::seekdir way,
                       wxSeekMode& seekMode)
{
    switch ( way )
    {
        case std::ios_base::beg:
            seekMode = wxFromStart;
            break;
        case std::ios_base::cur:
            seekMode = wxFromCurrent;
            break;
        case std::ios_base::end:
            seekMode = wxFromEnd;
            break;
        default:
            return false;
    }

    return true;
}

} // anonymous namespace

// ==========================================================================
// wxStdInputStreamBuffer
// ==========================================================================

wxStdInputStreamBuffer::wxStdInputStreamBuffer(wxInputStream& stream) :
    m_stream(stream), m_lastChar(EOF)
{
}

std::streambuf *
wxStdInputStreamBuffer::setbuf(char *WXUNUSED(s),
                               std::streamsize WXUNUSED(n))
{
    return NULL;
}

std::streampos
wxStdInputStreamBuffer::seekoff(std::streamoff off,
                                std::ios_base::seekdir way,
                                std::ios_base::openmode which)
{
    wxSeekMode seekMode;

    if ( !IosSeekDirToWxSeekMode(way, seekMode) )
        return -1;
    if ( !(which & std::ios_base::in) )
        return -1;

    off_t newPos = m_stream.SeekI((off_t) off, seekMode);

    if ( newPos != wxInvalidOffset )
        return (std::streampos) newPos;
    else
        return -1;
}

std::streampos
wxStdInputStreamBuffer::seekpos(std::streampos sp,
                                std::ios_base::openmode which)
{
    if ( !(which & std::ios_base::in) )
        return -1;

    off_t newPos = m_stream.SeekI((off_t) sp);

    if ( newPos != wxInvalidOffset )
        return (std::streampos) newPos;
    else
        return -1;
}

std::streamsize
wxStdInputStreamBuffer::showmanyc()
{
    if ( m_stream.CanRead() && (off_t) m_stream.GetSize() > m_stream.TellI() )
        return m_stream.GetSize() - m_stream.TellI();
    else
        return 0;
}

std::streamsize
wxStdInputStreamBuffer::xsgetn(char *s, std::streamsize n)
{
    m_stream.Read((void *) s, (size_t) n);

    std::streamsize read = m_stream.LastRead();

    if ( read > 0 )
        m_lastChar = (unsigned char) s[read - 1];

    return read;
}

int
wxStdInputStreamBuffer::underflow()
{
    int ch = m_stream.GetC();

    if ( m_stream.LastRead() == 1 )
    {
        m_stream.Ungetch((char) ch);
        return ch;
    }
    else
    {
        return EOF;
    }
}

int
wxStdInputStreamBuffer::uflow()
{
    int ch = m_stream.GetC();

    if ( m_stream.LastRead() == 1 )
    {
        m_lastChar = ch;
        return ch;
    }
    else
    {
        return EOF;
    }
}

int
wxStdInputStreamBuffer::pbackfail(int c)
{
    if ( c == EOF )
    {
        if ( m_lastChar == EOF )
            return EOF;

        c = m_lastChar;
        m_lastChar = EOF;
    }

    return m_stream.Ungetch((char) c) ? c : EOF;
}

// ==========================================================================
// wxStdOutputStreamBuffer
// ==========================================================================

wxStdOutputStreamBuffer::wxStdOutputStreamBuffer(wxOutputStream& stream) :
    m_stream(stream)
{
}

std::streambuf *
wxStdOutputStreamBuffer::setbuf(char *WXUNUSED(s),
                                std::streamsize WXUNUSED(n))
{
    return NULL;
}

std::streampos
wxStdOutputStreamBuffer::seekoff(std::streamoff off,
                                 std::ios_base::seekdir way,
                                 std::ios_base::openmode which)
{
    wxSeekMode seekMode;

    if ( !IosSeekDirToWxSeekMode(way, seekMode) )
        return -1;
    if ( !(which & std::ios_base::out) )
        return -1;

    off_t newPos = m_stream.SeekO((off_t) off, seekMode);

    if ( newPos != wxInvalidOffset )
        return (std::streampos) newPos;
    else
        return -1;
}

std::streampos
wxStdOutputStreamBuffer::seekpos(std::streampos sp,
                                 std::ios_base::openmode which)
{
    if ( !(which & std::ios_base::out) )
        return -1;

    off_t newPos = m_stream.SeekO((off_t) sp);

    if ( newPos != wxInvalidOffset )
        return (std::streampos) newPos;
    else
        return -1;
}

std::streamsize
wxStdOutputStreamBuffer::xsputn(const char *s,
                                std::streamsize n)
{
    m_stream.Write((const void *) s, (size_t) n);
    return (std::streamsize) m_stream.LastWrite();
}

int
wxStdOutputStreamBuffer::overflow(int c)
{
    m_stream.PutC(c);
    return m_stream.IsOk() ? c : EOF;
}

// ==========================================================================
// wxStdInputStream and wxStdOutputStream
// ==========================================================================

// FIXME-VC6: it is impossible to call basic_ios<char>::init() with this
//            compiler, it complains about invalid call to non-static member
//            function so use a suspicious (as it uses a pointer to not yet
//            constructed streambuf) but working workaround
//
//            It also doesn't like using istream in the ctor initializer list
//            and we must spell it out as basic_istream<char>.
#ifdef __VISUALC6__

wxStdInputStream::wxStdInputStream(wxInputStream& stream)
    : std::basic_istream<char, std::char_traits<char> >(&m_streamBuffer),
      m_streamBuffer(stream)
{
}

wxStdOutputStream::wxStdOutputStream(wxOutputStream& stream)
    : std::basic_ostream<char, std::char_traits<char> >(&m_streamBuffer),
      m_streamBuffer(stream)
{
}

#else // !VC6

wxStdInputStream::wxStdInputStream(wxInputStream& stream) :
    std::istream(NULL), m_streamBuffer(stream)
{
    std::ios::init(&m_streamBuffer);
}

wxStdOutputStream::wxStdOutputStream(wxOutputStream& stream) :
    std::ostream(NULL), m_streamBuffer(stream)
{
    std::ios::init(&m_streamBuffer);
}

#endif // VC6/!VC6

#endif // wxUSE_STREAMS && wxUSE_STD_IOSTREAM