diptrace_binary_reader.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#include "diptrace_binary_reader.h"
 
#include <algorithm>
#include <cstdio>
#include <cstring>
 
#include <ki_exception.h>
#include <wx/filename.h>
#include <wx/translation.h>
 
 
using namespace DIPTRACE;
 
 
BINARY_READER::BINARY_READER( const wxString& aFileName ) :
        m_offset( 0 ),
        m_version( 0 ),
        m_stringEncoding( STRING_ENCODING::BY_VERSION )
{
    FILE* fp = wxFopen( aFileName, wxT( "rb" ) );
 
    if( fp == nullptr )
        THROW_IO_ERRORF( _( "Cannot open file '%s'." ), aFileName );
 
    fseek( fp, 0, SEEK_END );
    long len = ftell( fp );
 
    if( len < 0 )
    {
        fclose( fp );
        THROW_IO_ERRORF( _( "Cannot determine length of file '%s'." ), aFileName );
    }
 
    // Reject absurd sizes before allocating so a corrupt or hostile length cannot drive an
    // arbitrarily large allocation; real DipTrace files are a few MB.
    static constexpr long MAX_FILE_SIZE = 1L << 30; // 1 GiB
 
    if( len > MAX_FILE_SIZE )
    {
        fclose( fp );
        THROW_IO_ERRORF( _( "DipTrace file '%s' is too large (%ld bytes)." ), aFileName, len );
    }
 
    // resize() can throw (bad_alloc/length_error); close the handle on that path too.
    try
    {
        m_data.resize( static_cast<size_t>( len ) );
    }
    catch( ... )
    {
        fclose( fp );
        throw;
    }
 
    fseek( fp, 0, SEEK_SET );
 
    size_t bytesRead = fread( m_data.data(), 1, m_data.size(), fp );
    fclose( fp );
 
    if( bytesRead != m_data.size() )
        THROW_IO_ERRORF( _( "Error reading file '%s'." ), aFileName );
}
 
 
BINARY_READER::~BINARY_READER()
{
}
 
 
// --- Position management ----------------------------------------------------
 
 
void BINARY_READER::SetOffset( size_t aOffset )
{
    if( aOffset > m_data.size() )
        THROW_IO_ERRORF( _( "Seek past end of file (offset %zu, size %zu)." ), aOffset, m_data.size() );
 
    m_offset = aOffset;
}
 
 
void BINARY_READER::Skip( size_t aBytes )
{
    // Wrap-safe: m_offset <= size is an invariant, so size - m_offset never underflows; writing it
    // as m_offset + aBytes would wrap for an attacker-sized count and pass the check.
    if( aBytes > m_data.size() - m_offset )
        ThrowEOFError( aBytes );
 
    m_offset += aBytes;
}
 
 
// --- Primitive readers ------------------------------------------------------
 
 
uint8_t BINARY_READER::ReadByte()
{
    if( m_offset + 1 > m_data.size() )
        ThrowEOFError( 1 );
 
    uint8_t val = m_data[m_offset];
    m_offset += 1;
    return val;
}
 
 
int BINARY_READER::ReadInt3()
{
    if( m_offset + 3 > m_data.size() )
        ThrowEOFError( 3 );
 
    const uint8_t* p = &m_data[m_offset];
    int raw = ( static_cast<int>( p[0] ) << 16 )
            | ( static_cast<int>( p[1] ) << 8 )
            | ( static_cast<int>( p[2] ) );
    m_offset += 3;
    return raw - INT3_BIAS;
}
 
 
int BINARY_READER::ReadInt4()
{
    if( m_offset + 4 > m_data.size() )
        ThrowEOFError( 4 );
 
    const uint8_t* p = &m_data[m_offset];
    unsigned int raw = ( static_cast<unsigned int>( p[0] ) << 24 )
                     | ( static_cast<unsigned int>( p[1] ) << 16 )
                     | ( static_cast<unsigned int>( p[2] ) << 8 )
                     | ( static_cast<unsigned int>( p[3] ) );
    m_offset += 4;
 
    // Subtract in int64 so a raw value with the high bit set (>= 2^31) cannot overflow the
    // intermediate signed int before the bias is applied.
    return static_cast<int>( static_cast<int64_t>( raw ) - INT4_BIAS );
}
 
 
wxString BINARY_READER::ReadString()
{
    if( m_stringEncoding == STRING_ENCODING::UTF16_BE )
        return ReadStringUTF16();
 
    if( m_stringEncoding == STRING_ENCODING::LEGACY_ASCII
        || m_version <= LEGACY_STRING_VERSION )
    {
        return ReadStringASCII();
    }
 
    return ReadStringUTF16();
}
 
 
void BINARY_READER::ReadColor( uint8_t& r, uint8_t& g, uint8_t& b )
{
    r = ReadByte();
    g = ReadByte();
    b = ReadByte();
}
 
 
void BINARY_READER::ReadBytes( uint8_t* aDst, size_t aCount )
{
    // Wrap-safe (m_offset <= size invariant); m_offset + aCount would wrap for a huge count.
    if( aCount > m_data.size() - m_offset )
        ThrowEOFError( aCount );
 
    std::memcpy( aDst, &m_data[m_offset], aCount );
    m_offset += aCount;
}
 
 
// --- Peek methods -----------------------------------------------------------
 
 
int BINARY_READER::PeekInt3() const
{
    if( m_offset + 3 > m_data.size() )
    {
        THROW_IO_ERRORF( _( "Unexpected end of file at offset 0x%06zX: need 3 bytes for int3, have %zu remaining." ),
                         m_offset,
                         m_data.size() - m_offset );
    }
 
    const uint8_t* p = &m_data[m_offset];
    int raw = ( static_cast<int>( p[0] ) << 16 )
            | ( static_cast<int>( p[1] ) << 8 )
            | ( static_cast<int>( p[2] ) );
    return raw - INT3_BIAS;
}
 
 
int BINARY_READER::PeekInt4() const
{
    if( m_offset + 4 > m_data.size() )
    {
        THROW_IO_ERRORF( _( "Unexpected end of file at offset 0x%06zX: need 4 bytes for int4, have %zu remaining." ),
                         m_offset,
                         m_data.size() - m_offset );
    }
 
    const uint8_t* p = &m_data[m_offset];
    unsigned int raw = ( static_cast<unsigned int>( p[0] ) << 24 )
                     | ( static_cast<unsigned int>( p[1] ) << 16 )
                     | ( static_cast<unsigned int>( p[2] ) << 8 )
                     | ( static_cast<unsigned int>( p[3] ) );
 
    // Subtract in int64 so a raw value with the high bit set cannot overflow the intermediate int.
    return static_cast<int>( static_cast<int64_t>( raw ) - INT4_BIAS );
}
 
 
uint8_t BINARY_READER::PeekByte() const
{
    if( m_offset >= m_data.size() )
        THROW_IO_ERRORF( _( "Unexpected end of file at offset 0x%06zX: need 1 byte." ), m_offset );
 
    return m_data[m_offset];
}
 
 
// --- Coordinate conversion --------------------------------------------------
 
 
int BINARY_READER::DipTraceToKiCadNm( int aDipTraceCoord )
{
    return static_cast<int>( static_cast<int64_t>( aDipTraceCoord ) * 100 / 3 );
}
 
 
double BINARY_READER::DipTraceToMM( int aDipTraceCoord )
{
    return static_cast<double>( aDipTraceCoord ) * DIPTRACE_COORD_TO_MM;
}
 
 
// --- Search helpers ---------------------------------------------------------
 
 
size_t BINARY_READER::FindPattern( const uint8_t* aPattern, size_t aPatternLen,
                                   size_t aStart, size_t aEnd ) const
{
    if( aEnd == 0 || aEnd > m_data.size() )
        aEnd = m_data.size();
 
    if( aStart >= aEnd || aPatternLen == 0 || aPatternLen > ( aEnd - aStart ) )
        return std::string::npos;
 
    auto it = std::search( m_data.begin() + aStart,
                           m_data.begin() + aEnd,
                           aPattern,
                           aPattern + aPatternLen );
 
    if( it == m_data.begin() + aEnd )
        return std::string::npos;
 
    return static_cast<size_t>( it - m_data.begin() );
}
 
 
size_t BINARY_READER::FindString( const wxString& aStr, size_t aStart, size_t aEnd ) const
{
    if( aStr.IsEmpty() )
        return std::string::npos;
 
    // Encode the string as UTF-16-BE, which is the v39+ on-disk representation.
    // The on-disk format has a 2-byte length prefix before the encoded characters.
    wxMBConvUTF16BE conv;
 
    // wxMBConvUTF16BE::FromWChar includes a BOM; we must skip it.
    // We encode manually: each wxChar becomes 2 bytes in UTF-16-BE.
    size_t charCount = aStr.length();
    std::vector<uint8_t> encoded( charCount * 2 );
 
    for( size_t i = 0; i < charCount; i++ )
    {
        wxChar ch = aStr[i];
        encoded[i * 2]     = static_cast<uint8_t>( ( ch >> 8 ) & 0xFF );
        encoded[i * 2 + 1] = static_cast<uint8_t>( ch & 0xFF );
    }
 
    // Search for the encoded character data in the file buffer.
    size_t matchPos = FindPattern( encoded.data(), encoded.size(), aStart, aEnd );
 
    if( matchPos == std::string::npos )
        return std::string::npos;
 
    // The length prefix sits 2 bytes before the encoded character data.
    if( matchPos < 2 )
        return std::string::npos;
 
    return matchPos - 2;
}
 
 
// --- Try-read methods -------------------------------------------------------
 
 
bool BINARY_READER::TryReadString( wxString& aResult )
{
    if( m_stringEncoding == STRING_ENCODING::UTF16_BE )
        return TryReadStringUTF16( aResult );
 
    if( m_stringEncoding == STRING_ENCODING::LEGACY_ASCII
        || m_version <= LEGACY_STRING_VERSION )
    {
        return TryReadStringASCII( aResult );
    }
 
    return TryReadStringUTF16( aResult );
}
 
 
void BINARY_READER::DetectStringEncoding( size_t aProbeOffset )
{
    size_t          savedOffset = m_offset;
    STRING_ENCODING savedEncoding = m_stringEncoding;
 
    // The probe helpers below dispatch on m_stringEncoding, so force each framing explicitly.
    m_offset = aProbeOffset;
    m_stringEncoding = STRING_ENCODING::LEGACY_ASCII;
    wxString asciiStr;
    bool     asciiOk = TryReadStringASCII( asciiStr ) && !asciiStr.IsEmpty();
 
    m_offset = aProbeOffset;
    m_stringEncoding = STRING_ENCODING::UTF16_BE;
    wxString utf16Str;
    bool     utf16Ok = TryReadStringUTF16( utf16Str ) && !utf16Str.IsEmpty();
 
    m_offset = savedOffset;
    m_stringEncoding = savedEncoding;
 
    // Only commit when exactly one framing yields a printable string; otherwise leave the
    // version-based default in place.
    if( asciiOk && !utf16Ok )
        m_stringEncoding = STRING_ENCODING::LEGACY_ASCII;
    else if( utf16Ok && !asciiOk )
        m_stringEncoding = STRING_ENCODING::UTF16_BE;
}
 
 
// --- Private string readers -------------------------------------------------
 
 
wxString BINARY_READER::ReadStringUTF16()
{
    if( m_offset + 2 > m_data.size() )
        ThrowEOFError( 2 );
 
    const uint8_t* p = &m_data[m_offset];
    int charCount = ( static_cast<int>( p[0] ) << 8 ) | static_cast<int>( p[1] );
    m_offset += 2;
 
    if( charCount == 0 )
        return wxString();
 
    if( charCount < 0 || charCount > MAX_STRING_CHARS )
        THROW_IO_ERRORF( _( "Unreasonable string length %d at offset 0x%06zX." ), charCount, m_offset - 2 );
 
    size_t byteCount = static_cast<size_t>( charCount ) * 2;
 
    if( m_offset + byteCount > m_data.size() )
        ThrowEOFError( byteCount );
 
    // wxMBConvUTF16BE converts from a big-endian byte stream.
    wxMBConvUTF16BE conv;
    wxString result = wxString( reinterpret_cast<const char*>( &m_data[m_offset] ),
                                conv, byteCount );
 
    m_offset += byteCount;
    return result;
}
 
 
wxString BINARY_READER::ReadStringASCII()
{
    int byteCount = ReadInt3();
 
    if( byteCount == 0 )
        return wxString();
 
    if( byteCount < 0 || byteCount > MAX_STRING_CHARS )
        THROW_IO_ERRORF( _( "Unreasonable v37 string length %d at offset 0x%06zX." ), byteCount, m_offset - 3 );
 
    size_t count = static_cast<size_t>( byteCount );
 
    if( m_offset + count > m_data.size() )
        ThrowEOFError( count );
 
    wxString result = wxString::From8BitData(
            reinterpret_cast<const char*>( &m_data[m_offset] ), count );
    m_offset += count;
    return result;
}
 
 
bool BINARY_READER::TryReadStringUTF16( wxString& aResult )
{
    size_t savedOffset = m_offset;
 
    if( m_offset + 2 > m_data.size() )
        return false;
 
    const uint8_t* p = &m_data[m_offset];
    int charCount = ( static_cast<int>( p[0] ) << 8 ) | static_cast<int>( p[1] );
    m_offset += 2;
 
    if( charCount == 0 )
    {
        aResult = wxString();
        return true;
    }
 
    if( charCount < 0 || charCount > 500 )
    {
        m_offset = savedOffset;
        return false;
    }
 
    size_t byteCount = static_cast<size_t>( charCount ) * 2;
 
    if( m_offset + byteCount > m_data.size() )
    {
        m_offset = savedOffset;
        return false;
    }
 
    wxMBConvUTF16BE conv;
    wxString candidate = wxString( reinterpret_cast<const char*>( &m_data[m_offset] ),
                                   conv, byteCount );
 
    if( !IsPrintableString( candidate ) )
    {
        m_offset = savedOffset;
        return false;
    }
 
    m_offset += byteCount;
    aResult = candidate;
    return true;
}
 
 
bool BINARY_READER::TryReadStringASCII( wxString& aResult )
{
    size_t savedOffset = m_offset;
 
    if( m_offset + 3 > m_data.size() )
        return false;
 
    const uint8_t* p = &m_data[m_offset];
    int byteCount = ( static_cast<int>( p[0] ) << 16 )
                  | ( static_cast<int>( p[1] ) << 8 )
                  | ( static_cast<int>( p[2] ) );
    byteCount -= INT3_BIAS;
    m_offset += 3;
 
    if( byteCount == 0 )
    {
        aResult = wxString();
        return true;
    }
 
    if( byteCount < 0 || byteCount > 500 )
    {
        m_offset = savedOffset;
        return false;
    }
 
    size_t count = static_cast<size_t>( byteCount );
 
    if( m_offset + count > m_data.size() )
    {
        m_offset = savedOffset;
        return false;
    }
 
    wxString candidate = wxString::From8BitData(
            reinterpret_cast<const char*>( &m_data[m_offset] ), count );
 
    if( !IsPrintableString( candidate ) )
    {
        m_offset = savedOffset;
        return false;
    }
 
    m_offset += count;
    aResult = candidate;
    return true;
}
 
 
bool BINARY_READER::IsPrintableString( const wxString& aStr )
{
    for( size_t i = 0; i < aStr.length(); i++ )
    {
        wxChar ch = aStr[i];
 
        if( ch == '\r' || ch == '\n' || ch == '\t' )
            continue;
 
        if( ch < 0x20 )
            return false;
    }
 
    return true;
}
 
 
void BINARY_READER::ThrowEOFError( size_t aBytesNeeded ) const
{
    size_t remaining = ( m_offset < m_data.size() ) ? ( m_data.size() - m_offset ) : 0;
 
    THROW_IO_ERRORF( _( "Unexpected end of file at offset 0x%06zX: need %zu bytes, have %zu remaining." ),
                     m_offset,
                     aBytesNeeded,
                     remaining );
}