kiid.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2020 Ian McInerney <[email protected]>
 * Copyright (C) 2007-2014 Jean-Pierre Charras, jp.charras at wanadoo.fr
 * 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 <kiid.h>
 
#include <boost/random/mersenne_twister.hpp>
#include <boost/uuid/uuid_generators.hpp>
#include <boost/uuid/uuid_io.hpp>
 
#if BOOST_VERSION >= 106700
#include <boost/uuid/entropy_error.hpp>
#endif
 
#include <json_common.h>
 
#include <cctype>
#include <cstdint>
#include <mutex>
#include <utility>
#include <stdlib.h>
 
#include <wx/log.h>
#include <wx/string.h>
 
// Use thread_local because boost:mt19937 is not thread-safe
// Static rng and generators are used because the overhead of constant seeding is expensive
// We rely on the default non-arg constructor of basic_random_generator to provide a random seed.
// We use a separate rng object for cases where we want to control the basic_random_generator
// initial seed by calling SeedGenerator from unit tests and other special cases.
static thread_local boost::mt19937                                       rng;
static thread_local boost::uuids::basic_random_generator<boost::mt19937> randomGenerator;
 
// These don't have the same performance penalty, but we might as well be consistent
static boost::uuids::string_generator                       stringGenerator;
static boost::uuids::nil_generator                          nilGenerator;
 
 
// Global nil reference
KIID niluuid( 0 );
 
 
// When true, always create nil uuids for performance, when valid ones aren't needed.
// Thread-local to prevent background library loading from affecting other threads.
static thread_local bool g_createNilUuids = false;
 
 
// For static initialization
KIID& NilUuid()
{
    static KIID nil( 0 );
    return nil;
}
 
 
KIID::KIID()
{
#if BOOST_VERSION >= 106700
    try
    {
#endif
 
        if( g_createNilUuids )
        {
            m_uuid = nilGenerator();
        }
        else
        {
            m_uuid = randomGenerator();
        }
 
#if BOOST_VERSION >= 106700
    }
    catch( const boost::uuids::entropy_error& )
    {
        wxLogFatalError( "A Boost UUID entropy exception was thrown in %s:%s.",
                         __FILE__, __FUNCTION__ );
    }
#endif
}
 
 
KIID::KIID( int null ) :
        m_uuid( nilGenerator() )
{
    wxASSERT( null == 0 );
}
 
 
KIID::KIID( const std::string& aString ) :
        m_uuid()
{
    if( !aString.empty() && aString.length() <= 8
        && std::all_of( aString.begin(), aString.end(),
                        []( unsigned char c )
                        {
                            return std::isxdigit( c );
                        } ) )
    {
        // A legacy-timestamp-based UUID has only the last 4 octets filled in.
        // Convert them individually to avoid stepping in the little-endian/big-endian
        // doo-doo.
        for( int i = 0; i < 4; i++ )
        {
            int start = static_cast<int>( aString.length() ) - 8 + i * 2;
            int end = start + 2;
 
            start = std::max( 0, start );
            int len = std::max( 0, end - start );
 
            std::string octet = aString.substr( start, len );
            m_uuid.data[i + 12] = strtol( octet.data(), nullptr, 16 );
        }
    }
    else
    {
        try
        {
            m_uuid = stringGenerator( aString );
        }
        catch( ... )
        {
            // Failed to parse string representation; best we can do is assign a new
            // random one.
#if BOOST_VERSION >= 106700
            try
            {
#endif
 
                m_uuid = randomGenerator();
 
#if BOOST_VERSION >= 106700
            }
            catch( const boost::uuids::entropy_error& )
            {
                wxLogFatalError( "A Boost UUID entropy exception was thrown in %s:%s.",
                                 __FILE__, __FUNCTION__ );
            }
#endif
        }
    }
}
 
 
KIID::KIID( const char* aString ) :
        KIID( std::string( aString ) )
{
}
 
 
KIID::KIID( const wxString& aString ) :
        KIID( std::string( aString.ToUTF8() ) )
{
}
 
 
bool KIID::SniffTest( const wxString& aCandidate )
{
    static wxString niluuidStr = niluuid.AsString();
 
    if( aCandidate.Length() != niluuidStr.Length() )
        return false;
 
    for( wxChar c : aCandidate )
    {
        if( c >= '0' && c <= '9' )
            continue;
 
        if( c >= 'a' && c <= 'f' )
            continue;
 
        if( c >= 'A' && c <= 'F' )
            continue;
 
        if( c == '-' )
            continue;
 
        return false;
    }
 
    return true;
}
 
 
KIID::KIID( timestamp_t aTimestamp )
{
    m_uuid.data[12] = static_cast<uint8_t>( aTimestamp >> 24 );
    m_uuid.data[13] = static_cast<uint8_t>( aTimestamp >> 16 );
    m_uuid.data[14] = static_cast<uint8_t>( aTimestamp >> 8 );
    m_uuid.data[15] = static_cast<uint8_t>( aTimestamp );
}
 
 
bool KIID::IsLegacyTimestamp() const
{
    return !m_uuid.data[8] && !m_uuid.data[9] && !m_uuid.data[10] && !m_uuid.data[11];
}
 
 
timestamp_t KIID::AsLegacyTimestamp() const
{
    timestamp_t ret = 0;
 
    ret |= m_uuid.data[12] << 24;
    ret |= m_uuid.data[13] << 16;
    ret |= m_uuid.data[14] << 8;
    ret |= m_uuid.data[15];
 
    return ret;
}
 
 
size_t KIID::Hash() const
{
    return boost::uuids::hash_value( m_uuid );
}
 
 
void KIID::Clone( const KIID& aUUID )
{
    m_uuid = aUUID.m_uuid;
}
 
 
wxString KIID::AsString() const
{
    return boost::uuids::to_string( m_uuid );
}
 
 
std::string KIID::AsStdString() const
{
    return boost::uuids::to_string( m_uuid );
}
 
 
wxString KIID::AsLegacyTimestampString() const
{
    return wxString::Format( "%8.8lX", (unsigned long) AsLegacyTimestamp() );
}
 
 
void KIID::ConvertTimestampToUuid()
{
    if( !IsLegacyTimestamp() )
        return;
 
    m_uuid = randomGenerator();
}
 
 
void KIID::Increment()
{
    // This obviously destroys uniform distribution, but it can be useful when a
    // deterministic replacement for a duplicate ID is required.
 
    for( int i = 15; i >= 0; --i )
    {
        m_uuid.data[i]++;
 
        if( m_uuid.data[i] != 0 )
            break;
    }
}
 
 
KIID KIID::Combine( const KIID& aFirst, const KIID& aSecond )
{
    KIID result( 0 );
 
    for( int i = 0; i < 16; ++i )
        result.m_uuid.data[i] = aFirst.m_uuid.data[i] ^ aSecond.m_uuid.data[i];
 
    return result;
}
 
 
KIID KIID::FromDeterministicString( const wxString& aName )
{
    // Dual FNV-1a accumulators fold the name into two 64-bit values, which are
    // then laid out as a v4-shaped UUID string and parsed back into a KIID so
    // boost's string_generator produces identical bytes on every call. Do not
    // alter the constants or bit layout: this output is embedded in persisted
    // diff/merge artifacts and must stay byte-identical.
    std::uint64_t h1 = 0xcbf29ce484222325ULL;
    std::uint64_t h2 = 0x84222325cbf29ce4ULL;
 
    for( wxChar c : aName )
    {
        h1 ^= static_cast<std::uint64_t>( c );
        h1 *= 0x100000001b3ULL;
        h2 ^= static_cast<std::uint64_t>( c ) * 0x9E3779B97F4A7C15ULL;
        h2  = ( h2 << 13 ) | ( h2 >> 51 );
    }
 
    const wxString uuid = wxString::Format(
            wxS( "%08x-%04x-%04x-%04x-%012llx" ),
            static_cast<unsigned>( h1 >> 32 ),
            static_cast<unsigned>( ( h1 >> 16 ) & 0xffff ),
            static_cast<unsigned>( h1 & 0xffff ),
            static_cast<unsigned>( h2 & 0xffff ),
            static_cast<unsigned long long>( h2 >> 16 ) & 0xffffffffffffULL );
 
    return KIID( uuid );
}
 
 
void KIID::CreateNilUuids( bool aNil )
{
    g_createNilUuids = aNil;
}
 
 
void KIID::SeedGenerator( unsigned int aSeed )
{
    rng.seed( aSeed );
    randomGenerator = boost::uuids::basic_random_generator<boost::mt19937>( rng );
}
 
 
KIID_PATH::KIID_PATH( const wxString& aString )
{
    for( const wxString& pathStep : wxSplit( aString, '/' ) )
    {
        if( !pathStep.empty() )
            emplace_back( KIID( pathStep ) );
    }
}
 
 
bool KIID_PATH::MakeRelativeTo( const KIID_PATH& aPath )
{
    KIID_PATH copy = *this;
    clear();
 
    if( aPath.size() > copy.size() )
        return false; // this path is not contained within aPath
 
    for( size_t i = 0; i < aPath.size(); ++i )
    {
        if( copy.at( i ) != aPath.at( i ) )
        {
            *this = copy;
            return false; // this path is not contained within aPath
        }
    }
 
    for( size_t i = aPath.size(); i < copy.size(); ++i )
        push_back( copy.at( i ) );
 
    return true;
}
 
 
bool KIID_PATH::EndsWith( const KIID_PATH& aPath ) const
{
    if( aPath.size() > size() )
        return false;                      // this path can not end aPath
 
    KIID_PATH copyThis = *this;
    KIID_PATH copyThat = aPath;
 
    while( !copyThat.empty() )
    {
        if( *std::prev( copyThis.end() ) != *std::prev( copyThat.end() ) )
            return false;
 
        copyThis.pop_back();
        copyThat.pop_back();
    }
 
    return true;
}
 
 
wxString KIID_PATH::AsString() const
{
    wxString path;
 
    for( const KIID& pathStep : *this )
        path += '/' + pathStep.AsString();
 
    return path;
}
 
 
void to_json( nlohmann::json& aJson, const KIID& aKIID )
{
    aJson = aKIID.AsString().ToUTF8();
}
 
 
void from_json( const nlohmann::json& aJson, KIID& aKIID )
{
    aKIID = KIID( aJson.get<std::string>() );
}