QIntC.hh
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// Copyright (c) 2005-2022 Jay Berkenbilt
//
// This file is part of qpdf.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Versions of qpdf prior to version 7 were released under the terms
// of version 2.0 of the Artistic License. At your option, you may
// continue to consider qpdf to be licensed under those terms. Please
// see the manual for additional information.
#ifndef QINTC_HH
#define QINTC_HH
#include <qpdf/DLL.h>
#include <qpdf/Types.h>
#include <stdexcept>
#include <iostream>
#include <limits>
#include <sstream>
#include <cassert>
#include <locale>
#include <type_traits>
// This namespace provides safe integer conversion that detects
// overflows. It uses short, cryptic names for brevity.
namespace QIntC // QIntC = qpdf Integer Conversion
{
// to_u is here for backward-compatibility from before we required
// C++-11.
template <typename T>
class to_u
{
public:
typedef typename std::make_unsigned<T>::type type;
};
// Basic IntConverter class, which converts an integer from the
// From class to one of the To class if it can be done safely and
// throws a range_error otherwise. This class is specialized for
// each permutation of signed/unsigned for the From and To
// classes.
template <typename From, typename To,
bool From_signed = std::numeric_limits<From>::is_signed,
bool To_signed = std::numeric_limits<To>::is_signed>
class IntConverter
{
};
template <typename From, typename To>
class IntConverter<From, To, false, false>
{
public:
static To convert(From const& i)
{
// From and To are both unsigned.
if (i > std::numeric_limits<To>::max())
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "integer out of range converting " << i
<< " from a "
<< sizeof(From) << "-byte unsigned type to a "
<< sizeof(To) << "-byte unsigned type";
throw std::range_error(msg.str());
}
return static_cast<To>(i);
}
};
template <typename From, typename To>
class IntConverter<From, To, true, true>
{
public:
static To convert(From const& i)
{
// From and To are both signed.
if ((i < std::numeric_limits<To>::min()) ||
(i > std::numeric_limits<To>::max()))
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "integer out of range converting " << i
<< " from a "
<< sizeof(From) << "-byte signed type to a "
<< sizeof(To) << "-byte signed type";
throw std::range_error(msg.str());
}
return static_cast<To>(i);
}
};
template <typename From, typename To>
class IntConverter<From, To, true, false>
{
public:
static To convert(From const& i)
{
// From is signed, and To is unsigned. If i > 0, it's safe to
// convert it to the corresponding unsigned type and to
// compare with To's max.
auto ii = static_cast<typename to_u<From>::type>(i);
if ((i < 0) || (ii > std::numeric_limits<To>::max()))
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "integer out of range converting " << i
<< " from a "
<< sizeof(From) << "-byte signed type to a "
<< sizeof(To) << "-byte unsigned type";
throw std::range_error(msg.str());
}
return static_cast<To>(i);
}
};
template <typename From, typename To>
class IntConverter<From, To, false, true>
{
public:
static To convert(From const& i)
{
// From is unsigned, and to is signed. Convert To's max to the
// unsigned version of To and compare i against that.
auto maxval = static_cast<typename to_u<To>::type>(
std::numeric_limits<To>::max());
if (i > maxval)
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "integer out of range converting " << i
<< " from a "
<< sizeof(From) << "-byte unsigned type to a "
<< sizeof(To) << "-byte signed type";
throw std::range_error(msg.str());
}
return static_cast<To>(i);
}
};
// Specific converters. The return type of each function must match
// the second template parameter to IntConverter.
template <typename T>
char to_char(T const& i)
{
return IntConverter<T, char>::convert(i);
}
template <typename T>
unsigned char to_uchar(T const& i)
{
return IntConverter<T, unsigned char>::convert(i);
}
template <typename T>
short to_short(T const& i)
{
return IntConverter<T, short>::convert(i);
}
template <typename T>
unsigned short to_ushort(T const& i)
{
return IntConverter<T, unsigned short>::convert(i);
}
template <typename T>
int to_int(T const& i)
{
return IntConverter<T, int>::convert(i);
}
template <typename T>
unsigned int to_uint(T const& i)
{
return IntConverter<T, unsigned int>::convert(i);
}
template <typename T>
size_t to_size(T const& i)
{
return IntConverter<T, size_t>::convert(i);
}
template <typename T>
qpdf_offset_t to_offset(T const& i)
{
return IntConverter<T, qpdf_offset_t>::convert(i);
}
template <typename T>
long to_long(T const& i)
{
return IntConverter<T, long >::convert(i);
}
template <typename T>
unsigned long to_ulong(T const& i)
{
return IntConverter<T, unsigned long >::convert(i);
}
template <typename T>
long long to_longlong(T const& i)
{
return IntConverter<T, long long>::convert(i);
}
template <typename T>
unsigned long long to_ulonglong(T const& i)
{
return IntConverter<T, unsigned long long>::convert(i);
}
template <typename T>
void range_check(T const& cur, T const& delta)
{
if ((delta > 0) != (cur > 0))
{
return;
}
if ((delta > 0) &&
((std::numeric_limits<T>::max() - cur) < delta))
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "adding " << delta << " to " << cur
<< " would cause an integer overflow";
throw std::range_error(msg.str());
}
else if ((delta < 0) &&
((std::numeric_limits<T>::min() - cur) > delta))
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "adding " << delta << " to " << cur
<< " would cause an integer underflow";
throw std::range_error(msg.str());
}
}
template <typename T>
void range_check_substract(T const& cur, T const& delta)
{
if ((delta >= 0) == (cur >= 0))
{
return;
}
if ((delta > 0) &&
((std::numeric_limits<T>::min() + delta) > cur))
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "subtracting " << delta << " from " << cur
<< " would cause an integer underflow";
throw std::range_error(msg.str());
}
else if ((delta < 0) &&
((std::numeric_limits<T>::max() + delta) < cur))
{
std::ostringstream msg;
msg.imbue(std::locale::classic());
msg << "subtracting " << delta << " from " << cur
<< " would cause an integer overflow";
throw std::range_error(msg.str());
}
}
};
#endif // QINTC_HH