73ef4ff3
 Hu Chunming
提交三方库
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//
// Copyright (c) 2020 Alexander Grund
//
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#define BOOST_NOWIDE_SOURCE
#ifdef BOOST_NOWIDE_NO_LFS
#define BOOST_NOWIDE_FTELL ::ftell
#define BOOST_NOWIDE_FSEEK ::fseek
#define BOOST_NOWIDE_OFF_T long
#elif defined(_WIN32) && !defined(__CYGWIN__) && !defined(__MINGW32__)
#define BOOST_NOWIDE_FTELL _ftelli64
#define BOOST_NOWIDE_FSEEK _fseeki64
#define BOOST_NOWIDE_OFF_T int64_t
#else
// IMPORTANT: Have these defines BEFORE any #includes
// and make sure changes by those macros don't leak into the public interface
// Make LFS functions available
#ifndef _LARGEFILE_SOURCE
#define _LARGEFILE_SOURCE
#endif
// Make off_t 64 bits if the macro isn't set
#ifndef _FILE_OFFSET_BITS
#define _FILE_OFFSET_BITS 64
#endif
#define BOOST_NOWIDE_FTELL ftello
#define BOOST_NOWIDE_FSEEK fseeko
#define BOOST_NOWIDE_OFF_T off_t
#endif
#include <boost/nowide/filebuf.hpp>
#include <cassert>
#include <cstdint>
#include <limits>
#include <stdio.h>
#include <type_traits>
namespace boost {
namespace nowide {
namespace detail {
template<typename T, typename U>
constexpr bool is_in_range(U value)
{
static_assert(std::is_signed<T>::value == std::is_signed<U>::value,
"Mixed sign comparison can lead to problems below");
// coverity[result_independent_of_operands]
return value >= std::numeric_limits<T>::min() && value <= std::numeric_limits<T>::max();
}
template<typename T, typename U>
T cast_if_valid_or_minus_one(U value)
{
return is_in_range<T>(value) ? static_cast<T>(value) : T(-1);
}
std::streampos ftell(FILE* file)
{
const auto pos = BOOST_NOWIDE_FTELL(file);
// Note that this is used in seekoff for which the standard states:
// On success, it returns the new absolute position the internal position pointer points to after the call,
// if representable [...] [or] the function returns pos_type(off_type(-1)). Hence we do a range check first,
// then cast or return failure instead of silently truncating
return cast_if_valid_or_minus_one<std::streamoff>(pos);
}
int fseek(FILE* file, std::streamoff offset, int origin)
{
// Similar to above: If the value of offset can't fit inside target type
// don't silently truncate but fail right away
if(!is_in_range<BOOST_NOWIDE_OFF_T>(offset))
return -1;
return BOOST_NOWIDE_FSEEK(file, static_cast<BOOST_NOWIDE_OFF_T>(offset), origin);
}
} // namespace detail
} // namespace nowide
} // namespace boost
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