ceph/src/boost/libs/nowide/src/filebuf.cpp

   1 //
   2 //  Copyright (c) 2020 Alexander Grund
   3 //
   4 //  Distributed under the Boost Software License, Version 1.0. (See
   5 //  accompanying file LICENSE or copy at
   6 //  http://www.boost.org/LICENSE_1_0.txt)
   7 //
   8
   9 #define BOOST_NOWIDE_SOURCE
  10
  11 #ifdef BOOST_NOWIDE_NO_LFS
  12 #define BOOST_NOWIDE_FTELL ::ftell
  13 #define BOOST_NOWIDE_FSEEK ::fseek
  14 #define BOOST_NOWIDE_OFF_T long
  15 #elif defined(_WIN32) && !defined(__CYGWIN__)
  16 #define BOOST_NOWIDE_FTELL _ftelli64
  17 #define BOOST_NOWIDE_FSEEK _fseeki64
  18 #define BOOST_NOWIDE_OFF_T int64_t
  19 #else
  20 // IMPORTANT: Have these defines BEFORE any #includes
  21 //            and make sure changes by those macros don't leak into the public interface
  22 // Make LFS functions available
  23 #define _LARGEFILE_SOURCE
  24 // Make off_t 64 bits if the macro isn't set
  25 #ifndef _FILE_OFFSET_BITS
  26 #define _FILE_OFFSET_BITS 64
  27 #endif
  28
  29 #define BOOST_NOWIDE_FTELL ftello
  30 #define BOOST_NOWIDE_FSEEK fseeko
  31 #define BOOST_NOWIDE_OFF_T off_t
  32 #endif
  33
  34 #include <boost/nowide/filebuf.hpp>
  35 #include <cassert>
  36 #include <cstdint>
  37 #include <limits>
  38 #include <stdio.h>
  39 #include <type_traits>
  40
  41 namespace boost {
  42 namespace nowide {
  43     namespace detail {
  44
  45         template<typename T, typename U>
  46         constexpr bool is_in_range(U value)
  47         {
  48             static_assert(std::is_signed<T>::value == std::is_signed<U>::value,
  49                           "Mixed sign comparison can lead to problems below");
  50             // coverity[result_independent_of_operands]
  51             return value >= std::numeric_limits<T>::min() && value <= std::numeric_limits<T>::max();
  52         }
  53
  54         template<typename T, typename U>
  55         T cast_if_valid_or_minus_one(U value)
  56         {
  57             return is_in_range<T>(value) ? static_cast<T>(value) : T(-1);
  58         }
  59
  60         std::streampos ftell(FILE* file)
  61         {
  62             const auto pos = BOOST_NOWIDE_FTELL(file);
  63             // Note that this is used in seekoff for which the standard states:
  64             // On success, it returns the new absolute position the internal position pointer points to after the call,
  65             // if representable [...] [or] the function returns pos_type(off_type(-1)). Hence we do a range check first,
  66             // then cast or return failure instead of silently truncating
  67             return cast_if_valid_or_minus_one<std::streamoff>(pos);
  68         }
  69
  70         int fseek(FILE* file, std::streamoff offset, int origin)
  71         {
  72             // Similar to above: If the value of offset can't fit inside target type
  73             // don't silently truncate but fail right away
  74             if(!is_in_range<BOOST_NOWIDE_OFF_T>(offset))
  75                 return -1;
  76             return BOOST_NOWIDE_FSEEK(file, static_cast<BOOST_NOWIDE_OFF_T>(offset), origin);
  77         }
  78     } // namespace detail
  79 } // namespace nowide
  80 } // namespace boost