libstdc++-v3/testsuite/27_io/basic_istream/get/char/lwg3464.cc

   1 // Copyright (C) 2020 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do run { target { ! lp64 } } }
  19
  20 #include <istream>
  21 #include <streambuf>
  22 #include <limits>
  23 #include <testsuite_hooks.h>
  24
  25 typedef char C;
  26
  27 struct buff : std::basic_streambuf<C>
  28 {
  29   typedef std::streamsize                 streamsize;
  30   typedef std::numeric_limits<streamsize> limits;
  31
  32   buff() : count(0), buf() { }
  33
  34   int_type underflow()
  35   {
  36     // Number of characters left until we overflow the counter
  37     const streamsize headroom = limits::max() - count;
  38
  39     if (headroom == 0)
  40       return traits_type::eof();
  41
  42     if (bufsz < headroom)
  43       count += bufsz;
  44     else
  45       count = limits::max();
  46
  47     this->setg(buf + 1, buf + 1, buf + bufsz);
  48
  49     return buf[0];
  50   }
  51
  52   int_type overflow(int_type c)
  53   {
  54     if (traits_type::eq_int_type(c , traits_type::eof()))
  55       return c;
  56     this->setp(buf, buf + bufsz - 1);
  57     return traits_type::not_eof(c);
  58   }
  59
  60   streamsize count;
  61
  62   static const streamsize bufsz = (2048 << limits::digits10) + 1;
  63   char_type buf[bufsz];
  64 };
  65
  66 void
  67 test01()
  68 {
  69   // Not possible to overflow 64-bit streamsize in reasonable time.
  70   if (std::numeric_limits<std::streamsize>::digits > 32)
  71     return;
  72
  73   std::basic_istream<C> in(new buff);
  74   buff out;
  75   in.get(out);
  76   VERIFY( in.gcount() == std::numeric_limits<std::streamsize>::max() );
  77
  78   delete in.rdbuf(new buff);
  79
  80   in.get();
  81   VERIFY( in.gcount() == 1 );
  82
  83   in.get(out, 'a');
  84   VERIFY( in.gcount() == std::numeric_limits<std::streamsize>::max() );
  85 }
  86
  87 int
  88 main()
  89 {
  90   test01();
  91 }