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

   1 // Copyright (C) 2020-2021 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 // { dg-timeout-factor 2 }
  20
  21 #include <istream>
  22 #include <streambuf>
  23 #include <limits>
  24 #include <testsuite_hooks.h>
  25
  26 typedef char C;
  27
  28 struct buff : std::basic_streambuf<C>
  29 {
  30   typedef std::streamsize                 streamsize;
  31   typedef std::numeric_limits<streamsize> limits;
  32
  33   buff() : count(0), buf() { }
  34
  35   int_type underflow()
  36   {
  37     // Number of characters left until we overflow the counter
  38     const streamsize headroom = limits::max() - count;
  39
  40     if (headroom == 0)
  41       return traits_type::eof();
  42
  43     if (bufsz < headroom)
  44       count += bufsz;
  45     else
  46       count = limits::max();
  47
  48     this->setg(buf + 1, buf + 1, buf + bufsz);
  49
  50     return buf[0];
  51   }
  52
  53   int_type overflow(int_type c)
  54   {
  55     if (traits_type::eq_int_type(c , traits_type::eof()))
  56       return c;
  57     this->setp(buf, buf + bufsz - 1);
  58     return traits_type::not_eof(c);
  59   }
  60
  61   streamsize count;
  62
  63   static const streamsize bufsz = (2048 << limits::digits10) + 1;
  64   char_type buf[bufsz];
  65 };
  66
  67 void
  68 test01()
  69 {
  70   // Not possible to overflow 64-bit streamsize in reasonable time.
  71   if (std::numeric_limits<std::streamsize>::digits > 32)
  72     return;
  73
  74   std::basic_istream<C> in(new buff);
  75   buff out;
  76   in.get(out);
  77   VERIFY( in.gcount() == std::numeric_limits<std::streamsize>::max() );
  78
  79   delete in.rdbuf(new buff);
  80
  81   in.get();
  82   VERIFY( in.gcount() == 1 );
  83
  84   in.get(out, 'a');
  85   VERIFY( in.gcount() == std::numeric_limits<std::streamsize>::max() );
  86 }
  87
  88 int
  89 main()
  90 {
  91   test01();
  92 }