diff options
Diffstat (limited to 'libstdc++-v3/include/std/istream')
| -rw-r--r-- | libstdc++-v3/include/std/istream | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/libstdc++-v3/include/std/istream b/libstdc++-v3/include/std/istream index b506c4f7504..416ef556fa1 100644 --- a/libstdc++-v3/include/std/istream +++ b/libstdc++-v3/include/std/istream @@ -784,7 +784,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION * - if `width()` is greater than zero, `n` is `min(width(), n)` * - otherwise `n` is the number of elements of the array * - (before C++20 the pointer is assumed to point to an array of - * - the largest possible size for an array of `char_type`). + * the largest possible size for an array of `char_type`). * * Characters are extracted and stored until one of the following happens: * - `n - 1` characters are stored @@ -802,19 +802,40 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION inline basic_istream<_CharT, _Traits>& operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s) { +#ifdef __OPTIMIZE__ + // Function inlining might make the buffer size known, allowing us to + // prevent overflow. size_t __n = __builtin_object_size(__s, 0); - if (__builtin_expect(__n < sizeof(_CharT), false)) + if (__n < sizeof(_CharT)) { // There is not even space for the required null terminator. __glibcxx_assert(__n >= sizeof(_CharT)); + // No point calling __istream_extract, but still need to reset width. __in.width(0); __in.setstate(ios_base::failbit); } + else if (__n != (size_t)-1) + { + __n /= sizeof(_CharT); + streamsize __w = __in.width(); + std::__istream_extract(__in, __s, __n); + if (__in.good() && (__w <= 0 || __n < __w)) + { + // Stopped extracting early to avoid overflowing the buffer, + // but might have stopped anyway (and set eofbit) if at EOF. + const typename _Traits::int_type __c = __in.rdbuf()->sgetc(); + const bool __eof = _Traits::eq_int_type(__c, _Traits::eof()); + if (__builtin_expect(__eof, true)) // Assume EOF, not overflow. + __in.setstate(ios_base::eofbit); + } + } else +#endif // __OPTIMIZE { - if (__n == (size_t)-1) - __n = __gnu_cxx::__numeric_traits<streamsize>::__max; - std::__istream_extract(__in, __s, __n / sizeof(_CharT)); + // Buffer size is unknown, have to assume it's huge. + streamsize __n = __gnu_cxx::__numeric_traits<streamsize>::__max; + __n /= sizeof(_CharT); + std::__istream_extract(__in, __s, __n); } return __in; } |