Thanks for the patch, Reimar. Can you please add tests to ensure this
functionality doesn’t regress? As null character is required by the standard
(27.7.2.3p21), a good starting point seems to be
test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size.pass.cpp
test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size_chart.pass.cpp
And what about free function std::getline that takes a stream and a string? The
standard (21.4.8.9p7) specifies
> […]After constructing a sentry object, if the sentry converts to true, calls
> str.erase()[…]
It doesn’t mention explicitly effects to str if the sentry converts to false
but it mentions that std::getline behaves as an unformatted input function
(27.7.2.3). And 27.7.2.3p1 mentions
> […]If the sentry object returns true, when converted to a value of type bool,
> the function endeavors to obtain the requested input. Otherwise, if the
> sentry constructor exits by throwing an exception or if the sentry object
> returns false, when converted to a value of type bool, the function returns
> without attempting to obtain any input. In either case the number of
> extracted characters is set to 0; unformatted input functions taking a
> character array of non-zero size as an argument shall also store a null
> character (using charT()) in the first location of the array.[…]
Technically, string is not a character array of non-zero size. But according to
the spirit of the standard, I would expect string to be empty after reading
into it from a stream that reached EOF. What do you think?
Regards,
Volodymyr
> On Oct 4, 2017, at 12:07, Reimar Döffinger via cfe-commits
> <cfe-commits@lists.llvm.org> wrote:
>
> If the sentinel failed (e.g. due to having reached
> EOF before) or an exception was caught it failed to
> do that.
> The C++14 standard says:
> "In any case, if n is greater than zero, it then stores
> a null character (using charT()) into the next
> successive location of the array."
> Other implementations like libstdc++ do 0-terminate and
> not doing so may lead security issues in applications.
> ---
> include/istream | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/istream b/include/istream
> index 0b8e05d95..5c73df38f 100644
> --- a/include/istream
> +++ b/include/istream
> @@ -1069,16 +1069,18 @@ basic_istream<_CharT, _Traits>::getline(char_type*
> __s, streamsize __n, char_typ
> this->rdbuf()->sbumpc();
> ++__gc_;
> }
> - if (__n > 0)
> - *__s = char_type();
> if (__gc_ == 0)
> __err |= ios_base::failbit;
> this->setstate(__err);
> }
> + if (__n > 0)
> + *__s = char_type();
> #ifndef _LIBCPP_NO_EXCEPTIONS
> }
> catch (...)
> {
> + if (__n > 0)
> + *__s = char_type();
> this->__set_badbit_and_consider_rethrow();
> }
> #endif // _LIBCPP_NO_EXCEPTIONS
> --
> 2.14.2
>
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