[cfe-dev] [PATCH] [libc++] Ensure std::getline always 0-terminates string.

[Reimar Döffinger via cfe-dev]

If the sentinel failed (e.g. due to having reached
EOF before) or an exception was caught it failed to
do that.
While it seems (unfortunately!) not required by the
specification, libstdc++ does 0-terminate and not
doing so risks creating 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
-- 
2.14.1