[libcxx] Make std::basic_istream::get 0-terminate input array in case of error.

[vsapsai]

Summary

It covers the cases when the sentry object returns false and when an exception
was thrown. Corresponding standard paragraph is C++14 [istream.unformatted]p9:

[...] In any case, if n is greater than zero it then stores a null
character into the next successive location of the array.

rdar://problem/35566567

[vsapsai]

Ping.

[mclow.lists]

A couple of nits, but other than that, looks fine.

libcxx/include/istream

970

I'm not a big fan of "putting braces around single statement blocks", and (see line 963) that doesn't match the rest of libcxx.

libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp

16

Does this need to XFAIL for clang < 6 as well?

[mclow.lists]

Please make the formatting match the rest of the file.

libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp

16

I don't think that it does. Never mind this.

[vsapsai]

• Remove curly braces for single-statement ifs.

[vsapsai]

Thanks for the review.

libcxx/include/istream

970

Thanks for pointing this out. I was making sure to follow the style of opening curly brace on its own line and missed that you don't need curly braces in this case.

libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp

16

In theory, it should be done for earlier versions too. But in practice that's not required.

libcxx/include/istream

#endif  // _LIBCPP_NO_EXCEPTIONS
                     }
                     char_type __ch = traits_type::to_char_type(__i);
                     if (traits_type::eq(__ch, __dlm))
                         break;
                     *__s++ = __ch;
                     ++__gc_;
                      this->rdbuf()->sbumpc();
                 }
-                *__s = char_type();
                 if (__gc_ == 0)
                    __err |= ios_base::failbit;
                 this->setstate(__err);
             }
             else
                 this->setstate(ios_base::failbit);
         }
+        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
     return *this;
 }
 
 template<class _CharT, class _Traits>
 basic_istream<_CharT, _Traits>&

libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: with_system_cxx_lib=macosx10.13
+// XFAIL: with_system_cxx_lib=macosx10.12
+// XFAIL: with_system_cxx_lib=macosx10.11
+// XFAIL: with_system_cxx_lib=macosx10.10
+// XFAIL: with_system_cxx_lib=macosx10.9
+// XFAIL: with_system_cxx_lib=macosx10.8
+// XFAIL: with_system_cxx_lib=macosx10.7
+
 // <istream>
 
 // basic_istream<charT,traits>& get(char_type* s, streamsize n);
 
 #include <istream>
 #include <cassert>
 
+#include "test_macros.h"
+
 template <class CharT>
 struct testbuf
     : public std::basic_streambuf<CharT>
 {
     typedef std::basic_string<CharT> string_type;
     typedef std::basic_streambuf<CharT> base;
 private:
     string_type str_;
int main()
         assert(std::string(s) == "    ");
         assert(is.gcount() == 4);
         assert(is.get() == '\n');
         is.get(s, 5);
         assert( is.eof());
         assert(!is.fail());
         assert(std::string(s) == " ");
         assert(is.gcount() == 1);
+        // Check that even in error case the buffer is properly 0-terminated.
+        is.get(s, 5);
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::string(s) == "");
+        assert(is.gcount() == 0);
+    }
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        testbuf<char> sb(" ");
+        std::istream is(&sb);
+        char s[5] = "test";
+        is.exceptions(std::istream::eofbit | std::istream::badbit);
+        try
+        {
+            is.get(s, 5);
+            assert(false);
+        }
+        catch (std::ios_base::failure&)
+        {
+        }
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::string(s) == " ");
+        assert(is.gcount() == 1);
     }
+#endif
     {
         testbuf<wchar_t> sb(L"  \n    \n ");
         std::wistream is(&sb);
         wchar_t s[5];
         is.get(s, 5);
         assert(!is.eof());
         assert(!is.fail());
         assert(std::wstring(s) == L"  ");
#endif
         assert(std::wstring(s) == L"    ");
         assert(is.gcount() == 4);
         assert(is.get() == L'\n');
         is.get(s, 5);
         assert( is.eof());
         assert(!is.fail());
         assert(std::wstring(s) == L" ");
         assert(is.gcount() == 1);
+        // Check that even in error case the buffer is properly 0-terminated.
+        is.get(s, 5);
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::wstring(s) == L"");
+        assert(is.gcount() == 0);
+    }
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        testbuf<wchar_t> sb(L" ");
+        std::wistream is(&sb);
+        wchar_t s[5] = L"test";
+        is.exceptions(std::wistream::eofbit | std::wistream::badbit);
+        try
+        {
+            is.get(s, 5);
+            assert(false);
+        }
+        catch (std::ios_base::failure&)
+        {
+        }
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::wstring(s) == L" ");
+        assert(is.gcount() == 1);
     }
+#endif
 }

libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: with_system_cxx_lib=macosx10.13
+// XFAIL: with_system_cxx_lib=macosx10.12
+// XFAIL: with_system_cxx_lib=macosx10.11
+// XFAIL: with_system_cxx_lib=macosx10.10
+// XFAIL: with_system_cxx_lib=macosx10.9
+// XFAIL: with_system_cxx_lib=macosx10.8
+// XFAIL: with_system_cxx_lib=macosx10.7
+
 // <istream>
 
 // basic_istream<charT,traits>& get(char_type* s, streamsize n, char_type delim);
 
 #include <istream>
 #include <cassert>
 
+#include "test_macros.h"
+
 template <class CharT>
 struct testbuf
     : public std::basic_streambuf<CharT>
 {
     typedef std::basic_string<CharT> string_type;
     typedef std::basic_streambuf<CharT> base;
 private:
     string_type str_;
int main()
         assert(std::string(s) == "    ");
         assert(is.gcount() == 4);
         assert(is.get() == '*');
         is.get(s, 5, '*');
         assert( is.eof());
         assert(!is.fail());
         assert(std::string(s) == " ");
         assert(is.gcount() == 1);
+        // Check that even in error case the buffer is properly 0-terminated.
+        is.get(s, 5, '*');
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::string(s) == "");
+        assert(is.gcount() == 0);
+    }
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        testbuf<char> sb(" ");
+        std::istream is(&sb);
+        char s[5] = "test";
+        is.exceptions(std::istream::eofbit | std::istream::badbit);
+        try
+        {
+            is.get(s, 5, '*');
+            assert(false);
+        }
+        catch (std::ios_base::failure&)
+        {
+        }
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::string(s) == " ");
+        assert(is.gcount() == 1);
     }
+#endif
     {
         testbuf<wchar_t> sb(L"  *    * ");
         std::wistream is(&sb);
         wchar_t s[5];
         is.get(s, 5, L'*');
         assert(!is.eof());
         assert(!is.fail());
         assert(std::wstring(s) == L"  ");
#endif
         assert(std::wstring(s) == L"    ");
         assert(is.gcount() == 4);
         assert(is.get() == L'*');
         is.get(s, 5, L'*');
         assert( is.eof());
         assert(!is.fail());
         assert(std::wstring(s) == L" ");
         assert(is.gcount() == 1);
+        // Check that even in error case the buffer is properly 0-terminated.
+        is.get(s, 5, L'*');
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::wstring(s) == L"");
+        assert(is.gcount() == 0);
+    }
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        testbuf<wchar_t> sb(L" ");
+        std::wistream is(&sb);
+        wchar_t s[5] = L"test";
+        is.exceptions(std::wistream::eofbit | std::wistream::badbit);
+        try
+        {
+            is.get(s, 5, L'*');
+            assert(false);
+        }
+        catch (std::ios_base::failure&)
+        {
+        }
+        assert( is.eof());
+        assert( is.fail());
+        assert(std::wstring(s) == L" ");
+        assert(is.gcount() == 1);
     }
+#endif
 }