Boost C++ Libraries: Ticket #1230: mbstate uninitialized

component changed; owner set

Marshall Clow — Wed, 26 Sep 2007 17:08:14 GMT

owner set to Beman Dawes
component None → filesystem

status, milestone changed; resolution set

Beman Dawes — Sun, 25 Nov 2007 15:27:02 GMT

status new → closed
resolution → fixed
milestone To Be Determined → Boost 1.35.0

It isn't clear to me mbstate needs to be initialized. But doing so is harmless, so it now does so.

Thanks for the report,

--Beman

Jan-Erik.Dahlin@… — Mon, 26 Nov 2007 09:43:20 GMT

It needs to be initialized. As the name implies the mbstate tracks the state of a multibyte access, e.g. if the previous access or conversion only was a partial translation (this can happen if the previous read operation only got half the multibyte character and the other half comes in the current read).

If we start with an uninitialized mbstate the current access can accidentally be performed as a continuation of a partial access. That will produce unexpected results.

vital — Thu, 26 Feb 2009 11:17:46 GMT

Hello[[BR]] It really must be initialized. We have a crash inside boost due to this bug in 1.34.1. I found corresponding bug to gcc (but left as "not a bug") where the reason of crash was also unitizalized state (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28059)

Stack of crash:
#0 0xb7f6c410 in kernel_vsyscall ()
#1 0xb6c66085 in raise () from /lib/tls/i686/cmov/libc.so.6
#2 0xb6c67a01 in abort () from /lib/tls/i686/cmov/libc.so.6
#3 0xb6e86480 in gnu_cxx::verbose_terminate_handler () from ../lib32/libstdc++.so.6
#4 0xb6e83d05 in std::set_unexpected () from ../lib32/libstdc++.so.6
#5 0xb6e83d42 in std::terminate () from ../lib32/libstdc++.so.6
#6 0xb6e83e6a in cxa_throw () from ../lib32/libstdc++.so.6
#7 0xb7be2220 in boost::throw_exception<boost::filesystem::basic_filesystem_error<boost::filesystem::basic_path<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >, boost::filesystem::wpath_traits> > > (e=@0xbf9a6fac)

at throw_exception.hpp:39[[BR]]

#8 0xb7be159e in boost::filesystem::wpath_traits::to_external (ph=@0xbf9a7138, src=@0xbf9a701c)

at boost/boost/libs/filesystem/src/path.cpp:94[[BR]]

#9 0xb76b8b43 in boost::filesystem::basic_path<std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >, boost::filesystem::wpath_traits>::external_directory_string (this=0xbf9a7138) at path.hpp:303[[BR]] ...