[Boost-bugs] [Boost C++ Libraries] #4798: date_time: valgrind warnings via strings_from_facet.hpp

Subject: [Boost-bugs] [Boost C++ Libraries] #4798: date_time: valgrind warnings via strings_from_facet.hpp
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-10-28 14:40:23

#4798: date_time: valgrind warnings via strings_from_facet.hpp
----------------------------------------------------+-----------------------
 Reporter:  Lars Immisch <lars.immisch@…>           |       Owner:  az_sw_dude
     Type:  Patches                                 |      Status:  new       
Milestone:  To Be Determined                        |   Component:  date_time 
  Version:  Boost Development Trunk                 |    Severity:  Cosmetic  
 Keywords:  valgrind                                |  
----------------------------------------------------+-----------------------
 On Ubuntu, with GNU libc6 (2.7-10ubuntu7), and a program that uses
 `boost::date_time::time_input_facet< boost::posix_time::ptime,char>`
 valgrind generates a warning:

 {{{
 ==11026== Conditional jump or move depends on uninitialised value(s)
 ==11026==    at 0x467C04B: __strftime_internal (strftime_l.c:574)
 ==11026==    by 0x467DD4F: strftime_l (strftime_l.c:490)
 ==11026==    by 0x456B420: std::__timepunct<char>::_M_put(char*, unsigned
 int, char const*, tm const*) const (in /usr/lib/libstdc++.so.6.0.13)
 ==11026==    by 0x452BB4C: std::time_put<char,
 std::ostreambuf_iterator<char, std::char_traits<char> >
 >::do_put(std::ostreambuf_iterator<char, std::char_traits<char> >,
 std::ios_base&, char, tm const*, char, char) const (in
 /usr/lib/libstdc++.so.6.0.13)
 ==11026==    by 0x452B0CF: std::time_put<char,
 std::ostreambuf_iterator<char, std::char_traits<char> >
 >::put(std::ostreambuf_iterator<char, std::char_traits<char> >,
 std::ios_base&, char, tm const*, char const*, char const*) const (in
 /usr/lib/libstdc++.so.6.0.13)
 ==11026==    by 0x8430C83: std::vector<std::basic_string<char,
 std::char_traits<char>, std::allocator<char> >,
 std::allocator<std::basic_string<char, std::char_traits<char>,
 std::allocator<char> > > >
 boost::date_time::gather_month_strings<char>(std::locale const&, bool)
 (strings_from_facet.hpp:58)
 ==11026==    by 0x84310D9:
 boost::date_time::format_date_parser<boost::gregorian::date,
 char>::format_date_parser(std::string const&, std::locale const&)
 (format_date_parser.hpp:188)
 ==11026==    by 0x8431435:
 boost::date_time::date_input_facet<boost::gregorian::date, char,
 std::istreambuf_iterator<char, std::char_traits<char> >
 >::date_input_facet(std::string const&, unsigned int) (date_facet.hpp:462)
 ==11026==    by 0x84315E0:
 boost::date_time::time_input_facet<boost::posix_time::ptime, char,
 std::istreambuf_iterator<char, std::char_traits<char> >
 >::time_input_facet(std::string const&, unsigned int) (time_facet.hpp:696)
 }}}

 The actual problem is in GNU libc6, ''strftime_l.c:574'', which computes a
 12 hour clock in `__strftime_internal` regardless of the format string:
 {{{
   if (hour12 > 12)
     hour12 -= 12;
   else
     if (hour12 == 0)
       hour12 = 12;
 }}}

 The attached patch works around the warning by using an initialised struct
 tm in two places:
 {{{
 tm tm_value = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
 }}}

 We'd very much appreciate if the attached patch was accepted, even if it
 is only cosmetic.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4798>
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