[Boost-bugs] [Boost C++ Libraries] #3486: local_time::posix_time_zone_base::calc_zone Misuses String Iterator

Subject: [Boost-bugs] [Boost C++ Libraries] #3486: local_time::posix_time_zone_base::calc_zone Misuses String Iterator
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-09-24 20:47:16

#3486: local_time::posix_time_zone_base::calc_zone Misuses String Iterator
--------------------------------------------------+-------------------------
 Reporter:  Rob Stewart <robert.stewart@…>        |       Owner:  az_sw_dude 
     Type:  Bugs                                  |      Status:  new        
Milestone:  Boost 1.41.0                          |   Component:  date_time  
  Version:  Boost 1.34.0                          |    Severity:  Showstopper
 Keywords:  calc_zone iterator                    |  
--------------------------------------------------+-------------------------
 calc_zone() starts like this:
     void calc_zone(const string_type& obj){
       const char_type empty_string[2] = {'\0'};
       stringstream_type ss(empty_string);
       typename string_type::const_iterator sit = obj.begin();
       string_type l_std_zone_abbrev, l_dst_zone_abbrev;

       // get 'std' name/abbrev
       while(std::isalpha(*sit)){
         ss << *sit++;
       }

 Notice that sit is never compared against obj.end().  This code apparently
 assumes that some non-alpha character will appear, if only a null
 terminator.  However, a checked STL flags *sit, in the conditional, as an
 error when trying to dereference the end iterator.

 The particular example I encountered in which it failed was when obj was a
 std::string, of length 9, containing "Australia".  There is no non-alpha
 character before advancing the iterator to the end, so operator *() fails
 with: "string iterator not dereferencable" in MSVC 8 (DevStudio 2005).

 I suggest changing the loop to the following:

       typename string_type::const_iterator it(obj.begin());
       typename string_type::const_iterator end(obj.end());
       // get 'std' name/abbrev
       while (it != send && std::isalpha(*it))
       {
         ss << *it++;
       }

 (You can reuse end in the rest of the function, while you're at it!)

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3486>
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