[boost] [format] bug and proposed patch

From: Joaquín Mª López Muñoz (joaquin_at_[hidden])
Date: 2006-05-25 02:49:05

Edson Tadeu reports on the following post

http://lists.boost.org/boost-users/2006/05/19723.php

about this bug in Boost.Format: line 138 of
boost/format/format_implementation.hpp

            if( bound_.size()==0 || !bound_[ items_[i].argN_ ] )

can try to invalidly evaluate bound_[...] on vector bound_
with a negative index, which happens when items_[i].argN_ is
one of the special values

enum arg_values {
  argN_no_posit   = -1, // non-positional directive. will set argN later

  argN_tabulation = -2, // tabulation directive. (no argument read)
  argN_ignored    = -3  // ignored directive. (no argument read)
};

as defined in boost/format/internals.hpp. The attached patches to
boost/format/format_implementation.hpp and
libs/format/test/format_test3.cpp avoid the invalid negative indexing
and add a testcase for the problem, respectively.

Any objections to my commiting? If there's no comment I'll be doing
it tomorrow.

Thank you,

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

138c138
<             if( bound_.size()==0 || !bound_[ items_[i].argN_ ] )
---
>             if( bound_.size()==0 || items_[i].argN_<0 || !bound_[ items_[i].argN_ ] )

95c95,102
<    
---
> 
>     // testcase for bug reported at 
>     // http://lists.boost.org/boost-users/2006/05/19723.php
>     format f("%40t%1%");
>     int x = 0;
>     f.bind_arg(1, x);
>     f.clear();
>