[Boost-bugs] [Boost C++ Libraries] #2521: date_time exceeds array bounds in special_value_from_string

Subject: [Boost-bugs] [Boost C++ Libraries] #2521: date_time exceeds array bounds in special_value_from_string
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-11-21 02:06:49

#2521: date_time exceeds array bounds in special_value_from_string
 Reporter: Brad Spencer <spencer_at_[hidden]> | Owner: az_sw_dude
     Type: Bugs | Status: new
Milestone: Boost 1.38.0 | Component: date_time
  Version: Boost 1.37.0 | Severity: Problem
 Keywords: |
 gcc-4.3.2 found this with its new -Warray-bounds feature. It took a few
 minutes to track down even with the compiler pointing in the right

 an array called special_value_names (defined in
 ) is passed into the function find_match() as array to search.

 The enumeration constant date_time::NumSpecialValues (defined in
 ) is passed to find_match() as the "limit" argument.

 The find_match() function (defined in
 ) uses "limit" as an "up to and including" bounds on its for() loop for
 iterating over the array(s).

 However, the NumSpecialValues enumeration member has a value of 6 (it
 follows the 6 valid enum values), and the special_value_names contains
 only 6 strings (corresponding to those 6 valid enum values). Because
 find_match() goes "up to and including" its limit, in this instance it can
 go off the end of the special_value_names array.

 The documentation on find_match() is ambiguous as to whether or not the
 "limit" index itself is intended to be referenced, but it is very explicit
 that date_time::NumSpecialValues is supposed to be a valid argument for
 limit. This would seem to imply that the for() loop condition is wrong,
 except that all the other uses of find_match() use a constrained_value
 with a max() value that is the maximum desired value.

 I think the best conclusion here is that passing a "count"-type value
 (NumSpecialValues) for a "max"-type value (the more ambiguously named
 "limit") is incorrect. Thus, the attached patch.

Ticket URL: <https://svn.boost.org/trac/boost/ticket/2521>
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