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From "Stefan Teleman (Updated) (JIRA)" <>
Subject [jira] [Updated] (STDCXX-1056) std::moneypunct and std::numpunct implementations are not thread-safe
Date Tue, 07 Feb 2012 21:26:59 GMT


Stefan Teleman updated STDCXX-1056:

    Attachment: runtests.out

Output capture from running all the tests in build/tests (32-bit). Environment:

- Linux darthvader #1 SMP PREEMPT 2011-10-19 22:16:41 +0200 x86_64 x86_64
x86_64 GNU/Linux

- g++ (SUSE Linux) 4.5.0 20100604 [gcc-4_5-branch revision 160292]

> std::moneypunct and std::numpunct implementations are not thread-safe
> ---------------------------------------------------------------------
>                 Key: STDCXX-1056
>                 URL:
>             Project: C++ Standard Library
>          Issue Type: Bug
>          Components: 22. Localization
>    Affects Versions: 4.2.1, 4.2.x, 4.3.x, 5.0.0
>         Environment: Solaris 10 and 11, RedHat and OpenSuSE Linux, Sun C++ Compilers
12.1, 12.2, 12.3
> Issue is independent of platform and/or compiler.
>            Reporter: Stefan Teleman
>              Labels: thread-safety
>             Fix For: 4.2.x, 4.3.x, 5.0.0
>         Attachments:, runtests.out, stdcxx-1056.patch
> several member functions in std::moneypunct<> and std::numpunct<> return
> a std::string by value (as required by the Standard). The implication of return-by-value
> being that the caller "owns" the returned object.
> In the stdcxx implementation, the std::basic_string copy constructor uses a shared
> underlying buffer implementation. This shared buffer creates the first problem for
> these classes: although the std::string object returned by value *appears* to be owned
> by the caller, it is, in fact, not.
> In a mult-threaded environment, this underlying shared buffer can be subsequently modified
by a different thread than the one who made the initial call. Furthermore, two or more different
threads can access the same shared buffer at the same time, and modify it, resulting in undefined
run-time behavior.
> The cure for this defect has two parts:
> 1. the member functions in question must truly return a copy by avoiding a call to the
copy constructor, and using a constructor which creates a deep copy of the std::string.
> 2. access to these member functions must be serialized, in order to guarantee atomicity
> of the creation of the std::string being returned by value.
> Patch for 4.2.1 to follow.

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