I've just pushed 2964 into illumos, which adds support for a bunch of new libc calls for thread safe and thread-specific locales, as well as explicit locale_t objects. Some of the interfaces added fall under the BSD/MacOS X "xlocale" class of functions.
Note that not all of the xlocale functions supplied by BSD/MacOS are present. However, all of the routines that were added by POSIX 2008 for this class are present, and should conform to the POSIX 2008 / XPG Issue 7 standards. (Note that we are not yet compliant with POSIX 2008, this is just a first step -- albeit a rather major one.)
The webrev is also available for folks who want to look at the code.
The new APIs are documented in newlocale(3c), uselocale(3c), etc. (Sadly, man pages are not indexed yet so I can't put links here.)
Also, documentation for some APIs that was missing (e.g. strfmon(3c)) are now added.
This project has taken over a year to integrate, but I'm glad it is now done.
I want to say a big -- huge -- thank you to Robert Mustacchi who not only code reviewed a huge amount of change (and provided numerous useful and constructive feedback), but also contributed a rather large swath of man page content in support of this effort, working on is own spare time. Thanks Robert!
Also, thanks to both Gordon Ross and Dan McDonald who also contributed useful review feedback and facilitated the integration of this project. Thanks guys!
Any errors in this effort are mine, of course. I would be extremely interested in hearing constructive feedback. I expect there will be some minor level of performance impact (unavoidable due to the way the standards were written to require a thread-specific check on all locale sensitive routines), but I hope it will be minor.
I'm also extremely interested in feedback from folks who are making use of these new routines. I'm told the Apache Standard C++ library depends on these interfaces -- I hope someone will try it out and let me know how it goes. Also, if someone wants/needs xlocale interfaces that I didn't include in this effort, please drop me a note and I'll try to get to it.
As this is a big change, it is not entirely without risk. I've done what I could to minimize that risk, and test as much as I could. If I missed something, please let me know, and I'll attempt to fix in a timely fashion.