Re: Unixware Patch (Was: Re: Beta2 Tag'd and Bundled ...)

Greg Stark wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> 
> > We could go down that road.  The only other OS that needs *_r functions
> > is Linux, and it uses all *_r functions.  How do we configure to throw
> > an error in that OS if we don't fined all of them?  Maybe we need a
> > three-valued variable instead of boolean NEED_REENTRANT_FUNC_NAMES.  We
> > could call it just REENTRANT_FUNC_NAMES and it could have values
> > 'require', 'prefer', 'disable'.  This mimicks libpq's new PGSSLMODE
> > values.
> 
> Actually I don't think that's true for linux. Linux only has *_r functions
> that are required, not unnecessary ones.
> 
> Note that there are two different types of _r functions being discussed here.
> 
> getpwuid, for example, has a thread-safe API. There's really no reason for a
> getpwuid_r to exist on any platform. If it exists then it must simply be a
> thread-safe version of the regular function. But if it doesn't the regular
> function must be thread-safe if the platform supports threads at all.
> 
> On the other hand, things like, getpwnam, strtok, etc have non-thread-safe
> APIs. They can never be made thread-safe. The *_r versions of these functions
> are standardized and required. If they don't exist then the platform simply
> does not support threads.
> 
> My questions are:
> 
> Are there OSes that have strtok_r et al. because standards require them but
> have no OS threads support at all? In which case the library would be
> "thread-safe" but not really usefully so.
> 
> Are there OSes that have extraneous *_r functions like getpwuid_r but only for
> compatibility and they're deprecated?

Have you read the comment at the top of port/thread.c?  There is a way
to make those thread-safe using per-thread global variables, I think.

Anyway, require doesn't mean we need all the *_r functions that exist,
just that we need the *_r functions that appear in thread.c.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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