Internal use of vsnprintf

[Florian Weimer]

Hi,

I'd like to add an internal use of vsnprintf (to implement a convenience 
wrapper for snprintf).

How do I do that?  We have an __vsnprintf definition in include/stdio.h, 
but I can't find a libc_hidden_proto/libc_hidden_define for it, and I 
get a PLT check failure as a result if I use it.

Or should I call _IO_vsnprintf instead (which is what the snprintf 
implementation does)?  I don't see the usual PLT avoidance stuff in the 
sources for _IO_vsnprintf, but it does happen.  So how does it work?

Thanks,
Florian