Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Fri, 31 Aug 2012 15:00:16 -0500

Hi Benjamin,

On 2012-08-29 Benjamin Franksen wrote:
> 
> Though using a C99 compatible snprintf that always returns the number of
> characters it /would/ have written, had it enough space, one could easily
> avoid that. Looking at the epicsStdio.h implementation for WIN32 I see that
> the real problem here is MINGW which seems to offer no way to find out how
> large the buffer /would/ have to be (whereas Windows has _vscprintf which
> does exactly that, and VxWorks has fioFormatV).

Newer versions of the MinGW tools do now provide _vscprintf().  I'll be 
deleting the MINGW-specific code from libCom/osi/os/WIN32/osdStdio.c before 
the next 3.15.0.2 release, so you should soon be able to use epicsSnprint() to 
find out how big a buffer you actually need.

Section 20.12 of the AppDevGuide says that the initial buffer size to find the 
length needed should be non-zero since SUSv2 says systems can return an error 
in that case (contrary to the C99 spec which allows it), but the manpage for 
Solaris permits a size of zero with a NULL buffer, so even that might be safe 
nowadays.

- Andrew
-- 
Never interrupt your enemy when he is making a mistake.
-- Napoleon Bonaparte

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System