Path: utzoo!attcan!uunet!samsung!umich!yale!ox.com!metapyr!marc
From: marc@metapyr.UUCP ( The Karate Kid )
Newsgroups: comp.windows.ms
Subject: Re: Possible bug in tricky use of wsprintf - MSC 6.0
Message-ID: <960@metapyr.UUCP>
Date: 19 Sep 90 14:01:03 GMT
References: <6578@sugar.hackercorp.com> <57528@microsoft.UUCP>
Reply-To: marc@metapyr.UUCP (Marc Paige - The Karate Kid )
Organization: Meta Systems, Ltd. -- Ann Arbor, MI
Lines: 40

In article <57528@microsoft.UUCP> kensy@microsoft.UUCP (Ken SYKES) writes:
>In article <6578@sugar.hackercorp.com> karl@hackercorp.com (Karl Lehenbauer) writes:
>>Looks like wsprintfs of the form:
>>
>>	wsprintf(outstr, "%.*s", numchars, text);
>>
>>...cause a trap.  I'll be sure in a bit.  In the meantime, beware.
>>-- 
>
>The * operator is not supported by wsprintf (look at the width description
>in the SDK.)  As a result it thinks numchars is the first part of the 
>string address then starts grabbing values from the bogus address.  Thus
>the fault.  You could get around this by writing a replacement that 
>handles the '*' by using wsprintf to convert the control string to a static
>string (replace *'s with the contents of numchar) then call wvsprintf to
>do the actual command.  Sloppy yes, but wsprintf is not documented as a 
>replacement for sprintf.  Consequently some of the features may not be
>provided.
>Ken Sykes

WHOA!  The asterisk's got nothing to do with it!  If Karl is using the medium
model (as he should be :-( I hate the medium model) then the constant being
passed by "%.*s" is a NEAR pointer.  NEAR pointers passed to FAR pointer
functions cause a trap 13.  I ported a 2.11 program that had to use sprintf
for the error message system.  Converting all the sprintf's to wsprintf's
made me painfully aware of this fact.  Cast the "%.*s" to (LPSTR) and the
trap should be gone.  As a matter of fact, I just had to fix one of these
little casts that I missed the first time.  Caused "Unrecoverable Application
Error".  NOTE: All string arguments in the wsprintf call are LPSTR
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
and must be either cast that way or generated by GlobalAlloc.  This should
help.



Marc Paige
Meta/LBMS

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