Fwd: Re: libassuan troubles

Michael Nottebrock michaelnottebrock at gmx.net
Mon Apr 19 08:22:50 PDT 2004

Standards issues like these are over my head, so I'm forwarding this here, 
hoping some experts can comment on it.

----------  Forwarded Message  ----------

Subject: Re: libassuan troubles
Date: Monday 19 April 2004 17:15
From: Marcus Brinkmann <marcus.brinkmann at ruhr-uni-bochum.de>
To: Michael Nottebrock <michaelnottebrock at gmx.net>
Cc: gpa-dev at gnupg.org

At Mon, 19 Apr 2004 16:54:37 +0200,

Michael Nottebrock wrote:
> [1  <text/plain; iso-8859-1 (quoted-printable)>]
> On Monday 19 April 2004 16:34, Marcus Brinkmann wrote:
> > This seems spurious.  Maybe putc_unlocked is only defined as a macro
> > on BSD, and thus circumvents the autoconf tests?  This would sound
> > broken to me (it may be allowed to define it as a macro, but it should
> > still be defined as a function in the library).
> Yes, it's a macro. However, I don't see what's wrong about that other than
> making autoconf's life harder.

putc_unlocked is specified as a function that may be defined as a
macro.  The fact that it is defined as a macro does not relief you
from also declaring and defining it as a function.  IE, the following
must be possible in a program:

#undef putc_unlocked
  putc_unlocked ('a');

At least this is my interpretation of the wording in POSIX.  In fact,
if you not only take into account the specification, but also the
application usage, it becomes apparent:

16065              Since they may be implemented as macros, getc_unlocked( )
 and putc_unlocked( ) may treat 16066              incorrectly a stream
 argument with side effects. In particular, getc_unlocked(*f++) and 16067    
          putc_unlocked(*f++) do not necessarily work as expected. Therefore,
 use of these functions in 16068              such situations should be
 preceded by the following statement as appropriate: 16069             
 #undef getc_unlocked
16070              #undef putc_unlocked

The autoconf test relies on the function in the library object file.
This will work for almost all functions, except those for which POSIX
explicitely allows the lack of a function definition (like setjmp,
FD_CLR, etc).



   ,_,   | Michael Nottebrock               | lofi at freebsd.org
 (/^ ^\) | FreeBSD - The Power to Serve     | http://www.freebsd.org
   \u/   | K Desktop Environment on FreeBSD | http://freebsd.kde.org
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